Built up roofing membrane - 4 ply

Roofing · Built-Up Roofing (Tar and Gravel) · printed page 23 (PDF page 24)

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Book index entries

Membrane – Four-ply Four-ply Built-up Roof Membrane Roofing – Four-ply Built-up Built-up Roofing

Text in the illustration

for UV protection
gravel for UV protection
flood coat of asphalt
exposure=9"
note:
for 3 ply-
exposure=12"
for 2 ply-
exposure=18"
36"
roofing felts
(36" wide)
hot asphalt
base layer of
felt (dry laid)
nailed to deck
with minimum
2" overlap at
edges
downward
slope of roof
roof sheathing

Generated explanation

The illustration shows a cutaway of a four-ply built-up roofing membrane over roof sheathing. A dry-laid felt base layer is nailed to the deck with a minimum 2-inch overlap at its edges. Above this base, 36-inch-wide roofing felts overlap with a 9-inch exposure and are embedded in hot asphalt; curled-back ends reveal the successive layers. A flood coat of asphalt and gravel surfacing provide the top finish, with the gravel identified as UV protection. Notes specify 12-inch exposure for three-ply roofing and 18-inch exposure for two-ply roofing, and an arrow indicates the downward roof slope.

Components

roof sheathing dry-laid felt base layer roofing felt plies hot asphalt interlayers asphalt flood coat gravel surfacing

Materials

roofing felt asphalt gravel