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Amy Witek Posted: May 17, 2010 01:15 PM	Retro fit where to start After some IR pics of my house I have isolated two problem walls. Wall 1: 2x4 construction, back wall of unheated garage (26 feet long) that shares heated living space on the other side. Minimal fiberglass batts. Wall2: 2x4 construction, northwest wall (60feet long) that has shown significant heat loss one foot from top of wall and one foot from the bottom. Fiberglass batts here, too. Entire house on a slab. I've gotten bids that range from: Injecting foam like AirKrete /InsulSmart into wall behind existing insulation. Won't this make a soggy mess out of the fiberglass? Tear out drywall, remove fiberglass, spray cc foam into the cavities from the inside. Remove the vinyl siding, cut through house wrap and fascia, pull out fiberglass, and inject cc foam or AirKrete. And finally, I actually had one company tell me the job was too small and they couldn't guarantee the additional insulation would make a difference. They claim adding insulation wont' overcome the heat loss through the concrete slab. They didn't see any need for insulating the garage wall. Really? What's the best plan of attack? If it's done from the the outside, what about a vapor barrier? If it's done from the inside, how messy is it? And if anyone does business in northeast Ohio, I would appreciate hearing from you.
mason Posted: May 17, 2010 03:00 PM	I disagree with the comment that insulating the walls will have a minimal effect due to the heat sink from the concrete slab. Consider the garage outside space. The most energy efficient solution is to take off the drywall in the garage and spray the foam to the interior sheathing. Then re-drywall the assembly. Injecting any type of foam insulation to a cavity that already has insulation will leave significant gaps and not provide good energy efficiency. As for wall 2, again remove the drywall and the SPF insulator can mask off the rest of the room with plastic and tape to shield it against overspray and then spray the wall. Then install additional drywall. I would not want to remove the vinyl siding and insulate from the outside. Too many bad things could go wrong, bad weather, warped and broken siding, etc. You will still have some heat loss (or gain) from the concrete slab, but insulating the walls will stop a lot of the heat loss from the building.

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Comments

Amy Witek

Posted: May 17, 2010 01:15 PM

Retro fit where to start

After some IR pics of my house I have isolated two problem walls.
Wall 1: 2x4 construction, back wall of unheated garage (26 feet long) that shares heated living space on the other side. Minimal fiberglass batts.
Wall2: 2x4 construction, northwest wall (60feet long) that has shown significant heat loss one foot from top of wall and one foot from the bottom. Fiberglass batts here, too. Entire house on a slab.
I've gotten bids that range from:
Injecting foam like AirKrete /InsulSmart into wall behind existing insulation. Won't this make a soggy mess out of the fiberglass?
Tear out drywall, remove fiberglass, spray cc foam into the cavities from the inside.
Remove the vinyl siding, cut through house wrap and fascia, pull out fiberglass, and inject cc foam or AirKrete.
And finally, I actually had one company tell me the job was too small and they couldn't guarantee the additional insulation would make a difference. They claim adding insulation wont' overcome the heat loss through the concrete slab. They didn't see any need for insulating the garage wall. Really?
What's the best plan of attack?
If it's done from the the outside, what about a vapor barrier?
If it's done from the inside, how messy is it?
And if anyone does business in northeast Ohio, I would appreciate hearing from you.

mason

Posted: May 17, 2010 03:00 PM

I disagree with the comment that insulating the walls will have a minimal effect due to the heat sink from the concrete slab.

Consider the garage outside space. The most energy efficient solution is to take off the drywall in the garage and spray the foam to the interior sheathing. Then re-drywall the assembly.

Injecting any type of foam insulation to a cavity that already has insulation will leave significant gaps and not provide good energy efficiency.

As for wall 2, again remove the drywall and the SPF insulator can mask off the rest of the room with plastic and tape to shield it against overspray and then spray the wall. Then install additional drywall.

I would not want to remove the vinyl siding and insulate from the outside. Too many bad things could go wrong, bad weather, warped and broken siding, etc.

You will still have some heat loss (or gain) from the concrete slab, but insulating the walls will stop a lot of the heat loss from the building.

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