organic / Timber / Millwork

Thermally Modified Timber, various species (19mm, 21mm, 25mm, 32mm)

Chemical-free heat treatment (190-230 degC) modifying timber at cellular level. Reduces moisture uptake to 4-6% EMC, achieves Class 1-2 durability (EN 350), improves insulation by 20-25%. Trade-off: 10-30% strength reduction and increased brittleness. Available from Abodo, Lunawood, and Thermory in Australia.

Atlas code

ORG-TBR-MW-004

organictimbermillworkthermally-modifiedthermowoodheat-treatedchemical-free

Thermally Modified Timber, various species (19mm, 21mm, 25mm, 32mm)

At-a-glance signals

Overview

Executive summary

Thermally modified timber (TMT) undergoes controlled high-temperature treatment (190-230 degC for Thermo-D class) in the absence of oxygen, using only heat and steam to fundamentally alter the wood's cellular structure. The process degrades hemicellulose — the cell wall component most responsible for moisture absorption — reducing equilibrium moisture content to 4-6% and delivering significantly improved dimensional stability and Class 1-2 durability (EN 350). No chemicals are used. Available species include Radiata Pine (Abodo Vulcan), Nordic Pine/Spruce (Lunawood, Thermory), and American White Ash (Burnt Ash). The process reduces mechanical strength by 10-30% and increases brittleness, but the trade-off delivers enhanced decay resistance, improved insulation (thermal conductivity reduced 20-25%), and a consistent dark brown colour across all boards.

Best when…

100% chemical-free — only heat and steam, no toxic treatments
Class 1-2 durability (EN 350) from plantation softwood base
Significantly improved dimensional stability — EMC reduced to 4-6%
Enhanced natural decay and insect resistance
20-25% reduction in thermal conductivity — improved insulation
Consistent darker brown colour throughout the board
Maintains natural timber workability (with pre-drilling)
Multiple species and brands available in Australia
FSC-certified plantation timber sources (Abodo, Lunawood)
Abodo Vulcan: H3 LOSP termite treated for Australian conditions

Top advantages

01 100% chemical-free — only heat and steam, no toxic treatments
02 Class 1-2 durability (EN 350) from plantation softwood base
03 Significantly improved dimensional stability — EMC reduced to 4-6%
04 Enhanced natural decay and insect resistance
05 20-25% reduction in thermal conductivity — improved insulation

Top limitations

01 Reduced mechanical strength — MOR decreases 10-50%, impact strength significantly reduced
02 Increased brittleness — pre-drilling mandatory, care with impact tools
03 NOT suitable for structural/load-bearing applications
04 Checking and surface cracking can occur (especially in exposed applications)
05 Greys/silvers when exposed to UV (like all timber) — requires coating or acceptance

Technical

Physical ·8

Density: 350-550 kg/m3 Density reduced 5-15% by thermal modification due to mass loss from hemicellulose degradation. Radiata Pine TMT ~380-420 kg/m3 (from ~510), Nordic Spruce TMT ~350-400 kg/m3, Burnt Ash TMT ~500-550 kg/m3 (from ~670). Source: Lunawood main properties, Thermory datasheet, research literature.
Specific gravity: 0.35-0.55 Reduced by 5-15% from base species. Radiata Pine TMT ~0.38-0.42, Nordic Spruce TMT ~0.35-0.40, Burnt Ash TMT ~0.50-0.55.
Porosity: 4-6 (EMC) % Increased porosity due to thermal degradation of hemicellulose cell wall components. EMC reduced to 4-6% at standard conditions. Source: ThermoWood handbook.
Water absorption: 4-6 (EMC) % EMC at standard conditions reduced to 4-6% (vs 12% untreated). Tangential swelling/shrinkage reduced to 5-6% for Thermo-D class (vs 7-8% untreated). Key benefit of thermal modification. Source: ThermoWood handbook, Lunawood main properties.
Hardness: 2.5-6.0 kN Brinell/Janka hardness reduced 10-20% by thermal modification. Radiata Pine TMT ~3.0-3.5 kN, Nordic Spruce TMT ~2.5-3.0 kN, Burnt Ash TMT ~5.0-6.0 kN. Hardwood species retain better hardness. Source: ThermoWood main properties, research literature.
UV resistance: Moderate (requires coating for colour retention) TMT is NOT inherently UV resistant. The dark brown colour will grey/silver when exposed to sunlight, similar to all timber. SiOO:X coating recommended for controlled greying. Coatings last longer on TMT due to dimensional stability. Source: Abodo, Lunawood.
Chemical resistance: Good Enhanced chemical resistance due to structural changes in cell wall chemistry. Reduced extractives and modified lignin provide improved resistance.
pH tolerance: 4-8 pH Natural timber pH tolerance maintained. Slightly more acidic surface due to degradation products.

Mechanical ·5

Tensile strength: 30-70 MPa Tensile strength reduced 15-25% by thermal modification. Hemicellulose and partial lignin degradation reduces load-bearing capacity. Source: research literature (Springer, ScienceDirect).
Compressive strength: 20-45 MPa Compressive strength reduced by 10-30% depending on treatment temperature. Higher temperatures = greater reduction. Source: research literature.
Flexural strength: 25-45 MPa MOR (Modulus of Rupture) is one of the most affected properties. Reductions of 10-50% reported depending on species and treatment temperature. Untreated spruce reference: 40-50 MPa. Source: SWST journal, research literature.
Impact resistance: 10-35 J/m Impact strength is significantly reduced — one of the main drawbacks of thermal modification. Increased brittleness makes material susceptible to splitting on impact. Source: SWST journal, ThermoWood handbook.
Creep resistance: Good (non-structural applications only) Good creep resistance due to improved dimensional stability and reduced moisture cycling. However, reduced overall strength means lower load capacity. NOT for structural applications. Source: ThermoWood handbook.

Sustainability & Health

Embodied carbon & energy ·7

Embodied carbon: 100-400 (before biogenic offset) kg CO2-eq/m3 Higher embodied energy than untreated timber due to thermal treatment process, but biogenic carbon storage (~250 kg CO2/m3 for softwood) may offset. No chemical production emissions. Extended service life (30-50+ years) reduces replacement cycles. Source: timber LCA literature, ThermoWood EPD data.
Carbon footprint: -50 to 200 (accounting dependent) kg CO2-eq/m3 Potentially carbon-neutral or negative when biogenic carbon included. Extended service life amortises processing emissions. Chemical-free process eliminates chemical production emissions. Source: timber EPD methodology.
Embodied energy: 600-1200 MJ/m3 Includes forestry, sawmilling, kiln drying, and thermal modification (heating to 190-230 degC for extended period). Higher than untreated timber but lower than chemically treated alternatives. Source: ThermoWood EPD, research literature.
Water footprint: 40-120 L/kg Forest growth water plus processing. Steam is used in the modification process but is largely recovered. Source: general timber lifecycle data.
Recycled content: 0 % 0% — virgin plantation timber required for consistent quality.
Renewable content: 100 % 100% renewable timber from FSC-certified plantation forests. Abodo: FSC-certified Radiata Pine. Lunawood: certified Nordic timber. Source: Abodo, Lunawood.
Circular score: 8.5 /10 Excellent circular economy. Renewable, chemical-free (modification process), 30-50+ year service life, biodegradable at end-of-life, recyclable as biomass fuel. Source: ThermoWood sustainability data.

Health & emissions ·1

VOC emissions: <10 ug/m3 Chemical-free process produces near-zero VOC emissions. Volatile extractives are actually reduced by thermal treatment (driven off during heating). Source: ThermoWood handbook.

Compliance & Fire

Fire performance ·6

Combustibility class: Combustible Combustible. Thermal modification does not change combustibility classification. BAL compliance depends on species — TMT softwoods (Radiata Pine, Spruce) are NOT listed in AS 3959 Appendix F for BAL-29. Abodo Vulcan pursuing BAL-29 testing (expected 2026). Source: AS 3959, Abodo.
Fire resistance level: Not currently BAL-29 rated (softwood base) minutes Abodo Vulcan is pursuing BAL-29 certification for 2026. Currently, TMT softwoods do not have BAL-29 rating under AS 3959. Australian hardwood substrates would be needed for current BAL compliance. Source: Abodo, AS 3959.
Ignition temp: 300-420 degC May be slightly higher than untreated timber due to reduced volatile content (hemicellulose degraded). Source: general timber fire science.
Flame spread index: 90-200 FSI Combustible material. Thermal modification does not inherently improve fire performance. Some products can be combined with fire-retardant treatments. Source: ThermoWood handbook.
Smoke dev. index: 150-300 SDI Standard timber smoke development. May be slightly reduced due to lower volatile content.
Heat release rate: 150-300 kW/m2 Reduced density may slightly lower total heat release compared to untreated timber of same dimensions. Still combustible. Source: general timber fire science.

Cost & Lifecycle

Capex & lead time ·6

Material cost (range): 130-250 AUD/m2 Vacoa (thermally modified Nordic Pine): from ~$130/m2 + GST. Burnt Ash (thermally modified American White Ash): from ~$210/m2 + GST. Abodo Vulcan Standard Series: more accessible pricing than Architectural Series. Lunawood: competitive pricing — 'well priced in the marketplace' (Provans Timber). Source: Mortlock Timber pricing, Abodo, Provans.
Material cost (per unit): 5500-12000 AUD/m3 Estimated $5,500-12,000/m3 depending on species and brand. Calculated from per-m2 pricing at 19-25mm thickness. Source: calculated from supplier pricing.
Lead time: 14-56 days Abodo Vulcan (via Britton Timbers): 14-28 days from Australian stock. Lunawood (Finland): 28-56 days for imported stock. Thermory (via City Timber): 21-42 days. Custom profiles may extend lead times. Source: Australian distributor estimates.
Lifecycle cost: 160-350 AUD/m2 Good lifecycle value. Higher upfront cost offset by 30-50+ year service life, reduced maintenance (coatings last longer), and no chemical treatment costs. Source: Abodo, Lunawood lifecycle data.
Annual maintenance: 1-3 AUD/m2/year Low maintenance. SiOO:X recoat ~$15-20/m2 every 10-15 years = ~$1-2/m2/year. Oil finish ~$10-15/m2 every 5-7 years = ~$1.50-3/m2/year. Uncoated: near-zero maintenance but colour change to grey. Source: Abodo, Mortlock Timber.
Market availability: Good — multiple brands and national distribution Multiple brands and distributors in Australia. Abodo: Britton Timbers (national), Duce Architectural, Austim (WA). Lunawood: Wright Forest Products, Barwon Timber, JBM Timber, Provans, Clennett's Mitre 10. Thermory: City Timber, PY Timber Warehouse, Geelong Timber Supplies. Mortlock Timber (Vacoa, Burnt Ash). Source: supplier websites.

Service life & durability ·3

Expected lifespan: 30-50+ years Abodo Vulcan (Class 1 EN 350): 50+ years anticipated. Lunawood (Class 2 EN 350): 30+ years uncoated cladding. Thermory Class 1: 50+ years. Actual lifespan depends on exposure, maintenance, and species. Source: Abodo, Lunawood, Thermory.
Maintenance interval: 5-15 years Uncoated: TMT greys naturally, minimal structural maintenance needed. With SiOO:X coating: recoat every 10-15 years. With oil finish: recoat every 5-7 years. TMT's dimensional stability means coatings last longer. Source: Abodo, Mortlock Timber.
Warranty period: 15-50 years Abodo Vulcan: anticipates 50+ year service life (Class 1 EN 350). Lunawood: 30-year uncoated cladding service life. Thermory: varies by species and class. Specific warranty terms vary by manufacturer. Source: Abodo, Lunawood.

Layer D

Where it's used

External cladding and facade systems

Window and door components

Decking and outdoor structures

Interior millwork and paneling

Bathroom and wet area applications

Garden and landscape architecture

Screening and privacy battens

Commercial and residential millwork

Where it's used

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