# Taping faced insulation batts



## kxweil38 (Jan 15, 2015)

I installed faced insulation batts in a upstairs attic that is being converted into a bedroom. The room contains a knee wall. I have a question about taping the batts to the horizontal frame at the top and bottom of the kneewall. Would it be beneficial, or is it required, that the batts be taped to the frame at the top and bottom with a Tyvek type tape to prevent any air leakage. 

Thank you,
Ken


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## joecaption (Nov 30, 2011)

No need if the insulation is installed correctly. On the back side cover it with Tyvek to prevent wind washing.


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## Windows on Wash (Aug 30, 2011)

Better yet...cover the assembly with rigid foam to help with the thermal loss through the stud wall.

Be sure to air seal the wall and the joist bays prior to closing it up.


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## Gary in WA (Mar 11, 2009)

The kraft facing is a vapor retarder, not an air barrier- never meant to be. It will adjust to the relative humidity passing through it, "Ginger vs. Mary Ann": http://www.buildingscience.com/documents/insights/bsi-024-vocabulary

The drywall should be your air barrier; http://www.buildingscience.com/documents/information-sheets/air-barriers-airtight-drywall-approach/

The tape at bottom/top plates is not required nor needed as the paper is surface weighed. Slashes, rips and tears won't affect it considerably;under Photo #6; http://www.buildingscience.com/docu...3-concrete-floor-problems/?searchterm=BSI-003

Be very meticulous with the insulation application; http://www.buildingscience.com/documents/information-sheets/installation-of-cavity-insulation/ Block under/over the knee wall leaving your air chute intact, cover any foam board with an ignition barrier; check with local AHJ or Fire Marshall.

Gary


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## kxweil38 (Jan 15, 2015)

Thank you all for the replies! This is excellent information.


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