Adding a roof drain

Exterior · Window Wells · printed page 346 (PDF page 347)

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Book index entries

Adding a Drain to a Flat Roof Drainage – for Flat Roofs – Adding Adding Downspout – and Gutter Gutter and Downspout

Text in the illustration

old roof drain
new roof drain
roof joists
wall framing
add new roof drain at low spot
A
extend drain through roof cavity to outside (or box pipe in if space is limited)
B
connect to new downspout on outside wall
C
cross section

Generated explanation

A cross section of a flat roof shows roof joists supported by wall framing, an existing roof drain, and a new drain at a roof low spot. The roof profile has depressions, with water shown collecting away from the old drain. The new drain connects through an elbow to a pipe extending through the roof cavity and out through the exterior wall. Outside, another elbow directs flow into a new downspout. The annotations present this as a drainage improvement and note that the pipe can be boxed in if space is limited.