FAQ

Pressure Treated Lumber FAQ
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What preservatives are used for pressure treating and how long are they
effective?
For a long time, CCA (Chromated Copper Arsenate) was the primary wood
preservative. CCA-treated wood protects against all major forms of destructive
attack and is effective for many years. More recently, preservative manufacturers
switched to ACQ (Alkaline Copper Quaternary). ACQ is also effective for
decades, reducing demands on forest resources. Another common preservative
is a solution containing natural, environmentally safe mineral salts called borates.
Borate lumber has a powerful barrier against termites — even the extremely
destructive Formosan termite. The new generation of pressure-treated wood
uses micronized copper as a preservative. This method enables pressure treated
lumber to stand up against termite damage and fungal decay.
When is special handling required?
The most important precaution is DO NOT BURN TREATED WOOD. When
pressure-treated wood is burned, the preservative chemicals concentrate in the
ash and may be inadvertently inhaled. Wear gloves when handling treated
lumber, and always wear safety goggles and a dust mask when sawing or cutting
treated lumber, just as you would with untreated lumber.
When should I apply wood sealer to pressure-treated lumber decking?
Climate change will affect when and how often wood sealer needs to be applied.
To maximize surface protection and to keep your deck looking good, apply a
quality wood sealant that contains an ultraviolet stabilizer.
Know when to apply a wood sealer by dripping water onto the deck surface. If the
water quickly absorbs into the wood it's time to apply a wood sealer — If the
water droplets bead up, your deck is protected. Be sure to test annually.
Do you recommend painting treated wood?
Although treated wood provides a surface that is easier for paints to cover, we do
not recommend painting it. Treated wood does not need protection from the
elements. But if your decorative decisions call for paint, make sure the wood is
dry before application. (Pour some water over the surface. If it beads, wait; if it
seeps into the wood, it's ready to paint.)
Can I use pressure-treated landscape timbers as a fence post or deck
post?
No. Landscape timbers (unlike 4×4 pressure treated dimensional lumber and 6×6
pressure treated timbers) are not recommended for use as a structural post
because they are not treated for ground contact and do not carry a lifetime
limited warranty.