How Do You Handle Drainage So a Deck Doesn't Trap Moisture Against the House?

Hey folks! This is the team at Euro Decks.

Welcome to another Q&A session where we answer questions from you all on the internet.

Today's question is:

"How Do You Handle Drainage So a Deck Doesn't Trap Moisture Against the House?"

Summary:

The owner ties this back to his earlier point about avoiding sealed, synthetic membrane decks, since nothing can stop that type of surface from being ruined by Washington's rainfall. With composite decking boards, however, he says there's very little extra work required. A slight pitch is built into the deck framing to help water run off, especially on second-story or upper-level decks, and the natural spacing between composite boards helps as well. As long as the deck is flashed properly where it attaches to the home and composite decking is used, water issues generally aren't a concern. He notes that water problems really only arise from improper flashing, decks not being attached directly to the house, or the use of solid-surface, synthetic membrane products that naturally hold and absorb water over time.

Answer:

That's a great question. This goes back to the earlier point about different types of products or decks in Washington compared to somewhere like Arizona. Number one is to not do a sealed-surface, synthetic membrane deck, because with the amount of water we get, there's nothing you can do to stop a deck like that from getting ruined by water. Now, if you use composite decking boards, it's really simple, and there's almost nothing extra you need to do. There's a very slight pitch incorporated into the deck framing to help water run off the deck, especially on second-story or upper-level decks. There's also spacing built in between each board, and as long as you flash the deck properly when you attach it to the home, and you use composite decking, you really shouldn't have to worry about water issues. Water issues only become a problem if you're not doing your flashing properly, if you're not attaching the deck directly to the house, or if you're using one of these solid-surface or synthetic membrane products that are naturally going to hold and take in water over time. Doing it the right way from the start, with proper flashing and the right materials, really does prevent the moisture problems that can otherwise build up against the house.