How To Waterproof A Deck

When a leak is detected inside a property and a “waterproof” deck over living area is the culprit, it is usually at a joint. There are two parts to waterproofing a deck, and these are sometimes two different trades.

Every deck, or type of deck requires different systems to allow for a water tight seal. With decks such as the one in the picture, it can be tricky to permanently keep the water out. This type of cantilever deck has multiple penetrations from the house that must be properly sealed. This deck is actually not a waterproof deck, which is where it gets tricky. If the deck were waterproof and had stucco below, there would be no chance of the water getting in through the cantilever floor joists. An extensive amount of flashing on all sides of each beam, complete with curfing was necessary to protect from water intrusion. These flashings, also known as deck metals, are installed prior to the waterproof coating.

It is very important not to overlook areas such as this for water intrusion, especially when there is no detail on the plans for the particular situation. Most plans will come with waterproofing instructions; when they don’t, unexpected trouble can occur.