Placing roof sheathing vertically

Clutchcargo

I'm putting the roof sheathing on my portico The size of each side is 52x65. The ridge length is 52. I was going to put the plywood up there vertically so that I could have the seam siting on a rafter.
I read someplace that roof sheathing should be placed so that the grain of the ply is perpendicular to the rafters. Should I continue to do the roof as I planned or run the ply perpendular to the rafters?

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jiggyjack

I'm assuming you are talking inches. Always run perpendicular to your rafters.

Darylh

Plywood has its 2 outside grains rinning the length of the plywood. One of the resaons you run plywood in the oppisite direction is if you do not it will sag in between the rafters and we also use H clips between the rafters also to help stiffen the sheets.

troubleseeker

Like the other guys said, any type of sheet materials should be run perpendicular to their supports. This goes for drywall also. Many people do not believe that there could be any difference in drywall, but you can see for yourself easily. Cut a 12" piece across the 48" width of the sheet, and cut a 48" piece from a 12" rip of the sheet. Set them across anything so they are supported at the ends, and begin puting equal amounts of weight in the center of each, and compare the sag.

builderr

for such a small roof area, just go with a 3/4 inch plywood just the way you described, and you will have no problems....Would be different if you were talking about something over 8 ft in rafter length, but heavier plywood would deftinitely work. If doubtful, add solid blocking.
David

the roofing god

perpendicular,or add cats(wood blocks)at the ends and seams of panels for support,perpendicular is always better though