Waterproofing outdoor decks against the elements protects them and maximizes their lifespan. Homeowners can use a few techniques to waterproof their decks, such as investing in sealants or coatings.

While decks tend to have spacing between boards that enables drainage, the water may seep underneath the deck, becoming trapped in vulnerable elements such as wooden joists. Composite boards, offered by various manufacturers, rarely require sealing or waterproofing since warping and rotting are not an issue. With wood boards, it’s important to use a clear sealant that prevents water seepage into porous surfaces.

Seal decks in one- to three-year intervals or anytime water fails to remain on the surface in droplets after it rains. Homeowners have three basic sealer options: water-based sealants are the most expensive, cream-based sealants are in the mid-range, and oil-based sealants are the cheapest. The more costly options are generally safer, less toxic, quicker to dry, and require fewer coats.

A thicker substance, coatings resurface the deck, requiring preparing and cleaning the deck surface before application. Applied like paint and available in various colors, waterproof coatings effectively mask wood splintering and cracks. Still, they are challenging to apply and create a rough, gritty texture when walking barefoot.

A third option is a vinyl membrane, which functions like waterproof flooring and delivers slip resistance. Moreover, it resists mildew, mold, and ultraviolet light. This option eliminates the need to periodically reapply fresh coats. Then, protect the joists and beams underneath deck boards with self-adhesive, non-skid deck flashing.