# What would you do...Garage ceiling?



## joecaption (Nov 30, 2011)

Not sure why you would have used unfaced insulation.
There should have been a vaper barrier toward the conditioned surface.
No way are you going to be able to reuse the drywall, it needs to also be 5/8 fire rock. And also air seal any holes where wiring and plumbing was run with fire proof caulking.


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## rebelranger (Aug 1, 2012)

@joe - Thanks for the info. I used unfaced because it was my first insulation install and I didn't know better. Now I know better. 

To reuse the drwall I was going to run a magnet along the joists to find the screws then remove.
Definitely will airseal with the can foam for any holes if I don't get spray foam.

5/8 Fire rock, like http://www.lowes.com/pd_11737-74265-5848FXT080000_0__?productId=3009511&Ntt=drywall+panels&pl=1&currentURL=%3FNtt%3Ddrywall%2Bpanels&facetInfo=?


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## joecaption (Nov 30, 2011)

That's the sheetrock. Not worth the time trying to remove the screws and reusing.
Rent or borrow a drywall lift to reinstall it.
DO not use reguler foam or caulking it needs to be fire rated.


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## gregzoll (Dec 25, 2006)

You would be better to have someone come in and spray foam the floor above the garage, along with sill & rim joist areas in the basement.

It will quickly pay itself back within two years.


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## rebelranger (Aug 1, 2012)

@gregzoll - I've inquired into spray foam for the garage and it's $1 per sqft per in of foam for closed cell and .78 per sqft per inch for open cell.

-I've used 2" XPS with can spray for the sill and rim joists in the basement... didn't really notice a change but per heat loss/gain but it tightened up my house for air leakage. 
-What do you base the "pay itself back within two years" off? I just don't know if I'll recoup $1k plus in heating/cooling savings over two years. Please enlighten me how I will.


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## gregzoll (Dec 25, 2006)

Raises the value of the home, along with saving you money on cooling and heating costs. It is a no brainer, and a no loss situation. I personally would not use XPS and caulk and spray foam for something that can be done cheaper and easier.


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## rebelranger (Aug 1, 2012)

A 4'x8' board of XPS cost me $22 and it covered 32 sqft. Two cans of spray foam cost me $6 and change so for $28 I did all my Rim and Sill joist areas. I would of cost me $400 for all spray foam, such a small job, for a company to do it. I took the cheaper route.

As for the garage ceiling, I'm seriously considering the 2" of spray foam route. What do I do if I need HVAC access? Just cut the foam?


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## gregzoll (Dec 25, 2006)

You are forgetting the time consumed, and the time spent laid up when you fall off the ladder. Besides, using XPS is not going to solve the problem, and even with the drywall up there, heat can still cause the XPS to start giving off fumes, if there is ever a fire in the garage space.


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## Gary in WA (Mar 11, 2009)

"*Figure 7: Cavity Insulation with Vapor Barrier*—Adding impermeable foil faced insulating sheathing over fiberglass cavity insulation is a hybrid approach that uses the best qualities of both materials. Note that the optimum location for the airspace is above the cavity insulation. Are you folks paying attention at the EPA ENERGY STAR® Program? Makes for warmer floors—this is the same detail that should be used under bedrooms over garages." Underline is mine, from; http://www.buildingscience.com/documents/insights/bsi-009-new-light-in-crawlspaces/

Gary
PS. Of course cover it with 5/8" Type-X drywall for fire-rating per Fire Marshall/Building Codes.


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## rebelranger (Aug 1, 2012)

@GBR - I was hoping you would comment. I have read that before when you posted it but it puzzles me again. Please tell me which it says (1) install fiberglass insulation with vapor barrier towards the upstairs living area and the unfaced insulation facing down then drywall, or (2) unfaced insulation installed then closed foam board then drywall, or (3) faced V.B. towards upstairs living area then foam board then drywall?

Figure 3 says don't install unfaced insulation without cover the bottom part.
Figure 4 says don't install V.B. faced insulation with uncovered insulation exposed. (wood moisture issues)
Figure 6 says no insulation just foam board across bottom of ceiling joists.
Figure 7 says (a) air pocket, (b) V.B. faced insulation facing ceiling [up], (c) foam board across bottom of joists.
- The rest says Spray foam closed cell.

Am I reading that wrong? Can I just install the V.B. insulation facing the rooms above and then drywall?


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## rebelranger (Aug 1, 2012)

I really can't/don't think I can lower the ceiling height even a 1/2" because the ceiling is already just over 7' (1960s house) and the two garage doors already just barely clear the ceiling...not to much the garage door openers actually touch the ceiling. Thus asking MUST I install the foam board before drywall?

Just based on everyones comments the Drywall is coming down so blown in loose fill it out.


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## Gary in WA (Mar 11, 2009)

I don't understand your questions. Fig.3 is showing radiation coupled- warmed cavity f.g, with cold bottom surface to cold dirt w. plastic. Fig.4 is vinyl flooring (vapor barrier) on the wrong side of the sheathing. Fig.5 is warming the joists= no moisture drive there. Fig.6 is foil-faced PIC on the bottom of the joists- (Vapor barrier and reflective surface) = no cavity insulation required if the f.b. meets your local energy code for R-value in cavity.

That is the best way if you have the clearance for it. Just drywall with 5/8" Type X for fire-stopping to meet your local code. 

Gary


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## rebelranger (Aug 1, 2012)

@GBR - thank you, that cleared it up a ton. I pulled down a corner section and think i can get 1/2" PIC in there which is only R3 so I'm going to stuff in some R13 as well, then 5/8. I'm trying to find someone who will just flash inside the joists for air sealing on the cheap but because such a small job most companies basically right off the bat say no thanks. Sigh.


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