It is wood that has been placed in a pressurized vacuum to force chemical preservatives deep into the grain. This makes it resistant to rot, fungi, and insects.
Where should I use it? It’s designed for outdoor projects where wood touches the ground or is exposed to the elements, such as:
- Decking and joists
- Fence posts and gates
- Retaining walls and garden beds
Is it safe? Modern treated wood (like ACQ) is safe for residential use. However, you should never burn it, and you should wear a mask when cutting it to avoid inhaling treated sawdust.
Can I paint it right away? No. Treated lumber is usually saturated with liquid when sold. You should wait several weeks (or until the wood is dry to the touch) before painting or staining, otherwise the finish will peel.
Does it last forever? While it resists decay for 20+ years, it can still warp or crack due to sun exposure. Applying a water-repellent sealer every year or two is recommended to keep it stable.