Choosing the Right Finish for your Deck
A deck can be like a room onto the great outdoors. It won't be long before you'll be enjoying a summer of barbecuing, sunbathing and gazing at the stars as the perfume from your garden floats in on a breeze…
In preparation for these activities, now is the time to examine your deck for damage and weathering. Trouble spots will most likely be at ground level, board ends, joints and any areas where water is likely to be trapped. Exposure to the elements day after day also means most decks require new finishing at least once a year. How often you need to refinish will depend on your climate and the type of wood used to construct your deck. A quick test to see if it's necessary is the water test. Sprinkle a few drops of water on the wood. If the water beads, the finish is fine. If the deck soaks it up readily, it's time to refinish.
Rot, mildew, fungus, greying wood, cracks and warps all await unprotected wood decks. Prevention is essential. Don't heed the advice of hardware salespeople who tell you to let a new deck age and dry for a season before finishing. New decks require only 2-4 weeks, depending on rainfall, in order to reach the proper moisture level. At that point, applying the correct finish will greatly extend the life of your deck and save you money in the long run.
If your deck was constructed with pressure-treated wood it has weather resistant properties but it still requires finishing. Just as with any other type of wood deck, it should be coated with water-repellent and regularly stained or painted. Unfinished, pressure-treated wood tends to turn grey quite quickly.
When deciding which finish to use consider the following benefits and limitations of various components:
- Water repellent: Wax, usually paraffin, is suspended in a binder to prevent water from soaking into the wood. Water repellent products require annual or biannual applications.
- Preservatives: These typically include a mildew inhibitor or insecticide to prevent fungi and mildew growth as well as to repel insects such as termites.
- Ultraviolet stabilisers: UV rays can penetrate 1/64 of an inch (or 1/21cm) into the wood. This turns wood grey and weakens it so that other cracking or warping problems develop. UV stabilisers are generally not as effective as pigment in preventing UV damage.
- Pigment: It provides the colour found in paint, solid-colour stain and semitransparent stain. Pigment protects well against UV and water damage but ages quickly on decks.
It is important to note that while the "wet look" of varnish is attractive it does not weather well. Sun and rain can penetrate resulting in discoloration. Paint with preservative is the best overall protection. There are always new products coming on the market which perform multiple functions and are available in a growing number of colours.
A sanding pole is a great way to prepare your deck for finishing without doing a lot of bending. Sanding is an essential first step in achieving even application of stain or paint.
Deck finishes can be applied with a brush, pad, roller, or sprayer. Paint stores sell inexpensive pump sprayers similar to those used by gardeners. Rollers and sprayers are quick, but wood will absorb more finish, thus protecting it better, if the finish is worked in with a brush. It is recommended that you use a brush for the first coat of finish on a new deck.
Be sure to use the right brush for the type of finish you are applying. Natural bristle brushes are usually recommended for solvent-based (oil-based) finishes; synthetic brushes are better for water-based finishes.
Whichever finish or method of application you choose be sure to let each coat dry for at least three days. Also remember that the best protection is prevention. Refinishing your deck once or twice a year is a small price to pay for your ringside seat on the great outdoors!