How to Care for Your Deck
Regular cleaning and proper maintenance are the best ways to ensure that your decks look as good as possible for as long as possible. Don't let stains set, sweep often and remember to clean between the boards to remove leaves and other debris.
Step One: Clean
Remove the furniture and any plants you can move, sweep, then water down and protect any plants you can't move, including ones in the ground nearby. Don't work in direct, hot sun as it could cause streaking and uneven application of materials, and if you've covered your plants, they could be damaged.
There are many special products to clean, brighten and prepare the deck for finishing. Don't use bleach alone to clean a deck because it only removes mildew stains and doesn't treat ground-in dirt and wood fibres that have been degraded by the sun. Also, there is research that indicates that finishes will fail much more quickly on surfaces that have been cleaned with chlorine based bleach alone. If the deck is fairly clean, just use a deck cleaner according to the manufacturer's directions, and rinse thoroughly by hosing and brushing. If the deck is very dirty, pressure-washing may be needed. Never seal a dirty deck and don't apply a finish until the deck has dried for at least two days of warm weather. Many professionals will use a moisture meter to be certain the deck is dry enough for finishing.
Step Two: Sand and Make Repairs
Lightly sand any weathered areas that remain from Step One, or any raised grain, splinters, pencil marks, lumber stamps, superficial burns or any other marks that could show through the finish. Correct or repair anything that's causing damage, like placement of sprinkler heads, or the dark places where planters, furniture or a barbeque have had prolonged contact with the deck. Try not to let anything sit in exactly the same spot for very long, or it may need extra treatment.
Step Three: Finish and Preserve
Once careful prep work is done, including a final sweep, the deck is ready for the finish. Be sure that you don't apply the finish in the heat of the day, or when the deck feels hot to the touch as it could lead to streaking, and even worse, premature failure of the finish. As a general rule the temperature of the surface shouldn't exceed 24 degrees.
A Few Words About Finishes
Products that only waterproof your deck provide very limited, short term protection. We prefer materials specifically designed for decks that contain agents to penetrate, preserve and protect the wood, block ultraviolet light, waterproof and protect against biological damage.
Oil Based vs Water Based Finishes
The two major categories of finishes are oil (alkyd resin) based and water (latex or waterborne) based finishes, and each has its advantages and disadvantages. Latex or waterborne coatings are flexible, film finishes that are designed to breathe and allow water to pass through. Oil or solvent based finishes are brittle and designed to seal. Oil based products applied by hand will penetrate deeper into wood fibres on a deck to create a superior barrier and enhance the wood's texture, grain and overall beauty. Because they don't build a film on the surface, they also are less likely to bubble or peel. Look for finishes that contain alkyd resins for durability and resistance to abrasion, and linseed oil for better penetration into the wood. Finishes that claim superior protection because they will cause water to bead indicate only the presence of wax in the product, and wax has limited durability. A sheeting action is more important as it indicates that the finish has really penetrated into the wood. In general, water based products offer better mildew resistance and colour retention. They have less odour and are easier to use, and the clean up is easier too. The durability and effectiveness of these products has improved considerably in recent years, and there are some new products that are oil/water based hybrids that offer some of the benefits of each. On existing decks, the choice of which product is better will be determined by what finish was used previously and the condition of the wood.
Clear Finishes vs Finishes with Colour
There are three basic types of finishes: clear, semi-transparent and solid body stains. Each has its advantages and disadvantages. A clear finish will allow most of the wood's natural colour and texture to show, but it will provide the least protection and you will have to reapply the finish more often. A semi-transparent finish or a wood toner with even a little bit of colour will give a more attractive, uniform look and protect better than a clear finish. The pigment in a semi-transparent stain filters the sun's ultraviolet rays to protect the wood while some wood toners contain special trans-oxide pigments that polarize these rays and throw them off the deck at an angle. The effect you get from a semi-transparent stain or toner will be determined by the type and colour of the finish and the kind of wood it's being applied to. Pressure-treated lumber accepts a finish differently from redwood or cedar, so do samples on all the woods in your deck. There are also special products that are designed for pressure treated wood. A solid body finish will provide the maximum protection for the wood, but the disadvantages are that it hides much more of the natural colour and texture and it is more likely to lift. The amount of preparation needed before you can re-stain areas where a solid finish has failed is more extensive than with a clear or semi-transparent finish, because a solid stain is more like a coating. We don't recommend paint for the floor of a deck. Because there are so many products to choose from, we suggest you talk with the experts at your local paint store so they can help you determine which finish is best for your deck.
How Long Will the Finish Last?
Much depends on your situation and the product you choose. You can expect to redo the finish every six months with severe exposures, or every year or two under normal circumstances, if the deck was in good condition to begin with, you've taken very good care of it and you have a little luck. You'll know it's time to redo your deck when it starts to look weathered or turn grey, or if water no longer sheets.