PRINCIPLES/DESIGN AND CONSTRUCTION
During the estimating and budgeting phase, it may become apparent that the construction
managers and owner's representatives do not understand the principles of air barriers. They may
regard them suspiciously as something they have never done before and a waste of money. The
owner and construction manager may be likely to listen to the contractor's claims that such an
elaborate air barrier system is unnecessary, and that they never include them in the walls they
build. If building or energy codes mandated the inclusion of an air barrier, it would certainly
strengthen the case of the air barrier proponent.
An air barrier will be incorporated into the shop drawings, and therefore into the building envelope,
only if a specific requirement for an air barrier system is made by the wall designer. Shop drawings
are generally not submitted for masonry walls, rather the working drawings are used during
construction. It is therefore very important that the masonry contract drawings and specifications
are thorough so that there are no questions regarding the existence of the air barrier, its location,
materials and its treatment at junctions. Since masonry contractors typically do not develop shop
drawings and design details in response to performance specifications, they are relying on the
designer to develop these details. In other curtain wall systems the specifications are generally
performance based and the manufacturer incorporates them into the engineering and shop
drawings, which become the construction drawings. The air barrier will be correctly incorporated
into the construction drawings only if the designer has included the system into their drawings and
included appropriate language in the specifications.
If the commitment to an air barrier has survived to the construction phase, there are two remaining
issues to deal with, education and supervision. All site personnel must be educated on the air
barrier system and its importance to the project. An inspection agent should be employed and an
inspection program developed to insure a proper installation of the entire wall, with special attention
given to items that are new to the site worker. A field mock-up of the wall is a very good way to
educate the site personnel and to identify construction problems with the system as designed.
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