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Blisters. Just as painful on a roof.

Posted: 11/12/2019

Cold Weather Installation: Part I

Almost everyone has spent a day on their feet, only to come home to have painful blisters waiting for them when they take off their shoes.  It can be just as painful to spend a day on a roof, only to return the next day to find blisters in the roof membrane.

Working in low temperatures creates special challenges, such as lower production rates, shorter work days, and longer drying times for solvent based products. During periods of cold weather (40°F or less), special storage and application methods must be used to facilitate the installation of roofing materials. Solvent based adhesive and sealants must be stored in original unopened containers at temperatures between 60°F and 80°F…if the material falls below this range it must be heated until the material reaches the proper temperature range (may take 1 or more days for cold materials to be warmed to proper temperature). Products stored at cold temperatures and then restored to room temperatures may experience separation of solvents. Always remix products thoroughly prior to use and re-mix a minimum of twice a day.

Failure to allow the products to properly flash off will often result in solvent blistering of the membrane. Broom or roll the membrane immediately after bonding the sheet. If blisters occur (typically occurs within 24 hours of the installation and typically manifests when the sun warms the membrane), allow solvent to dissipate naturally for 4 to 5 days and then re-broom the membrane.

In addition to solvent blistering, there is an increased likelihood of condensation forming on the surface of adhesives or primers if installing membrane in the early morning or later in the afternoon. If condensation forms, the surfaces cannot be mated properly and work must stop until conditions improve. When conditions improve allow the adhesive to dry completely and any condensation to evaporate. Make sure the surface is completely dry before reapplying another coat of adhesive or primer and completing the membrane installation.

Following these simple precautions will lessen the potential for an uncomfortable conversation with a building owner or their representative, and explaining why their roof that seemed so well installed the night before looks completely different.

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