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ceiling insulation ?????

405 Views 5 Replies 6 Participants Last post by ssabin, Jan 22, 2004

jpmassey

Discussion Starter · Jan 20, 2004

I have a pre-finished basement theater in progress in which the ceiling

was stuffed with R-13 kraft faced batts. My original plan was to add a second layer of R-13 to the existing insulation which would fill the cavity.

Is this a bad idea having two Kraft faced batts together in a ceiling cavity?

Do I need to worry about moisture? Will this comprimise the overall R-value? Any thoughts or suggestions would be appreciated. Thanks

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Jpmassey

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Tight_Wad

· #2 · Jan 21, 2004

It won't effect the r rating of the insulation. Two layers with paper should not hurt anything in a ceiling cavity that has a living space above and below, but You can also remove the paper facing from the insulation very easily. Just grab a corner and pull gently and use your other hand to keep excess insulation from staying on the paper.

Good luck

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curtisG

· #3 · Jan 21, 2004

jpmassey

The reason you don't want to have multiple vapor barriers (as in the case of multiple layers of faced fiber glass batts) is to avoid a moisture trap which could cause problems down the road.

As Tight_Wad indicated however, since both sides of the barrier are living spaces, you might get away with it, but would definitely recommend you don't take the chance and remove the paper facing on both layers.

Alternatively, decide which of the two living space (above or below) will be the 'warm side' and stick a single vapor barrier on that side.

--curtis

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rgladiator

· #4 · Jan 21, 2004

I don't know much about insulation, but couldn't you just take a utility knife and quickly slash up the paper facing? A few quick slashes down the length of each batt should be enough to eliminate them as vapor barriers.

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dwightrahl

· #5 · Jan 21, 2004

rgladiator,

Yup, slashing the kraft paper is pretty much the standard practice when attempting to eliminate the problem of multiple vapor barriers.

Dwight

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ssabin

· #6 · Jan 22, 2004

SInce it doesn't take much to slash or remove paper, you might as well do it. But keep in mind that you don't have a real tight vapor barrier anyway if the batting is just stuffed in there. A true vapor barrier is created by pulling the kraft paper across the stud space, kind of Saran-wrapping the fibergalss in the cavity. If the paper isn't fastened to the joists, you aren't going to trap any moisture. And even if it is, you aren't going to trap any moisture, unless your basement is much cooler than your upper floor.

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