Wayne from Halifax, NS writes: Is there any problem painting or staining new projects that are built with pressure treated wood?
My reason for this question is....I was always told to wait at least one year before painting. You had a Canadian Wood Council representative on your show approximately 2 months ago and he said that this is just a myth. In fact he said that they now desire you to paint it immediately, to keep the preservatives locked inside. I am currently on several projects in my back yard and when we bought paint from a local dealer, they suggested we wait for a year before painting or staining our projects. We told them what the Wood Council rep said but they didn't. So who is right? I have e-mailed to the Wood Council back a few weeks ago but haven't received any answer. It's important to me because of my trade (Architectural Tech.)in guiding our clients as to what is correct when dealing with pressure treated wood.
I don't recall someone from the Wood Council saying to paint to lock in the preservative. Was that on my show or on another? The reality and the confusion actually comes from different treatments of preserved wood, and regional differences in drying times.
The preservative itself should not present any problem for painting unless there is a residue on the surface, which there shouldn't be but there often is. This is because the preservative is "fixed" to the cellulose of the wood by the pressure and kiln drying process.
If there is a residue, simply spray washing should prepare it for painting.
The real problem comes from 1) the actual water content of the wood and 2) any water repellents included in the product. In some areas of the country, like Alberta, all wood dries so quickly that we usually recommend water repellents or paint be applied within two weeks of installation. In other parts of the country, like your nice moist Nova Scotia, we often recommend waiting a full season to give the wood a chance to dry. Even kiln dried construction lumber in the Maritimes often registers too high a moisture content out of the yard for good paint adhesion.
Using the standard water test (pour water on dry boards to see if it beads up or soaks in) lets you know when the product you want to put on the board has a chance to get a foot hold in the fibres.
I hope this clears up the question.