Thread: Extending R-value for cathedral ceiling
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[email protected] trader4@optonline.net is offline
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Default Extending R-value for cathedral ceiling

Chris Friesen wrote:
wrote:
Chris wrote:

The roof rafters are 2" x 8". For that size, I should use R20
(6") in order to keep 2" for ventilation on the top of insulation.

Why not put up a good plastic film vapor barrier under 8" of insulation?

You're supposed to leave space for airflow between the insulation and
the underside of the roof.

Chris

I would extend the rafters down so you can use the thicker insulation.
I'd also use the air channel baffle material the entire length, as that
is the best insurance that you will have a clear space for air movement.

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