What is Best Membrane to Use for a Roof Top Deck? - December 2nd 2008
Q: I have an existing tar and gravel roof and wish to utilize it as a summer deck. Other than laying down new tar and gravel plywood and fibreglass, can you suggest another solution to finish the area that would give me total water protection since there is a finished room under this area?
A: Fibreglass would not be my first choice for reasons of maintenance and heat. Probably one of the most common methods of waterproofing an upper-level deck is to lay down a waterproof membrane. My suggestion would be to use Duradek vinyl, which has a 60-mil grade that qualifies as a roof membrane and is installed by professional contractors providing a fire-rated, building-code-approved roof deck system.
To begin, remove all the loose gravel from the roof and the perimeter flashing. To prepare for a flat sundeck surface, a sleeper joist system will be required. Calculating the dimension of the sleeper joist will require taking a level off the top of the perimeter facing board and taking a measurement. Use 2 x 4 treated lumber at 16 inches on centre (shimming with treated cedar shingles where required) to give a slope to one or two sides to run water; or proper drains may be required to adapt to existing drains.
If you want to install ceramic tile on a deck, you will require an approved roofing membrane under the ceramic tile. To tile the surface , I would strongly suggest you have a qualified installer take care of this to ensure there are no water leaks or structural integrity issues. Tiledek, by Duradek is an outdoor anti-fracture roofing membrane designed specifically for outdoor tile decks in which the tiles are bonded to the fabric-covered membrane with thinset mortar. However, this system is not available to the do-it-yourself market.
Note: Around the perimeter it is best to install 4 x 4 treated lumber to prepare for secure safety railings such as ProBuilt's Aluminum Do-It-Yourself Railings. Finish surface with tongue-and-groove select fir plywood.
Contact Duradek at 1-866-591-5594 and they will refer you to the appropriate installer in your area.