CC over fiberglass | Insulation/Energy/Building Envelope Q&A | Spray Foam Technical Questions and Answers | SprayFoam Magazine Q&A Forums

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Author	Comments
Tim O'Keefe Posted: Jul 07, 2007 07:22 PM	CC over fiberglass Observed an interesting installation. Foam contractor installed CC down into the ceiling joists (from above in the attic) right on top of the fiberglass that was already in place without removing it. Any thoughts? Tim Granite State Spray Foam Co.
Richard Russell Posted: Jul 09, 2007 07:52 AM	Thoughts? Assuming the foam is supported adequately by the joists, the only issue I can think of is whether water vapor can diffuse readily through the ceiling and into the FG space. The CC foam constitutes a VR and shouldn't be too far across the total R from warm to cold side. How much R is there for the remaining FG thickness vs. the R of the applied CC foam, and is there a VR under the ceiling sheetrock or VR paint over it?

Author

Comments

Tim O'Keefe

Posted: Jul 07, 2007 07:22 PM

CC over fiberglass

Observed an interesting installation. Foam contractor installed CC down into the ceiling joists (from above in the attic) right on top of the fiberglass that was already in place without removing it. Any thoughts?

Tim
Granite State Spray Foam Co.

Richard Russell

Posted: Jul 09, 2007 07:52 AM

Thoughts? Assuming the foam is supported adequately by the joists, the only issue I can think of is whether water vapor can diffuse readily through the ceiling and into the FG space. The CC foam constitutes a VR and shouldn't be too far across the total R from warm to cold side. How much R is there for the remaining FG thickness vs. the R of the applied CC foam, and is there a VR under the ceiling sheetrock or VR paint over it?

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