Waterproof upper-level deck

Waterproof upper-level deck with waterproof membrane to protect room below
Shell Busey, Special to Vancouver CourierPublished: Wednesday, April 07, 2010

Q: I have a tar and gravel roof and want to create a summer deck. Other than laying down new T&G plywood and fibreglass, is there another solution to finish the area to give me total water protection since there is a finished room under this area?
A: One of the most common methods of waterproofing an upper-level deck is to lay down a waterproof membrane. Fibreglass would not be my first choice for reasons of maintenance and heat.
My suggestion would be to use Duradek Vinyl, which has a 60-ml 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 is 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 2x4 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.
Around the perimeter, it's best to install 4x4 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.