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Basement Insulation Between Joists


JCOLE's Avatar
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02-18-03, 07:14 PM   #1  
JCOLE
Basement Insulation Between Joists

I AM FINISHING A BASEMENT AND HAVE INSULATED THE WALL WITH R13 FIBERGLASS WITH KRAFT PAPER (VAPOR RETARDANT)ON MY EXTERIOR BLOCK WALLS STAPLED BETWEEN THE 2X4s.
I NOW WANT TO INSULATE BETWEEN THE JOISTS AT THE TOP OF THE CEMENT BLOCK WALLS. THE EXISTING INSULATION IS FIBERGLASS WITHOUT ANY VAPOR RETARDANT (INSTALLED BY THE BUILDER SEVERAL YEARS AGO). THE EXISTING INSULATION SHOWS SOME MINOR EVIDENCE OF CONDENSATION.
THE INSTRUCTIONS ON THE INSULATION INDICATE THAT KRAFT PAPER BACKING SHOULD NOT BE USED WHEN INSULATING BETWEEN THE JOISTS (FIRE HAZARD). I VERIFIED THAT INFO WITH THE MANUFACTURER'S Q&A HOTLINE.
HOW DO I PROPERLY INSULATE IN THAT AREA WITHOUT CONCERN OF A CONDENSATION PROBLEM? WHAT TYPE OF VAPOR BARRIER SHOULD BE USED? THE LOCAL DO IT YOURSELF STORE RECOMMENDED USING A FOIL VAPOR RETARDER OVER THE UNFACED INSULATION STAPLED BETWEEN THE JOISTS.
THANKS.

 
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02-19-03, 07:08 PM   #2  
Ordinarily, covering the insulation and kraft facing with sheetrock or panels of OSB or plywood will satisfy the worry about a fire hazard.

 
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02-20-03, 07:40 AM   #3  
lou s.
If you only have minor condensation,that isn't something to worry about,since it is glass,and cold vs.warm will make it sweat,like how a cold drink in a glass will sweat when brought outside in hot weather.If it worries you too much,pull out the blocks,and caulk around the box ends,and replace.Minimal condensation will be absorbed by the wood at plate line.As long as there isn't a major air leak,you'll be fine.Any facing you put on will basically block off the moisture,but it would only flow down into the plateline,anyway (gravity).I wouldn't waste the money&time on foil facing-it isn't cheap!

 
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