Staggering side laps in single ply modified bitumen roofs

Roofing · Roll Roofing · printed page 25 (PDF page 26)

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Staggering Side Laps in Single-ply Side Laps – Staggered, in Modified Bitumen Roofs Modified Bitumen Roof

Text in the illustration

39" (1 m)
the side laps of adjacent rows should be staggered so that stresses do not concentrate along a single line
watch for opened seams if the laps have not been staggered
membrane may be peel-and-stick mopped or torched
typically installed with a 3" overlap at the edges and sides
roof sheathing
downward slope of roof

Generated explanation

The illustration shows overlapping strips of single-ply modified bitumen roofing over roof sheathing, with several edges lifted to reveal the layers. A circled area highlights staggered lap joints in adjacent rows, which distribute stresses rather than concentrating them along one line. Annotations identify a 39-inch (1 m) membrane width and a typical 3-inch overlap at edges and sides. The membrane may be peel-and-stick, mopped, or torched, and an arrow indicates the downward roof slope. A warning advises checking for opened seams where laps have not been staggered.

Related illustrations

0097

Single ply modified bitumen roof

· p. 24

The illustration shows parallel strips of single-ply modified bitumen roofing laid over roof sheathing, with several ends curled back to expose the underlying assembly. The membrane strips are marked as 39 inches (1 m) w