Waterproofing over living area

[Member1171]

I have a client who wants a garage with a flat roof which he is basically going to use as a deck. He wants to use wood decking. Can someone point me in the right direction on how to waterproof this? I am planning on putting plywood over the framing and place some sort of waterproofing membrane over this, but once the deck screws puncture this, doesn't the membrane lose its purpose?

 

[JAE]

What you want to do is create vertical columns stubbing up from the roof (that is waterproof) and then build a wood deck above the roof some distance.

The columns can be flashed properly to prevent moisture from getting through. Also, the deck should be built in such a way as to allow future access to the roof should a leak occur or a new roof be needed.