About to start tearing down the drywall in the garage to add insulation to the walls. 4x8 OSB is currently running almost $5/sheet less than drywall. Any reason why I should not just use OSB instead of drywall, besides the smooth look of finished drywall?

I think it's a great idea. Will make hanging things (lightweight unless it's at a stud) that much easier too. I'd suggest to roll it white or a light color. A full room/garage of OSB is going to be fairly dark.

Yeah, been doing some research (watching YouTube) on it and found this video. Pretty much sold me that I can still get the final look I want, even with OSB.

I sheathed my current garage (unfinished 1977 build) in half and 3/4 ply. No question about OSB opposed to sheet rock. All day everyday!

I've sheathed an old barn, for a shop, with 3/8" sheathing and I sheathed a garage with 7/16" OSB. Both worked great. OSB will 'drink' a lot of paint. Highly recommend you put a good prime coat on before you hang it. Let the primer dry a little extra time before painting. Primer can be a cheap store brand

You can rent a blow in insulation machine and drill 4 inch holes on each cavity to insulate the walls without tearing the rock out. Average 20x20 garage would be about 60 4 inch holes to patch.


As far as osb I have put it in many garages trimmed out with cedar and I like the look. I have also put 4x8 smart siding inside on garages but its about $40 a sheet versus $10 right now.

Hopefully someone more knowledgeable than me can chime in, but there are code requirements for garage walls. I think the wall shared with the house has to be drywall.

https://www.howtolookatahouse.com/Blog/Entries/2022/3/what-are-the-minimum-code-requirements-for-a-residential-garage.html

https://garagemadesimple.com/code-for-drywall-in-a-garage/

You are correct. any wall that is adjacent to the house must have at least 1/2" gyp board on it and any doors must be 20 minute fire rated. That would not stop anyone from putting OSB on the walls that are not common to the living areas.

Thanks for clarifying. I knew code covered. I also know you have ceiling restrictions if there is living above. I appreciate you replying to add clarity.

You are welcome. You are also correct in that if there is living area above the garage it must have 5/8" gyp board on it. .

Where are you located that sheets of OSB are $5 less than drywall?

I think it's a good idea as long as you are keeping sheetrock in the right places to ensure the fire rating.

Beyond the fire rating, if this is an attached garage would CO be a concern with the gaps between the OSB sheets not being sealed? I realize you shouldn't be running your car in the garage for extended periods of time, but I wouldn't want to find out how long is too long and it be because the living space wasn't properly sealed off from the garage.

YellAg2004 said:

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Where are you located that sheets of OSB are $5 less than drywall?

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This is in Dallas.

• 4x8 Drywall (1/2") $12.84
• 4x8 OSB (7/16") $7.75

Interesting...

In Houston, drywall is $11.21 and OSB is $9.70, at least per HD's site.

Code requires a fire rating for the Garage wall adjacent to living space IRC R302.6. Drywall is rated. Unless you buy "fire rated" plywood or OSB, you have an unrated wall that is a fire hazard.

txag2008 said:

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YellAg2004 said:

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Where are you located that sheets of OSB are $5 less than drywall?

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This is in Dallas.

• 4x8 Drywall (1/2") $12.84
• 4x8 OSB (7/16") $7.75

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I so not want to say that you are wrong

It is 9.31 when o buy 2 pallera of osb

$7.75 online & have seen it in stores.


BCS

Does anyone know if I just install the OSB on to the existing drywall on the shared wall, do I lose my fire rating? I have sourced 5/8 fire-rated OSB and LP Flameblock's installation detail shows that I still get a 1-hour rating with the coated side installed against the studs. This would give me the uniform OSB look. But if I can just put normal OSB over drywall that would be the most cost effective and time saving method.