Insulating Attic On New Addition


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Old 11-07-06, 11:22 AM
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Insulating Attic On New Addition

This is probably a stupid question. I'm building a new addition on our home. The room will be 25' x 28' with a 5/12 slope interior ceiling. I had wanted to use a foam insulation but hadn't planned on having an access port from the room into the attic area. Short of accessing the area through the roof, installing drywall in the ceiling and then blowing in the foam, I can't think of anyway to get the foam into the ceiling/attic area. Am I just better off using Batt insulation up there? I assume putting Batt up there would consist of just installing the fiberglass rolls inbetween the trusses, covering with a vapor barrier and then drywalling over the top....is that correct?
 
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Old 11-07-06, 04:22 PM
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When I did my addition, it was code to have some type of access. (not necessarily in the ceiling, but some access).

Anyway - back to you question, I used faced insulation, which allowed me to staple the insulation between the rafters.

If you want to supply you your vapor barrier, then you'll have to come up with a way to hold up the insulation (thin wire between rafters if one way)
 
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Old 11-07-06, 04:50 PM
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You dont say how deep the roof rafter is. You cant put insulation in so it is up tight to the plywood roof. You need the foam vents put in first. That is why we all ways use a open truss. with the slope inside this lets you put good insulation in there and also let you vent the attic part
 
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Old 11-11-06, 02:03 PM
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Couguy - is this an attic-less addition? It sounds like you plan on a sloped ceiling all the way to the peak. If that's the case, I wouldn't worry about ventilation. I would use batts the full thickness of the rafters rather than foam. Just hang the batts and drywall over them.
 
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Old 11-12-06, 02:31 PM
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City says I'm required to have an access opening into the attic area: Minimum 24" x 30" and have at least 30" of headspace at the immediate opening. Rather than going through the ceiling, I'm thinking of installing an access door in an upstairs bedroom that will be easily hidden. That way, the ceiling of the addition room will be totally clean.

I've decided definitely to go the easy route and use batt stapled to the scissor trusses for the ceiling insulation. Easier -- and I just got back the foam insulation estimate -- about 3X the cost of using batt.
 
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Old 11-13-06, 11:18 AM
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With a R 30 batts . Dont forget the foam rafter vents so you can get air from the vents in the over hang .
 
 

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