Roof Blisters

A large blister in a modified bitumen roof membrane, which you can see has compromised the integrity of the roof.

Tell-tale appearance of a roof blister in a built-up roof. Note the loss of gravel surfacing.

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More Pictures:

1. Blisters in a Modified Bitumen Roof

Useful Links:

1. General: A good short article on roof blisters, "Blisters: Repair or Re-Cover?" by roof expert Dick Fricklas, is archived on the website. The article is from 2015.

2. Built-up Roofs: "Blistering in Built-up Roofs: A Review" can be seen at the NRCA website.

3. Built-up Roofs: "Ways to Reduce Blistering in Built-Up Roofs" is a short, informative article available at the National Research Council Canada website. It includes a good explanation of how blisters form in built-up roofs.

4. Modified Bitumen: "Blistering in SBS Polymer Modified Bituminous Roofs" is a terrific article, also available on the National Research Council Canada website

5. Modified Bitumen: "Investigating the Cause of Blistering in SBS Polymer Modified-Bitumen Roofing Membranes" is heavy on technical detail and explanation of methodology; scroll to the end for the conclusions if you're short on time. Available on the National Research Council Canada website.

6. Shingles: "Blistering of Organic Asphalt Shingles" is a short technical bulletin available at the website of the Canadian Asphalt Shingle Manufacturers' Association.

7. Spray Polyurethane Foam: "Spray Polyurethane Foam Blisters - Their Causes, Types, Prevention and Repair" is a concise, authoritative article produced by the Spray Polyurethane Foam Alliance and available on the website of NCFI Polyurethanes.