If your deck looks a little dingy, or has mold and mildew, cleaning it can help. But to really get your deck in shape, you also need to seal the wood. Constant exposure to the sun’s UV rays, rain, mold and mildew can cause neglected decks to fade, crack, split and warp. Not only does a properly-maintained deck look better, but it also lasts longer.
If your deck is newly built, it should be allowed to weather for one year before a sealant is added. This ensures that the wood can dry out and the fibers can open so that they will be able to soak in the protective sealant. To assist this weathering process the new wood should be treated with a new wood treatment. A new wood treatment will provide protection from sun and rain and allow the wood to weatherize for its first year.
When applying protective sealant, it’s important to prepare the deck first. Clean the deck to remove dirt, debris and dry rot. Then, remove any old paint or sealant and sand the wood to remove rough spots and splinters. The most important part of re-sealing your deck is to start with a fresh surface of exposed wood that is able to absorb the new sealant. The deck should be completely dry before sealant is applied: wait a minimum of 2-3 days after cleaning to allow for this. If the wood is not dry, the sealant will not absorb properly. Read and follow the instructions on the product label carefully when applying sealant. Be sure you choose a product that will serve your needs. For advice pertaining to your personal situation, check with a knowledgeable sales person at a quality paint store.
A clear sealant lets the natural beauty of the wood show through, but won´t provide the same UV protection as a pigmented finish. For this reason, a clear sealant needs to be reapplied every 12 to 18 months, while a pigmented one can last for up to three years. The sealant should protect your wood against both moisture and sun damage.
Make sure to choose a specially-formulated deck stain or sealer to repel water, resist mildew, and prevent fading in high traffic areas. Sealers and stains are either water-based or oil-based. Oil-based finishes require less upkeep and less frequent re-coating than water-based finishes.
- Clear water repellent provides basic protection, including waterproofing, minimal UV protection, and sometimes mildew growth prevention. Because of the minimal UV protection, this type of sealer allows the wood to turn gray, though without splitting, warping, cupping, or cracking. Re-coating is required at least once a year.
- Wood toners are similar to clear water repellent, but they include a hint of color to help maintain or restore the natural beauty of wood. They provide similar levels of protection against splitting, warping, cupping and cracking, but tend to last a little longer. There can be color variations due to the age, type and texture of wood.
- Clear wood preservative with UV protection protects your deck and prevents graying. These are often used on cedar and redwood decks to preserve the original color. Oil-based preservatives can last for up to two years.
- Semi-transparent/pigmented stains/sealers These stains contain pigment that protects against sun damage better than a clear preservative. Oil-based semi-transparent stains/sealers provide the most protection, better color retention and longer life.When choosing a stain/sealer, remember that the finished color varies based on the wood itself. If you are applying a new stain/sealer over an old one, choose a color that is similar to or darker than the original. Test the color in an inconspicuous area to ensure proper color. Keep in mind that all wood is different and each piece of wood on a deck can be different in age, type and texture and may show some color variations when using pigmented sealers or stains due to the amount of sealer or stain that is absorbed into the fibers of the wood vs. what remains on the surface of the wood. This is the nature of real wood. Greener wood vs. weathered or aged wood for example dry wood will absorb stain or sealers deeper into the wood fibers than greener wood. Tinted sealers are applied to the deck floor top, step tops and rails only, which is what is exposed to rain and UV rays.Redwood and cedar contain pigments that may bleed to the surface. On these woods, use a dark color stain that makes the bleeding less noticeable. These stains require re-coating every two to three years.
- Solid stain is available but tends to wear quickly when applied to high traffic areas. If you decide to use a solid stain, apply it to rails, deck flooring and benches only. If you use a solid stain on the entire deck, it will require frequent maintenance for peeling and cracking, so choose a semi-transparent stain for main traffic areas. If your deck already has solid stain on it, you must either keep using a solid color or use deck stripper. Deck stripper removes clear and solid/semi-transparent stains.