Residential Flat Roofing
Flat and low-slope roofing on additions, extensions and modern homes.
Residential Flat Roofing
No flat roof is actually flat. Every one is built with a deliberate fall toward a drain, a scupper or an edge, and the roofs that fail early are almost always the ones where that fall was an afterthought rather than a design decision.
We install TPO, EPDM and modified bitumen on residential low-slope roofs, and we would rather spend the extra day getting the drainage right than come back in three years to a membrane that has spent every rainfall underwater.
What a flat roof has to get right
- A membrane matched to the roof: TPO, EPDM or modified bitumen
- Tapered insulation to build positive fall toward drainage
- Properly detailed edges, parapets and wall junctions
- Drains, scuppers and overflow provision that actually work
- Correction of existing ponding rather than roofing over it
Why flat roofs get a bad reputation
They fail at details, not in the middle. Water sits where the fall is wrong, freezes and thaws through the winter, and works at every edge, upstand and penetration it can reach. A membrane that would have lasted twenty years on a well-drained deck gives up in eight on a badly drained one.
The reputation belongs to bad flat roofs rather than to flat roofs. Built properly, with real fall and honest detailing, they perform perfectly well here.
Drainage is most of the job
Standing water an inch deep weighs a little over five pounds per square foot, and a large pond deflects the deck slightly, which deepens the pond. Left alone that cycle gets worse rather than settling.
Where we find ponding on an existing roof, the fix is tapered insulation to rebuild the fall, or additional drainage, or both. Putting a new membrane over the same puddle is how a roof gets replaced twice.
Questions about residential flat roofing
No, but they are less forgiving than a pitched roof. Snow load, freeze-thaw and ice all punish poor drainage and weak detailing, so the standard of the installation matters more than it would further south.
Fifteen to twenty-five years for a single-ply membrane that drains properly. On a roof that ponds, expect considerably less regardless of which membrane was used.
Sometimes. If the membrane is otherwise sound, adding tapered insulation in the affected area or improving drainage can solve it. We will tell you after inspecting which of the two you are looking at.
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