When wood absorbs moisture its fibers swell and as it dries they will shrink. This will cause the wood to crack and warp. The sun will break down to surface layer of cells and turn the 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 the deck. Sealants help the deck shed water instead of absorbing it. Most high quality products also have a mildecide and UV protectant added. These prevent mold and mildew growth on the surface of the deck and add protection from the sun’s ultra-violet rays.

New decks have mill-glaze on the lumber which is used during sizing to prevent the saw blades from burning it. Sealant applied to a new deck can become spotty where it has not penetrated into the wood as well, because of the presence of mill-glaze. Mill-glaze can be removed by sanding, chemicals and power washing, or exposure to the elements over time. The recommended method for preparing a new deck is sanding all horizontal surfaces in the direction of the wood grain with 60-80 grit sandpaper (using a finer grit sandpaper will close the grain and the sealer will not soak into the wood which will shorten how long the protectant will last). This can be easily accomplished using a pole sander and 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.

Cedar and redwood decks are usually ready to be sealed in 6 to 8 weeks, depending upon the time of year. Pressure treated decks should be exposed to the elements for 6 months to a year. Ipe decks are ready to be sealed immediately after installation. 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 they 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 upon exposure. 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.

Sherwin Williams – 100 W. Higgins Rd., South Barrington (847) 551-1713
Please ask for Ewelina Czupryna, Jenna Cionko, or Stephanie Church. Please let them know we sent you in and they will give you a discount on the suggested products.