Waterproof decks over living space have proven to be a popular architectural detail. While the functionality of the deck over living space is nice, things turn ugly without proper waterproofing. A very large percentage of flat top roof decks end up leaking within the first several years due to improper design and/or use of the wrong materials. Using a waterproof deck contractor is a good starting point. This is a specialized field that even most general contractors don’t like to deal with.
Some major considerations in proper deck design include proper slope, a good drainage scheme, and roof grade flashing details around all edges and walls. Without these crucial elements in place, it really does not matter what waterproofing system you employ. Using a trained waterproof deck expert will dramatically reduce your risk when installing a deck over living space.
Design of the deck over living space should always be done in consultation with the waterproof deck contractor, before construction begins. Framing details, drainage, and floor substrate materials are all needed to compliment the waterproofing system being used. Deck design, waterproofing systems, and tie in trades such as stucco repair are all important.
There are a wide selection of waterproofing systems available on the market today. Two main types are liquid coating systems, and membrane based systems. Generally speaking, the membrane based systems are more durable, have a longer life, and can withstand the movement inherent in wood frame construction. Most failures with liquid coating systems stem from cracks that develop over time due to expansion and contraction. These types of problems are almost non-existent with membrane type systems. One of the most well proven membrane systems is made by Duradek. Many questions arise with respect to tile decks. While this is an entirely different discussion, keep in mind that tile and mortar are not waterproofing systems. Waterproofing must be considered first prior to considering tile, and the system must be designed with tile in mind. Experienced General Contractors can handle all of this for you.
Balconies and second floor decks typically have doors to access the deck. A critical waterproofing detail is to properly flash the door as part of the waterproof deck installation. This detail is known as a door pan flashing. As crucial as this is, it’s often overlooked by less experienced contractors.
In conclusion, second story decks over living space are great features, but must be designed properly. Consulting with a professional waterproof deck contractor expert in advance will prevent many problems that are common to decks that are not planned properly.