Op-Ed

Massachusetts Code Requirements for Air Barriers

Two readers offer more details on Massachusetts' building code requirements for air barriers.

There is misinformation in the article on air barriers [see EBN Vol. 17, No. 6]. Massachusetts has a requirement of 0.004 cfm/ft2 @ 75 Pa for materials, not assemblies. Big difference. Massachusetts’ requirements are the same as the National Building Code of Canada. Massachusetts does not have a requirement for the airtightness of assemblies or whole buildings.

The comment on Massachusetts requiring a hole in the top of elevator shafts is also wrong. National elevator codes in the U.S. require a louver to vent smoke at the top of elevator shafts. Massachusetts rectified the problem by requiring an airtight operable damper in the closed position linked to the fire-alarm system.

 

Wiss, Janney, Elstner Associates

Cambridge, Massachusetts

 

I think you have an error in the article on air sealing. The article mentions “a very stringent requirement for air barrier assemblies in commercial buildings of 0.004 cfm/ft2” in Massachusetts—and speculates as to whether somebody goofed up in the drafting. In fact the stringent requirement applies to air barrier components rather than assemblies.

So far as the assembly is concerned, the Massachusetts commercial code is reduced to adjectives—“continuous” and “air-tight,” “durable or maintainable,” and capable of withstanding lateral pressure “without displacement or damage.” All laudable, but not measurable. The difference between a component specification and the assembly performance is fundamentally tied to how well this string of adjectives is implemented and enforcement of how they are interpreted. As John Straube and others have noted, a performance standard and a testing protocol is where we ultimately need to be.

 

Coldham & Hartman Architects

Amherst, Massachusetts

Editors’ response:

Coming from the drafter of the Massachusetts code and an authority on air barriers, Wagdy Anis’s clarification is much appreciated. We are not the first to point out, though, that the language can be misleading. In any case, including materials meeting 0.004 cfm/ft2 @ 75 Pa is easy; providing continuity is tough. We second the call for a performance standard and testing protocol.

 

Published June 27, 2008

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