August 18 - August 22, 2014
In what type of environment is the use of a vapor-impermeable air/moisture barrier recommended? Are there guidelines or standards to help determine this?
Michael Quaranta of OPERATIONS 40 on
August 22, 2014:
Great subject and question. While there are lots of consensus standards out of manufacturer's committees, it is difficult to arrive at a single definition of a "membrane" (liquid/solid) or the value of a vapor barrier, and there are a lot of pretenders. The most amusing membrane is the 15# felt application guide. See for yourself when you review the MSDS for their products filled with N/A's. There is a development program to provide transparent, sustainable product data that can be scanned and read on the iPhone. Believe me, it will resolve a lot of questions.
peter golter of 3M on
August 22, 2014:
Typically, this type of air and vapor barrier is installed on the exterior side of the exterior sheathing (or CMU) with continuous insulation installed on top of it. This type of assembly will work anywhere in the country. I, too, would recommend Joe Lstiburek's white paper, "The Perfect Wall".
Eric Murrell of SME on
August 20, 2014:
Climate zone 5 and higher for a building with typical interior environmental conditions. Check out Joe Lstiburek"s white paper "The Perfect Wall" on buildingscience.com
Steve Black of Power Construction Company, LLC on
August 19, 2014:
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Such materials are recommended for heating season-dominated climates with the insulation to the exterior or cold side of the membrane. There are a number of tools and guides to assist in the placement of the vapor barrier, such as the Whole Building Design Guide, WUFI and various membrane manufacturers' technical departmentss.
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