R-value: OSB vs Drywall

[38Chevy454]

Interesting information regarding R-value of OSB vs drywall. It appears that OSB is slightly better.

I searched and found the following values:
7/16 OSB = .51, .60, .71 (not very good consistency); all values were greater than drywall though.
Drywall = .45 (pretty standardized on this from several sources).

I am getting closer to finishing out the inside walls of my detached garage and heve been leaning to OSB. Out of curiosity I wondered if there was any difference between insulating value of OSB and drywall. Granted it is not a significant difference, but I thought others might be interested to see these results.

[sneezer41]

wood is generically 1 1/4 per inch, giving the .51 number the best guess. Both are pretty close to zero. Drywall has thermal mass, which may help more than its insulating value, and it is not flammable, another point in its favor. At any rate the.06 difference is not enough to change any heatloss calcs

[38Chevy454]

Originally Posted by sneezer41

wood is generically 1 1/4 per inch, giving the .51 number the best guess. Both are pretty close to zero. Drywall has thermal mass, which may help more than its insulating value, and it is not flammable, another point in its favor. At any rate the.06 difference is not enough to change any heatloss calcs

I was not actually factoring anything based on these numbers, it was just curiosity to see what the differences were. My detached garage will not be heated full time, only when I am out there doing work. My calculation for heat required is very basic.

[fflintstone]

I am a big fan of OSB (painted white) for an interior wall for a shop. It is much more forgiving if you bang something into it. You can hang something anywhere and do not have to worry about finding a stud. As the previous post says drywall has a fire rating though, and would be a code requirement on an attached garage.

[DuluthMN]

For what it's worth my father-in-law said that there is absolutely no R-value in OSB or Drywall.

[redsky49]

For a nominal 1/2" thickness, the insulating values for gypsum board, plywood, waferboard, particle board, etc. are similar and the slight differences between the various materials are essentially insignificant. The ASHRAE listed R factors range from 0.41 to 0.62.

Every component in a wall or roof structure contributes to insulation. A standard asphalt shingle for example has an R factor of 0.30. Hollow backed vinyl siding over equals 0.61. Even the boundary layer of air that lies against the material (surface film) adds to the total assembly performance.

More to the point is the fire rating possible with gypsum board, particularly if the garage abuts the residence. Not possible with wood materials. Even a detached garage may be better constructed with gyp board with flammable materials, welding, etc. being present.

Additional factors that would indicate one material over another include installation costs; resistance to denting/damage; ability to take a finish; the need for structural strength to support equipment, etc.; local costs and availability; height of the walls (big sheets of OSB might be a handful); etc.

Check with local standards and requirements,as well as your insurance carrier as to the preferred material(s).

As always, offered only as opinion

[Busted_Knuckles]

As a former volunteer fire fighter, from what Ive seen (the only structure fires we went to where garage related), I wouldn't even dream of OSB in a garage... WOW, is my comment. I know there are thousands of garages/shops sheathed in OSB, my neighbors is...and I see it all the time here, but it don't take nothing to start a fire in a garage, last thing I would want is a combustible on all sides, you readily remove your window of time to get a handle on it, or you can stand back and watch it burn,,... sheet rock is the only way to go, just my 2 cents.

[z28toz06]

Originally Posted by fflintstone

I am a big fan of OSB (painted white) for an interior wall for a shop. It is much more forgiving if you bang something into it. You can hang something anywhere and do not have to worry about finding a stud. As the previous post says drywall has a fire rating though, and would be a code requirement on an attached garage.

what is the fire rating difference between the two?

[fflintstone]

Originally Posted by z28toz06

what is the fire rating difference between the two?

GYPSUM DOES NOT BURN AT ALL (it is the principle lining in gun safes)
The paper on gypsum does burn and then the wallboard crumbles.

Once it reaches an ignition temperature, OSB will burn very very hot very very quickly.

From a fire standpoint (only) there is no comparison. Drywall good OSB bad

I would never put OSB in a welding area. I am hoping to use cement backer board (nothing at all to burn) in my shop.

You can twist, bend, drop, and bump into, ETC OSB with no damage. Not true for drywall. Drywall will snap under its own weight. Score one for OSB during instalation.

Assuming the shop has a structural exterior sheeting, if you ad OSB to the interior wall you create a shear wall, essentially a large box beam.

Which is more likely to happen? Fire or a hurricane? I am not god, I can minimize fire danger but I cant control wind.

It is a personal decision, if not dictated by local code. If it is an attached garage it should be all drywall. I have never owned an attached garage. I always envision a shop as a separate structure.

[Falcon67]

> Fire or hurricane
Out hee-ya, it's fire or tornado. I've been considering making part of the coming shop expansion into a kind of "safe room" for a tornado hidie-hole. However, the best hidie from that is a real hole in the ground.

This rock vs OSB is an ongoing debate in my head too. I had not thought about the fire danger - thanks for bringing that into the discussion.

If one had a dedicated welding corner, it would be easy enough to wrap the wall area with .040 aluminum as a spark shield. My little weld area uses a 2x4 piece of steel shelving as a wall shield with a spare one used as a side shield. I plan to "upgrade" to a real metal moveable table sometime soon.

[D.J.]

OSB is not fire rated and 5/8" Gyp board is fire rated, is what I've always heard but I don't know the numbers off hand.
________
NEW MEXICO MEDICAL MARIJUANA DISPENSARY

[ScaldedDog]

I mentioned this on here before, but I went with both. It was more expensive, of course, but I wanted to do everything I could to keep the noise I make inside the garage. The only downside is that studs are harder to find when you really need one.

Mark

[Busted_Knuckles]

Originally Posted by D.J.

OSB is not fire rated and 5/8" Gyp board is fire rated, is what I've always heard but I don't know the numbers off hand.

I knew at one time, seems to me its 1hr with 5/8s. I did some building in Chicago, we had to wrap the posts holding up the store in 4 wraps of 5/8s rock ! so if there was a fire, they could put it out before the post would collapse. We we got done with the store, about the only thing combustible was the merchandise.

[38Chevy454]

Well, I know that OSB is obviously not fire rated. My point in the orig post was that there is not really any significant difference as far as insulating value of OSB vs drywall.

I know about fire differences, strength and appearance issues to name some other areas that OSB and drywall can be compared. Thanks for the inputs from all, but I am not trying to start a fire rating discussion.

[Mellotron]

I suppose if you're bent to do OSB in a garage or shop and you want safety you could get a fire sprinkler system installed?

[cowboyjosh]

Sheet rock is the only way to go, and its code where I live. I know in allot of areas OSB is allowed.

I know a fella in the midwest who almost lost his garage and potentially the house because the OSB caught fire after a pile of dirty/ oily shop rags spontaneously combusted in a freaking plastic trash can, the only reason the fire didn't take off as he slumbered away in the attached house was because there wasn't enough air, no windows in the garage, pretty new insulated steel garage door, etc; still the fire burnt thru the OSB and burnt the face off the insulation and burnt thru some ROMEX wiring before burning out due to lack of oxygen; he was damn lucky; but they still had a sooty mess to clean up and his pride is wounded because he is that guy who is always "perfect".

I remember in shop class in High School if we didn't put the rags in the designated metal container, it was a automatic detention; but I digress and I got off topic.

Go with Drywall in your garage. I don't think nor do I know for certain if their is any nominal R value difference between OSB and DRYWALL.

[jklingel]

osb off-gasses nasty stuff and swells when it gets wet. it is not that good of a product, really. i'd suggest you use plywood instead of osb; i, too, used both.

[fflintstone]

Originally Posted by jklingel

osb off-gasses nasty stuff and swells when it gets wet. it is not that good of a product, really. i'd suggest you use plywood instead of osb; i, too, used both.

Plywood off gasses as well, just not as much. It also doesn’t like water, and drywall falls apart when it gets wet. I think plywood is a superior product but it caries a premium price well over double OSB.
Right now in my neck of the woods drywall is $5.50 a sheet, OSB is $7, and plywood is over $15 a sheet. For my shop it would cost a fortune.

[Sparks4184]

Maybe I'm a bit late on this one, but IMO sheet rock AND insulation is the way to go. You can get some excellent R values using either fire-retardant fiberglas OR foam in your wall cavities b/t the studs. As far as keeping track of stud locations, just having a floor plan and using 16" OC should help you do that even if you tape and put drywall mud over the screws. Aside from producing a good thermal barrier, you'll really insulate the shop noise too, especially with foam and a piece of 3/4 " sound board behind your drywall.
Mark

[walrus]

Originally Posted by fflintstone

Plywood off gasses as well,

Dry wall can off gas also.