Building a Deck Over a Living Space
If you don't want the roof to leak, careful flashing details and a watertight membrane should be your primary concerns.
Synopsis: How to build an exterior deck over a flat roof so it won’t leak, including details on how roofing membrane and wood components should be layered.
Everyone thinks that roofs are pitched to shed water, but they’re also pitched to shed people. Walking on roofs can ruin the shingles, so flat roofs tempt fate in two ways: They give water a better chance to leak into the house, and they tempt homeowners to build rooftop decks. If not built properly, these decks can cause water problems galore.
When Marie called me over to check out her rooftop patio, I expected the worst. And that’s just what I found. Built over the family room, the deck consisted of a thin concrete slab poured over 2×8 rafters that leaked sideways and down. All in all, it should never have been built, but Marie didn’t want to lose the convenience…