Top Air & Vapor Barrier Installation Errors

Although a single-ply membrane, as stated in the International Energy Conservation Code (IECC), qualifies as an air barrier; and can satisfy the requirement for an air barrier on any given project; there are benefits to adding an additional air and vapor barrier to the roofing assembly. Avoiding some of the below most common installation errors will ensure your air and vapor barrier installation is a success:

1. Air and vapor barrier (A&VB) membrane not kept at proper temperature before installation: It is critical to keep the temperature of the A&VB membrane above 60°F, as low temperatures can negatively affect adhesion. If the membrane’s temperature is below 40°F during installation, adhesion will be significantly diminished.
2. Primer not kept at proper temperature before installation: Primer must be kept above 60°F prior to installation. If primer temperatures drop, use approved warming equipment to bring primer back up to temperature.
3. A&VB membrane not properly rolled in: SBS (Styrene-Butadiene-Styrene) asphalt adhesive is pressure-sensitive. To ensure proper contact, A&VB field sheets must be rolled with a 100- to 150-lb. roller, and vertical surfaces must be rolled with a hand roller. When installing VapAir Seal™ MD directly over metal decks, brooming the sheet is acceptable.
4. No primer on parapet: When installing VapAir Seal MD on vertical and non-metal surfaces, priming is required. When installing VapAir Seal MD directly over metal decks, priming is not required.
5. Seams not rolled in properly: To ensure proper adhesion, it is critical that seams are rolled in with a seam roller. Using a 150-lb. roller on seams is not sufficient.
6. Improper details: It is critical that A&VBs are properly sealed per Carlisle specifications and details.
7. Improper A&VB membrane for project: Many variables (deck type, weather, job conditions, etc.) determine which type of A&VB to use on a project. Click here for more information on Carlisle's Air & Vapor Barriers.
8. Installing A&VB over wet concrete: Because adhesion can be compromised when A&VBs are installed over wet concrete, it is critical that the concrete be allowed to dry before installation. The concrete must be allowed to dry naturally; “torch drying” or “force drying” are not acceptable, as these methods push moisture back into the concrete. Additionally, if rain falls on a dry concrete deck, it must be allowed to dry naturally prior to installing the A&VB.

For more information, reference Carlisle’s Air and Vapor Barrier Field Guide, or contact Carlisle’s Air & Vapor Barrier Product Manager, Paul Markel.