Exterior insulation and garage
Salibonz
| Posted in General Questions on
I am preparing to build a new home in climate zone 6a. I am going to. E installing 2 inches of exterior gps foam boards. The home has an attached garage with bedroom above it. How do I air seal and insulatevthe wall adjoining the garage and living space, as well as to how do I deal with the ceiling of the garage, to air seal it as well.
I was thinking maybe frame the garage after the adjoining wall is zip sheathed, taped and exterior insulation added, and then tapping siga majvest to zip and attaching to the underside of the floor trusses as an air seal. Is this the typical protocol. Thanks for the help
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Since there is a bedroom above, even if you don't intend to insulate the garage, it will be insulated 'by accident'
Thus any energy penalty from the garage house interface will be minimal
Do you mean when I insulate the exterior? How do I address the wall separating the garage from the living space? There will be 2 walls to deal with. Do i zip sheathed it,tape and seal it and then add 2 inches of insulation? And continue it to the ceiling separating the garage from living space? Also would I still need 2 layers of 5/8" rock for fire rating?
The best approach is to fully build, wrap and air-seal the house, then build the garage. That way you have good air separation between the two. You can add the exterior insulation at the house before or after building the garage, depending how stringent you want to be about thermal bridging. Drywall used for fire ratings usually has to continue to the roof sheathing, unless the garage ceiling and other walls are fully fire-rated instead.
Ok sounds good thank you.
I dunno Michael, I think in terms of the shell being inviable. Build the shell to keep the weather out. The garage is part of that shell. It has a bedroom above, it has to be.
The garage will be insulated from the house, but unless there is some odd insulation strategy, the garage will end up insulated also
5/8 sheet rock in garage under will extend across ceiling, no?
Framer is not going to charge for coming back twice?
For what potential yearly savings?
A garage under is difficult to seal, but I see no advantage to framing after, and potential problems
There are certainly other ways it can be done. I've done it both ways. I don't recommend putting living spaces above garages because even with good detailing it's very difficult to keep noxious fumes from getting through from the garage. I actually prefer to keep garages physically separated from homes, but if they have to be attached, I do everything I can to keep the building envelopes separated. I don't design commodity homes and I understand that costs for those limit the opportunities to provide safe, healthy indoor air quality.
Hey Michael, I'm thinking you and gushfb gave me good ideas. I'm thinking treat house and garage as 1 build. Zip sheathed tape and air sealed and 2 inches of halo exterra. On the 2 garage walls adjoining living space I'll use the solitex mento 1000 as a vapor and air barrier and carry to the ceiling of garage after interior insulation. That way I won't need zip sheathing there.Then add the 2 inches of insulation board for thermal bridging and carry that up the garage ceiling as well for no thermal bridging. Strapping for a service cavity so my air barrier will not be compromised( besides i need it after rigid insulation)iAnd then 2 layers of 5/8 rock as a fire retarder. Is this good? Thanks guys for all the help!!!!