Replacing insulation, why on ceiling?

Old 09-12-05, 03:07 PM
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Replacing insulation, why on ceiling?

Hey all,

We just purchased a home and are replacing the insulation in the attic. The existing insulation (which is quite old and has evidence of an earlier mouse infestation) is both on the floors of the attic and on the ceiling/roof. They installed the floor insulation with the vapor barrier facing upwards, which leads me to think that they may not have known what they were doing. We aren't planning to use the attic as living space, so I was wondering if anyone knows any reasons people would insulate the ceiling as well? One other detail is that half of the house has cathedral ceilings, so the attic space is just a 10 foot deep area in the front of the house, with a living area wall projecting into it. They have insulated the walls as well, but I'm wondering if having additional insulation may be typical in houses with this layout.

Thanks in advance for any information you can give me!
Old 09-16-05, 05:00 PM
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I am not very clear on what questions you are asking, but here it goes...

Your insulation installers were not (hopefully not...) idiots. The vapor barrier is most commonly installed towards the heated living space. In the floor this means the insulations facing is up agains your floor, and in the attic the facing would be down towards your ceiling. In both cases you should be looking at fiberglass and not facing material.

Generally you insulate around the heated living spaces of the house and ventilate the attic areas to help cool the shingles and remove any water vapor that makes it's way into the attic. Basically you want to keep your roof cold in both summer and winter. I wonder if someone started work on finishing off your attic and only got as far as insulating the bottom of your roof. Generally though, insulating the bottom of your roof is not a good idea.
Old 09-17-05, 01:41 PM
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Thanks! That definitely may have been what they were planning on doing, they left a few half-finished projects behind in other areas of the house. We'll go ahead as planned, then, and insulate the way we thought we should.
Old 09-18-05, 03:48 PM
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the reason for insulating the ceiling is that heat rises. If you do not insulate all that heat escapes. It is more expensive to heat and cool. The real question with regards to insulation is why insulate a floor? You not only need a good layer of insulation in the attic you also need good air flow over it. It helps to keep out condensation in the winter and in summer months to help cool the attic.

Good luck.

Brian Garrison

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