Preparing New Pressure Treated Wood Deck to Take a Finish
The warm weather is finally here and if you've just finished installing a brand new deck, it'll need some kind of protection before you can invite friends and family over to enjoy it. Chances are you used pressure treated wood (PTW), the most common and inexpensive choice for decking. If so, you should hold off picking up a brush. Chances are your brand new PTW is not ready to take a finish just yet.
left: weathered new wood showing dead fibers
right: prepped wood ready for finish
Pressure treatment is a process that forces chemical preservatives deep into the wood, commonly giving it a slight green tint. Wood is placed inside a sealed container, and vacuum pressure is applied to force the preservatives into the wood. The preservatives help protect the wood from insects, decay and help preserve the stability of the wood. As a result, new PTW will often have a high moisture content and needs to dry out before a coating can be applied. (If the PTW has been sitting at the lumber yard for a few months, it may be OK.) So, before you dip a brush into a can of stain or paint, you should check the moisture level in the wood--you should also do this if you had the deck power washed in preparation to refinishing. You can check the moisture level with a moisture meter, commonly for sale or for rent at your local hardware store. An ideal level of moisture would be below 15%. Your newly installed PTW deck could dry out to under 15% moisture content in as little as four days. However, it is good practice to always check with a meter to ensure the moisture level is below this level.
If the deck is not coated with in a week of being installed you may notice the wood turning gray. This is a thin layer of dead wood fibers that must be removed prior to sealing or staining chemically with prep products such as Benjamin Moore's Restore followed by Brightener & Neutralizer. Afterwards sanding with 80 grit paper will provide you with a smooth finish that will allow a more even application and penetration of your stain in addition to removing any mill-glaze. Regardless of which path you take, it will prepare your deck and restore it to its natural color ready to take a new finish and a visit from family and friends.
In the next two posts we'll cover finish options for previously stained decks as well as preparation and application.