Because of the challenge of protecting a waterproof deck against weather and wear, if you are considering waterproofing your deck, it will be important for you to have a good understanding of the various types of materials available.
In comparing prospective coatings, there is more to consider than just protection against moisture and wear.
If you want your deck to retain its natural grain appearance, you'll need to use a product that is transparent and is not easily marred, dulled, or scratched. If you prefer a satin finish, there are products that can give your deck a varnish-like appearance much like that of wood furniture. This natural appearance may be particularly desirable if you've built your deck with redwood or cedar.
For older decks there are coverings that have the appearance of paint but perform like a stain. With these coverings there's no film to peel away when the coating ages and is exposed to weather. They are breathable and flexible when applied to bare wood and will require maintenance more frequently if exposed to direct sunshine.
Surfaces exposed to pedestrian traffic and are more vulnerable to scratches made by the furniture, sand, mud, and gritty dirt tracked onto it by dogs and children. They will need a coating that is less likely to wear and will require less frequent re-painting.
For decking that is 2 feet or less off the ground, you should consider only a non-film forming wood protector and sealer that will protect your deck from moisture and fungus.
Porch and deck floors are typically difficult surfaces to protect. Softer coatings wear away more easily but tolerate expansion better. Conversely, coatings that resist wear are less able to handle expansion and contraction of the wood, so these are tradeoff's you should take into account.
If your deck is exposed to direct sun light, you should use a product that resists degradation from UV (the sun's ultraviolet rays).
Deck Construction Material
Some wood has a high oil content that can sometimes interfere with bonding of certain types of coverings such as those that are water based and are not compatible with oils or oil based coatings.
Most deck coatings have their own distinct performance and application characteristics, so it will be important for you to match these characteristics against factors such as those mentioned above.
In general, the four types of coverings from which you can typically choose, include:
- Polyurethanes – this covering holds up well in moisture, has a hard finish, wears well, is flexible and works well with decks where there is movement. But it deteriorates more quickly when exposed to UV. It emits a strong chemical odor, and it requires a primer to be applied prior to the urethane coat.
- Acrylics – they have a water base and deteriorate more readily in puddling water. They are not as durable in heavy wear, and are more versatile in allowing creation of various color shades.
- Epoxies – these are harder than acrylics, but when compared with urethanes they are more vulnerable to UV, are more brittle, and are not as hard.
- Silicones – don't offer good waterproofing protection and they are hard to cover with other coating materials. UV has a tendency to degrade silicones and sometimes turns their coating yellow. However, they are flexible, and work better with decks that are more likely to flex or move. They work better for vertical surfaces, penetrate wood surfaces better, and don't need a primer.
With all the variables related to these deck coatings, you will need considerable preparation in learning characteristics of your deck and how these characteristics match up with those of the various types of deck coatings.