Expansion gaps for interior plywood?

[go4donuts]

I'm planning on sheeting the inside of my 24x24 double garage with 1/2 inch or 5/8 G1S plywood, running across the studs. This is a detached garage in cold Canada that will see outdoor temperatures of -40 degrees F, to +100 degrees F. I am making the garage heat-able but will not be keeping it heated constantly during the winter.

Any thoughts on whether I should leave, say, 1/8" gaps at the joints and fill them with paintable caulk? Also, if I left expansion gaps, would that be just on the **** joints, or all around?

 

[Neighbor]

yes leave a gap for expansion of about thickness of a framing nail.

But,,,,, 5/8 thick??? That's really, really heavy. I would think 3/8 or 7/16 would be sufficient.

OSB is a lot heavier than regular plywood.

 

[bigguns69]

I lined my 36 x 50 x 15 building with 7/16 OSB with the smooth side down with no gap other than from misalignment and painted white. That was 5 years ago and no signs of buckling anywhere. I went 16" on center and used deck screws to attach.

As a mechanical engineer, I don't understand the whole gap for expansion idea in this application. If my panel has fastners that hold it to the frame work, then in order for the panel to expand or contract, the structural material needs to move, which since they are of similar material, and connected, they should grow or contract at the same rate, which should never cause an end to end panel collision. Plus at the outer edges of the panel there is usually a fastner close by so the unsupported length is maybe 1" so the growth length opportunity is so small for wood the gap isn't necessary. It's not like bolting aluminum to steel with different expansion rates.

 

[go4donuts]

yes leave a gap for expansion of about thickness of a framing nail.

But,,,,, 5/8 thick??? That's really, really heavy. I would think 3/8 or 7/16 would be sufficient.

OSB is a lot heavier than regular plywood.

My post might have been confusing. I mentioned OSB because I had seen a post about expansion gaps with OSB, but to clarify, I am thinking using 1/2" or 5/8" plywood. I want it thick enough that I can fire a screw into it to hang items. I have deleted the reference to OSB.

 

[go4donuts]

As a mechanical engineer, I don't understand the whole gap for expansion idea in this application. If my panel has fastners that hold it to the frame work, then in order for the panel to expand or contract, the structural material needs to move, which since they are of similar material, and connected, they should grow or contract at the same rate.

Yeah, I was thinking exactly the same thing. But I've seen this suggestion made in so many applications, I thought there must be something I don't understand going on. Thought I better ask.

 

[buddyboy]

measure your sheets. if they are a little short they were cut for gaps.

1/8th inch

if they are full size and you put in gaps you could start overrunning your studs.

 

[Architorture]

I lined my 36 x 50 x 15 building with 7/16 OSB with the smooth side down with no gap other than from misalignment and painted white. That was 5 years ago and no signs of buckling anywhere. I went 16" on center and used deck screws to attach.

As a mechanical engineer, I don't understand the whole gap for expansion idea in this application. If my panel has fastners that hold it to the frame work, then in order for the panel to expand or contract, the structural material needs to move, which since they are of similar material, and connected, they should grow or contract at the same rate, which should never cause an end to end panel collision. Plus at the outer edges of the panel there is usually a fastner close by so the unsupported length is maybe 1" so the growth length opportunity is so small for wood the gap isn't necessary. It's not like bolting aluminum to steel with different expansion rates.

although they both happen to be made of wood in general, they aren't in the same format and end up with very different expressions of expansion. the grain in a stud is going to all run in the same direction, the grain in a sheet of plywood will alternate from layer to layer....they aren't likely to expand in predominately the same direction or in the same amount.

the same would be true of poured concrete and concrete block...same materials, but different expressions of expansion (or contraction as the case may be)

 

[jasong70]

I would tongue and grove them, or half lap combined with a vertical batten glued on one side...that is it aesthetics were important. The biggest issue is to lap your plywood on a stud and if you space them out too much, it won't align.