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-   -   Garage insulation - to replace or not, and related questions (http://www.diychatroom.com/f15/garage-insulation-replace-not-related-questions-59452/)

DaveinGA 12-17-2009 11:12 AM

Garage insulation - to replace or not, and related questions
 
Hi folks,

I have an attached garage that leads into my at-grade "basement" (basically just the lower level of split foyer home). On the second level of the home directly above the garage are the bedrooms and bathrooms. The framing of the garage walls and ceiling are exposed; walls are insulated with rigid foam sheathing and the ceiling is insulated with fiberglass batts.

The batts have seen better days. There are areas where the insulation is missing altogether - having likely been removed to accommodate some sort of HVAC, electrical or plumbing repair, and never replaced. There are other areas that seem rotted/mildewed from possibly an old plumbing leak or other source of moisture or humidity (house is located in a humid climate). Some spots have been pecked at presumably by birds and other such critters who have gained entry when doors were open.

I've not measured the depth of the batts, but I can only imagine that the current R value is below standard. Bottom line is, while some areas of insulation appear fine and without problems, the integrity of at least 30-40% the insulation has failed and I feel that an upgrade is in order.

My gut is that if I'm replacing some of the insulation, I might as well replace all of it. First question - is that unnecessary and/or a waste of time and money? Or should I simply replace the missing/defective portions and be done with it?

Assuming that new fiberglass batts with paper facing are the way to go, should the batts be applied so the paper faces the living space upstairs? Or should I go with unfaced batts and poly sheeting? Does it matter? I'm unclear here on the benefits of one vs. another.

I also plan to install a suspended ceiling, 1) for aesthetic reasons and 2) to cover/shield the insulation and plumbing/electrical/ductwork in the ceiling. I would also like to install fiberglass batts between the wall studs and hang drywall all around.

Are there pitfalls in these plans that I'm not thinking of? Thanks in advance for reading - I look forward to any comments you may have.

Gary in WA 12-19-2009 02:02 AM

"The framing of the garage walls and ceiling are exposed; walls are insulated with rigid foam sheathing and the ceiling is insulated with fiberglass batts. " ----- YIKES!!!! You do know when a vehicle is running the exhaust fumes rise through the floor above? This is why all attached garages are required by the International Residential Code to fire-tape the applied fire-rated drywall for an air barrier(exhaust).
Be safe, Gary

Bob Mariani 12-19-2009 08:33 AM

In your case I would use spray foam for the ceiling. This will give you a warm enough floor and help stop any fumes rising into the building above. Then you need to seal this with 5/8" (minimum) drywall, finished to at least level 2.

DaveinGA 12-19-2009 03:34 PM

Thanks to you both for the advice.

Any other options than drywall for the ceiling? Trying to avoid the possibility of having the tear out the ceiling to access plumbing, electrical, HVAC, gas lines, etc. that are located in this area should problems/repairs arise in the future.

If drywall is the only option, could I install some strategically placed access doors and seal the joints around them with caulk?

firehawkmph 12-19-2009 09:20 PM

[quote
If drywall is the only option, could I install some strategically placed access doors and seal the joints around them with caulk?[/quote]

Dave,
I would take some pictures and measurements as to where your gaslines and plumbing runs are and drywall over it. It's easy enough in the future to cut out some drywall and replace it. If your plumbing and gaslines are in good shape you probably won't have to access them again.
Mike Hawkins:)

Scuba_Dave 12-19-2009 09:23 PM

Paper faces the heated rooms
5/8" drywall is required to meet building & fire codes
It must be sealed & taped

DaveinGA 12-20-2009 11:25 AM

okay, cool... drywall it is. Thanks folks!


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