Osb – Do I start the first sheet 5/8″ out from edge

roofing

I am putting on a flat roof on a building that is 24 x 44 block. The roof consists of : top and bottom sill plate, face plate, 9 – 4×4 treated posts for support, 2x10x12 joist every 16" on center with a 2x4x12 wedged to allow for slope of 1 3/4" per 12 foot side, 5/8" osb, roof felt, tar, and rolled roofing. My question is when I start the osb should I leave a 5/8" gap on the edge between the osb and the face plate? I know there is a 1/8" gap between the osb but what about the first piece so it will line up to the 16" on center joists for nailing?

Best Answer

I would say that it depends on the drip-edge and how the fascia are laid out on the edge. Galvanized drip-edge should easily span a 5/8" gap, and will certainly be less waste than flushing up the sheathing and cutting off 15" for starter courses. It mainly depends on having the drip-edge supported on both sides and having adequate room for nailing it down.

This will work:

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This won't:

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