Spacing of roof sheathing

[Stephen Tashiro]

The spacing for roof sheathing is often given as 1/16 th inch between the edges of adjacent sheets. For plywood, if it is nailed every 8 inches along the joists, what part of the sheet can move that much? Is it just the region away from nails that can expand and contract? Or can the whole sheet move? Does it bend the nails?

[Cliff Rohrabacher]

Laying sheets too close to each other can result in nails popping and buckling.

What moves? Everything.
The trusses, the joists, the nails, the glue, the plywood - - everything responds to thermal and humidity changes.

Well, the nails don't respond to humidity, but what's a few millionths of an inch between friends.

[kenmiller saas]

Roof boards are used for under materials that require solid and continuous support, such as asphalt shingles, composition roofing and metal-sheet roofing, must be laid closed. Closed roof sheathing may also be used for wood shingles. Closed roof boards should preferably be of dressed and matched or shiplap material, 8 inches in width and 1 inch in thickness. Where rood boards are re-used from concrete dormwork, they should be thoroughly cleaned and redried before use.

[Denny Rice]

If you are covering the rafters with OSB or plywood go to the BORG or any other lumber lard and buy a box of H clips. These clips are are made out of steel and are put on the top and bottom of the OSB. These clips are usually spaced at least every 24 inches apart and keep an even 1/8" space between the sheets of plywood or OSB. When I built my garage 20 years ago, I used these clips. They work great.

[Ben Franz]

Don't install sheet goods without a 1/8" spacing such as that provided by the H clips mentioned above. You won't enjoy trying to fix the buckled plywood/OSB, especially if the roof is already installed. DAMHIKT - see signature. I sheathed one roof with 1/2" CDX thats supposed to handle short term rain exposure - didn't tarp it and the resulting amusement park ride surface was a real pain to fix.

[Gene Howe]

Until I found out about the H clips, I used 16 penny nails as spacers.
But to your point, YES you need to space them as well as stagger the seams.
Gene

[Dave Wagner]

Yes, H-Clips. It also help support the board between the joists if on 24" centers, when you are on the roof, shingling, etc...
In our area, you have to consider snow loads too. It adds support and no sagging, etc...