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Roofing/TPO roofing membrane


Air bubble
Air bubble  

We had our flat roof covered with TPO roofing membrane.
The flat roof intersects with a regular shingled roof. This picture shows an air bubble in the membrane which was not glued down. As a result, water collects around it after rain. Will this cause problems in the future?

The roofers anchored the TPO membrane by putting it under the
Roofing shingles. Is this the correct procedure?


The wrinkle/bubble will not be a problem as it relates to the performance of the roof membrane.  Longevity may be affected if a large area of debris collects and remains on the upslope side of the wrinkle as TPO has a history of premature failure when exposed to prolonged periods of high heat.  Sometimes the dirt collection is sufficient to absorb enough heat for this to be a problem ten years down the road.  Please also note that TPO is very thermally responsive so it will expand with warmer temperatures and contract when cooler.  The bubble should be noticable smaller in the winter months which may alleviate some of the water and debris collection.  If the membrane is adhered as you indicate, the installers will generally adhere one half of the membrane at a time and they did not peel back and apply glue to the  fold when the second half was adhered, or the sheet did not roll out into the adhesive straight and they wound up with a bunched up area.  This area could be cut, adhered and patched, but then there is a patch to look at.

The shingle installation appears to be fine, but the membrane may have a compatibilty issue with asphalt, so the TPO should not be in direct contact with the shingles.  We often see the underlayment of the existing shingle roof is not weatherlapped over your new single ply membrane.  This is worth checking out.  A new strip of synthetic underlayment should be tucked under the existing shingle underlayment and over the new TPO and trimmed to the edge of the new overlying shingles.

Bruce Ryan II, RRO
Professional Roof Consultants, Inc


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Bruce A. Ryan II, RRO


I offer solid knowlege of all types of Commercial and Residential Roofing, Waterproofing, and, Building Envelope systems. Experience ranges across low slope and steep slope roof systems. I am also well versed in matters regarding condensation and ventilation. I enjoy donating some of my time and knowledge to the betterment of others.


Bruce Ryan has 20 years of roofing, waterproofing, and building envelope consulting experience with PRC, with 5 years of commercial roofing experience prior to joining the firm. He became Vice President of the company in 1998. Bruce Ryan plays a key role in the development of practical, long-term roofing and waterproofing solutions, along with implementation of on-site forensic studies. Bruce also has a high level of experience with regard to the impacts of roofing materials and construction for demanding clients with heavily occupied structures.

Oregon Construction Contractors Board Construction Specifiers Institute National Roofing Contractors Association The Institute of Roofing, Waterproofing, & Building Envelope Professionals Oregon Board of Investigators Installation Masters

University of Maryland BS Business & Administration Registered Roof Observer - RCI Private Investigator Certified EIFS inspector - Northwest Wall and Ceiling Bureau Certified InstallationMaster™ - The Installation Masters™ Training and Certification Program (developed by American Architectural Manufacturers Association)

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