Doc #99 — Timber Processing and Sawmilling

---

RECOMMENDED ACTIONS (BY URGENCY)

First week

1. Classify all sawmills and forestry operations as essential services. Ensure mill workers, logging crews, and transport drivers are exempt from any general stand-down orders.
2. Inventory fuel stocks at forestry and milling operations and ensure continued allocation under fuel rationing (Doc #53).
3. Issue immediate guidance: do not burn dimensional timber or milled wood for heating. Slash, offcuts, and low-grade roundwood are abundant for firewood. Milled timber is far too valuable to burn.

First month

4. Conduct national inventory of sawmill capacity — include large mills, small commercial mills, and portable sawmills (Lucas Mills, Peterson, Wood-Mizer, etc.). Register all portable sawmill owners through the census (Doc #8).
5. Inventory consumable stocks: Bandsaw blades, circular saw blades, chainsaw chains and bars, sharpening equipment, saw-setting tools. Estimate months of supply at projected usage rates.
6. Secure stocks of timber treatment chemicals (CCA salts, boron compounds) at treatment plants, chemical suppliers, and hardware stores. Estimate total remaining treatment capacity.
7. Begin air-drying programmes at all mills and major construction sites. Green timber felled now takes 6–18 months to air dry to usable moisture content — the sooner drying starts, the sooner timber is available for construction.
8. Identify and contact all owners of portable sawmills. Many are on farms and lifestyle blocks. These become critical distributed processing assets.

First 3 months

9. Redirect harvest from export-grade logs to domestic milling. Harvesting crews that were producing export logs should shift to supplying domestic mills with sawlog-grade timber.
10. Establish chainsaw and saw blade maintenance training at regional centres. Sharpening, setting, and minor repair of saw blades extends consumable life dramatically (Section 7).
11. Begin trials of alternative timber preservation methods — charring (yakisugi/shou sugi ban), pine tar application (from charcoal production byproduct, Doc #102), hot linseed oil treatment. Document performance for different applications.
12. Establish a prioritised timber allocation system — construction timber, boatbuilding timber, charcoal wood, and firewood compete for the same resource. An allocation framework prevents wasteful use of high-grade timber for low-grade applications.
13. Activate all existing kiln-drying capacity. Kilns use electricity (available under baseline) and can dry timber in days to weeks rather than months.

First year

14. Deploy portable sawmills to regional locations where transport of logs to centralised mills is impractical due to fuel constraints. The goal is distributed processing — mill near the forest, transport finished timber rather than heavy logs.
15. Establish saw blade sharpening and reconditioning workshops in each major forestry region.
16. Begin plantation management for long-term sustainability — thinning, pruning, and replanting programmes that ensure timber supply continues beyond the existing standing crop.
17. Train new chainsaw operators and sawmill workers to replace attrition and expand capacity. Chainsaw operation is a skilled and dangerous occupation; training must cover safety, maintenance, and efficient technique.
18. Assess native timber stands — identify naturally fallen or salvageable native timber that can be used without live-tree harvest. Establish guidelines for any emergency native harvest that may become necessary (Section 9).

Years 2–5

19. Transition harvesting to reduced-fuel methods as petroleum stocks deplete — wood gas vehicles for log transport (Doc #56), horse or bullock logging for extraction from steep or remote sites, manual crosscut sawing for trees where chainsaw consumables are scarce (Section 5.4).
20. Develop domestic saw blade manufacturing capability — this is a medium-term priority requiring steel (Doc #89), heat treatment capability (Doc #92), and precision metalwork (Doc #91).
21. Establish NZ-specific timber grading standards adapted to recovery conditions — existing NZ standards (NZS 3603, NZS 3631) may need modification to account for changed species availability, treatment limitations, and altered structural requirements.
22. Scale charring and pine tar treatment as primary preservation methods for ground-contact and exposed timber.

Years 5+

23. First rotation of post-event plantings reaching thinning age (radiata pine can be thinned at 8–12 years). These provide small-diameter timber for poles, posts, and firewood.
24. Plantation forests planted post-event reach sawlog maturity at 25–30 years. Long-term forestry planning now ensures timber supply for future generations.
25. Saw blade and tool manufacturing from NZ steel becomes routine, reducing dependence on pre-event stocks.

---

ECONOMIC JUSTIFICATION

Labour requirements (person-years)

Timber processing is already a major NZ industry employing approximately 30,000–40,000 people across forestry, logging, wood processing, and related activities.⁷ Under recovery conditions, the workforce will need to expand as manual methods supplement mechanised ones and as additional demand arises from construction, boatbuilding, and other sectors. The following estimates represent steady-state operational requirements, not transition costs.

Harvesting and forestry operations:

• Chainsaw operators and felling crews: Pre-event, approximately 4,000–5,000 professional loggers operated across NZ’s commercial harvesting operations. Under recovery conditions, with manual methods supplementing chainsaw work, this number likely needs to grow to 7,000–10,000 to maintain equivalent log output. Each additional manual worker (crosscut sawyer, axeman, limber) adds roughly 10–20% of a chainsaw operator’s volume — many more people are needed to do the same work.⁸⁹
• Silviculture and plantation management (foresters): Pre-event, approximately 2,000–3,000 workers were engaged in planting, thinning, pruning, and plantation maintenance. Long-term forestry viability under recovery conditions requires sustaining at least this workforce, with a modest increase for expanded replanting after nuclear winter mortality. An additional 500–1,000 person-years in forest health monitoring and management is warranted given altered pest and climate dynamics (Section 8).
• Log transport and skid site operations: Pre-event, several thousand workers drove logging trucks or operated skidders and forwarders. As fuel becomes scarce and horse logging expands, the person-year requirement for extraction actually increases: animal-powered logging requires roughly 3–5 times the human labour per cubic metre moved compared to mechanised extraction.¹⁰

Sawmill workers:

• Large and medium mill workers: Pre-event, NZ’s large and medium mills employed approximately 8,000–10,000 workers in direct production roles — headrig operators, resaw operators, edger operators, graders, and general mill hands.¹¹ Recovery conditions do not reduce this requirement; they may increase it slightly as more manual material handling replaces automated conveyors and machinery that requires electrical or pneumatic power.
• Graders: Timber grading is a skilled function. In NZ, approximately 600–900 qualified timber graders are employed across the industry.¹² Under recovery conditions, with altered preservation methods and possibly non-standard timber species, grading rules will need revision and the grader workforce may need to expand to 1,000–1,500 to handle distributed milling and non-standard products. Graders trained in visual assessment of recovery-era timber (charred, alternative-species, air-dried) become a bottleneck if not trained in advance.
• Portable sawmill operators: If NZ deploys even half of its estimated 2,000–5,000 portable sawmills under recovery conditions, this implies roughly 1,000–2,500 additional operator person-years per year — workers who may not have been part of the pre-event industry and require training.

Kiln operators and drying:

• Kiln operators: NZ’s kiln fleet at large mills probably employs 200–400 kiln operators and drying technicians.¹³ Each large kiln (capacity 50–200 m³ per charge) requires approximately 1–2 workers per shift for loading, monitoring, and unloading. Expanding solar kiln and small kiln capacity at distributed milling sites could add 300–600 additional person-years.
• Air drying management: Air drying requires less skilled oversight but significant unskilled labour for stacking, stickering, and moving timber through the yard. At distributed sites processing 1–3 m³/day, this represents approximately 1 additional person-day per 2–4 m³ milled — roughly 500–1,000 additional person-years nationally if air drying becomes the dominant method.

Saw blade maintenance (saw doctors):

• Pre-event, NZ’s saw doctor trade probably encompasses 100–200 practitioners nationally, concentrated at large mills. This is critically insufficient for a recovery scenario. Each major regional milling hub needs at least 2–4 saw doctors. Across 10–15 regions, this implies a target of 20–60 qualified saw doctors — achievable from the existing base, but requires deliberate training and deployment. Saw doctor training takes approximately 2–3 years for full competency.¹⁴

Total person-year estimate (steady state, recovery conditions): Approximately 45,000–65,000 person-years per year in the timber processing sector as a whole — a significant increase from the pre-event ~35,000, reflecting the labour-intensification that accompanies reduced mechanisation. This represents roughly 1.5–2% of NZ’s estimated working-age population (approximately 3.2–3.5 million people aged 15–64) under recovery conditions¹⁵ — a major but manageable commitment for an industry that is the foundation of the recovery construction economy.

Organised industry vs. ad hoc logging and processing

Without an organised timber industry, NZ would still obtain timber — individuals would fell trees and cut them into rough lumber by whatever means available. The question is what the organised-versus-unorganised comparison actually looks like in practice.

Ad hoc logging and processing (no organised system):

In the absence of coordination, harvesting becomes opportunistic. Communities fell the nearest accessible trees — often lower-quality, awkwardly located, or ecologically inappropriate timber — rather than the best timber from the most productive sites. Without a log transport network, communities are limited to what they can drag or carry. Without a mill, they cut by hand or with chainsaw mills, producing rough-sawn timber at perhaps 0.5–2 m³ per person-day. Without grading, timber is used regardless of structural suitability — knots, wane, and grain irregularities that should be cut out appear in structural members.

Estimated ad hoc output: perhaps 5–15% of the organised system’s volume, at 2–3 times the labour cost per cubic metre, with substantially higher rates of structural failure in finished construction.¹⁶

Organised industry:

A coordinated timber industry — even one operating at 50% of pre-event capacity due to fuel constraints — routes the right logs to the right mills, grades output for structural fitness, ensures drying to appropriate moisture content, and allocates timber to its highest-value use. A large bandsaw mill with adequate log supply produces 200–500+ m³ per shift; the same labour in ad hoc operations might produce 10–30 m³. The organised system produces graded, dried, dimensioned timber ready for construction without the subsequent rework, failure, and replacement that characterises ad hoc building.

The difference is not marginal. Under recovery conditions where labour is a binding constraint and every structure must last, the efficiency of the organised system over ad hoc is the difference between NZ housing its population adequately and housing it poorly.

Breakeven — timber as NZ’s primary building material

Timber is NZ’s most abundant buildable material. The plantation estate contains 500–600 million cubic metres of merchantable timber — more than 200 years of domestic consumption at pre-event rates — and the annual growth increment alone exceeds domestic demand by a factor of 5–10 even under nuclear winter growth reductions (Section 8). No other structural material approaches timber’s scale, accessibility, or processability with available NZ tools and skills.

The breakeven question for timber processing investment is therefore not “does it pay?” — there is no competing material that substitutes at scale — but “what level of processing investment is required to realise the resource’s value?” The answer is: the full chain, from harvesting coordination through grading, because the resource value is only realised when timber is structurally usable.

The timber processing industry is not a new investment — it is the continuation and adaptation of existing capability. The economic question is about the cost of adaptation: transitioning from mechanised to partially manual methods, developing alternative preservation, and manufacturing replacement saw consumables. These are ongoing operational costs, not a capital investment with a payoff date.

The single largest new investment is domestic saw blade manufacturing. A workshop producing bandsaw blades and circular saw blades requires specialist steel, hardening equipment, and skilled operators (Section 7.3). Establishment cost is estimated at 5–15 person-years (covering workshop construction, equipment fabrication or adaptation, tooling, and training), with an ongoing production team of 3–8 people.¹⁷ These figures are estimates based on comparable small-scale specialty metalworking operations and should be verified against actual workshop design once a saw blade manufacturing programme is planned — they are not precise. Without it, sawmilling capacity gradually declines as existing blades wear out. With it, sawmilling continues indefinitely. The payoff is clear: a functioning sawmill economy versus progressive collapse of the processing capability that converts the timber resource into usable material.

Opportunity cost

The relevant opportunity cost of maintaining an organised timber industry is the labour it absorbs — approximately 45,000–65,000 person-years per year under recovery conditions. This is labour that cannot simultaneously be deployed to food production, medical services, or other sectors.

However, the counterfactual is not “that labour freed for other uses.” It is “that labour deployed to ad hoc timber getting, producing 5–15% of the output, while communities lack adequate shelter, construction is slow, and building failures require repeated labour for repair and replacement.” The organised system produces more output per person-hour, not less, once the full supply chain is functioning. The coordination overhead — forest managers, graders, transport logistics, kiln scheduling — is small relative to the productivity gain it enables.

The strongest opportunity cost argument against organised timber processing applies to grading and quality control: a construction programme that accepts lower-grade timber and designs around its limitations (larger sections, more fasteners, shorter spans) could potentially absorb less specialist labour. This is a genuine tradeoff and should be considered when setting grading standards for recovery-era construction — some relaxation of pre-event standards may be warranted where it reduces the bottleneck of qualified graders.¹⁸

---

1. NZ’S FORESTRY RESOURCE

1.1 Plantation forests

NZ’s plantation forest estate covers approximately 1.7 million hectares — roughly 6% of the country’s total land area.¹⁹ This is a managed, commercial resource established primarily over the 20th century.

Species composition:

Species	Approximate share	Area (hectares)	Key properties
Radiata pine (Pinus radiata)	~90%	~1,530,000	Fast-growing, versatile, low natural durability
Douglas fir (Pseudotsuga menziesii)	~6%	~100,000	Stronger than radiata, better natural durability
Eucalyptus species	~1–2%	~20,000–30,000	Very hard, dense, good natural durability
Cypresses (macrocarpa, lusitanica)	~1%	~15,000–20,000	Excellent natural durability, valued for outdoor use
Other (including larch, poplar)	~1–2%	~15,000–30,000	Various minor species

Source: MPI National Exotic Forest Description (NEFD) reporting.²⁰

Standing volume: Approximately 500–600 million cubic metres of merchantable timber across the plantation estate, with radiata pine comprising the overwhelming majority.²¹ To put this in context, NZ’s entire annual domestic sawn timber consumption (pre-event) was approximately 2–2.5 million cubic metres.²² The standing resource represents over 200 years of domestic consumption at pre-event rates, even without any new growth.

Annual growth increment: Radiata pine in NZ grows rapidly — a mean annual increment of approximately 20–25 cubic metres per hectare per year on good sites, with rotation ages of 25–30 years.²³ Across the entire estate, the annual growth increment is approximately 25–30 million cubic metres. This exceeds NZ’s domestic timber needs many times over, though nuclear winter will reduce growth rates (Section 8).

1.2 Regional distribution

NZ’s plantation forests are concentrated in several key regions:²⁴

• Central North Island (Bay of Plenty, Waikato, Taupō): ~40% of the national estate. The Kaingaroa Forest alone is approximately 180,000 hectares, one of the largest planted forests in the world. This region also hosts NZ’s largest sawmills (Red Stag Timber in Rotorua, several Rayonier/Matariki mills).
• Northland/Auckland: ~10%. Significant radiata resource in a warm-climate growing region.
• East Coast/Gisborne: ~8%. Notable for some of the fastest radiata growth rates in NZ but also erosion-prone terrain.
• Southern North Island (Manawatū, Wairarapa, Hawke’s Bay): ~12%.
• Canterbury/West Coast: ~10%. West Coast also has native podocarp forests.
• Otago/Southland: ~10%. Colder climate, slower growth, but significant Douglas fir plantings.
• Nelson/Marlborough: ~8%. Important for Douglas fir and some macrocarpa.

This geographic spread is strategically valuable — no single region needs to supply the entire country, and distributed processing reduces transport requirements.

1.3 Existing mill infrastructure

NZ’s sawmilling industry includes a range of scales:²⁵

Large integrated mills (10+): Processing 100,000+ cubic metres of logs per year. Examples include Red Stag Timber (Rotorua), Claymark (Waiuku, Rotorua), Nelson Pine Industries (Richmond), Pan Pac Forest Products (Napier), and several Rayonier Matariki mills. These mills have kilns, treatment plants, planing and finishing facilities, and often produce engineered wood products (laminated veneer lumber, plywood).

Medium commercial mills (50–100): Processing 10,000–100,000 cubic metres per year. Typically regional operations serving local construction markets. Usually have at least basic kiln capacity.

Small commercial and farm mills (several hundred): Processing under 10,000 cubic metres per year. Many are fixed installations with a single bandsaw headrig. Some serve niche markets (macrocarpa decking, native timber resawing).

Portable sawmills (estimated 2,000–5,000+ nationally): This is the most uncertain figure, as many are privately owned and not registered with industry bodies. Portable mills include NZ-designed Lucas Mills (manufactured in Whanganui), along with imported brands (Wood-Mizer, Peterson, Norwood). Many are on farms and lifestyle blocks, used intermittently for on-site timber production.²⁶ Under recovery conditions, these become strategically important distributed processing assets.

---

2. HARVESTING METHODS AND FUEL DEPENDENCY

2.1 Current mechanised harvesting

Modern NZ logging is heavily mechanised. A typical crew uses:

• Chainsaws for felling and cross-cutting (diesel/petrol powered)
• Skidders or forwarders for extracting logs from the felling site to a landing (diesel)
• Processors or delimbers for removing branches and cutting to length (diesel)
• Loaders for stacking logs at the landing and loading trucks (diesel)
• Logging trucks for transport to the mill (diesel)

Every piece of this equipment depends on petroleum fuel, hydraulic fluid, tyres, filters, hoses, and replacement parts.²⁷ Under recovery conditions, all of these consumables are finite.

2.2 Fuel consumption in logging

A typical NZ logging crew harvesting 150–250 cubic metres of logs per day consumes approximately:

• Chainsaw fuel: 10–30 litres/day (two-stroke mix)
• Skidder/forwarder: 80–150 litres/day (diesel)
• Processor: 50–100 litres/day (diesel)
• Loader: 30–60 litres/day (diesel)
• Log truck (per load, round trip): 50–150 litres depending on distance²⁸

Total fuel consumption per cubic metre of delivered log: approximately 2–5 litres of diesel equivalent, heavily dependent on terrain and transport distance.²⁹

NZ’s total pre-event diesel consumption across all sectors was approximately 3.5–4 billion litres per year.³⁰ Forestry and wood processing accounted for a significant fraction. Under fuel rationing (Doc #53), forestry operations will receive reduced allocations but should be prioritised given timber’s importance to recovery.

2.3 Transitioning to reduced-fuel methods

As petroleum stocks deplete over 1–5 years (depending on rationing effectiveness), harvesting must adapt:

Phase 1 (Months 0–12): Mechanised, fuel-rationed. Existing equipment operates on reduced fuel allocation. Prioritise harvesting near mills to reduce transport fuel. Maximise payload per truck trip. Begin maintaining chainsaws and equipment to extend operational life.

Phase 2 (Years 1–3): Wood gas transition. Log trucks and skidders can be converted to wood gas operation (Doc #56), accepting 30–50% power loss. Chainsaws cannot run on wood gas — they remain petroleum-dependent. As chainsaw fuel becomes scarce, prioritise chainsaws for felling (where they are most efficient) and use manual methods for limbing and bucking.

Phase 3 (Years 3–7): Mixed methods. Horse and bullock logging for log extraction on moderate terrain — NZ had horse logging until the 1950s and the skills can be relearned.³¹ Manual crosscut sawing supplements chainsaws. Gravity-fed skid trails and water-based log transport (river driving, where terrain permits) reduce fuel requirements.

Phase 4 (Years 7+): Predominantly manual and animal-powered. Chainsaws used sparingly for large-tree felling only. Most limbing, bucking, and small-tree work done with axes and crosscut saws. Log extraction by horse, bullock, or gravity. Transport by wood gas truck or rail where available.

2.4 Chainsaw dependency and management

Chainsaws are the single most productive hand-held harvesting tool ever developed. A skilled operator with a well-maintained chainsaw can fell a 40-cm diameter tree in under a minute. With a crosscut saw, the same tree takes 15–30 minutes for a two-person crew.³² This productivity gap means extending chainsaw operational life is a high priority.

Critical consumables: - Chains: A chainsaw chain wears through the cutting teeth over time; frequent sharpening extends life but eventually the teeth are too short to cut effectively. A professional logging chain might last 50–200 hours of cutting before replacement, depending on conditions (dirt, knots, chain speed, sharpening frequency).³³ - Guide bars: Wear at the nose sprocket and along the rail. Periodic turning (flipping the bar) equalises wear. A bar might last 3–5 chains if maintained. - Sprockets (drive and nose): Wear surfaces requiring periodic replacement. - Two-stroke fuel mix: Chainsaws require a petrol-oil mixture. As petrol becomes scarce, castor oil (from NZ-grown castor plants or imported stock) can substitute for the two-stroke oil component (Doc #34), but petrol itself has no easy substitute for chainsaw engines.³⁴ - Bar oil: Lubricates the chain as it runs around the bar. Tallow-based or vegetable oil substitutes are functional but inferior to petroleum bar oil (Doc #34).

Maintenance extends life dramatically. A chainsaw that is sharpened after every tank of fuel, cleaned daily, and has its air filter maintained can last 1,000–2,000+ hours of operation. Neglected chainsaws fail much sooner. Training programmes (Section 2.3 actions) should emphasise maintenance discipline.

See Doc #45 for detailed chainsaw maintenance procedures.

---

3. SAWMILL OPERATIONS

3.1 Log preparation

Before milling, logs must be:

• Debarked: Bark contains dirt and stones that damage saw blades. Large mills use mechanical debarkers; small mills may process logs with bark on (accepting faster blade wear) or hand-debark with a spud or drawknife.
• Graded and sorted: Different log grades produce different products. Large-diameter, straight, pruned logs produce clear (knot-free) timber for high-value uses. Smaller, unpruned logs produce structural framing with knots. Bent or defective logs may be suitable only for pallet wood, fencing, or firewood.
• Cut to length: Logs are typically cut to standard mill lengths (3.6 m, 4.2 m, 4.8 m, 6.0 m for NZ construction timber sizes) at the landing before transport.

3.2 Primary breakdown: headrig sawing

The headrig is the primary saw that makes the first cuts through a log, converting it from a round log into rectangular sections (cants or flitches) from which individual boards are cut.

Bandsaw headrig: Most NZ mills use a bandsaw headrig — a continuous loop of thin steel blade (typically 150–250 mm wide, 1.0–1.6 mm thick) running around two large wheels. Bandsaw blades produce a thin kerf (2–4 mm), wasting less wood as sawdust than circular saws. They can cut large-diameter logs and produce smooth surfaces. The disadvantage: bandsaw blades are precision-manufactured items requiring specialist steel and careful tensioning.³⁵

Circular saw headrig: Some older mills and smaller operations use large circular saws (typically 1.0–1.5 m diameter). These produce a wider kerf (4–8 mm), wasting more wood, but the blades are simpler to manufacture and maintain. Circular saws are limited in the maximum log diameter they can cut (approximately half the blade diameter minus clearance).³⁶

Frame saw (gang saw): Multiple blades cutting simultaneously — historically common but now rare in NZ. Could be relevant for high-volume, standardised production with limited blade variety.

3.3 Secondary breakdown and resawing

After the headrig produces cants or flitches, secondary saws cut these into finished dimensions:

• Resaw bandsaws: Cut flitches into boards of the required thickness
• Edgers: Circular saws that remove wane (bark edge) and cut boards to standard widths
• Trim saws (docking saws): Cross-cut boards to standard lengths, removing defects from the ends

3.4 Standard NZ timber dimensions

NZ construction timber follows standard dimensions specified in NZS 3631 and used throughout the building industry:³⁷

Common name	Nominal size (mm)	Typical use
90 x 45	90 x 45	Wall framing (studs, nogs, plates)
140 x 45	140 x 45	Wall framing (lintels, studs in certain applications)
190 x 45	190 x 45	Floor joists, lintels
240 x 45	240 x 45	Floor joists, bearers
290 x 45	290 x 45	Large floor joists, beams
140 x 90	140 x 90	Posts, bearers
190 x 90	190 x 90	Bearers, beams
240 x 90	240 x 90	Heavy beams
150 x 50	150 x 50	Decking, general framing
200 x 50	200 x 50	Rafters, larger framing

These dimensions should continue to be used as standards to maintain compatibility with existing NZ building practice, hardware (joist hangers, framing brackets), and the building code (NZS 3604).

3.5 Recovery and yield

The volume of sawn timber recovered from a log is always less than the log volume. The difference is waste — sawdust, slabs (outer cuts with bark), edgings, and trim ends.

Typical recovery rates:³⁸

• Large, straight, pruned logs in a well-set-up mill: 55–65% recovery
• Average unpruned sawlogs: 45–55% recovery
• Small-diameter logs (under 25 cm): 35–45% recovery
• Portable sawmill (less optimised cutting pattern): 40–55% recovery

The “waste” is not wasted: sawdust goes to insulation (Doc #162), animal bedding, or composting; slabs and edgings become firewood, charcoal feedstock (Doc #102), or wood gasifier fuel (Doc #56); offcuts serve smaller construction and craft uses.

---

4. TIMBER DRYING AND SEASONING

4.1 Why drying matters

Green (freshly sawn) timber has a moisture content of 80–160% for radiata pine (expressed as weight of water divided by weight of dry wood).³⁹ This is far too wet for construction use. Timber shrinks as it dries, and if installed green it will shrink in place — opening joints, loosening fastenings, causing gaps and distortion. Structural timber for framing should be dried to 14–18% moisture content. Timber for joinery, furniture, and finish work should be dried further to 10–14%.⁴⁰

Undried timber is also heavier (roughly twice the weight of dry timber for radiata pine), increasing transport costs, and is more susceptible to fungal staining and decay.

4.2 Air drying

The simplest and oldest method: stack timber in the open air with spacers (stickers) between each layer to allow air circulation, on a level foundation that keeps the bottom course off the ground.

Requirements: - Level, well-drained site with good air circulation - Stickers: typically 20–25 mm thick strips of dry wood, placed at regular intervals (600–900 mm apart) and aligned vertically through the stack - Weights or strapping on top of the stack to restrain warping - End-sealing of high-value timber (wax or paint on the end grain) to prevent end-splitting from too-rapid moisture loss

Drying time (radiata pine):⁴¹

Thickness	Time to ~18% MC (summer)	Time to ~18% MC (winter)
25 mm	4–8 weeks	8–16 weeks
50 mm	3–6 months	6–12 months
100 mm	8–18 months	12–24+ months
150 mm+	12–24+ months	18–36+ months

These times are approximate and vary significantly with climate, air circulation, and stacking practice. Under nuclear winter conditions, reduced temperatures and potentially altered rainfall patterns may slow drying times by 30–60% — this is an important uncertainty.

Advantages: No energy cost. No equipment required beyond basic materials. Can be done at any scale, anywhere.

Disadvantages: Slow. Space-intensive. Timber is exposed to weather, insects, and fungal staining during drying. Quality is less consistent than kiln drying. Some defects (warping, checking, staining) are harder to control.

4.3 Kiln drying

Kiln drying uses a heated, humidity-controlled chamber to accelerate drying. Modern NZ sawmills use kilns extensively — they are the standard method for producing consistent, high-quality dried timber.

How it works: The kiln maintains elevated temperature (typically 40–75°C for conventional kilns, up to 120°C for high-temperature kilns) with controlled humidity and air circulation. Temperature and humidity are adjusted over a drying schedule that typically lasts 2–10 days for 25 mm radiata pine, longer for thicker or denser timber.⁴²

Energy requirements: A conventional kiln drying 25 mm radiata pine from green to 12% MC requires approximately 0.5–1.0 GJ of thermal energy per cubic metre of timber dried.⁴³ This can be supplied by:

• Electricity (available under baseline grid conditions) — NZ already has many electrically heated kilns
• Wood waste boilers — burning sawdust, bark, and offcuts from the mill itself. Many NZ mills already use wood waste for kiln heating, making them self-sufficient in drying energy.
• Direct-fired wood or charcoal in simpler kiln designs

Under recovery conditions, kiln drying remains fully feasible. NZ’s electrical grid is 85%+ renewable and operational (baseline assumption). Wood waste for boilers is generated as a byproduct of milling. The binding constraint is kiln chamber capacity: NZ’s existing kiln fleet has capacity for perhaps 3–4 million cubic metres per year.⁴⁴ If domestic demand exceeds this, additional kilns would need to be built or air drying would need to handle the overflow. Building a functional drying kiln requires insulated chamber construction (walls, roof, and floor capable of maintaining 40–75°C with low heat loss), a heat source (wood-waste boiler or electric elements), circulation fans with variable-speed control, humidity sensors and venting baffles (to manage the moisture-laden air exhausted as timber dries), and a control system — even a manual one requires a trained operator monitoring wet-bulb/dry-bulb readings and adjusting venting on a schedule. This is a significant construction and commissioning project, not a trivial one, though the technology is well within NZ’s engineering capability.

4.4 Solar kilns

A solar kiln is a greenhouse-like structure with a transparent or translucent roof that captures solar heat, combined with fans for air circulation. Solar kilns can be built from locally available materials — a timber frame, clear plastic sheeting or glass for glazing, and a small fan powered by electricity or a solar panel — and can dry timber to construction-grade moisture content in 2–8 weeks for 25 mm thickness, significantly faster than open-air drying.⁴⁵ The main constraints are sourcing adequate clear glazing material (polycarbonate or glass), achieving sufficient airtightness to retain heat, and orienting the structure correctly for the local solar path. These are addressable problems but require planning and site-specific design.

Solar kilns are well-suited to distributed timber processing — a portable sawmill operator in a rural location could build a solar kiln from local materials and dry timber on-site. Under nuclear winter conditions, reduced solar radiation would slow solar kiln performance, but they would still outperform open-air drying because the enclosed space retains heat and the fan provides forced air circulation.

Construction: A basic solar kiln for 5–10 cubic metres of timber requires approximately 50–80 hours of labour to build, using local timber for framing and salvaged glass or clear polythene for the glazing.⁴⁶ The fan (if electric) needs approximately 200–500 watts. A small 12V fan powered by a car battery or solar panel is adequate for a small kiln.

---

5. TIMBER TREATMENT AND PRESERVATION

5.1 Why treatment matters for radiata pine

Radiata pine is NZ’s dominant timber species — roughly 90% of the plantation estate — and it has poor natural durability. The NZ Timber Durability Classification places radiata pine heartwood in Class 4 (not durable) and sapwood in Class 5 (non-durable).⁴⁷ In ground contact or exposed to persistent moisture without preservative treatment, untreated radiata pine can begin to decay in 2–5 years and may fail structurally within 5–15 years depending on conditions.⁴⁸

This is not a trivial problem. NZ’s building code (NZS 3604) requires treated timber for all framing within 150 mm of the ground, all exterior cladding, all decking, all piles and posts in ground contact, and many other applications.⁴⁹ The treatment system underpins the durability of NZ’s entire modern housing stock.

5.2 Current treatment methods and their import dependency

CCA (Copper-Chrome-Arsenic): The most widely used NZ timber treatment. Timber is placed in a pressure vessel (autoclave) and impregnated with a solution of copper sulphate, potassium dichromate, and arsenic pentoxide under pressure. CCA is highly effective — treated radiata pine can last 40–60+ years in ground contact.⁵⁰

Import dependency: CCA chemicals are manufactured from raw materials (copper, chromium, arsenic) that NZ does not produce domestically at the required purity and scale. Existing stocks of CCA concentrate at treatment plants and chemical suppliers represent a finite resource — perhaps 1–3 years of treatment at pre-event rates, possibly longer if treatment is rationed to high-priority applications only.⁵¹ Once stocks are exhausted, CCA treatment ceases.

Boron (LOSP — Light Organic Solvent Preservative, or boron diffusion): Used for NZ building framing (H1.2 treatment level). Boron compounds protect against borer and fungi but are water-soluble and therefore not suitable for exposed or ground-contact applications.⁵²

Import dependency: Boron compounds (borax, boric acid) are imported. NZ has some geothermal deposits that contain boron in low concentrations (notably in the Taupō Volcanic Zone geothermal fluids), but extracting boron at useful purity and scale from geothermal sources is a non-trivial chemical engineering challenge — feasible but not currently done commercially.⁵³ Doc #162 identifies geothermal boron extraction as a research priority.

Copper azole (ACQ, CuAz): An alternative to CCA for some applications, also dependent on imported copper compounds.

5.3 Alternative preservation methods

With imported treatment chemicals depleted within a few years, NZ must transition to alternative preservation methods. None match CCA’s performance, and this performance gap must be acknowledged honestly.

Charring (yakisugi / shou sugi ban): Surface charring of timber to a depth of 3–8 mm using fire creates a carbon layer that resists decay, insects, and moisture penetration. The technique has been used in Japan for centuries and has a demonstrated service life of 50–80+ years on exterior cladding.⁵⁴

• Applications: Exterior cladding, fence palings, posts (surface treatment only)
• Limitations: Labour-intensive for large volumes. Does not penetrate to the core — cut ends and joints must be recharred or sealed. Not effective for ground-contact applications where the char layer is in constant contact with wet soil. Performance on radiata pine specifically is less well-documented than on Japanese cypress (hinoki) — trials are needed.
• Feasibility: [A] — requires only timber and fire. Can be done at any scale.

Pine tar and wood tar: A byproduct of charcoal production (Doc #102). Pine tar has been used in Scandinavian building traditions for centuries as a wood preservative, particularly on exterior timber.⁵⁵

• Applications: Exterior cladding, boat timbers, fence rails
• Limitations: Pine tar is a surface coating that must be reapplied periodically — Scandinavian practice suggests every 3–10 years depending on exposure, species, and application thickness, though these figures are from Norwegian and Swedish conditions and may not transfer directly to NZ’s climate and decay fungi.⁵⁶ Pine tar does not penetrate deeply into the timber. Its efficacy against NZ’s specific decay fungi (Serpula lacrymans, Coniophora puteana, Trametes versicolor) and borer species (Anobium punctatum, native phorids) is not well characterised — empirical NZ trials are needed before relying on pine tar as a structural preservation method.
• Feasibility: [A] — produced as a byproduct of charcoal kilns that NZ will be operating anyway. Stockholm tar (the highest-quality pine tar, produced by retort distillation of pine roots) requires a specific kiln design that differs from standard charcoal kilns; the additional steps are within NZ’s metalworking and construction capability but require deliberate setup.

Hot linseed oil: Immersing timber in linseed oil heated to approximately 60–80°C allows the oil to penetrate the wood surface, creating a water-repellent layer. NZ grows linseed (flax, Linum usitatissimum — not to be confused with NZ flax/harakeke) in small quantities; production could be expanded.⁵⁷

• Applications: Interior timber, furniture, tool handles, exterior timber (with periodic reapplication)
• Limitations: Moderate durability — linseed oil provides water repellence but limited biological resistance; surface performance in exposed exterior conditions likely requires reapplication every 3–10 years, varying with exposure and initial application quality.⁵⁸ Performance data for NZ conditions and decay organisms is limited — this figure is extrapolated from European building practice. Does not protect against borer. Linseed oil supply is limited; NZ’s current production of Linum usitatissimum is minimal and expansion competes with food and fibre crops for arable land.
• Feasibility: [B] — requires expanded linseed cultivation, which competes for arable land.

Smoke treatment: Prolonged exposure to wood smoke deposits phenolic compounds and creosote-like substances on the timber surface. Traditional Māori raupo whare (reed houses) used smoke from the internal fire to preserve the raupo cladding. Smoke treatment provides some protection against insects and surface decay but is not a high-performance preservation method.⁵⁹

• Applications: Sheltered timber, interior use, temporary structures
• Limitations: Inconsistent penetration. Limited protection against ground-contact decay. Not suitable for structural applications requiring long service life.
• Feasibility: [A] for incidental use (any fire produces smoke); not scalable as a deliberate industrial treatment.

Copper naphthenate from recycled copper: If NZ develops local production of naphthenic acid (derivable from petroleum residues or possibly from wood tar fractions) and has recycled copper, copper naphthenate is a moderately effective wood preservative that can be brush- or dip-applied.⁶⁰ This is a longer-term possibility, not an immediate solution. The naphthenic acid production step requires either petroleum still residues (a finite Phase 1–2 resource) or bio-based synthesis routes that are not yet demonstrated at NZ scale. - Feasibility: [C] — requires two non-trivial precursor production chains (naphthenic acid and refined copper) that do not currently exist at relevant scale in NZ.

5.4 The naturally durable species alternative

NZ has access to several timber species with good to excellent natural durability that do not require chemical treatment:

Species	Durability class	Source	Availability
Tōtara (Podocarpus totara)	Class 1 (very durable)	Native forest	Protected; limited emergency harvest (Section 9)
Macrocarpa (Cupressus macrocarpa)	Class 2 (durable)	Plantation/shelterbelts	Moderate — significant volumes in farm shelterbelts and small plantations
Cypress (lusitanica)	Class 2 (durable)	Plantation	Limited — ~15,000–20,000 hectares nationally
Douglas fir (Pseudotsuga menziesii)	Class 3 (moderately durable)	Plantation	Moderate — ~100,000 hectares
Eucalyptus (some species)	Class 1–2 (durable to very durable)	Plantation/shelterbelts	Limited — ~20,000–30,000 hectares
Black beech, red beech	Class 3 (moderately durable)	Native forest	Protected; limited emergency harvest

Source: NZS 3602 Timber and Wood-Based Products for Use in Building.⁶¹

Macrocarpa deserves particular attention. It is widely planted throughout rural NZ as shelterbelts and on farms. Heartwood macrocarpa has natural durability comparable to western red cedar — it is resistant to decay and borer without treatment and is widely used in NZ for outdoor furniture, fencing, and cladding.⁶² While the total macrocarpa resource is small compared to radiata pine, it is significant and geographically distributed. Under recovery conditions, macrocarpa should be prioritised for applications where untreated radiata pine would fail: fence posts, exterior cladding, ground-contact situations.

Douglas fir is also important — heartwood Douglas fir has moderate natural durability and is significantly stronger than radiata pine (modulus of rupture approximately 85–100 MPa for structural grades).⁶³ It is widely used in NZ for heavy structural applications and is suitable for boatbuilding (Doc #140).

5.5 Strategic approach to preservation

The practical approach is a combination of methods, matched to application:

Application	Current treatment	Recovery alternative
House framing (interior, dry)	H1.2 boron	Untreated radiata (acceptable if kept dry)
House framing (within 150 mm of ground)	H3.1 CCA/ACQ	Macrocarpa, Douglas fir, or charred radiata
Piles, posts (ground contact)	H4 CCA	Macrocarpa, tōtara (if available), charred radiata with tar
Exterior cladding	H3.1 CCA/ACQ	Charred radiata, pine tar treatment
Decking	H3.2 CCA/ACQ	Macrocarpa, charred radiata
Fencing	H3.2/H4 CCA	Macrocarpa posts, charred pine rails
Boat timbers	H4+ CCA or epoxy	Douglas fir, macrocarpa, pine tar (Doc #140)
Retaining walls	H5 CCA	Macrocarpa, concrete (Doc #97)

This approach accepts shorter service lives for some applications. Charred, tar-treated radiata pine in ground contact may last 10–20 years rather than CCA-treated pine’s 40–60+ years.⁶⁴ This performance gap is significant: a fence post or building pile that must be replaced every 15 years rather than every 50 years represents a recurring labour and material cost across every farm, building, and infrastructure project in NZ. The design response — more frequent inspection, raised foundations, and structural overcapacity to tolerate early-stage decay — should be built into recovery-era building standards from the outset.

---

6. PORTABLE SAWMILLS — DISTRIBUTED PROCESSING

6.1 The Lucas Mill: an NZ asset

Lucas Mill is a NZ company, based in Whanganui, that has manufactured portable swing-blade sawmills since 1987.⁶⁵ The Lucas design is distinctive: a single operator controls a swing-blade (a circular saw that pivots to cut both horizontally and vertically) to process logs into finished timber without needing to move the log. The mill is towable behind a vehicle and can be set up in an hour.

Lucas Mills are found throughout NZ — on farms, in rural communities, in developing countries (Lucas has exported thousands of units).⁶⁶ The exact number in NZ is unknown but is likely in the hundreds to low thousands. The company’s Whanganui factory, if it survives the immediate disruption with its workforce and tooling intact, could potentially continue manufacturing mills under recovery conditions. Continued production would require: steel plate and bar for the mill frame and blade carriage (available from NZ Steel at Glenbrook, Doc #89, though not all required profiles are currently produced); electric motors (from salvage if domestic manufacturing is not available); and continued access to precision machining capability (Doc #91). Even at reduced throughput, domestic mill manufacturing capacity is a recovery priority given the long service lives of existing mills.

6.2 Other portable mills

NZ also has significant numbers of other portable sawmill types:

• Wood-Mizer (US-manufactured, bandsaw type): horizontal bandsaw on a rail bed. Higher cutting accuracy and thinner kerf than swing-blade mills, but more complex blade requirements.
• Peterson (NZ-manufactured in Rotorua): portable swing-blade mills similar in concept to Lucas.
• Alaskan mill (chainsaw mill): The simplest portable milling method — a frame that guides a chainsaw along a log to produce slabs and boards. Very slow, high kerf waste, heavy chainsaw wear, but requires no dedicated milling equipment beyond a chainsaw and the guide frame. Can be fabricated locally from steel bar and plate.⁶⁷

6.3 Strategic value under recovery conditions

Portable sawmills become disproportionately important as transport fuel becomes scarce. Their key advantage: they go to the timber rather than requiring timber to come to them.

A large centralised mill is far more efficient in terms of volume processed per hour — a single bandsaw headrig can process 10–50 times more timber per day than a portable mill. But a centralised mill requires:

• Logs transported from the forest (fuel cost)
• Finished timber transported from the mill to the building site (fuel cost)
• Concentration of skilled workers at one location
• Dependence on a single facility (vulnerability to breakdown)

A portable mill at the forest edge: - Eliminates log transport (the heaviest, most fuel-intensive part) - Produces timber near where it will be used (shorter finished-timber transport) - Distributes processing across many locations (resilience) - Can be operated by a single person (lower labour threshold)

The trade-off is productivity. A portable mill producing 1–5 cubic metres per day requires 20–100 portable mill-days to produce what a large mill produces in one day. But if fuel for log trucks is unavailable, the large mill sits idle regardless of its theoretical capacity.

Recommendation: Maintain large mills operating at capacity as long as fuel supply permits. Simultaneously activate all available portable mills for distributed regional processing. As fuel becomes scarcer, shift the balance progressively toward portable mills until they become the primary milling method.

6.4 Chainsaw milling (Alaskan mill)

The Alaskan mill deserves separate discussion because it is the milling method of last resort — the one that works when everything else fails. It requires only a running chainsaw and a guide frame (which can be fabricated by a blacksmith from steel bar in a day).

Performance: Very slow — perhaps 0.5–1.5 cubic metres of sawn timber per day, with high chainsaw wear. Kerf waste is high (chainsaw kerf is typically 7–10 mm). The operator is exposed to sustained chainsaw vibration, noise, and sawdust. It is hard, slow, unpleasant work.

When it matters: In remote locations with no access to a portable sawmill, or when all portable sawmill blades are worn out but chainsaw chains are still available. A chainsaw mill can produce structural timber from a log on a hillside with no road access, no electricity, and no other equipment. This is the bottom of the technology ladder, and it is worth knowing about precisely because it works when nothing else does.⁶⁸

Feasibility: [A] — requires only a running chainsaw, fuel, and a fabricated guide frame. Guide frames are within the capability of any blacksmith or metalworker (Doc #92). Productivity is very low: treat Alaskan milling as an emergency supplement, not a primary production method.

---

7. SAW BLADE MAINTENANCE AND MANUFACTURING

7.1 Sharpening and setting: extending blade life

Saw blade maintenance is among the highest-leverage skills for sustaining NZ’s timber processing capability, because blade condition directly limits both output volume and timber quality at every mill in the country. A dull saw wastes energy, produces poor-quality timber, stresses the sawmill, and wears out blades faster. A properly maintained blade cuts cleanly, produces smooth surfaces, and lasts much longer.

Chainsaw chain sharpening: - Requires a round file of the correct diameter (typically 4.0, 4.8, or 5.5 mm depending on chain type), a flat file for depth gauges, and a file guide - Should be done after every 2–3 tanks of fuel, or whenever the chain stops producing chips and starts producing dust - A skilled operator can sharpen a chain in 10–15 minutes - Each tooth can be sharpened approximately 5–10 times before the cutter is too short for effective use - File supply is critical — chainsaw files are hardened steel consumables that wear out. NZ does not manufacture them. Existing stocks should be inventoried and allocated carefully. Diamond chainsaw sharpeners (if available) last much longer than files.⁶⁹

Bandsaw blade maintenance: - Bandsaw blades require periodic sharpening (grinding the tooth tips), setting (bending alternate teeth slightly outward to create kerf clearance), and tensioning (stretching the blade body to the correct tension profile so it runs straight on the wheels) - Large mills have dedicated saw shops with automatic sharpening and setting machines - Blade sharpening can be done with a hand-operated grinding wheel in the absence of automated equipment, but it is slower and requires considerable skill - A well-maintained bandsaw blade can be resharpened 10–20+ times before the teeth are too short for effective use - Blade cracking (from fatigue, improper tensioning, or material defects) is the most common failure mode. Some cracks can be repaired by brazing or welding, though this weakens the blade⁷⁰

Circular saw blade maintenance: - Large circular saw blades are sharpened by grinding and can be retipped with new teeth (historically, teeth were hammer-set using hand tools) - Carbide-tipped blades (common in modern NZ mills) hold their edge much longer than steel blades but cannot be easily resharpened without specialised equipment. Carbide tips can be replaced, but carbide itself is an imported material (tungsten carbide) - Stellite-tipped blades (an alloy of cobalt, chromium, and tungsten) are used on some bandsaw blades and can be resharpened by grinding, but Stellite is also an imported material⁷¹

7.2 Blade stocks and depletion timeline

NZ sawmills maintain inventories of replacement blades, and blade suppliers hold additional stock. A rough estimate of the national blade inventory:

• Bandsaw blades: Several thousand blades across all mills, plus supplier stock. Each blade might last 6–12 months of continuous use with resharpening. National stock probably represents 3–7 years of operation at current consumption rates, possibly longer with careful maintenance and reduced milling volume.⁷²
• Chainsaw chains: Hundreds of thousands in retail and trade stock nationally. At recovery-era usage rates (reduced from normal but still significant), stocks might last 5–15 years. This is one of the longer-lasting consumable categories.
• Circular saw blades: Similar to bandsaws — several years of stock at recovery-era usage rates.
• Files and sharpening equipment: Adequate for several years, but files themselves are consumables that wear out. Diamond sharpening tools last much longer.

These are rough estimates. The national consumables inventory recommended in Section 2 (Recommended Actions item 5) would establish actual figures.

7.3 Domestic blade manufacturing

Eventually, NZ must manufacture replacement saw blades from domestic resources. This is feasible but requires:

Steel: Saw blade steel is high-carbon or alloy steel, heat-treated to specific hardness. NZ Steel at Glenbrook (Doc #89) produces carbon steel that can be used as feedstock, but saw blade manufacturing requires precise control of carbon content, hardness, and tempering. A saw blade that is too hard will crack; too soft will lose its edge quickly.⁷³

Manufacturing process (bandsaw blades): 1. Source or produce suitable steel strip (high-carbon steel, approximately 0.7–1.0% carbon) 2. Cut to blade length 3. Punch or cut tooth profile (this can be done with a press or by hand filing, though hand filing is extremely labour-intensive for a production run) 4. Set teeth (bend alternate teeth outward) 5. Harden and temper the blade (heat treatment — see Doc #92 for forge work and heat treatment) 6. Tension the blade (roll-tensioning using specialised equipment or hammering — this is a skilled operation) 7. Braze or weld the blade into a continuous loop

This process requires a dedicated workshop with heat treatment capability, a blade welding or brazing setup, tensioning equipment (which could be purpose-built), and workers trained in saw doctoring — a specialist trade.⁷⁴

Timeline: Establishing domestic blade manufacturing is probably a 2–5 year project, requiring steel supply from Glenbrook, heat treatment expertise from the machine shop network (Doc #91), and training of saw doctors from experienced mill maintenance workers. Priority should be given to bandsaw blade manufacturing (the most widely needed type) followed by chainsaw chain manufacturing (which is more complex, as chains have multiple moving parts and require case-hardened cutters).

Chainsaw chain manufacturing is significantly harder than bandsaw blade manufacturing. A chainsaw chain is a precision assembly of drive links, tie straps, and cutters, each requiring specific metallurgy, heat treatment, and dimensional accuracy. NZ-based manufacturing of chainsaw chain is feasible in principle (the technology is 1940s-era) but would require a dedicated small factory with multiple press tools, heat treatment furnaces, and quality control processes.⁷⁵

Feasibility of domestic bandsaw blade manufacturing: [B] — the materials and underlying processes (steel, heat treatment, brazing) exist within NZ’s industrial base, but a dedicated workshop with appropriate tooling must be established and saw doctor expertise must be concentrated. Achievable within Phase 2–3 (Years 1–7) with deliberate investment. Feasibility of chainsaw chain manufacturing: [B/C] — more complex tooling and tighter metallurgical tolerances push this toward [C]; the precedent technology is well-established but the tooling does not currently exist in NZ.

---

8. NUCLEAR WINTER EFFECTS ON FORESTRY

8.1 Growth reduction

Nuclear winter modelling predicts surface cooling and sunlight reduction that depend critically on the size of the exchange modelled. Robock et al. (2007) modelled a large-scale exchange (5,000 warheads) and found 8–10°C global cooling; Toon et al. (2019) modelled a regional India-Pakistan exchange and found 2–5°C cooling. The recovery library baseline assumes a major but sub-maximal exchange; a range of 3–8°C surface cooling sustained for 5–10 years, with associated reductions in sunlight of 20–40% during the first 2–3 years, is a working estimate that should be revisited if the exchange parameters are better defined.⁷⁶ NZ’s Southern Ocean latitude (35°S–47°S) means less stratospheric soot deposition than Northern Hemisphere locations, but the Southern Hemisphere does not escape nuclear winter effects — the soot eventually disperses globally.

For NZ’s plantation forests, the expected effects are:

Reduced photosynthesis: Less sunlight means less photosynthetic activity. Radiata pine growth is estimated to decline 25–60% during peak nuclear winter, with the higher end of the range during the first 2–3 years when light reduction is most severe and in worst-case exchange scenarios.⁷⁷ This is an estimate based on general plant physiology and light-response curves; no direct experimental data exists for radiata pine under nuclear winter conditions specifically.

Temperature effects: Radiata pine is adapted to a temperate climate and grows across a wide temperature range in NZ (from subtropical Northland to cool Southland). A 3–8°C cooling would shift NZ’s climate toward conditions analogous to southern Chile or Tasmania — still within radiata’s tolerance range, but at the cooler end for most growing regions. Growth reduction from temperature alone would be approximately 15–40% depending on the cooling magnitude, based on temperature-growth relationships observed across radiata’s natural range.⁷⁸

Combined effect: Total growth reduction of 35–70% during peak nuclear winter is a reasonable working range. The lower end applies to moderate exchange scenarios with faster atmospheric clearing; the higher end to large exchanges with multi-year severe cooling. This means the annual growth increment drops from approximately 25–30 million cubic metres to perhaps 8–18 million cubic metres during the worst years, recovering as nuclear winter abates.

8.2 Why this is not a crisis for timber supply

Even a 70% growth reduction still leaves an annual increment of approximately 8 million cubic metres — substantially more than NZ’s domestic timber consumption. More importantly, NZ has approximately 500–600 million cubic metres of standing timber that can be harvested immediately, regardless of growth rates. This stockpile represents decades of supply.

The growth reduction matters for long-term sustainability, not short-term supply. If NZ harvests 5 million cubic metres per year but only grows 8 million, the resource is still expanding (albeit slowly). If harvest exceeds growth for an extended period, the resource depletes — but given the enormous standing stock, this is a problem that develops over decades, not years.

8.3 Mortality risk

Some trees may die from the combined stress of cold, reduced light, and altered precipitation. Young stands (recently planted) are more vulnerable than mature trees with established root systems and energy reserves. The extent of mortality is genuinely uncertain — it depends on the severity and duration of cooling, which is itself uncertain.

Practical implication: Prioritise harvesting from mature stands (which have the most commercial timber value anyway) and protect young plantings where possible. Accept that some recent plantings may fail and plan for replanting when conditions improve.

8.4 Altered pest and disease dynamics

Reduced temperatures may suppress some forest pests (e.g., bark beetles, which are temperature-sensitive in their reproductive rates) while potentially favouring others (fungal pathogens may thrive in cooler, damper conditions). Needle cast diseases (Dothistroma, Cyclaneusma), which are already significant problems in NZ radiata pine, may increase or decrease depending on the specific moisture and temperature regime.⁷⁹ This is an important uncertainty — forest health monitoring should continue and adapt to changed conditions.

---

9. NATIVE TIMBER: PROTECTION, PRAGMATISM, AND EMERGENCY HARVEST

9.1 The resource

NZ has approximately 6.4 million hectares of native forest, overwhelmingly protected in the conservation estate (national parks, conservation land managed by DOC).⁸⁰ Native logging was a major industry through the 19th and early 20th centuries but has been almost entirely curtailed since the late 1990s, when government policy effectively ended logging on Crown-owned native forests and the Indigenous Forests Amendment Act (1993) imposed strict sustainability requirements on private native forest harvest.⁸¹

Key native timber species:

• Tōtara (Podocarpus totara): Exceptional durability (Class 1). Traditionally the preferred Māori timber for carving, construction, and waka. Slow-growing but some large stands remain.
• Rimu (Dacrydium cupressinum): Beautiful appearance, moderate durability (Class 3). Historically NZ’s most commercially harvested native timber. Large old-growth rimu is now rare.
• Kahikatea (Dacrycarpus dacrydioides): NZ’s tallest native tree. Low natural durability but odourless and non-tainting — historically used for food containers (butter boxes, cheese crates) and building. Fast-growing (for a native) — can reach millable size in 60–80 years.⁸²
• Kauri (Agathis australis): Iconic NZ timber — exceptionally dimensionally stable, workable, and durable. Now very rare and protected. Kauri dieback disease (caused by Phytophthora agathis) threatens remaining stands.⁸³
• Beech (Nothofagus species): Red beech and silver beech are relatively common in montane forests. Moderate durability. Beech forests are extensive — approximately 2.7 million hectares — but many are in steep, inaccessible terrain.⁸⁴

Traditional selection and processing knowledge for native species:

Māori knowledge of native timber encompasses specific technical criteria for tree selection, seasoning, and durability assessment that are directly applicable to recovery-era use of native species:

• Selection: Trees were traditionally selected based on grain direction, branch structure, and sound when struck (to assess internal soundness). Waka builders would select a tree years in advance and return to fell it at the right season — typically winter, when sap content is lowest, producing timber that dries with less splitting and shrinkage.⁸⁵
• Seasoning: Traditional methods included controlled drying over fire, submersion in water (particularly for tōtara waka hulls, to prevent splitting during initial seasoning), and extended air drying under cover. These methods address the same drying challenges described in Section 4 but are calibrated for native species, which have different moisture-loss profiles than radiata pine.
• Durability assessment: Detailed understanding of which species and which parts of the tree are most durable for different applications — heartwood versus sapwood, butt versus top, slow-grown versus fast-grown. This knowledge directly informs timber grading and allocation decisions for native species.

This knowledge, held primarily by elder practitioners and waka builders, should be captured through heritage skills documentation (Doc #159) and integrated into recovery-era forestry practice.

9.2 The ethical and practical tension

Under normal conditions, native forest protection is both an environmental imperative and a legal framework. Under permanent import isolation, the calculation shifts. NZ’s native forests contain timber with properties (natural durability, structural characteristics) that cannot be fully replicated by plantation species, particularly for applications where untreated radiata pine is unsuitable.

This document does not recommend wholesale native forest logging. The ecological, cultural (particularly for Māori), and long-term environmental consequences of large-scale native harvest would be severe. Native forests provide ecosystem services (watershed protection, biodiversity, carbon storage) that have real value in recovery. And native podocarps grow so slowly (tōtara takes 100–200+ years to reach millable size) that any harvest is effectively non-renewable on human planning timescales.⁸⁶

What this document does recommend:

1. Salvage harvest first. Windthrown, storm-damaged, and naturally fallen native trees should be recovered and milled wherever accessible. This is already permitted under current law and provides high-quality timber at no ecological cost. NZ has significant volumes of fallen native timber in forests and on farms.

2. Demolition and recycled native timber. Many older NZ buildings (pre-1970s) were constructed from native timber — rimu, matai, kahikatea, tōtara. As buildings are demolished, renovated, or consolidated, this timber should be carefully recovered and stockpiled. Recycled native timber is an existing resource that does not require any new felling.

3. Selective harvest of private native timber where permitted under existing law (Indigenous Forests Amendment Act provisions for sustainable management on private land). Some private landowners have native timber stands that are neither protected forest nor ecologically critical. A regulated selective harvest — taking individual mature trees rather than clear-felling — could provide high-value timber for specific applications (boat keels, marine piles, bridge timbers) without landscape-scale ecological damage.

4. Emergency native harvest as a last resort, only if alternative preservation methods prove inadequate and naturally durable timber is genuinely needed for critical infrastructure. Any emergency harvest should be:

   • Authorised at the highest government level
   • Selective, not clear-fell
   • Focused on species and stands where ecological impact is lowest (e.g., mature beech from accessible stands rather than remnant kauri)
   • Subject to mandatory replanting
   • Developed in partnership with tangata whenua — Māori are kaitiaki (guardians) of these forests, and emergency harvest on conservation land requires Treaty engagement and access to mātauranga Māori about sustainable harvest practices⁸⁷

---

10. TIMBER AS A SUBSTITUTE MATERIAL

10.1 Timber replacing steel

Steel remains available from NZ Steel at Glenbrook (Doc #89), but in limited quantity and with constrained product range. Timber can substitute for steel in many applications:

• Structural framing: Timber framing is already NZ’s standard for residential construction. No change needed.
• Bridges: Timber bridges are well-established engineering. For spans up to 15–20 metres, glulam (glue-laminated) or large-section sawn timber beams are fully adequate. NZ already has examples of modern timber bridges.⁸⁸
• Poles and towers: Timber power poles are standard in NZ. Radio masts and observation towers can be built from timber.
• Marine structures: Timber wharves and jetties using naturally durable species (tōtara, macrocarpa) or treated pine.
• Agricultural buildings: Timber pole barns, implement sheds, stockyards — these are conventional construction forms with well-established NZ practice and do not require specialist engineering beyond basic carpentry.

Where timber cannot substitute for steel: High-load applications (crane structures, heavy industrial frames), tension members (wire rope, reinforcing bar), precision machinery, springs, cutting tools, boilers and pressure vessels. Steel remains essential for these and should be reserved accordingly.

10.2 Timber replacing concrete

Concrete (Doc #97) requires cement, aggregate, and water. Cement production is energy-intensive and dependent on limestone and clay supply. Timber can substitute for concrete in:

• Foundations: Timber piles and bearers on concrete pads (reducing total concrete volume). Treated or naturally durable timber in ground contact.
• Walls: Timber framing replaces concrete block or in-situ concrete for most residential and light commercial walls.
• Floors: Timber floor framing on piles versus concrete slab-on-ground. The timber option uses less concrete and is easier to build with hand tools.

Where timber cannot substitute for concrete: Water-retaining structures (tanks, dams), heavy foundations, firewall construction, underground structures.

10.3 Timber replacing plastics

With petrochemical plastics manufacturing effectively ended, timber fills many of the roles plastics have assumed:

• Packaging: Wooden crates and pallets (already common)
• Containers: Buckets, barrels, boxes — coopers and crate-makers become relevant trades
• Pipes: Wooden pipes for low-pressure water conveyance (historical precedent — wooden water mains were used in many cities into the 19th century)⁸⁹
• Handles, utensils, equipment housings: Wood replaces plastic in tool handles, kitchen implements, electrical switch boxes, and hundreds of other small items
• Composites: Wood fiber composites (particleboard, MDF, hardboard) continue to be producible if NZ retains adhesive capability (urea-formaldehyde or phenol-formaldehyde resins from local chemistry)

10.4 Timber for other recovery applications

• Boatbuilding (Doc #140): Radiata pine, Douglas fir, macrocarpa — the boatbuilding document specifies timber requirements in detail
• Charcoal production (Doc #102): Any species, though denser woods produce better charcoal
• Wood gasification (Doc #56): Dry wood blocks or chips — species is less critical than moisture content
• Paper and printing (Doc #108): Wood pulp from radiata pine is well-established at industrial scale (see Doc #108 for the process dependencies, including chemical pulping reagents)
• Firewood: Approximately 1–3 tonnes per household per winter for heating, depending on house insulation (Doc #162) and climate zone. This is a significant demand — 2–5 million tonnes nationally — but well within NZ’s capacity.

---

11. IMPLEMENTATION: PHASED TIMBER ECONOMY

Phase 1 (Months 0–12): Use what we have

• Existing sawmills operate at capacity on reduced fuel allocation
• Portable sawmills activated for distributed processing
• Air drying programmes established at all milling sites
• Existing kiln capacity fully utilised
• CCA and boron treatment stocks rationed to highest-priority applications (ground-contact piles, critical infrastructure)
• Timber allocation system established to prevent waste of high-grade resource on low-grade uses

Phase 2 (Years 1–3): Adapt and extend

• Wood gas conversion of log transport vehicles (Doc #56)
• Horse/bullock logging reintroduced for extraction
• Alternative preservation methods scaled up (charring, pine tar)
• Saw blade sharpening and reconditioning programmes mature
• Solar kiln construction at distributed milling sites
• Macrocarpa and Douglas fir preferentially harvested for applications requiring natural durability
• Crosscut sawing reintroduced for supplementary felling

Phase 3 (Years 3–7): Transition to self-sufficiency

• Domestic saw blade manufacturing established (bandsaw blades first)
• CCA stocks largely exhausted; charring and pine tar are primary preservation
• Chainsaw use increasingly limited to large-tree felling; manual methods predominate for smaller work
• Plantation management programmes (thinning, pruning, replanting) in full operation
• Native timber salvage and recycling provide specialty timbers
• Timber grading adapted to recovery conditions

Phase 4 (Years 7–15): Mature timber economy

• First post-event radiata plantings reach thinning age
• Domestic saw blade and chain manufacturing routine
• Horse and manual logging methods well-established alongside remaining mechanised capability
• Timber construction techniques adapted to preservation limitations (design for durability — raised foundations, wide eaves, ventilation)

Phase 5 (Years 15–30+): Sustained forestry

• Post-event plantings reach sawlog maturity
• The timber economy is self-sustaining: the resource regenerates, processing capability is maintained from domestic materials, preservation methods are established
• Timber remains NZ’s primary structural and manufacturing material

---

CRITICAL UNCERTAINTIES

Uncertainty	Impact if unfavorable	Mitigation
Nuclear winter severity and duration	Worse-than-expected growth reduction; possible widespread tree mortality in young stands	Massive standing stockpile provides buffer for decades; prioritise harvest of mature timber
Actual national consumable stocks (blades, chains, files)	If lower than estimated, processing capacity declines sooner	National inventory (Recommended Action #5); immediate maintenance discipline
Alternative preservation performance on radiata pine	If charring and pine tar prove inadequate, untreated radiata has very short service life	Empirical trials (Recommended Action #11); increase macrocarpa/Douglas fir harvest
Speed of domestic blade manufacturing	If slower than 2–5 year estimate, gap between stock depletion and domestic production	Prioritise blade stocks for essential milling; extend blade life through meticulous maintenance
Fuel depletion rate	Faster depletion accelerates transition to manual/animal methods	Begin transition planning immediately; do not wait for fuel crisis
Geothermal boron extraction feasibility	If successful, provides domestic preservative supply; if not, boron treatment ceases when stocks run out	Research priority (Doc #162); do not depend on this until demonstrated
Native timber policy acceptance	Emergency harvest of native forest may face strong public and Māori opposition	Exhaust all alternatives first; engage tangata whenua early; maintain salvage and recycling programmes
Chainsaw chain domestic manufacturing	The most complex consumable to manufacture locally; failure extends dependence on dwindling stocks	Prioritise chains for felling only; shift all other tasks to manual methods

---

CROSS-REFERENCES

Document	Relationship
Doc #45 — Chainsaw Maintenance	Detailed maintenance procedures for chainsaws — the primary felling tool
Doc #56 — Wood Gasification	Wood gas as transport fuel for log trucks; wood as gasifier feedstock
Doc #89 — NZ Steel: Glenbrook Operations	Steel supply for saw blades, fastenings, mill components
Doc #91 — Machine Shop Operations	Precision metalwork for blade manufacturing and mill repair
Doc #92 — Blacksmithing	Heat treatment for blade manufacturing; tool fabrication
Doc #97 — Cement and Concrete	Concrete as complementary material; timber as substitute
Doc #100 — Harakeke Fiber	Harakeke rope for rigging and lashing in forestry
Doc #102 — Charcoal Production	Charcoal from timber; pine tar as preservative byproduct
Doc #105 — Wire and Fencing	Fencing posts from treated/durable timber
Doc #108 — Paper Production	Wood pulp as paper feedstock
Doc #141 — Wooden Boatbuilding	Timber species selection and preparation for marine construction
Doc #163 — Housing Insulation	Timber framing; sawdust as insulation; construction standards
Doc #163 — Housing Construction	Timber as primary construction material
Doc #34 — Lubricants	Bar oil substitutes; tallow for tool maintenance
Doc #53 — Fuel Allocation	Fuel supply for logging and transport operations
Doc #160 — Heritage Skills	Crosscut sawing, hand felling, traditional woodworking
Doc #162 — University Research Priorities	Geothermal boron extraction; timber treatment research
Doc #8 — National Census	Identifying portable sawmill owners, forestry workers, saw doctors

---

FOOTNOTES

---

1. Ministry for Primary Industries (MPI), National Exotic Forest Description (NEFD), annual reporting series. The 2023 NEFD reports approximately 1.72 million hectares of planted production forest. Species composition data also from NEFD and NZ Forest Owners Association (NZFOA) publications. https://www.mpi.govt.nz/forestry/↩︎

2. Standing volume estimates of 500–600 million cubic metres are based on MPI NEFD reporting of total standing volume in planted production forests. This figure includes all age classes and is approximate.↩︎

3. MPI forestry statistics. NZ roundwood harvest averaged approximately 30–35 million cubic metres per year in the early 2020s, of which roughly 55–60% was exported as unprocessed logs (primarily to China). See MPI Forestry Production statistics. https://www.mpi.govt.nz/forestry/↩︎

4. Red Stag Timber, Rotorua, is one of the largest single-site sawmills in the southern hemisphere, processing over 500,000 cubic metres of radiata pine logs per year. Other large mills include Claymark, Pan Pac, and Nelson Pine Industries. Figures from company reports and NZ Forest Owners Association data.↩︎

5. NZ domestic sawn timber production was approximately 4.5–5 million cubic metres per year in the early 2020s. Source: MPI forestry statistics and NZFOA Facts and Figures.↩︎

6. Māori use of native timbers is extensively documented in Māori ethnobotany and traditional arts literature. See Best, E. (1927), The Pa Maori; and Buck, P.H. (1926), The Evolution of Maori Clothing; and more recently, Wehi, P.M. et al. (2019), “Indigenous knowledge in the Anthropocene,” People and Nature.↩︎

7. NZ forestry and wood processing employment estimates from MPI and Stats NZ. The figure of approximately 35,000 encompasses forestry and logging, wood processing and manufacturing, pulp and paper, and support services. https://www.stats.govt.nz/↩︎

8. Chainsaw felling productivity varies enormously with terrain, tree size, operator skill, and undergrowth density. The 10–30 cubic metres per day range reflects typical commercial radiata pine harvesting on moderate terrain. Steeper terrain, larger trees, or safety-constrained working conditions reduce output significantly.↩︎

9. Manual crosscut sawing productivity is based on historical forestry records and modern re-enactment data. A well-maintained two-person crosscut saw in radiata pine can fell a 40 cm tree in approximately 15–30 minutes. Total daily output including limbing and rest breaks is roughly 2–5 cubic metres. See also Doc #160 (Heritage Skills).↩︎

10. Horse logging in NZ was standard practice until the 1950s–1960s when mechanical extraction (skidders, tractors) became dominant. The skills are largely lost from the professional logging workforce but retained by some heritage practitioners and equestrians. Draft horse breeds suitable for logging (Clydesdales, Percherons) are present in NZ in small numbers.↩︎

11. NZ sawmill employment estimates for large and medium mills are not separately published by Stats NZ. The 8,000–10,000 figure is estimated from MPI and NZFOA industry data for total wood processing employment (~35,000) allocated across sub-sectors. This figure requires verification from industry bodies (Wood Processing Industry Association, NZFOA). Stats NZ Business Demography statistics provide a cross-check by ANZSIC industry code.↩︎

12. Timber grader employment: NZ has a formal timber grading qualification (NZ Certificate in Wood Processing) and an industry grading body. The 600–900 estimate is based on the approximate number of qualified graders in the industry; no precise publicly available figure is known. Verify with the Wood Processing Industry Training Organisation (Competenz) or NZFOA.↩︎

13. Kiln operator employment: NZ does not separately report kiln operator numbers. The 200–400 estimate is based on typical large kiln staffing requirements (1–2 operators per shift, 2–3 shifts per day) scaled across the estimated 15–25 large mills with kiln capacity. Verify with individual mill operators or industry associations.↩︎

14. Saw doctoring as a specialist trade: historically, every significant sawmill had a resident saw doctor whose sole job was blade maintenance. This trade has declined with automation and imported replacement blades. Remaining saw doctors (mostly older workers at large mills) represent critical knowledge. Heritage skills preservation (Doc #159) should prioritise these individuals.↩︎

15. NZ working-age population (15–64) under recovery conditions: pre-event figure was approximately 3.2–3.5 million based on Stats NZ 2023 census data. Under nuclear winter and recovery conditions, the working-age population may be modestly reduced by mortality and age-structure changes, but the baseline estimate is acceptable for planning purposes. See Doc #8 (National Census) for population data.↩︎

16. Manual crosscut sawing productivity is based on historical forestry records and modern re-enactment data. A well-maintained two-person crosscut saw in radiata pine can fell a 40 cm tree in approximately 15–30 minutes. Total daily output including limbing and rest breaks is roughly 2–5 cubic metres. See also Doc #160 (Heritage Skills).↩︎

17. Domestic saw blade manufacturing establishment cost: the 5–15 person-year estimate is based on analogy with small-scale specialty metalworking operations of comparable complexity (spring manufacture, precision tool manufacture) rather than from direct experience with NZ saw blade manufacture. Key tasks include: workshop construction or conversion (2–4 person-years of general construction); heat treatment furnace fabrication or procurement and commissioning (1–3 person-years of metalworking and commissioning); blade welding/brazing setup (1–2 person-years); tooling for tooth cutting and setting (1–3 person-years); and initial training and process development (1–3 person-years of skilled metalworker time). The ongoing 3–8 person estimate assumes a small specialist workshop producing replacement blades for NZ’s milling industry at recovery-era consumption rates. Both figures require verification from people with direct saw-doctoring and tool manufacturing experience.↩︎

18. NZ timber dimensions: NZS 3631 (NZ Timber Grading Rules) and NZS 3604 (Timber-Framed Buildings) specify standard sizes for structural timber. These dimensions are used throughout NZ construction and are stocked by all timber merchants.↩︎

19. Ministry for Primary Industries (MPI), National Exotic Forest Description (NEFD), annual reporting series. The 2023 NEFD reports approximately 1.72 million hectares of planted production forest. Species composition data also from NEFD and NZ Forest Owners Association (NZFOA) publications. https://www.mpi.govt.nz/forestry/↩︎

20. Ministry for Primary Industries (MPI), National Exotic Forest Description (NEFD), annual reporting series. The 2023 NEFD reports approximately 1.72 million hectares of planted production forest. Species composition data also from NEFD and NZ Forest Owners Association (NZFOA) publications. https://www.mpi.govt.nz/forestry/↩︎

21. Standing volume estimates of 500–600 million cubic metres are based on MPI NEFD reporting of total standing volume in planted production forests. This figure includes all age classes and is approximate.↩︎

22. NZ domestic sawn timber production was approximately 4.5–5 million cubic metres per year in the early 2020s. Source: MPI forestry statistics and NZFOA Facts and Figures.↩︎

23. Radiata pine growth rates in NZ: mean annual increment of 20–25 cubic metres per hectare per year on good sites is well-established in NZ forestry research. See Maclaren, J.P. (1993), Radiata Pine Growers’ Manual, NZ Forest Research Institute Bulletin No. 184.↩︎

24. Regional distribution of NZ plantation forests from MPI NEFD regional breakdowns. The Central North Island contains the largest concentration, centred on the Kaingaroa Forest.↩︎

25. Red Stag Timber, Rotorua, is one of the largest single-site sawmills in the southern hemisphere, processing over 500,000 cubic metres of radiata pine logs per year. Other large mills include Claymark, Pan Pac, and Nelson Pine Industries. Figures from company reports and NZ Forest Owners Association data.↩︎

26. Lucas Mill and similar portable sawmill productivity: manufacturer specifications and user reports suggest 1–5 cubic metres of sawn timber per day with a single experienced operator, depending on log size, timber dimensions, and setup time. See Lucas Mill product specifications: https://lucasmill.com/↩︎

27. Logging equipment dependencies detailed in Doc #53 (Fuel Allocation) and Doc #88 (Spare Parts Triage). Hydraulic hoses, filters, and tyres are particularly critical consumables.↩︎

28. Fuel consumption estimates for NZ logging operations are approximate, based on industry averages and NZ Transport Agency data for heavy vehicle fuel consumption. Terrain is the dominant variable — steep-country logging consumes significantly more fuel than flat-land operations.↩︎

29. Fuel consumption estimates for NZ logging operations are approximate, based on industry averages and NZ Transport Agency data for heavy vehicle fuel consumption. Terrain is the dominant variable — steep-country logging consumes significantly more fuel than flat-land operations.↩︎

30. NZ diesel consumption: approximately 3.5–4 billion litres per year across all sectors, based on MBIE Energy in NZ data tables. https://www.mbie.govt.nz/building-and-energy/energy-and-n...↩︎

31. Horse logging in NZ was standard practice until the 1950s–1960s when mechanical extraction (skidders, tractors) became dominant. The skills are largely lost from the professional logging workforce but retained by some heritage practitioners and equestrians. Draft horse breeds suitable for logging (Clydesdales, Percherons) are present in NZ in small numbers.↩︎

32. Manual crosscut sawing productivity is based on historical forestry records and modern re-enactment data. A well-maintained two-person crosscut saw in radiata pine can fell a 40 cm tree in approximately 15–30 minutes. Total daily output including limbing and rest breaks is roughly 2–5 cubic metres. See also Doc #160 (Heritage Skills).↩︎

33. Chainsaw chain life estimates from manufacturer data (Stihl, Husqvarna) and professional logging experience. Chain life is highly variable — cutting in dirty conditions (soil contamination, embedded stones) dramatically shortens chain life compared to clean wood.↩︎

34. Two-stroke oil substitution: castor oil was used as two-stroke lubricant before modern synthetic oils and remains effective. See Doc #34 for detailed assessment. Petrol substitution for small two-stroke engines remains an unsolved problem — ethanol can work in modified engines but chainsaw carburetor modifications are complex.↩︎

35. Bandsaw technology and blade specifications: standard sawmill engineering references. See Williston, E.M. (1988), Saws: Design, Selection, Operation, Maintenance. Modern NZ bandsaw blades are typically imported from specialist manufacturers in Sweden, the US, or Japan.↩︎

36. Circular saw limitations: a circular saw blade can cut to a depth of approximately blade radius minus arbor and guard clearance. A 1.2 m blade can typically cut logs up to approximately 450–500 mm diameter.↩︎

37. NZ timber dimensions: NZS 3631 (NZ Timber Grading Rules) and NZS 3604 (Timber-Framed Buildings) specify standard sizes for structural timber. These dimensions are used throughout NZ construction and are stocked by all timber merchants.↩︎

38. Timber recovery rates from NZ sawmilling industry data. Recovery rate depends on log quality, mill efficiency, and target product mix. Pruned logs yield higher recovery because the clear outer wood produces high-grade boards with less waste from defect cutting.↩︎

39. Green moisture content and target drying levels: standard wood science. Radiata pine sapwood can have moisture content of 100–160%; heartwood typically 30–50%. Target MC for structural framing: 14–18%. For joinery: 10–14%. See Walker, J.C.F. (2006), Primary Wood Processing: Principles and Practice, Springer.↩︎

40. Green moisture content and target drying levels: standard wood science. Radiata pine sapwood can have moisture content of 100–160%; heartwood typically 30–50%. Target MC for structural framing: 14–18%. For joinery: 10–14%. See Walker, J.C.F. (2006), Primary Wood Processing: Principles and Practice, Springer.↩︎

41. Air drying times for radiata pine: NZ Forest Research Institute (Scion) timber drying guidelines. Times vary significantly with location, season, and stacking practice. The estimates given are for well-stacked timber in sheltered conditions in the North Island.↩︎

42. Kiln drying energy requirements and schedules: Scion (NZ Forest Research Institute) kiln drying guides. Conventional kiln schedules for 25 mm radiata pine typically run 3–7 days; high-temperature kilns can dry in 24–48 hours but with increased risk of checking and collapse.↩︎

43. Kiln drying energy requirements and schedules: Scion (NZ Forest Research Institute) kiln drying guides. Conventional kiln schedules for 25 mm radiata pine typically run 3–7 days; high-temperature kilns can dry in 24–48 hours but with increased risk of checking and collapse.↩︎

44. NZ kiln capacity estimate based on known mill infrastructure. Most large and medium mills have kiln capacity. Exact national aggregate figures are not publicly reported but industry participants estimate total capacity at 3–4 million cubic metres per year.↩︎

45. Solar kiln design and performance: extensive literature. See Bois, P.J. (1977), Constructing and Operating a Small Solar-Heated Lumber Dryer, USDA Forest Products Laboratory; and Langrish, T. and Walker, J.C.F. (1993), “Drying of timber,” in Primary Wood Processing.↩︎

46. Solar kiln design and performance: extensive literature. See Bois, P.J. (1977), Constructing and Operating a Small Solar-Heated Lumber Dryer, USDA Forest Products Laboratory; and Langrish, T. and Walker, J.C.F. (1993), “Drying of timber,” in Primary Wood Processing.↩︎

47. NZ Timber Durability Classes: NZS 3602 (Timber and Wood-Based Products for Use in Building). Radiata pine heartwood is Class 4 (not durable); sapwood is Class 5 (non-durable). Macrocarpa heartwood is Class 2 (durable). Tōtara heartwood is Class 1 (very durable).↩︎

48. NZ Timber Durability Classes: NZS 3602 (Timber and Wood-Based Products for Use in Building). Radiata pine heartwood is Class 4 (not durable); sapwood is Class 5 (non-durable). Macrocarpa heartwood is Class 2 (durable). Tōtara heartwood is Class 1 (very durable).↩︎

49. NZS 3604 (Timber-Framed Buildings) specifies treatment levels for different building applications. The Hazard Class system (H1 through H5) corresponds to increasing exposure risk, with higher hazard classes requiring higher levels of preservative treatment.↩︎

50. CCA treatment efficacy: CCA-treated radiata pine has demonstrated service lives of 40–60+ years in ground contact in NZ conditions. See Hedley, M.E. (1997), “An assessment of the service life of CCA-treated posts in New Zealand,” NZ Journal of Forestry Science.↩︎

51. CCA stock depletion estimate is approximate and depends on the volume of CCA concentrate held at treatment plants and chemical suppliers nationally. This figure requires verification from Timber Preservation Council NZ and major treatment operators. The estimate of 1–3 years assumes pre-event treatment rates; rationing would extend this.↩︎

52. Boron treatment: boron compounds (borax, boric acid) diffuse into green timber and protect against borer and fungi. However, boron is water-soluble and leaches from timber in exposed or wet conditions, making it unsuitable for ground contact or exterior use. NZS 3640 (Chemical Preservation of Round and Sawn Timber) specifies boron treatment requirements.↩︎

53. Geothermal boron in NZ: the Taupō Volcanic Zone geothermal fluids contain boron at concentrations of approximately 10–50 mg/L, depending on the field. Extraction at useful purity and scale is chemically feasible but not currently practiced commercially in NZ. See Mroczek, E.K. and McDowell, G. (2004), “Boron in geothermal fluids,” Proceedings, NZ Geothermal Workshop.↩︎

54. Yakisugi (shou sugi ban) — Japanese charred wood cladding — has documented service lives of 50–80+ years on buildings in Japan. The technique is applicable to any softwood, though performance varies with species, char depth, and exposure conditions. See Ebner, D.H. et al. (2021), “Charred wood as a building material,” Wood Material Science & Engineering.↩︎

55. Pine tar as wood preservative: see footnote in Doc #102. Scandinavian pine tar (Stockholm tar) has centuries of documented use for wood preservation, particularly in maritime and building applications. See Hyvönen, A. et al. (2006), “Pine tar in wood protection,” Wood Material Science & Engineering.↩︎

56. Pine tar reapplication frequency in Scandinavian practice: traditional Norwegian and Swedish maintenance schedules for Stockholm tar on exterior timber suggest reapplication every 3–10 years depending on exposure (south-facing, exposed surfaces every 3–5 years; sheltered surfaces every 7–10 years). See Svensson, C. and Turczyn, R. (2012), “Traditional wood preservation methods in Scandinavia,” Wood and Fiber Science. These figures are not directly transferable to NZ’s climate (higher UV, different humidity patterns, different decay organisms) and should be treated as a starting point for NZ-specific trials.↩︎

57. Hot linseed oil treatment: a traditional surface treatment for timber. Linseed oil penetrates the wood surface when heated, providing water repellence and some anti-fungal protection. Not as effective as CCA or boron for structural preservation but suitable for many above-ground applications. NZ linseed production is very small (hundreds of hectares) but could be expanded.↩︎

58. Hot linseed oil service life: performance data for linseed oil on softwood exterior timber in European conditions suggests maintenance reapplication every 2–5 years for heavily exposed surfaces and every 5–10 years for sheltered surfaces. See Ekstedt, J. (2002), “Studies on the durability and degradation mechanisms of clear coatings for outdoor use on wood,” Royal Institute of Technology, Stockholm. Extrapolation to NZ conditions and radiata pine is approximate — NZ-specific trials are needed.↩︎

59. Smoke preservation: the antimicrobial and insect-repellent properties of wood smoke are due to phenolic compounds, acetic acid, and other volatiles deposited on surfaces. This is a surface treatment only and does not provide the deep penetration of pressure treatment. Māori use of smoke preservation in whare construction is documented in Best, E. (1924), The Maori As He Was.↩︎

60. Copper naphthenate: an organic copper compound used as a wood preservative, particularly for brush or dip application. It requires naphthenic acid (a petroleum derivative) and copper. Feasibility depends on NZ’s ability to produce or source naphthenic acid from petroleum residues or bio-based alternatives. This is a speculative option, not a near-term solution.↩︎

61. NZ Timber Durability Classes: NZS 3602 (Timber and Wood-Based Products for Use in Building). Radiata pine heartwood is Class 4 (not durable); sapwood is Class 5 (non-durable). Macrocarpa heartwood is Class 2 (durable). Tōtara heartwood is Class 1 (very durable).↩︎

62. Macrocarpa durability and use in NZ: macrocarpa heartwood is widely recognised in NZ building and farming practice as naturally durable timber suitable for exterior use without treatment. See Page, D. and Singh, T. (2014), “Durability of NZ-grown timbers,” NZ Journal of Forestry.↩︎

63. Douglas fir structural properties: modulus of rupture approximately 85–100 MPa for structural grades, compared to radiata pine at approximately 80–90 MPa. Douglas fir heartwood has moderate natural durability (NZ Durability Class 3). See NZS 3603 (Timber Structures Standard) for structural design properties.↩︎

64. Service life of charred and tar-treated radiata pine in ground contact: no NZ-specific long-term trials data is publicly available for this combination. The 10–20 year range is extrapolated from (a) documented service lives of charred softwood posts (cedar, pine) in Japan and North America — typically 10–25 years in ground contact, highly variable with soil conditions; and (b) the additional protection expected from pine tar surface treatment. This figure requires empirical validation in NZ soil conditions. Trials establishing actual decay rates at representative NZ sites are a research priority (see also Recommended Action #11).↩︎

65. Lucas Mill, Whanganui, NZ. Manufacturer of portable swing-blade sawmills since 1987. The company has sold thousands of units domestically and internationally. See https://lucasmill.com/↩︎

66. Lucas Mill, Whanganui, NZ. Manufacturer of portable swing-blade sawmills since 1987. The company has sold thousands of units domestically and internationally. See https://lucasmill.com/↩︎

67. Alaskan (chainsaw) mill: a simple guide frame, typically made from aluminum or steel channel, that bolts to the chainsaw bar and rides on a flat surface (a board attached to the log for the first cut, or the flat top of the previous cut for subsequent cuts). Originally popularised for remote milling in Alaska and the Pacific Northwest. Can be fabricated from steel bar stock by any competent metalworker. See Philips, D. (2007), The Chainsaw Mill Manual.↩︎

68. Alaskan (chainsaw) mill: a simple guide frame, typically made from aluminum or steel channel, that bolts to the chainsaw bar and rides on a flat surface (a board attached to the log for the first cut, or the flat top of the previous cut for subsequent cuts). Originally popularised for remote milling in Alaska and the Pacific Northwest. Can be fabricated from steel bar stock by any competent metalworker. See Philips, D. (2007), The Chainsaw Mill Manual.↩︎

69. Chainsaw file specifications and life: round files for chainsaw sharpening are hardened steel consumables that wear relatively quickly — a single file may sharpen 3–8 chains before becoming too dull for effective use, depending on the steel quality and sharpening technique. Diamond files and grinding wheels last much longer. File supply is a critical consumable — see Doc #91 and Doc #88 for metalworking file supply more broadly.↩︎

70. Bandsaw blade maintenance: saw doctoring (the skilled trade of maintaining bandsaw blades) includes sharpening, setting, tensioning, levelling, and crack repair. Blade fatigue cracking typically initiates at the tooth gullet root. Small cracks can be arrested by drilling a hole at the crack tip, then brazing. Extensively cracked blades must be retired. See Williston (1988), Saws, cited above.↩︎

71. Stellite and carbide tipping: Stellite is a cobalt-chromium-tungsten alloy used for tipping bandsaw teeth; tungsten carbide is used for tipping circular saw teeth. Both are imported materials with no NZ production. Once existing stocks of tipped blades are exhausted, NZ must use plain high-carbon steel blades, which require more frequent sharpening but are domestically producible.↩︎

72. National blade stock estimates are rough — no centralised inventory of sawmill consumables exists. These estimates are based on typical mill blade inventories scaled to the estimated number of operating mills, plus wholesale and retail supplier stocks. The recommended national inventory (Recommended Actions) would establish actual figures.↩︎

73. Saw blade steel requirements: bandsaw blades require steel with approximately 0.7–1.0% carbon content, hardened to approximately Rockwell C 42–48 for the tooth tips and approximately C 38–42 for the blade body. This differential hardness is achieved through selective heat treatment. NZ Steel at Glenbrook produces carbon steel but not specifically saw-grade steel — adaptation of Glenbrook product for saw blade use is feasible but requires metallurgical development.↩︎

74. Saw doctoring as a specialist trade: historically, every significant sawmill had a resident saw doctor whose sole job was blade maintenance. This trade has declined with automation and imported replacement blades. Remaining saw doctors (mostly older workers at large mills) represent critical knowledge. Heritage skills preservation (Doc #159) should prioritise these individuals.↩︎

75. Chainsaw chain manufacturing: a chainsaw chain consists of drive links, tie straps (both stamped from steel strip), and cutter assemblies (which require precise geometry and case hardening for the cutting edge). The manufacturing process involves blanking, forming, heat treatment, riveting, and quality control. This is 1940s-era manufacturing technology but requires dedicated tooling.↩︎

76. Nuclear winter modelling: Robock, A. et al. (2007), “Nuclear winter revisited with a modern climate model and current nuclear arsenals,” Journal of Geophysical Research; Toon, O.B. et al. (2019), “Rapidly expanding nuclear arsenals in Pakistan and India portend regional and global catastrophe,” Science Advances.↩︎

77. Growth reduction estimates under nuclear winter are extrapolated from general plant light-response curves and temperature-growth relationships. No direct experimental data exists for radiata pine under nuclear winter conditions. The 25–60% range reflects the combined effects of reduced light and temperature across the range of plausible exchange scenarios and severity levels. The higher end applies during peak nuclear winter in severe scenarios (years 1–3); the lower end reflects moderate exchanges or the recovery phase (years 4–7).↩︎

78. Temperature-growth relationships for radiata pine: radiata grows across a wide climatic range, from subtropical to cool temperate. Growth rate declines approximately linearly with temperature below the optimum range (approximately 15–20°C mean annual temperature for NZ). A 3–8°C cooling shifts NZ’s climate below the optimum for most radiata growing regions, with the severity of impact depending on the exchange scale. See Watt, M.S. et al. (2010), “The influence of climate, soil, and tree species on tree growth,” Forest Ecology and Management.↩︎

79. Dothistroma needle blight (Dothistroma septosporum) and Cyclaneusma needle cast are the most significant needle diseases in NZ radiata pine. Both are influenced by temperature and moisture — Dothistroma thrives in warm, wet conditions, so cooling may reduce its impact; Cyclaneusma is less temperature-sensitive. See Bulman, L.S. et al. (2004), “Dothistroma septosporum in New Zealand,” NZ Journal of Forestry Science.↩︎

80. NZ native forest area: approximately 6.4 million hectares (24% of NZ’s land area), based on Ministry for the Environment Land Cover Database and DOC statistics. https://www.doc.govt.nz/↩︎

81. NZ native forest logging history and policy: the Forests (West Coast Accord) Act 1986 and the Indigenous Forests Amendment Act 1993 progressively restricted native forest logging. By 2002, all Crown-owned native forest logging had effectively ceased. Small-scale sustainable harvest on private land continues under strict regulation.↩︎

82. Kahikatea properties and growth rates: NZ’s tallest native tree, reaching 55–65 metres. Growth is slow by plantation standards but faster than other podocarps — potentially reaching millable size (40+ cm diameter) in 60–80 years on good sites. Historically used for food containers because of its odourless, non-tainting properties. See Bergin, D. and Gea, L. (2007), Native Trees: Planting and Early Management for Wood Production, Tane’s Tree Trust.↩︎

83. Kauri dieback: caused by Phytophthora agathis, a water mould first identified in NZ in 2008. Kauri dieback has infected trees across kauri’s natural range in Northland and Auckland. There is no known cure. The disease is spread through soil movement, making it critical to control access to kauri forests. See Waipara, N.W. et al. (2013), “Surveillance methods to determine tree health and the presence of kauri dieback disease,” NZ Plant Protection.↩︎

84. NZ beech forests: approximately 2.7 million hectares of beech forest (red beech, silver beech, mountain beech, black beech, hard beech) primarily in the South Island mountains and parts of the central North Island. Beech timber has moderate durability and acceptable structural properties but is difficult to access in much of its range. See Wardle, J.A. (1984), The New Zealand Beeches, NZ Forest Service.↩︎

85. Māori tree selection and seasoning practices: documented in Best, E. (1925), Maori Agriculture; and in oral histories and contemporary waka building practice. Waka builders traditionally selected trees in summer, observing growth patterns and testing for soundness, then felled in winter when sap was lowest.↩︎

86. Podocarp growth rates: tōtara may take 100–200+ years to reach millable size (40+ cm diameter). Rimu is similarly slow. Kahikatea is somewhat faster. These growth rates mean that any harvest of native podocarps is effectively mining a non-renewable resource on human planning timescales. Replanting is essential but the replacement timber will not be available for generations.↩︎

87. Treaty of Waitangi obligations regarding native forest: Māori customary rights to forest resources are recognised under the Treaty and various statutory frameworks (including the Resource Management Act 1991 and the Conservation Act 1987). Any emergency harvest regime must be developed in consultation with tangata whenua. The Waitangi Tribunal’s Ko Aotearoa Tēnei (Wai 262) report is relevant.↩︎

88. Timber bridges in NZ: NZ has numerous timber bridges, particularly in rural areas and on walking tracks. Modern engineered timber bridges (glulam beams, stress-laminated decks) are proven technology for spans up to 20+ metres. See Buchanan, A. (2007), Timber Design Guide, NZ Timber Design Society.↩︎

89. Wooden water pipes: wooden pipes (typically bored logs) were used for urban water supply in many cities until the late 19th century. London, Boston, Philadelphia, and many other cities had extensive wooden water main networks. The technology is simple — a log bored with an auger — but the service life is limited (10–30 years depending on species and conditions) and wooden pipes are restricted to low-pressure gravity systems.↩︎