Wood degrades naturally unless we intervene and take counter measures. Insects too can take their toll. Alexander the Great’s engineers soaked wood for bridges in olive oil. The Romans painted their ship’s wooden hulls with tar. Valiant Exteriors installs siding over pressure treated wood. Read on to learn more about this fundamental process.
How Does Pressure Treated Wood Work?
Painted tar over wooden ship hulls remains on the surface. Capillary action cannot draw olive oil deep into the timber. Dry wood cracks and creates deep fissures as it dries. Insects can chew their way to the heart of a log. Pressure treating wood uses mechanical pressure to force chemicals deep into the material, where they remain for some time.
North Americans traditionally treated their exterior-grade wood with arsenic through to 2004. Then the U.S. Environment Protection Agency outlawed the substance, and the timber industry switched to more expensive copper. This put pressure on some operators to use untreated wood against the industry standard.
When to Insist on Using Treated Timber
Pressure treated wood should be mandatory for decks, timber posts sunk into the ground, and in basements where it contacts, or is close to the earth. However, it may be possible to use untreated pine, spruce, and fir behind interior cladding, where it is less exposed to the environment. We have extensive experience in this regard.
- Alkaline copper quaternary (ACQ) wood is safe and effective, although it often changes the color of the timber.
- Pressure treated borate products may retain the natural color, although they are unsuitable for constantly wet conditions.
Can I Safely Paint Pressure Treated Wood?
The treatment initially traps the natural moisture inside, and if anything it adds to it. Freshly pressure-treated wood can take paint, but there is a catch as it does not bond well. Then later, as the timber naturally dries, it shrinks and the paint wrinkles, cracks, or flakes off. Clear stains and sealers are a better option after the wood has finished drying.
Wood Treated This Way Does Not Last Forever
Pressure treated wood is not a cure-for-all. Nothing can stop organic material decaying. Pressure treating wood simply delays the process.
- Lightly-treated wood used above ground for fences, railings and decks could last for a decade or more.
- Intensely-treated wood used in contact with the ground should last for longer if correctly used.
You should speak to Valiant Exteriors first before you use wood for construction that’s exposed to the outdoor elements, and / or attack by insects. We will give you honest advice and a fair quote. Then it’s over to you to decide whether to place your order with us.
More Information
Why Proper Roof Drainage Really Matters
The Forces of Nature Colonize Wood (Gunnar Ries BY CC 2.5 Generic)