Replacing small piece of drywall with existing moisture barrier

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garyb
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Replacing small piece of drywall with existing moisture barrier

Post by garyb » Sat Nov 18, 2017 11:15 am

Hi all,

While replacing the baseboard heater in our bathroom, I noticed some black mold on the drywall in the corner by the tub, so I sawed it out (thanks to my experience from Shannon's video on sawing drywall! :D).

Looks like the drywall we have in there is green, with a black paper backing. (I assume this is the moisture-resistant stuff?) My question is since we already have that moisture barrier behind the drywall (the plastic sheeting stuff) will a 7" x 7" piece of non-moisture-resistant drywall be ok to use instead?

Only reason I ask is because we have that moisture barrier, I have some of the non-moisture-resistant drywall on-hand, and I'm not sure if stores sell small patches of the moisture-resistant stuff. (I don't need a huge sheet of it!)

Image

Thanks!!

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Shannon
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Re: Replacing small piece of drywall with existing moisture barrier

Post by Shannon » Sat Nov 18, 2017 6:06 pm

The poly vapour barrier actually is totally different from the drywall. Moisture resistant drywall is formulated so the paper surface is less likely to promote mould growth. moisture resistant drywall would be the better choice here. Also cleaning the mould form the poly surface is wise since you have it exposed .
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garyb
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Re: Replacing small piece of drywall with existing moisture barrier

Post by garyb » Sat Nov 18, 2017 6:08 pm

Thanks Shannon, what about “normal” drywall with Kilz oil based stain blocker over it? :)

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Shannon
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Re: Replacing small piece of drywall with existing moisture barrier

Post by Shannon » Sat Nov 18, 2017 11:40 pm

Not really sure that does the same thing other than making it less permeable from the outer surface? But then again if that was moisture resistant drywall originally that you removed obviously there was an issue with it also by looking at the mould on the vapour barrier, so who knows for sure ? Was there a bad seal against the tub or over flower tub at sometime?
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garyb
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Re: Replacing small piece of drywall with existing moisture barrier

Post by garyb » Sat Nov 18, 2017 11:58 pm

Shannon wrote:
Sat Nov 18, 2017 11:40 pm
Not really sure that does the same thing other than making it less permeable from the outer surface? But then again if that was moisture resistant drywall originally that you removed obviously there was an issue with it also by looking at the mould on the vapour barrier, so who knows for sure ? Was there a bad seal against the tub or over flower tub at sometime?
Ok cool, I'll pick up a sheet of the moisture resistant stuff tomorrow. I don't have a truck so I'll just have to cut it in half a couple of times to fit it in my car.

It's caulked where it meets the tile/tub, but it must have gotten a bunch of water on it some time in the past, before we moved in, yeah.

Anyway thanks!

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Shannon
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Re: Replacing small piece of drywall with existing moisture barrier

Post by Shannon » Sun Nov 19, 2017 9:57 pm

Maybe you could buy a damaged sheet for less since you do not need the entire thing??
Visit a house being drywalled and see if you can buy or have a piece of scrap?
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Aaron
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Re: Replacing small piece of drywall with existing moisture barrier

Post by Aaron » Mon Nov 20, 2017 2:03 am

Menards down here sells piles of scrap drywall for super cheap. Probably salvaging busted pieces from accidents moving it around in the store. You just have to sort through the pile to get the type and thickness you want.

garyb
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Re: Replacing small piece of drywall with existing moisture barrier

Post by garyb » Mon Nov 20, 2017 2:11 am

I just stopped by my local Ace and got a whole sheet... I figured I'll prolly need it for other patches later on down the road. :)

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A. Spruce
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Re: Replacing small piece of drywall with existing moisture barrier

Post by A. Spruce » Mon Nov 20, 2017 10:52 am

Evil Orange and Lowe's sells partial sheets, which is nice if you only need a little bit, but by the time you buy one or two of those you could have purchase a whole sheet for less. Same goes for plywood too.
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garyb
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Re: Replacing small piece of drywall with existing moisture barrier

Post by garyb » Mon Nov 20, 2017 1:36 pm

A. Spruce wrote:
Mon Nov 20, 2017 10:52 am
Evil Orange and Lowe's sells partial sheets, which is nice if you only need a little bit, but by the time you buy one or two of those you could have purchase a whole sheet for less. Same goes for plywood too.
Right but not the moisture-resistant kind of drywall, at least around here. :(

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A. Spruce
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Re: Replacing small piece of drywall with existing moisture barrier

Post by A. Spruce » Mon Nov 20, 2017 1:41 pm

Now you're just being picky . . . ;) ;) :mrgreen:

I saw your comment earlier about probably needing to do other patches later on. MR drywall is perfectly fine to use anywhere in the house, should you need patch material. You probably figured that out already, but thought I'd float that out there just the same. 8-)
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