Insulating a new detached garage

Old 09-15-04, 06:41 AM
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Insulating a new detached garage

Hello, I'm new to the forum. I've got a question regarding insulation of a new detached garage I built a few weeks ago. It's completely exposed on the inside right now. I don't really ever intend to heat the garage, I'm just thinking that insulating may help the resale on my house. I had a new R10-value 16' garage door installed last week. I was thinking of putting insulation between the studs and sealing it off with sheetrock. The roof is what I have the question about. I would like to keep the bottom of the roof trusses exposed, so insullating would mean I'd have to insullate the top of the roof trusses. I've read a few threads that say you can do this, but you need at least 2" between the insullation and the OSB for proper ventilation. Here's where it get's tricky ... I have a ridge vent, but zero over-hang on the roof to match the look of the house. So, I wondering how I can insullate the garage, leave the bottom of the trusses exposed, and still get the roof ventilation I need? And also what type of insulation should I be using?
Old 09-15-04, 09:20 AM
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Whoever built my detached garage thought it would be a good idea to insulate the underside of the roof without any baffles for ventilation. You would not believe how much condensation drips off the vapor barrier in springtime. . . . One of these days I will rip it out.

The garage was insulated with R-11 on the walls and roof joists and is unheated. It's an oven in the summertime due to ambient temperature and the insulation trapping the heat from the cars, and still gets pretty cold in the winter. It's only spring and fall that the insulation does anything for me. You might have a similiar experience.

To get proper air flow to the ridge vent, you will need some type of baffle to maintain the cavity and some sort of soffit/eave venting. Could you cut some holes for circular vents in the top of the exterior wall where the rafters come in?
Old 09-15-04, 09:39 AM
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I think the resale value of your HOME w/o an insulated detached garage is a very small point. If it's not going to be heated I see no sense in insulating it.
Put the money in the house.

Old 09-15-04, 08:45 PM
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1) The affect upon valuation of partially finishing a detached garage, as mentioned, is zero, because its detached.
2) Your comment regarding insulating rafter bays and the clearance to allow for ventilation, ONLY applies if you are installing a finish product to the underside of those rafters.
Old 10-05-04, 04:34 PM
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As long as you do not dry wall the ceiling, there should be no problem.

P.S. I agree that insulating an unheated detached garage won't do much for resale.

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