Insulating floor and ceiling


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Old 02-18-13, 03:41 PM
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Insulating floor and ceiling

I have a great room with hardwood floors and a cathedral ceiling. It's always cold,especially the floor. There is no basement under that part of the house but a air space that t think I can get in. How can I insulate this floor? Can I insulate the ceiling also? Would I install "vats" to allow air to circulate and then fiberglass?
 
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Old 02-18-13, 04:44 PM
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Hi dam
It sounds like just an open space underneath. In that case you would add insulation to the floor and cover the entire area to keep out the critters and eliminate as much air flow as possible. We can go into more detail as needed. Is there anything else down there, plumbing, heat ducts, or just support posts?

If you have an uninsulated cathedral ceiling, then you probably do not have vents in place. Typically you would need soffit vents and gable or ridge vents before you add insulation. BUT, rafters are often not deep enough to accommodate the desired amount of insulation.

Can you tell us how this room came to exist in PA without insulation. I'm not getting a good picture.

Bud
 
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Old 02-21-13, 07:38 AM
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The floor is totally enclosed by stone foundation . There's just no basement under that part of the house. I would have to cut access in floor to get under it. There is wiring. The outlets are in the floor but I plan on changing that when I gut the room. The roof has vents but no vents in soffit. Not my doing. My house was a hunting cabin for a police department a long time ago and was upgraded to a house via add ons etc.
 
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Old 02-21-13, 06:31 PM
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The floor is totally enclosed by stone foundation . There's just no basement under that part of the house.
How airtight is the stone foundation? The choice is whether to insulate that space to include it in the conditioned area or to exclude it.

The outlets are in the floor but I plan on changing that when I gut the room.
Why do you want to change that? That can be one of the handiest and least visible places to have receptacles.

The roof has vents but no vents in soffit.
What kind of vents, where are they and how much space do you have between the ceiling and the roof? Is the ceiling attached to the bottom of the rafters or are there separate ceiling joists?
 
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Old 02-22-13, 03:57 PM
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The foundation is fairly air tight.
The outlets and wiring are old. There's no ground on them or in the wiring. Or I'll rewire if I insulate the floor.
There's 6" between the ceiling and roof. They are true 2 x 6 's. There are only rafters like a cathedral ceiling. There are 4 square alum. vents near the peak.
 
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Old 02-27-13, 08:03 PM
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The foundation is fairly air tight.
Then it might be easier to include the crawl space in your conditioned area. To do that, you would lay a vapor barrier on the ground and insulate the inside of the foundation and the rim joist. Period. The underside of the floor would remain open so you could work on the wiring or anything else you needed to without having to move insulation.''

The outlets and wiring are old. There's no ground on them or in the wiring. Or I'll rewire if I insulate the floor.
Ideally you would replace the wiring so you have the ground, even if you don't need to insulate the floor (see above). I would use rated floor boxes to keep the receptacles in the floor, both for convenience and to preserve the original character of the room. That said, they are more expensive, so that will figure into the decision.

There's 6" between the ceiling and roof. They are true 2 x 6 's. There are only rafters like a cathedral ceiling. There are 4 square alum. vents near the peak.
If I'm hearing you right, there are a series of framing members that are both roof rafters and ceiling joists. If you just add insulation between those, you will lose a lot of heat through those members. It's called the "bridging effect." To defeat that, you can demo the ceiling, add 2" of rigid foam to the face of each rafter, install up to 6" of insulation between them and install a new ceiling. Alternatively, you could add 2" of rigid foam over the existing ceiling and then a new ceiling over that, but you wouldn't have as good an insulation envelope.

Either way, the 4 existing roof vents need to be replaced with a ridge vent and soffit vents, so that every rafter bay is ventilated.
 
 

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