Home>Discussions>INSULATION & HVAC>how much air gap does R-30 RIGID insulation need on ceiling?
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Bluefairy
how much air gap does R-30 RIGID insulation need on ceiling?

Does anyone know what is the general thickness of R-30 Rigid Insulation?

Does it need air gap and how much?

Which is the best company name to use?

HoustonRemodeler
Re: how much air gap does R-30 RIGID insulation need on ceiling?

Where are you fixin to install the stuff?

Have you checked the manufacturers instructions?

keith3267
Re: how much air gap does R-30 RIGID insulation need on ceiling?

If you are talking about rigid foam insulation, it depends on the type of foam used. Some are rated as low as R4/inch, some as high as R8/inch but R-6 to R-6.5/inch is pretty typical. No gap between the foam and the interior side wall siding, at least 3/4" gap to the exterior side wall siding.

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