TechNews: Air and Vapor Barrier Installation Errors

July 17, 2025
Avoiding some of the most common errors will help ensure your air and vapor barrier installation is a success.

Errors to Avoid
  1. Air and vapor barrier (AVB) membrane not kept at proper temperature before installation: It is critical to keep the temperature of the AVB 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. AVB membrane not properly rolled in: SBS asphalt adhesive is pressure-sensitive. To ensure proper contact, AVB 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 AVBs are properly sealed per Versico specifications and details.
  7. Improper AVB membrane for project: Many variables (deck type, weather, job conditions, etc.) determine which type of AVB to use on a project. Click here for more information on Versico’s Air and Vapor Barriers.
  8. Installing AVB over wet concrete: Because adhesion can be compromised when AVBs 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 AVB.
For more information, check out the following references.

AVB Field Guide
AVB page on Versico website
All Versico Specs and Details

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