Attic - general insulation question


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Old 11-22-21, 11:18 AM
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Attic - general insulation question

My son bought a house which has an 800 sq ft attic. The attic was supposed to be finished but never was except for plywood on the floor. The insulation is up on the roof rafters with the paper facing down. There are baffles from the soffit to the ridge vent. The issue is that in the summer, the bedrooms below were hot, and now that it has cooled off, they are cold. My thinking is that there is transfer through the ceiling in the bedrooms, and there should be insulation between them and the attic so that there is a barrier (heat can't escape up in winter or radiate down in summer).

I've never seen an attic that has insulation in both places (floor and rafters). Is that legit?.
 
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Old 11-22-21, 11:26 AM
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It should be in one place or the other but not both. A finished attic would be conditioned space (climate controlled) and the insulation would be above. An unfinished attic is not climate controlled and the insulation would be in the floor.
 
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Old 11-22-21, 11:30 AM
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What is the temperature in the attic? As X stated, this needs to be conditioned if the insulation is in the ceiling/rafters.
 
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Old 11-22-21, 12:40 PM
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The attic isn't conditioned space, so the winter temp is whatever it is outside + a few degrees from leakage and the summer ....... well.......you know.

New project.
 
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Old 11-22-21, 01:15 PM
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OK, then the insulation should be in the floor, not the rafters.
 
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Old 11-22-21, 02:12 PM
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That's not a finished attic then. It just like an other attic... unconditioned storage space... and yes, the insulation should be in the floor. By putting a floor down you are compromising the amount of insulation that SHOULD be up there. Attic floors ought to have R-49 more or less.

See map.

One way around that is to build an elevated floor and small staircase above the insulation for storage purposes. If that's not possible, you could look into installing a minisplit up there in order to have conditioned space up there. Then you could rightly finish the attic, assuming the floor was engineered to be living space.
 
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Old 11-23-21, 10:43 AM
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I think we are just gonna pull the insulation from the rafters and put it where it needs to be. Thanks for the confirmation.
 
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Old 12-01-21, 04:40 PM
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One more question - why is it not advisable to leave the insulation on the rafters and just add new insulation between the plywood floor and the drywall ceiling?.
 
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Old 12-01-21, 04:49 PM
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The attic is going to be hot in the summers, and you should want to ventilate it, not insulate it and hold the heat and humidity inside.
 
 

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