Wood Deck Maintenance
Damage from the Elements
When wood absorbs moisture, its fibers swell, and as it dries, its fibers shrink. This movement causes the wood to crack and warp. Additionally, the sun will break down to the surface layer of the wood’s cells and turn its color to silver or gray. This damage will continue to worsen with time and exposure to the elements. Applying a penetrating oil sealer is recommended to help protect your wood deck. Sealants help the deck shed water instead of absorbing it. Most high quality products also have a mildecide and UV protectant added to prevent mold and mildew growth on the surface of the deck and to add protection from the sun’s ultra-violet rays.
Sanding
New decks have a mill-glaze on the lumber which can cause applied sealant to become spotty by preventing it from penetrating into the wood. In order to remove mill-glaze from new decks, the recommended method is by sanding all horizontal surfaces in the direction of the wood grain with 60 to 80 grit sandpaper. Using a finer-grit sandpaper will close the grain so that the sealer will not soak into the wood, which will shorten how long the protectant will last. Sanding can be easily accomplished using a pole sander and by hand sanding. If the deck has extensive damage, using a vibrating floor sander for decking and a belt or palm sander for treads and top rail will be less labor intensive.
Sanding
New decks have a mill-glaze on the lumber which can cause applied sealant to become spotty by preventing it from penetrating into the wood. In order to remove mill-glaze from new decks, the recommended method is by sanding all horizontal surfaces in the direction of the wood grain with 60 to 80 grit sandpaper. Using a finer-grit sandpaper will close the grain so that the sealer will not soak into the wood, which will shorten how long the protectant will last. Sanding can be easily accomplished using a pole sander and by hand sanding. If the deck has extensive damage, using a vibrating floor sander for decking and a belt or palm sander for treads and top rail will be less labor intensive.
Sealing
Cedar and redwood decks are usually ready to be sealed within 6 to 8 weeks after installation, depending upon the time of year. Pressure treated decks should be exposed to the elements for 6 months to a year before being sealed. Ipe decks are ready to be sealed immediately after installation. The deck should then be resealed 6 months later, and once a year regularly after that for the lifetime of the deck.
When a deck is completed during the hot summer months, it should be wet each day for the first couple weeks to slow down the drying process. This will help prevent cracking due to the lumber shrinking so quickly. Test the deck by sprinkling drops of water on it. It is ready to be sealed when the drops are absorbed within a few seconds.
Sealant should be applied with a brush. A sprayer may be used, but be careful of wind blowing sealant onto the house or vegetation. When using a sprayer or roller, be sure to back brush all surfaces for better penetration. Penetrating sealers are available in natural and wood tones as well as solid colors. High-quality products will out-perform less expensive brands. Most paint supply stores will carry high quality products while most building material supply companies carry less expensive brands.
The deck will need to be resealed approximately every two years depending on exposure level. When resealing a deck, it should be cleaned with deck cleaning chemicals and/or power washed to remove dirt and oxidized sealant. Allow 72 hours of dry weather before resealing.