Home>Discussions>INSULATION & HVAC>Cantilever Over Hang Insulation question
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Tcp
Cantilever Over Hang Insulation question
Tcp

Hey guys doing some renovations on the home and while I had the walls down I noticed there wasnt much of any insulation inside the spaces of the cantilevers. Could feel the cold. I filled in any gaps with foam and stuff the spaces with roxul comfort batt. Is this right?

ed21
Re: Cantilever Over Hang Insulation question
ed21

The underside of the cantilevered joists should be insulated too. Fiberglass batts would be easiest

Tcp
Re: Cantilever Over Hang Insulation question
Tcp

Yes I continued the insulation out. I just wasnt sure about any moisture issues I might have with the way I insulated.

Mastercarpentry
Re: Cantilever Over Hang Insulation question
Mastercarpentry

What's under the overhang? As long as it's not sealed so well that household humidity can't escape you're probably OK.

Phil

Tcp
Re: Cantilever Over Hang Insulation question
Tcp

well the entire overhang is closed in with plywood. I peeled back the plastic siding from the outside to see and it was just straight plywood. From the inside its completely sealed also no holes. There were some small air leaks from where the plywood met the wall of the home but I filled them with the foam stuff. Directly over the overhang is the 2nd floor living space. Most of the cantilevered space above has a heat run going across it.

keith3267
Re: Cantilever Over Hang Insulation question
keith3267

I would just run a vapor barrier across the end of the insulation, that is a vapor barrier between the first floor living space and the cantilever cavity.

Mastercarpentry
Re: Cantilever Over Hang Insulation question
Mastercarpentry

Either as Keith says or ensure it is equally sealed in some other way- caulked or foamed blocking between the joists at the supporting wall will do the job just as well.

Phil

Tcp
Re: Cantilever Over Hang Insulation question
Tcp

well the contractors already got the walls up. I'm thinking next spring ill fix it from the outside. So did a little research and it seems like it would be very difficult to vapor barrier because the subfloor is down on the joist. Any ideas? Now if I blocked off the overhang with a piece of foam what about the rest of the cavity? The cavity felt cold and it was like 60 degrees out.

keith3267
Re: Cantilever Over Hang Insulation question
keith3267

It's not important how the cavity feels. What is important is whether the floor above the cantilever is warm or cold. I would not worry about putting a vapor barrier between the floor and the insulation unless the bottom side of the cantilever is very tightly sealed. You really needed to keep vapor from the room below getting into the cantilever cavities. But again, those cavities are not normally sealed up that well so you will probably be OK.

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