question on insulating a block garage

[ratrodder123]

hey guys! i have a old concrete block garage that i am insulating and my question is this. i put up plastic sheeting against the block, studded my walls and then put up faced insulation. will i have moisture issues in the insulation? the garage will only get heated when i am going to work in it. i am drywalling over this. its a detatched garage. i put up the plastic to keep any moisture from the block from hitting the studs or insulation but i am now wondering if the faced insulation is going to trap moisture somehow. if so would putting slices in the facing prevent it or am i just worrying too much? i havent hung the drywall yet. i appreciate any help yins guys can give me!

 

[pop pop]

Yep. Perfect trap.

 

[ishiboo]

hey guys! i have a old concrete block garage that i am insulating and my question is this. i put up plastic sheeting against the block, studded my walls and then put up faced insulation. will i have moisture issues in the insulation? the garage will only get heated when i am going to work in it. i am drywalling over this. its a detatched garage. i put up the plastic to keep any moisture from the block from hitting the studs or insulation but i am now wondering if the faced insulation is going to trap moisture somehow. if so would putting slices in the facing prevent it or am i just worrying too much? i havent hung the drywall yet. i appreciate any help yins guys can give me!

Yup, you've got it backwards. Vapor barrier should have been towards the inside. Had to figure out the "right way" when I started working on my current house which is double-layer brick.

I would pull the insulation down and pull all the vapor barrier out, I don't think some cuts are sufficient.

 

[foss]

Yup, you've got it backwards. Vapor barrier should have been towards the inside. Had to figure out the "right way" when I started working on my current house which is double-layer brick.

I would pull the insulation down and pull all the vapor barrier out, I don't think some cuts are sufficient.

Exactly, You need the vapour barrier over the insulation ,before the drywall.

 

[Treeman]

To me, it sounds like he installed plastic vapor barrier over the cement block wall. Then installed "faced" (vapor barrier) insulation onto the the studded wall.

Isn't he asking if the insulation trapped between the two vapor barriers will trap moisture? The plastic on the cement wall is to protect moisture vapor from moving in from the cement block.

His solution is to slit the insulation vapor barrier on the inside wall to prevent entrapment. They say it is feasible to install a second layer of faced insulation in your attic if you slit the barrier.

This is an interesting conundrum. Depending on location, he may be able to have no vapor barrier. But in general, yes you put it on the warm, interior side.

But, what about a cement wall where there is little way for moisture to move out? What do they do in basements? Even with an interior vapor barrier, and leakage could condense on the cold cement block wall and result in mold. Foam would be a better solution.

 

[ratrodder123]

Thanks for the info guys, after some research and talking to some people I agree that right now the best way to do this would have been foam board insulation, stud the wall, insulate, vapor barrier, drywall. With this garage im gonna keep on with how I did it. The garage will only be heated a handful of days a year and the insulation I have had up for a few months shows no signs of any moisture in it when i pulled it back to take a look. The block walls are exposed to the outside and any wet spots "dry out" to the outside.

 

[71flh]

If its hollow block, and you can access the top, maybe something is available to pour into the cavity?
Just an idea.

 

[ratrodder123]

Well, now all the plastic is coming down. I found a spot of mold. So now I'm pretty much screwed. I am going to cut down all of it. Now what are my options? Put foam board between each stud (the thin stuff that is folded up and I think used for siding underlayment), rolled insulation, plastic, drywall? foam board , no insulation, plastic, drywall? no foam board, plastic over the studs, drywall? Tear down the garage sounds like the best option to me!

 

[jdaallen]

Well, now all the plastic is coming down. I found a spot of mold. So now I'm pretty much screwed. I am going to cut down all of it. Now what are my options? Put foam board between each stud (the thin stuff that is folded up and I think used for siding underlayment), rolled insulation, plastic, drywall? foam board , no insulation, plastic, drywall? no foam board, plastic over the studs, drywall? Tear down the garage sounds like the best option to me!

Your batt insulation is just fine. The wall MUST breath and when you installed the plastic, you stopped the breathing, held moisture, and promoted mold growth. Clean out the mold growth and mist walls with a 10% solution of clorine bleach and 90% water. This will kill most mold spores on the surface. Re insulate with whatever you want then vapor barrier and drywall.

 

[Bent Valve]

Your batt insulation is just fine. The wall MUST breath and when you installed the plastic, you stopped the breathing, held moisture, and promoted mold growth. Clean out the mold growth and mist walls with a 10% solution of clorine bleach and 90% water. This will kill most mold spores on the surface. Re insulate with whatever you want then vapor barrier and drywall.

I would never use bleach. I would use boric acid(roach power). It will kill the mold and all bugs(not spiders) and it will not hurt humans(it's used in eyewash). All fiberglass will mold. The best is cellulose(it has boric acid in it). Next best is thick foam board calked or foamed in.
Good Luck!

 

[impala_631]

I would do the foam boards, they are pricey, but very mold resitant