Advise needed on walls

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Forum topic by TigerFan07 posted 08-02-2017 01:59 AM 1297 views 0 times favorited 25 replies Add to Favorites Watch
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8 posts in 1091 days

08-02-2017 01:59 AM

I have an external garage for a workshop and I am going to sheath the walls. I was going to use drywall, but a friend told me drywall would get mold since it is not conditioned (I am in SC). The walls are insulated with fiberglass.

Do any of you have experience with drywall in an external garage in a humid area? I liked drywall b/c of the fire resistance, but will do OSB if the drywall will grow mold.


25 replies so far

View Loren's profile


10477 posts in 4426 days

#1 posted 08-02-2017 02:10 AM

You can get mold resistant drywall.

View squazo's profile


173 posts in 2423 days

#2 posted 08-02-2017 03:00 AM

it wont mold, mine isnt moldy my friends arent moldy my parents, brothers, uncles, arent moldy. think about how many garages there are that have dry wall and arent air conditioned. I live in Louisiana. Besides OSB will mold all the same.

View msinc's profile


567 posts in 1282 days

#3 posted 08-02-2017 03:58 AM

I would say that if you have a shop that is so high in humidity that the drywall or OSB will mold then you will need to run a dehumidifier or probably not use that building for a wood working shop. Not because of the wood, but because of what it will do to your machines.
There is dry wall and there is fireproof drywall…the fireproof stuff is good, it’s also heavy…it’s also about $3.00 or so more a board, but it is what should be in a garage. The other thing is…South Carolina in the summer…trying to do wood working in a shop with no air conditioning????? Humidity would not be my first concern. If I owned the state of South Carolina and hell…I’d rent out S.C. and live in hell!!!!

View pauljuilleret's profile


107 posts in 2431 days

#4 posted 08-02-2017 11:31 AM

why don’t you use plywood get them with one face sanded and heavy enough that it will allow you to hang stuff where you want it to go. just a thought for you to consider.

View jonah's profile


2122 posts in 4077 days

#5 posted 08-02-2017 11:35 AM

Why is it insulated if it won’t be conditioned space?

View hotbyte's profile


1001 posts in 3753 days

#6 posted 08-02-2017 12:16 PM

I did OSB in my standalone shop because it is smaller and I’m always moving things around, shoving them against wall etc. I figured I would be constantly patching holes in drywall. Plus, I can attach/mount smaller things.

Will you also be using garage for cars and needing to move equipment around?

View Lazyman's profile


5455 posts in 2165 days

#7 posted 08-02-2017 01:33 PM

If there is enough moisture to grow mold, then just about anything you put up may have the same problem, including plywood. Using a mold resistant drywall may actually be better than any of the the alternatives to drywall. You can also get a paint additive that will add a little extra mold resistance as well.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

View TigerFan07's profile


8 posts in 1091 days

#8 posted 08-02-2017 10:12 PM

I guess I should say that it won’t be conditioned all the time. I plan to use a window unit in the summer and space heater in the winter but just while I’m in there to knock the edge off.

Other than fire resistance, does drywall have any advantages? I do like the idea of being able to hang stuff more places with OSB.

If I go with drywall, is it a mistake to leave it unpainted and not taped/mudded (other than the looks)?

View Woodknack's profile


13399 posts in 3158 days

#9 posted 08-02-2017 11:25 PM

When people get mold, it’s often because of condensation from improper moisture barrier, assuming it isn’t a leaky roof or some other really obvious cause. You want to keep moisture out but the walls still need to breath and let moisture escape or you get mold. So drywall will be fine if the wall is constructed correctly. That aside, my walls are wood and I like being able to hang anything anywhere.

-- Rick M,

View TaySC's profile


270 posts in 1111 days

#10 posted 08-02-2017 11:58 PM

I’m in SC and decided to do OSB in my garage. Sheet rock would look better if you take the time to tape it, paste it, sand it and then paint it, but it is definitely easier to ding up than OSB.

Personally, I like the look of OSB and haven’t had any problems with it at all.

Someone else mentioned why insulate it if you aren’t using AC….. for me personally, I wanted the potential to eventually AC it if I like and didn’t want to have to undo what I had already done to insulate after the fact. Insulation is cheap enough that it just made sense to do it while I was putting the OSB up.

View bigJohninvegas's profile


776 posts in 2240 days

#11 posted 08-03-2017 12:04 AM

Rick M, and lazyman are both right. Anything you put over the fiberglass can mold with out the proper vapor barrier.
Where I live its dry, and most everyone has stucco and 2X4 walls on most homes. In general, not a lot of mold hear in the desert, but.
I had mold on the fiberglass insulation when I demoed my shower last year for a remodel. Not a big shock since the shower was falling apart.
There are some really good mold resistant drywall products, and paint out there.
Taping is as important as the vapor barrier. Seals everything up well. Texture and paint is a good protective barrier for the sheet rock. And it too looks good.
You should check and see what is needed for your structure in your area.
Also, you can hang anything from it as long as you find a stud to anchor to. And drywall is super easy to repair and maintain. everything will get a ding and scratch in it. A little mud and paint and it all goes away.
What is your shop constructed from. Block, stucco, etc. Also with unfinished walls. Do you have all the electrical done that you want? My shop/garage was pre finished and insulated. So when I needed to add electical outlets , all the conduit had to be run on the outside of the drywall.
I tried to buy my house with the garage unfinished, but I just could not get the builder to go for it.

-- John

View patcollins's profile


1687 posts in 3643 days

#12 posted 08-03-2017 12:11 AM

Why insulate even though the garage isn’t heated or air conditioned….because it moderates the temperature swings of the garage and reduces sound.

My garage was unfinished, i decided to insulate and put up some cheap paneling (cheapest Lowes had) afterwards the temperature never drops below 50 degrees even on the coldest winter days and on the hottest summer days when I get home from work and open the garage door I can feel the cool air dump out of the garage from 10 ft away.

If drywall is unpainted it will eventually turn a dark brown grocery paper bag color. The ceiling of my garage was not taped, mudded or painted and had turned the same color as a paper bag. Painted it white and now the garage is a lot brighter with the same amount of lights.

View clin's profile


1113 posts in 1774 days

#13 posted 08-03-2017 12:50 AM

Why is it insulated if it won t be conditioned space?

- jonah

Because, even if not heated or cooled, the temperature swings will be much lower through the day. This generally means it will stay cooler in the summer.

I even insulated my storage shed. It probably peaks in the summer 10-15 degrees cooler than the outside. If it were un-insulated, it would be much hotter than outside, due to the sun beating on it. This greatly reduces the temperature swings on the stuff I store in there. So they’ll hold up better over time.

-- Clin

View JBrow's profile


1368 posts in 1698 days

#14 posted 08-03-2017 01:13 PM


If I go with drywall, is it a mistake to leave it unpainted and not taped/mudded (other than the looks)?

My understanding is that drywall that is not taped compromises its fire rating to some degree. Taped with one coat of joint compound should seal things up, but over time, the tape could fail and work loose. Therefore, at least two coats of joint compound would be better than one coat of joint compound if you tape the joints.

The reason I would paint the drywall would be to 1) make the surface reflective and 2) to resist staining. While my garage workshop is painted, I wish I had gone with a more reflective semi-gloss or gloss white paint. The smoother surface makes cleaning a bit easier should you ever wish to remove dust and restore the light reflective properties of the paint in the future. A mildicide could be added to the paint to resist mold.

Some ideas that would make installing heavier items on the wall easier, whether covered with OSB or drywall, are to mark the floor on each side of the wall studs. When the time comes to hang a cabinet, locating the studs would become very easy. In addition to marking the stud locations, some 2×6 or 2×8 blocking could be installed in locations where you envision hanging cabinets and other heavy items before covering the walls. The blocking would allow hanging the cabinets without having to locate studs and then determining where to place the screws inside the cabinet. Of course, one would need to remember where the blocking is horizontally and vertically located.

View r33tc0w's profile


191 posts in 1262 days

#15 posted 08-03-2017 01:23 PM

Goto and place a radiant barrier between the drywall and the exterior. You’ll be suprised how much cooler it’ll be and easier it’ll be to cool if you choose to AC the space

-- Matthew 13:53-58

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