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Roof Sheathing Cuts

Roof Sheathing Cuts

#1
11-27-06, 09:06 AM
Member
Join Date: Dec 2005
Posts: 66
Roof Sheathing Cuts

I will be sheathing a roof on a flat roof garage with 3/4" osb. The long dimension of the sheathing (4X8) will be put on perpendicular to the long dimension of the roof (across the joists). The long dimension of the roof will be 20' 4". That means five runs of the 4' wide osb which will leave an uncovered strip of 4" (give or take since I will leave a 1/8" gap between the edges of the sheets).

Is it okay to cut such a narrow strip (4") to fill in the space or should I have six runs of osb with two of the runs cut a little over 2 feet so I have wider pieces? That seems like a lot of wasted board.

If I can go narrow, should this strip run on one or the other end of the roof or should I sheath from either end with the big pieces and leave the narrow strip across the middle of the roof?

Thanks,
Jeff

#2
11-29-06, 07:19 AM
Member
Join Date: Feb 2006
Location: USA
Posts: 6,379
Sheathing Cuts

What is the short dimension of the roof?

If the long dimension is 20'4", then 2 8 ft. sheets plus 52 inches would make a run. Depending on the joist spacing, you could start the next run with all but a few inches of the left-over piece from the first run.

#3
11-29-06, 09:25 AM
Member
Join Date: Dec 2005
Posts: 66
Roof Sheathing Cuts

The roof will be 20'4" by 17'4". I wanted to put the long dimension of the OSB across the joists because I thought it would be better structurally, but I could run it the other way if it won't make a difference. In that case I would have four runs of the OSB going with the joists and have 16" left over that would span two joists center to center. The joists will be 16" oc. Does this sound okay?

Same question as before, should I put the narrow (16") piece down the center of the roof, on an outer edge or does it make any difference?

Thanks.

#4
11-30-06, 05:54 AM
Member
Join Date: Feb 2006
Location: USA
Posts: 6,379
Osb

You are correct about running the long dimension of the OSB perpendicular to the joists. Stagger the end joints rather than having them all on the same joist. The narrow piece of OSB needs to be supported on all four sides. This may require addding some additional blocking between the joists for support. I would use the narrow piece at the side rather than down the center. Good luck with your project.