The Facts About Pressure Treated Lumber

Pressure-treated wood is advertised as having a long life [some are said to be over 40 years] in direct contact with the earth. Manufacturers immerse wood in chemicals that penetrate the outer surface. The most vulnerable area is where the wood is cut. Such purpose requires local treatment if buried. In my experience, this wood usually lasts longer. There are several fence posts that were placed 20 years ago. All these were as good as the day I put them on the ground. On the other hand, several times I found pressure-treated wood under the deck. There was even a post placed on the pier where the wood was corrupt. Like everything in life, this indicates that design, planning, odds, and sometimes something can go wrong. It is out of “norm”.

Pressure treated timber and how to deal with it is not clearly defined by the Wood Destroying Biology Act in Washington, where I work. Since timber is manufactured for contact with the ground, it is not a defect to have it touch the ground. At one point I asked WSDA about this issue and was told this. Inspectors should examine all pressure-treated wood that is in contact with the soil, if possible, and call it if it is rotten. If the rot is not apparent, the inspector says that grading the soil from wood or placing it on a concrete pier will be longer to help the client. This advice may or may not make sense depending on the design elements of the structure [eg deck].

Personally, as an inspector, here is what I do. If pressure-treated wood plays an important role and is in contact with the soil, it calls for grading or soil removal. For example, if you find pressure-treated timber in the soil and use it as a post under a house or on a deck of any height, it is called a problem. In its important role, it does not want to give chances to spoilage, the result of contact between wood and the ground, and the moisture that is brought to the wood.

On the other hand, if I'm inspecting the house and find a couple for railing support, on both sides of the staircase from an affordable porch or deck to support the railing, I will check the wood level and And if that goes well, I don't say much. The rating is not applied and the post is sunk and seems to be well supported. In my view, simple and unimportant outdoor use, such as fence posts, is common, and in the future will be easier to repair and more accessible to the area. Repairs can be done by affordable craftsmen, and structural damage is unlikely.