Manufacturers pressure treat wood by placing it into a large cylinder or chamber. Manufacturers add small incisions or tiny markings all over them designed to help the chemicals permeate the surface into the wood.

Some wood, like Douglas fir, doesn’t readily absorb chemicals as easily as southern yellow pine.That includes 4×4 fence posts, floor joists, decking, fencing, etc. When identifying wood on an existing project, you can (or should) find pressure treated wood on anything that touches the ground.Look for that as it differs dramatically from standard yellow pine and other woods. Pressure treated wood also has a greenish tint to it.You may find something that says “PT” or even “pressure-treated lumber”. Similar to the above-look for any stamps or markings on the wood that indicate it is pressure treated.Most pressure-treated lumber has a tag stapled to the end that tells you what kind of material you have. For raw lumber, check for a tag on the end.If you want to know how to tell if wood is pressure treated you have several ways of doing so: