An outdoor living space such as a deck must be able to handle a great deal of abuse over the years. Rain, snow and ice, abrasion from foot traffic and furniture, and many hours of direct sunlight day after day are reasons why it is important to choose the right kind of deck finish for this outdoor room.

To make matters worse, the joints between the numerous parts of a deck retain moisture long after a recent rainfall leaving the wood at the mercy of rot, mildew, algae formation and wood eating insects. In order to deal with these problems, deck finish manufacturers offer a wide variety of product formulations that include sealers, preservatives, UV-light inhibitors, pigments and resins.

Some are oil based and are especially effective at penetrating the wood. Some are acrylic and form a film over the surface of the wood. Others are a mixture of the two. Some finishes are more popular than others because of manufacturer advertising. The trick is to do the reasearch and select the finsh best suited to the wood and local climate.

Clear sealers or water repellent preservatives are the most popular choice for newly built decks. They are especially created to protect the wood from moisture thereby saving it from repeated cycles of soaking up water and then drying out. Any wood left unprotected will eventually crack, warp, cup, splinter or check.

Sealers need to be reapplied regularly in order to remain effective. This could be yearly or longer depending upon the quality of the sealer. Homeowners must realize that even when a sealer finish is applied the wood will likely weather to a grey color. Water repellent preservatives have the added advantage of containing a fungicide to fight the onset of mildew.

Transparent stains or toners offer more protection than clear sealers. They have the advantage of deepening and enhancing the color of the wood while still allowing the grain to be visible. Transparent stain finishes applied to pressure treated wood can approximate the look of more expensive wood materials such as redwood or cedar.

The best and most effective products in this deck finish category penetrate the wood surface. They protect the wood from damaging UV light and mildew and leave a substantial top surface layer to resist moisture. Transparent stains or toners are relatively expensive finishes but will retain the original color of most woods if they are applied strictly according to the manufacturer's instructions.

Exotic tropical hardwoods such as Ipe or mahogany are dense with natural oils and do not absorb penetrating transparent stains as well as woods that are softer. They can be allowed to weather to a teak-like grey or treated with a finish specifically formulated and designed to maintain the original wood color.

Semitransparent stains contain more pigment that transparent stains. They do a much better job of disguising wood imperfections and unattractive grain patterns. Oil based and alkyd based versions of semitransparent stains are very effective because they penetrate the wood better than acrylic formulated products. All are readily available in a wide variety of wood tones and colors.

Solid stains are more heavily pigmented than semitransparent stains to the point where they resemble thinned paint. They offer superior protection against UV rays and are able to hide the color and the grain of the wood. Solid stains are available in a wide variety of colors. Water based solid stain products are easier to clean while oil based formulas generally last for longer periods of time.

Deck and porch paints are different from many stains in that they are film forming products. This results in superior UV and moisture protection. It is also great for camouflaging lesser grades of lumber. The disadvantage is that the paint may blister and peel and will eventually show wear in higher foot traffic areas. Use paint if a bright gloss or semgloss finish is desired to match or complement paint on the exterior of the house.

Acrylic and alkyd based paints are available and are most effective when applied over an oil based primer. To improve slip resistance, mix the paint with clean sand. Keep painted decks swept free of dirt as it wears finishes away faster or place outdoor carpets along heavily travelled traffic areas. Sand and recoat when necessary.

Preservatives are specially formulated by manufacturers to prevent rot, fungal growth and decay. Some varieties also are designed to protect against wood-boring insects. Preservatives are especially recommended for treating untreated wood. They are also handy for treating the cut ends of pressure treated lumber on site during construction.

Preservatives are not finishes by themselves. However, they may be sold in combination with sealers in order to provide moisture protection as well as making them a 1 step finish. Some preservatives can be used before the application of paint for additional protection against rot and decay.

The rule of thumb for the application of a deck finish is to be generous. The idea is for the liquid to saturate the wood fibers. As always it is wise to follow the manufacturer's instructions regarding applying the product and observe all warnings. In some cases it may be necessary to wear a face mask, eye protection or rubber gloves and a long sleeved shirt in order to minimize skin irritation and protect against splashes and drips.

Failure to apply some type of protective deck finish to the wood will undoubtedly lead to problems down the road and will affect the aesthetic appearance of the deck. It's always better to be safe than sorry especially when it comes to applying a deck finish.