Home>Discussions>INSULATION & HVAC>Insulated attached garage, will moisture be a problem?
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Tcp
Insulated attached garage, will moisture be a problem?
Tcp

So when I moved into my high ranch home last year I did some renovations. One thing I noticed was that my attached garage was not heated and was afraid it would make the upper floor cold during the winter. Since the ceiling and walls were down I decided to insualte with roxul comfortbatt on the ceiling/rafters since they were fire resistance being that it was a garage and the boiler room was right next door. Also our three bedrooms are right above this space. However, this past winter it seems as though the boiler room kept the garage space pretty warm and maybe cold temps wouldnt have been an issue. My concern is did I create a potential moisture issue in the ceiling? The space was filled completely from the bottom of the 2nd fl subfloor to the sheetrock of the garage ceiling. I also had one side that was cantilevered out which I filled also. Does this space need air movement like the way an attic does?

Tcp
Re: Insulated attached garage, will moisture be a problem?
Tcp

Anyone? Bump?

dj1
Re: Insulated attached garage, will moisture be a problem?
dj1

Just keep the air in the garage moving, make sure vents are not blocked and are functioning correctly. You might want to add a fan and in extreme cases, a dehumidifier.

Mastercarpentry
Re: Insulated attached garage, will moisture be a problem?
Mastercarpentry

The cantilevered section could have benefited from a vapor barrier but it's not wort digging into just for that. As long as the rest was unfaced you're probably OK. While there might have been some winter benefit from letting the boiler heat rise, it would be a liability in summer so I think you did well.

What concerns me more is whether you used 5/8 "Type X" fire-rated sheetrock instead of the usual 1/2" kind. That is now a code requirement in most places where there is habitable space over a garage or workshop area. My local city codes require two layers on the ceiling now with one on the walls, and the inspector wants to see the entire first layer properly taped before you cover it. They will make you take the second layer down to inspect the first one which has caught a few contractors out who weren't familiar with their requirements!

Phil

Tcp
Re: Insulated attached garage, will moisture be a problem?
Tcp
dj1 wrote:

Just keep the air in the garage moving, make sure vents are not blocked and are functioning correctly. You might want to add a fan and in extreme cases, a dehumidifier.

What vents would you be referring to? And yes I already have a dehumidifier in the garage space for those really humid days.

dj1
Re: Insulated attached garage, will moisture be a problem?
dj1

There are various types and sizes of garage / attic fans to choose from. You have to find the one for the size of your garage. Find them on line, HD or electrical supply places.

You have to have a vent to the outside, like a gable vent, to mount the fan onto. If not, create a vent through the exterior wall. You also need to bring power to the fan (not an extension cord).

Tcp
Re: Insulated attached garage, will moisture be a problem?
Tcp

The garage space is like a normal room with two windows with bedrooms above them. So there would be no "attic" space. I may not be understanding you correctly. So the ceiling of the garage wont have a huge shared space but individual 2x6's 16oc supporting the floor above.

dj1
Re: Insulated attached garage, will moisture be a problem?
dj1

With the new info: look into exterior door mounted or wall mounted fans (one brand is Dragon fan).

These fans resemble "doggie doors". Do some research on your own, answers don't fall from the blue sky.

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