Custom Residential Architects Network

We're working on an historic firehouse, converting it into a residence.  The building has brick/block walls.  We plan to add 2x4 studs to the inside with R-13 kraft-faced batt insulation.  My question relates to adding a vapor barrier, or Tyvek, to the inside face of the unfinished block wall before studs/ drywall/ insulation.  The building is in the Washington, DC area.

You may want to contact your local Dow rep about the Thermax system. She/He can run a dew point program on your wall for all seasons and make recommendations. They can give you the file of these, too, so you have them for your file. And they can then make recommendations for what to use. At least, ours here is extremely helpful in this manner.

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Pamela Leonard AIA
Architect

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Original Message:
Sent: 06-18-2013 19:16
From: Craig Moloney
Subject: vapor barrier

We're working on an historic firehouse, converting it into a residence.  The building has brick/block walls.  We plan to add 2x4 studs to the inside with R-13 kraft-faced batt insulation.  My question relates to adding a vapor barrier, or Tyvek, to the inside face of the unfinished block wall before studs/ drywall/ insulation.  The building is in the Washington, DC area.

You should review the latest research about interior insulation of masonry walls from the Building Science people.  Their research paper "Internal Insulation of Masonry Walls: Final Measure Guideline" done for US Department of Energy is recommending 2" of spray foam insulation against the masonry.  Actually they recommend that the insulation be placed on the exterior of the building, but give the other solution as the next best option.

http://www.buildingscience.com/documents/reports/rr-1105-internal-insulation-masonry-walls-final-measure-guideline/view?searchterm=RR-1105

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Jay Raskin AIA
Principal
Ecola Architects, PC
Portland OR
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Original Message:
Sent: 06-18-2013 19:16
From: Craig Moloney
Subject: vapor barrier

We're working on an historic firehouse, converting it into a residence.  The building has brick/block walls.  We plan to add 2x4 studs to the inside with R-13 kraft-faced batt insulation.  My question relates to adding a vapor barrier, or Tyvek, to the inside face of the unfinished block wall before studs/ drywall/ insulation.  The building is in the Washington, DC area.

It is not a good idea to place a vapor barrier at the inside face of the brick. moisture would condense on the warm side of the membrane, inside the stud cavity. You can add Tyvek on that side of the studs and you can create a pretty good weather barrier at that wall line but be careful to plan for a place to allow any moisture that may make it through the masonry and gets stopped by the tyvek to be able to escape to the exterior. Masonry can be surprisingly porous and can allow driving rain to weep through the wall.
The best vapor barrier to use on the inside face of stud would be Certainteed's "Smart Membrane" it is made of polyamide instead of visqueen. It will not allow vapor to pass through the membrane but it does allow actual moisture to pass through so if there is water inside the wall it doesn't get trapped.

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William Mammen AIA
Mammen Associates Architecture
Park City UT
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Original Message:
Sent: 06-18-2013 19:16
From: Craig Moloney
Subject: vapor barrier

We're working on an historic firehouse, converting it into a residence.  The building has brick/block walls.  We plan to add 2x4 studs to the inside with R-13 kraft-faced batt insulation.  My question relates to adding a vapor barrier, or Tyvek, to the inside face of the unfinished block wall before studs/ drywall/ insulation.  The building is in the Washington, DC area.