Garage: vapour barier + insulation + air tight

3648 Views 12 Replies 4 Participants Last post by jklingel, Dec 29, 2012

Carling

Discussion Starter · Dec 28, 2012 (Edited)

Hi,

I have a 2 car garage in a raised bungalow that has 2 bedrooms sitting right above it. The house was built in the 70's and the previous owner just had insulation with some styrofoam sheets as a ceiling.

There are a few issues:

1. Bedrooms are colder than the rest of the house.
2. Gas fumes/paint/etc get into the house and basement.
3. Garage door/working in garage noise travels through out the house.

I ripped everything out of the joists and put Roxul R22 everywhere. Now I'd like to put in a vapour barrier, but from my understanding the vapour barrier has to be on the hot side of the joists (under the floor plywood of the bedrooms) not on the garage ceiling side.

What can I do to properly install the vapour barrier? Do I remove all insulation and put poly in there and over the joists then put insulation back and drywall?

I am not quite sure. So far with the insulation being in place the rooms are warmer and it's quieter inside, but fumes still travel through out the home. I'd like to properly seal this ceiling/garage before drywalling.

Thanks.

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Windows on Wash

· #2 · Dec 28, 2012

Where is the home located?

Why do you think you need a vapor barrier? Stopping the air flow is key and the vapor is a secondary concern.

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Carling

Discussion Starter · #3 · Dec 28, 2012

Windows on Wash said:
Where is the home located?

Why do you think you need a vapor barrier? Stopping the air flow is key and the vapor is a secondary concern.

The home is located in Toronto, Canada.

Objective is for fumes not to get into the house and to reduce noise. I was under the impression a vapour barrier is a must.

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Windows on Wash

· #4 · Dec 29, 2012

Some pictures would certainly help in this case get you more directed feedback.

The vapor barrier would be required on the warm side and if the rooms are over the garage, that is going to be impossible to do with common poly type materials.

Air sealing and making sure the air barrier is complete and unbroken will eliminate the fume issue.

Spray and rigid foams are 2 prominent arrows in the quiver of the weatherization/air sealing approach.

Pictures and notes will help with the feedback.

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Gary in WA

· #5 · Dec 29, 2012

Don't park in the garage until the Type-X (fire-rated) drywall is air-sealed to the joists and fire-taped per most garage-living- space-above minimum codes; http://www.buildingscience.com/documents/information-sheets/air-barriers-airtight-drywall-approach/

http://publicecodes.cyberregs.com/icod/irc/2009/icod_irc_2009_3_par058.htm

"Makes for warmer floors—this is the same detail that should be used under bedrooms over garages."---- Fig. #7;(under the drywall, after the Roxul); http://www.buildingscience.com/documents/insights/bsi-009-new-light-in-crawlspaces/

Gary

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Carling

Discussion Starter · #6 · Dec 29, 2012

Pic of house + garage and bedrooms:

After ripping all the nonsense out of it:

Roxul R22

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Windows on Wash

· #7 · Dec 29, 2012

I would seal everything up (i.e. large gaps, crack, etc) with foam, fill the interstitial spaces with Roxul like you are doing, cover the joists with 1-2" of rigid foam, and drywall (making sure its air tight).

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jklingel

· #8 · Dec 29, 2012

Another idea for you that I got from a good builder: Have an exhaust fan (and fresh air inlet) run for 20 minutes when the garage door is closed. Taking the bulk of the fumes out is better than trying to keep them all in the garage. Just a thought.

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Carling

Discussion Starter · #9 · Dec 29, 2012

Windows on Wash said:
I would seal everything up (i.e. large gaps, crack, etc) with foam, fill the interstitial spaces with Roxul like you are doing, cover the joists with 1-2" of rigid foam, and drywall (making sure its air tight).

So I don't need a vapour barrier in this case? I can leave the roxul in there, fill all large gaps with this stuff??

Then rigid foam with house wrap tape and then drywall over?

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Carling

Discussion Starter · #10 · Dec 29, 2012

Additional pics of the garage.

I wanted to expose some of the areas I am not sure how to fix, I assume this is where I'd be spraying foam?

I wrapped the bulkhead with poly temporary and shoved insulation in there to keep the hvac pipes warm. They are the longest runs in the house that heat the bedrooms above the garage and they obviously lose a lot of heat getting there. What is the proper way to protect them before I drywall the bulkhead?

Here is one of the runs to the bedroom with roxul cut in half, still doesn't sit flush. Before putting rigid board should I take the insulation out from underneath?

Space with old pink stuff (i ripped most pink stuff out and replaced with roxul). Should I pull this out and spray foam it?

Another area with lots of gaps:

Overall view of garage for any additional ideas/tips:

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jklingel

· #11 · Dec 29, 2012

Carling said:
So I don't need a vapour barrier in this case? •• Vapor barriers are pretty much reserved for climate zones 6-8; cold, to very cold. Are you up in the mountains where it is very cold?

I can leave the roxul in there, fill all large gaps with this stuff??
Then rigid foam with house wrap tape and then drywall over? •• Yes. There are tapes made just for foam. Spray foam any larger gaps first.

•• They make capped nails to hold rigid foam in place instead of blocks.

See after bullets.

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Carling

Discussion Starter · #12 · Dec 29, 2012

jklingel said:
See after bullets.

It get's pretty cold here.

The rooms above are at 66 F
The garage is usually around 36 F degrees when it's very cold out (0F-5F). Even with windchill and colder temps I haven't see the garage drop below 36F.

Is it still ok to NOT have a vapor barrier?

Should I put anything between the joists where the X braces hold them spaced out properly and I have no roxul?

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jklingel

· #13 · Dec 29, 2012

Carling said:
...very cold out (0F-5F)... •• That is getting cold. Not being an expert, I will suggest that you check buildingscience.com for what zone you are in, and their recommendation. I suspect you are 6-ish (we are 8) and a vapor barrier there would likely not hurt anything if you don't run air conditioning AND you air seal. A cold house hit w/ warm, moist air from the outside makes for condensation in the wall, at the vb.

Is it still ok to NOT have a vapor barrier? •• A very knowledgeable builder here (and I am sure others as well) does not use one because he wants his walls to dry in both directions. If it works here, and extensively in Europe, it should work for you, but he AIR SEALS obsessively. That is the key factor, not the vb. You can also read about vb's on greenbuildingadvisor.com. I am not going to have one in my new house, though I may use Membrain.

Should I put anything between the joists where the X braces hold them spaced out properly and I have no roxul? •• Continuous insulation is important. At the least, stuff in pieces of Roxul; even compressed, which won't happen much with that stuff, and mangled it has got to be better than nothing. Spray foam is another option.

See after bullets. Retro-fitting is never slick and easy.

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