OSB for interior walls - do I need an expansion gap?

[sevensandeights]

I am putting up OSB on the interior of my garage and am wondering if I should leave an expansion gap around each edge. The OSB has something stamped on it that says to leave an 1/8" gap on all sides but it measures as a true 4'x8' so if I left a gap then sooner or later I would start missing studs.

It is a stick built garage on top of a cinder block foundation and the walls consist of the following (from outside to inside):

1.)vertical steel siding
2.) 2"x4" girts on 2' centers (perpendicular to the studs)
3.) 2"x6"x11' studs on 16" centers

I am using 7/16" OSB and the garage will be heated with radiant in-floor heat but not until next year. I live in the northwest corner of Pennsylvania and we do get a fair amount of humidity in the summer time. The garage will be fully insulated with R-19 batts in the sidewalls and R-38 cellulose in the ceiling. All of the insulatation should be in place withing the next month.

 

[toolfreak]

Yes, my brother thought he didn't need to gap the edges and when it started to warm up the walls waved at him.

 

[DGC15]

X2 on the gap. Absolutely necessary ! Top and bottom also

 

[PassnThru]

I have OSB on my walls and on my ceiling. I have no gap and I have no issues with waving or anything else. Of course, I painted my OSB. One coat of primer and two top coats. The back side is unfinished but it is also against the vapor barrier on the insulation. My real world experience is that it is not an issue without gaps. As with everything, YMMV.

 

[Bull]

I am also using 7/16 OSB to do the inside of my Geobarn. I made that choice after reading a couple threads on here, neither of which mentioned any need for a gap. So, I hope I wont need one, because I haven't been leaving one! I have been caulking the seams prior to priming and painting, for a bit of a more finished appearance, too.

 

[ishiboo]

Definitely need the expansion gap - fill it with painters caulk if you're painting, or tan caulk if you're not. Some people may get lucky but varying humidity, temperature swings, etc will definitely cause it to expand/contract.

 

[sevensandeights]

For all of those who are using gaps - what are you doing about hitting studs after putting up 4 or 5 sheets? My walls are 60' long so it is a real concern.

The OSB I bought (made by Georgia Pacific) measures dead on at 48" x 96" so I would have to rip a 3/16" off the corner sheet and then 1/8" off every sheet after than or let it go for a few studs and then take 1" of one sheet to get back to the center of the stud. That certainly does not seem right.

 

[Dragster Racer]

No gaps, and no problems after two years.

 

[walrus]

No gap here, not in the ceilings or the walls. No issues here

 

[garagejunkie]

Gaps?I didn't know I was supposed to leave gaps.Been up for 3 yrs & looks great.

 

[WNYflyer]

I believe GP's OSB panels are supposed to come from the mill at 7'-11 7/8" to allow for the 1/8" gap with like a tolerence of 0" over and -1/8" under. If your panels are truely 8'-0" as you said then I would say they don't meet GP's own spec. and I would probably be looking to return them.

 

[PassnThru]

I'll expand on my previous post with some more detail. My garage is 24X32 so the longest no-gap span I have is 32 feet. My garage has a natural gas heater in it but it does not run when I'm not in there. Over a year, I'd say the garage ranges in temperature between the low thirties and 100 degrees. The humidity here seems to range between 0 and 300 percent (yes - that's a joke - but we hit 100 often and it feels even worse than that). The OSB has also been up for 7 years. Are my walls and ceiling perfectly straight at all times? No - they aren't. But I seem to recall that they weren't before I put the OSB up either. I forgot to check the box for 100% straight lumber before they started. Everything expands and contracts with temperature - that's a scientific fact. The key is how much and so far it hasn't been enough to be noticeable for me.

 

[Abbott]

No gap here and everything is just fine.

 

[cowboyjosh]

In our AHJ no OSB is allowed for interior garage walls, doesn't matter if the garage is attached or detached, no OSB.

In areas that allow OSB, I have never seen any intentional expansion.

 

[santagary]

I have probably a hundred sheets butted up and no problems in my 80 by 90barn and 66 by 40 garage...never a problem!

 

[moparhunter]

4 yearsno gap alls good here.

 

[moparhunter]

4 years no gap alls good here.

 

[AMCguy]

Because the strands are oriented mostly lengthwise there is very little (if any) expansion lengthwise. You can expect some expansion widthwise. Depending on humidity anywhere from zero to 1/8''. Just sitting in the yard, they may have grown all they are going to. I'd install them tight. Assuming you are running the sheets horizontally, you are only worried about the gap on either side of the middle sheet. If you left a bit of a gap above the top board and below the bottom board I can't see there ever being a problem.

Keep in mind, it is manufactured and marketed as an exterior sheeting, not an interior wall board. The installation instructions are there to give the best results in that application.

 

[nmanitou]

I just installed my interior walls with OSB and no intentional gaps. Some gaps are there due to odd cuts here and there. What AMCguy said seems right to me.

 

[sevensandeights]

I believe GP's OSB panels are supposed to come from the mill at 7'-11 7/8" to allow for the 1/8" gap with like a tolerence of 0" over and -1/8" under. If your panels are truely 8'-0" as you said then I would say they don't meet GP's own spec. and I would probably be looking to return them.

I just measured again and started at the 2" mark on the tape to eliminate any error with the end clip. The length was dead on at 96" and the width was 47-15/16".

Do other OSB manufacturers not require a 1/8" gap or is this just a GP thing?

 

[Wanna Ride]

Here's my experience... I live in central Illinois. In the summer, it regularly gets to 98 degrees, with 90per cent humidity. In the winter, it often gets down to zero, and may not get above 15 degrees for weeks on end. We get many days of rain in the spring and it can go from highs of 40 degrees one day, to 75 degrees the next. Same thing in the fall. We often have a good accumulation of snow on the ground by December 1st.

I have a well-insulated 40' x 30' garage, a with a gas furnace that I keep regulated at about 50 degrees in the winter. I don't turn o nthe furnace until it gets down below freezing for a couple days.

I built my garage back in about '97. as soon as the framing was completed, and the outside was sheathed and roofed, I immediately moved inside and sheathed the interior walls with 7/16" OSB. I butted it all up tight, no gaps horizontally or vertically. I've never experienced a single problem anywhere with buckling, rising, etc. I left it unpainted for about 10 years and then painted it a couple years ago. I put on two coats of primer and then two coats of paint.

 

[DzNuts]

I put my osb up last winter(extremely dry time), and this summer I noticed that around the window (that isn't trimmed) it was bowing away. Other wise when looking down the wall, bowing isn't noticable. For the people that put osb up and don't see any bowing, I wonder if its cause they put it up in the middle of the summer (in high humidity so they were already fully expanded) or if they just don't notice it.
I can't help you on how to account for the gap as my longest wall was just 24'. But I would recommend leaving a gap. I may end running a circular saw up the wall putting a blade width inbetween each sheet. Woulda been easier to do it in the first place.

Ryan D

 

[walrus]

For the people that put osb up and don't see any bowing, I wonder if its cause they put it up in the middle of the summer (in high humidity so they were already fully expanded)

I put mine up in the middle of Winter. Very Dry here in winter(plus wood stove for heat which drys it out more) and this was as hot and humid a summer as we've ever had in Maine. My Shop is extremely well insulated and my OSB is painted with oil based Kilz and 2 coast of Latex paint. No issues with bowing as of yet

 

[rasit]

Seems some people have a problem and others don't, which makes me wonder what different attachment methods might have been used. Nailed, screwed, with or without glue, horizontal, verticle? Although I only did one
24' wall, I layed it horizontally, screwed the perimeter with one screw in the field each stud, no glue, one year ago with no problems so far. A friend of mine did his whole garage, vertical, screwed perimeter with double tap each stud one foot centers, no glue and it looks terrible.

 

[jwith68]

Mine was put in tight, attached with 2 1/2" nails out of a framing nailer, on 24" centers. The sheets are vertical. It was primed with 2 coats of exterior primer, then one coat of good quality exterior latex paint. The shop is well insulated, but is allowed to get up to ~85° in the summer, and as low as 45° in the winter. I have had zero issues over 7 years, and would not hesitate to do it that way again.
We did Dad's shop the same way, but he is not heating or cooling it. Again, no issues. FWIW, both were done during the winter, and were unheated while the walls were being covered.

 

[Leeboy20]

No gaps for me( and some of sheets/pieces i had to hammer int place they were so snug) .....Primed and painted, 2 years and going strong

 

[dirttracker18]

No gaps in mine, 30 X 36 with 12' walls and 2 coats of white stain (saved a bundle on primer and paint!) screwed not nailed and horizontal.
No issues at all after 3 years.

 

[T1320T]

Interesting thread. Are you guys hangin your OSB w the smooth or rough side in??

 

[Leeboy20]

Smooth for me, and primed and painted right over the little stickers....Dont even know they're there. I used wood screws on the ceilings, ran out on the walls, and finished off with drywall screws.

 

[sevensandeights]

Smooth side facing the interior for me.

 

[babzog]

I have OSB on my walls and on my ceiling. I have no gap and I have no issues with waving or anything else. Of course, I painted my OSB. One coat of primer and two top coats. The back side is unfinished but it is also against the vapor barrier on the insulation. My real world experience is that it is not an issue without gaps. As with everything, YMMV.

+1. OSB in the garage is tight and flat after 20yrs. So, that's how I'm doing the finishing in my shop.

 

[rodnok1]

I think it might depend on how dry/wet studs are when you put it up, on a building that has been up awhile and wood is dry **** up against everything, but remember window wood might actually swell more than the OSB. Bowing/waves is probably due more to stud quality and warping than the OSB. Hell I have OSB outside on building painted that hasn't warped in 3 years.

 

[ishiboo]

I think it might depend on how dry/wet studs are when you put it up, on a building that has been up awhile and wood is dry **** up against everything, but remember window wood might actually swell more than the OSB. Bowing/waves is probably due more to stud quality and warping than the OSB. Hell I have OSB outside on building painted that hasn't warped in 3 years.

One of those things that for 19 out of 20 people they will have no issues, but to risk hanging several dozen sheets of OSB, perhaps hung with glue and/or lots of nails, and having them all warp... I'd rather just stick the gap between them!

You could run clear PVC hose for all your natural gas lines and 19 out of 20 people wouldn't have an issue too... Obviously the end result would be a lot more painful than having some bowed walls...

 

[Falcon67]

FWIW - I've been pricing materials and McCoys lists 1/2 drywall at 4.79 and Lowes lists 1/4 OSB at $7 each.

 

[ishiboo]

FWIW - I've been pricing materials and McCoys lists 1/2 drywall at 4.79 and Lowes lists 1/4 OSB at $7 each.

Here both Menards and Lowes are at $3.55/sheet for 1/2 drywall, and OSB is at $6.47/sheet for 7/16". No need to price quarter inch - its rarely cheaper than 7/16 and less than half as strong.

I think there is a big durability advantage to OSB which is why people are speccing it, not because it's cheaper. (After finishing, it still is... unless your time is worthless )

 

[Falcon67]

Time value depends on whether the wife is pricing it or me. I can certainly see the advantage to the OSB. I used some 1/4 in parts of my shop and it has worked well. I like drywall - but I don't care much for tape and bed work!

 

[Josh Bremer]

I believe GP's OSB panels are supposed to come from the mill at 7'-11 7/8" to allow for the 1/8" gap with like a tolerence of 0" over and -1/8" under. If your panels are truely 8'-0" as you said then I would say they don't meet GP's own spec. and I would probably be looking to return them.

Wow! You're kidding right?

 

[Josh Bremer]

Here's my experience... I live in central Illinois. In the summer, it regularly gets to 98 degrees, with 90per cent humidity. In the winter, it often gets down to zero, and may not get above 15 degrees for weeks on end. We get many days of rain in the spring and it can go from highs of 40 degrees one day, to 75 degrees the next. Same thing in the fall. We often have a good accumulation of snow on the ground by December 1st.

I have a well-insulated 40' x 30' garage, a with a gas furnace that I keep regulated at about 50 degrees in the winter. I don't turn o nthe furnace until it gets down below freezing for a couple days.

I built my garage back in about '97. as soon as the framing was completed, and the outside was sheathed and roofed, I immediately moved inside and sheathed the interior walls with 7/16" OSB. I butted it all up tight, no gaps horizontally or vertically. I've never experienced a single problem anywhere with buckling, rising, etc. I left it unpainted for about 10 years and then painted it a couple years ago. I put on two coats of primer and then two coats of paint.

Now this is a helpful post. If you don't know what you are talking about DON'T clutter up the forum.

 

[rcayot]

wood expands across the grain, OSB although it says oriented, it is oriented in teh flat plane of the board, not longways or across ways. Thus the tendency to expand or contract with moisture will be couteracted by another piece of ship that is oriented another direction.

Of course there could be other reasons why OSB could expand or contract, it is just that moisture is not going to be one, at least in terms of humidity, WET is another story.


Roger

 

[jwillis]

I watched This Old House Hour last Friday (did you guys see it?) and they were putting on OSB for the roof that was to be used as a deck later on. They butted the sheets up against each other. I would think that OSB would have enough glue in it that would keep it from expanding and contracting. Now, regular plywood might be another thing. It seems to deteriorate over time. If you think you need a gap, then leave a gap. You can always put in another stud whenever you need it. Good luck.