vapour barrier post drywall

[b-rock106]

So the builder of my house didn't put a vapour barrier up before he drywalled the ceiling of my garage. Now I am looking at ways to have one as well as some r40 or so up in the attic space above my garage. I am not going to remove the drywall due to it being 14 feet up from my garage floor. So I am looking at the most cost effective (cheap) way of creating one. I live in a area where the winter in -40°c in the winter and +30°c in the summer (Ontario, Canada). So I feel that some sort of vapour barrier is needed. So far I have 3 ideas.

1- vapour barrier paint then just r22 between joists and not leave area heated 24/7.
2- layer of styrofoam insulation then blow in for r40 or so.
3- spray foam then blow in (hire it out and spend way to much money) for r40 or so.

The area is to work on everything from cars/metal/wood/electrical and anything the boy and I want to try. Wife also parks in the empty bay when I am not working in there.

Any other ideas? Input?

Thanks

 

[cowboy73]

I'd probably go with #2. You can seal the edges of Styrofoam to the ceiling joists with cans of spray foam. Cut the sheets of foam so they fit nice and tight. You could get buy with 1/2" or 3/4" foam. 1/2" would be easier to squeeze in between ceiling joist. I wouldn't go real thick with the foam because blow in insulation is a lot cheaper.

 

[CTyankee]

Couldn't you just lay some plastic down before you insulate the attic space?

 

[b-rock106]

CTyankee - my understanding is the air gaps create issues.

 

[beakie]

I'm in Ontario, east 1hour of GTA.

IF you are going to heat it at all, insulate as much as you can. Walls & Attic both.
I would go with option #3, or #1 if you spend the time and effort to lay the vapour barrier (vb) properly. Loose so it gets into the corner, but also tapped ao it actually is a VB.

#4 would be to have those who fudged up correct their mistake (providing you asked for VB initially)

#2 Might work, but depending on your roof pitch, trying to get into every nook & cranny with a tiny can (and there will be lots of little cans for this job) would ****.



#3 you know it's done right, you can blow the loose stuff in yourself (HD buy X # of bales, get machine for free)

 

[myredracer]

When it comes to a house, a vapor barrier is important. Besides moisture getting into framing leading to rot and mold, moisture in insulation can significantly reduce the R value.

But your situation is not as bad as it may seem. A garage is not a place where there is a significant amount of moisture as compared to a house. There is some debate out there as to whether or not a vapour barrier is even a good idea in a house as in this article. http://www.ecohome.net/guide/painting-vapour-barrier It may be that in a garage a vapour barrier isn't a necessity.

The solution is to use a vapour barrier primer. There is one that supposedly meets Code for permeance (in a house I assume) as in this article by John Eakes. http://joneakes.com/jons-fixit-database/1614-Vapour-barrier-paint-it-does-exist-it-does-work Then use any insulation material of your choice.

FWIW, both of the above articles related to Ontario.

Along with vapour barrier primer, you want to ensure any penetrations through the ceiling are sealed up with caulking. You also want the attic space to be well ventilated.

 

[walrus]

So the builder of my house didn't put a vapour barrier up before he drywalled the ceiling of my garage. Now I am looking at ways to have one as well as some r40 or so up in the attic space above my garage. I am not going to remove the drywall due to it being 14 feet up from my garage floor. So I am looking at the most cost effective (cheap) way of creating one. I live in a area where the winter in -40°c in the winter and +30°c in the summer (Ontario, Canada). So I feel that some sort of vapour barrier is needed. So far I have 3 ideas.

1- vapour barrier paint then just r22 between joists and not leave area heated 24/7.
2- layer of styrofoam insulation then blow in for r40 or so.
3- spray foam then blow in (hire it out and spend way to much money) for r40 or so.

The area is to work on everything from cars/metal/wood/electrical and anything the boy and I want to try. Wife also parks in the empty bay when I am not working in there.

Any other ideas? Input?

Thanks

Is the space above ceiling ventilated, are you using the space above the ceiling or is just trusses? Ventilation should take care of it. Insulate it well and whatever moisture goes out the vents.

 

[pstnbly]

My vote #3

 

[Nowater]

Spray foam also air seals, and you may get by with just a 1/2" (10 to 15 mm) coating on drywall. That is my first choice.

After that you could blow in insulation with a rental blower.

Oil base paint is supposed to work almost as well as the plastic. I don't know about the permeability of oil base primer on your drywall. That could be worth looking in to.

Maybe line the work side of the drywall with plastic and then install a metal ceiling like others here have done.

I wonder is a coat of shellac would act as a vapor barrier. Shellac is supposed to be very resistant to water, but I don't know.

 

[b-rock106]

Is the space above ceiling ventilated, are you using the space above the ceiling or is just trusses? Ventilation should take care of it. Insulate it well and whatever moisture goes out the vents.

It is just empty space, so just trusses and roof with vents.

 

[b-rock106]

When it comes to a house, a vapor barrier is important. Besides moisture getting into framing leading to rot and mold, moisture in insulation can significantly reduce the R value.

But your situation is not as bad as it may seem. A garage is not a place where there is a significant amount of moisture as compared to a house. There is some debate out there as to whether or not a vapour barrier is even a good idea in a house as in this article. http://www.ecohome.net/guide/painting-vapour-barrier It may be that in a garage a vapour barrier isn't a necessity.

The solution is to use a vapour barrier primer. There is one that supposedly meets Code for permeance (in a house I assume) as in this article by John Eakes. http://joneakes.com/jons-fixit-database/1614-Vapour-barrier-paint-it-does-exist-it-does-work Then use any insulation material of your choice.

FWIW, both of the above articles related to Ontario.

Along with vapour barrier primer, you want to ensure any penetrations through the ceiling are sealed up with caulking. You also want the attic space to be well ventilated.

My pre-research had those two links catch my interest. That what I am thinking the oil based primer that is listed as a vapour barrier.

 

[walrus]

It is just empty space, so just trusses and roof with vents.

I'd think blowing r 40 cellulose up there would be fine. Closed cell foam on the sheet rock and then cellulose would work great. Make sure all penetrations are sealed.

 

[Rod N]

I'd think putting up vapour barrier and another layer of drywall would be less work than crawling around in your attic.

 

[b-rock106]

I'd think putting up vapour barrier and another layer of drywall would be less work than crawling around in your attic.

No way to get drywall up unless I rent a scissor lift. I am ok with work, if it works and save $$$

 

[bczygan]

Did he put vapor barrier on the walls?

 

[Dick in Wisconsin]

What does code require? If code requires VB, then have him come back, pull the drywall down, and redo it. Or have him pay for the spray foam.

 

[b-rock106]

The two house walls yes. Vapour is inside house as its the warm side. Garage side is just drywall. That's why the paint on vapour is starting to win in my mind.

 

[b-rock106]

What does code require? If code requires VB, then have him come back, pull the drywall down, and redo it. Or have him pay for the spray foam.

"code" was what he did at time of building it (7 years ago). Lots has changed since then.

 

[Rod N]

No way to get drywall up unless I rent a scissor lift. I am ok with work, if it works and save $$$

What about a lighter metal ceiling? I use a mobile scaffold with a ladder on top and it worked pretty well.

 

[CTyankee]

CTyankee - my understanding is the air gaps create issues.

JMO, but I'm not seeing this as a big deal. People put up unfaced batts all the time and then plastic. There are bound to be some air gaps. You should be able to carefully lay out and staple the plastic over the joists and down into the bays ans then insulate. Yeah, the joists will be on the opposite side, but again not a big deal IMO.

 

[Jess]

I'm on the others side of the known world from you, but with our wet climate, the garage can be damp. Mine was like yours, with no insulation or vapour barrier on the garage ceiling or exterior walls. I was going to drop it all redo it but after some discussion with a contractor friend, we used vapour barrier paint on the ceiling, cut 20" strips of poly and put them down on the attic side of the drywall and used acoustic sealant along each ceiling joist closest to the drywall. Once that was done, I put down 2 layers of R20 6" batts and called it quits. I have yet to get at the walls which we will drop, insulate and hang new drywall. The garage is way warmer than before and it was less work that taking down the door tracks and old ceiling and replacing. Its still damp in there from the cars but we don't normally heat it either.

 

[Kpaige]

A friend of mine built a large shop and garage. The entire thing is done with vapor barrier paint as the insulation is spray foam and with spray foam poly is not supposed to be used. Been 12 yrs has no issues.

 

[speed bump]

I put down a 6 mil vapor barrier over the top of the studs and then blew several inches of cellulose.

 

[BADSIX]

around here we sheetrock the overhead then insulate with bats or blow in no vapor barrier. we have soffit and roof vents to ventilate the antic area. i've been in homes around here that are over 40 years old constructed this way and they have no moisture problems.
Jay D.

 

[Dick in Wisconsin]

around here we sheetrock the overhead then insulate with bats or blow in no vapor barrier. we have soffit and roof vents to ventilate the antic area. i've been in homes around here that are over 40 years old constructed this way and they have no moisture problems.
Jay D.

Huh. I would have expected problems.

 

[b-rock106]

A friend of mine built a large shop and garage. The entire thing is done with vapor barrier paint as the insulation is spray foam and with spray foam poly is not supposed to be used. Been 12 yrs has no issues.

That's good to hear.

 

[b-rock106]

around here we sheetrock the overhead then insulate with bats or blow in no vapor barrier. we have soffit and roof vents to ventilate the antic area. i've been in homes around here that are over 40 years old constructed this way and they have no moisture problems.
Jay D.

What type of temp do you get?

 

[BADSIX]

On the coast here summers are 60s to high 70s winters upper 20s to 60s. it's really all over the place, right now its in the upper 60s last week lower 40s. my home and shop are sheet rocked 5/8 on the overhead then about 20" of blow in no vapor barrier. I have a small storage area in the house attic and its always dry no signs of moisture same with the attic above the shop. i have been in homes were there is no soffit and roof vents .my boy had one and yes it was damp and musty, sweaty sometimes in the attic, it needs to ventilate.
Jay D.

 

[Toolfool]

Drywall subcontractors here shoot a coat of PVA (polyvinyl acetate) primer over the finished drywall face. It meets code as a vapor barrier.

 

[b-rock106]

Sounds to me that I am making a mountain out of a mole hill.

Got to check out Home Depot for the vapour paint.

 

[ishiboo]

Believe it or not, taped and mudded drywall is basically air tight as it is. I would just insulate as planned.