When Can I Paint Treated Lumber

When Can I Paint Treated Lumber?

The simple answer is when water soaks into the wood and no longer beads, but the real question is “how do I paint treated lumber?”  The problem is, treated lumber is saturated with copper azole or a similar chemical to make it resistant to insects and rot, leaving it unpaintable for what could be months.  Having patience and waiting it out will save you money and days of wasted labor.  Here are some tips on painting a treated deck.

Clean the surface using a mild detergent and a stiff brush (never power wash).  This will undoubtedly increase the drying time but it is essential to remove dirt and oils that will affect your finish. If time is a factor in your project we suggest using wood that has been kiln dried after treatment- it will be stamped KDAT.  KDAT lumber will be dry when purchased but the same rules apply, as moisture can be introduced during building with rain and humidity.

Try to do your best in predicting the weather–a 4 day window without rain is certainly optimal. Start with a primer suitable for treated wood following the manufacturer’s guidelines – allow it to dry completely before applying a top coat (usually no more than one day).  Latex is better suited for treated lumber than oil based paints and, as a rule, brushing is better than spraying.  Finishes will last longer on vertical surfaces like fences and railings than on horizontal surfaces like decks. So you may want to consider staining the deck surface for less maintenance.

The same rules of “When” apply to staining and sealing your deck-applying any type of finish prior to the lumber being completely dry will definitely cost time and money.