Spaces between decking boards on outdoor decks serve the importation function of drainage. These paces can help prevent puddles from forming and will help the surface dry quicker after snowstorms or rain. Along with the application of home deck waterproofing, the spaces between boards will also help prolong the life of the decking material. If you are hoping to use the space beneath the deck as storage space or additional outdoor living, then you will need to install a barrier that will prevent water from draining to the surface directly below.
Use Downspouts and Deck Membranes: The most popular solution for this is to drape plastic membranes below the decking to form troughs. A gutter is attached to the structure that is just below the downspouts to collect water and then lead it away from the area you want to protect. The deck membranes come in a system that are loosely fastened to the top edge of the deck joints. The downspouts can then fit in between the joists. Decking boards are installed over the top and tape is used to seal the seams.
Under Deck Ceilings: This is a fairly new way of creating a waterproof dry space. It uses aluminum or plastic panels that are designed to catch water that drains though the decking, and moves it away from the area below. There are many different systems for this. The panels should be seamless and be made to the size of the deck, so they will lock together to form leak proof joints. Then a perimeter frame and space nailers are fastened below the deck so the plane of the ceiling will slope slightly away from the house. A system compatible aluminum trough is then fasted below the joist header to carry any runoff to the downspouts that drain to the ground outside the protected area. These systems provide all-in-one drainage that is suitable for areas that are below a deck and are high enough off the ground to provide a sheltered outdoor living space. Other moisture protection measures can be used for ceiling fans and any overhead light fixtures that may be installed to keep the space more comfortable.
Waterproofing Decking Flanges: This is a simpler way to create a waterproof dry space, and by using waterproof decking flanges you can create an effective way to divert water that would normally drain through the spaced deck boards. These flanges are designed to act as spaces between boards and serve as mini gutters to help channel water toward the deck edges. Flanges are available in different sizes to match the edge grooves in place.
By not only using home deck waterproofing methods, but also using one of these methods for a dry space underneath the deck, you can add more functionality and enjoyment to your deck and home.