Pressure-Treated Timber.
Pressure-treated timber has a low CO₂ footprint but requires proper disposal. Consider thermally modified timber or larch as alternatives with a better environmental profile at end of life. Read the numbers together with function, lifespan, detailing and the specific building element.
- Carbon Footprint (GWP)
- 0.5 kg CO₂-eq/kg
- Source: estimatee based on the EN 15804 average
- Density
- 550 kg/m³
- Expected Lifespan
- 25–40 years (in outdoor use), 40–60 years (with minimal moisture exposure)
How to use this assessment
The assessment of pressure-treated timber is a first decision basis. Carbon numbers, density and lifespan give a point of comparison, but the material must always be read together with structure, moisture, fire requirements, detailing, maintenance and the condition of the existing building. A good material choice is therefore both a data question and an architectural judgement. The useful next step is to clarify which questions should be examined further before the material is specified in a project.
What is pressure-treated timber?
Pressure-treated timber is structural timber treated with protective chemicals under pressure to resist rot, fungi, and insects. Used for decking, carports, fencing, and structures in moist environments. Modern preservatives (CCA-free) are far less toxic than older chromium-copper-arsenic (CCA) treatments.
Carbon Footprint Compared
Negative carbon footprint (green) indicates carbon storage. Data based on EPD averages from ECO Platform and estimates per EN 15804.
Typical Applications
- check_circle Decking and terraces
- check_circle Fences and picket fences
- check_circle Carports and sheds
- check_circle Structures in soil and water (piles, foundations)
In Renovation
Pressure-treated timber is used in renovation for new decking, fences, and carports. Consider thermally modified wood or larch as alternatives that give a more natural appearance and are easier to dispose of.
Questions about pressure-treated timber
Is pressure-treated timber safe?
Modern pressure treatment without CCA (typically copper-azole or copper-quat) is classified as safe for normal construction and decking use. Old CCA-treated materials should be handled with care and delivered to hazardous waste.
Can pressure-treated timber be painted?
Yes, but the timber must be dry (typically 3–6 months after treatment). Use diffusion-open paint that allows the timber to breathe. Green freshly treated timber should not be painted immediately.
Are there alternatives to pressure-treated timber for decking?
Yes — thermally modified wood, Siberian larch, African hardwood (teak, merbau), and composite decking boards are alternatives. Thermally modified wood and larch are most sustainable. Tropical timber requires FSC certification.
Can pressure-treated timber be recycled?
Pressure-treated timber is hazardous waste and must NOT be burned in normal wood stoves or delivered as normal firewood. It must go to specialist chemical waste handling or is only suitable for landfill.
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