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vapor barrier on floor of bonus room over garage?

ty163's Avatar

Join Date: Jan 2005
Posts: 42

11-01-08, 12:47 PM   #1  
vapor barrier on floor of bonus room over garage?

We have a bonus room over our garage that was unfinished when we built our house two years ago. It had insulation, and a vapor barrier, and I recently finished the wiring and sheetrock. I noticed the floor is cold, but I know the floor is insulated because we had the builder insulate the garage. I am wondering however if I need to put a vapor barrier on the floor over the plywood before I put carpeting down. I don't remember which way they put the insulation when they did they garage. It is an unheated garage and I don't want to create a mold problem between the floor and ceiling of the garage.


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airman.1994's Avatar

Join Date: Dec 2005
Posts: 5,582

11-01-08, 02:00 PM   #2  
You don't won't a VB on top of the wood. Floor could be cold because you need more insulation or garage is cold. Temp will have nothing to do with a VB.

Bud9051's Avatar

Join Date: Oct 2008
Posts: 9,772

11-01-08, 03:08 PM   #3  
Airman is correct, "You don't want a VB on top of the wood." But I would be surprised if you don't already have one just above the garage sheetrock. Isolating a potential living space from the garage is a major concern, due to carbon monoxide and related fumes. But did they completely fill the cavity with insulation? My guess is they didn't. Cutting a small access hole to take a look is simple and easy to patch and will be covered with your carpet anyway. You can also check to see if there is a VB down on top of the sheetrock.
There should be no penetrations in the ceiling below, electrical boxes or anything. Totally isolated to prevent any air from getting up into that bonus room. Since I doubt they achieved that, add a CO detector to your list.

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