What is true is there are still shingle companies that will void their warranty if you foam to the underside of the deck…. Honestly, I thought this issue was dead.  In 2008, when I got into foam, I heard this objection all the time.  In 2008 I literally carried an original letter from shingle manufacturers confirming that they will in fact honor any legitimate warranty claim, even if the roof is foamed from below.

What is the truth, foam insulation increases the temperature of the shingles by roughly 3 degrees, hardly enough to modify the lifetime of the shingle.  Allison Bailes, who is a leading expert did the study himself showing that foam does not dramatically impact the life of the shingles.

Additionally, the godfather of building science, Joseph W. Lstiburek has published extensive studies looking into the question of shingle temperature and warranty issues.  As you can see if this article, Joe does not find justification for the claim of significant temperature differences from unvented/ hot roofs.

So who are the holdouts, a quick search including the call that started this research includes Atlas Roofing and Tamko as two holdouts in embracing this 60 plus year old technology that is both proven and successful.

Atlas Roofing Shingles warranty warning is what started this specific research into the current state of shingle warranty issues.  They are not unclear about their policy but when talking with the roofing warranty manager he said off the record that “zero claims have been denied because of foam on the underside of the roof” but if that were to be part of litigation that they would stand on their warning.  Again, he said “zero claims have been denied” but.. it is their policy.  I think it is ironic that Atlas is a manufacture of foam board products but not spray applied foam.

Tamko Shingles, is clearly not on board with the standards of foam insulation applied to the underside of a roof though they have not updated their stance since 2009 and so far have not returned my calls or emails with questions.  It does appear that Tamko is investigating the impact of foam on their shingles.  Cameron Ashley a distributor of many construction products including both shingles and foam insulation has this update they are “investigating” the impact of foam on the temperature of shingles.

Gaf/ Eli/ Owens Corning and CertainTeed have all documented their support of the application of foam under their shingles as not negatively impacting their warranty.

GAF/ Elk has no issues honoring their warranty on foamed roofs’ if there is a warranty claim.  These warranty issues are far less common than they were in 2008.  The issue has diminished as the companies that own the major mixing houses are also now the same chemical or organizations that own both shingle manufacture and foam manufactures.  The reality is that foam does not impact the life of shingles.  Respected studies are sited here that show the actual temperature difference between a “hot roof”/ “Unvented attic” is roughly 3 degrees.  Its hard to justify any impact on the warranty with such a small difference in temperature.  When talking to manufactures now like Atlas Roofing Materials, they stand firm in their objection to warranty claims on hot roofs/ unvented attics but also admit zero claims have been denied due to foam being on the underside of the deck of an Atlas Shingle.

Owens Corning, who had the longest and most vocal battle against the use of spray applied foam, has even conceded that foam is not the source of roof shingle failures… See this link for the OC bulletin regarding foam/ shingle warranty issues.  They explicitly say that if ventilation or lack of ventilation is in place and a manufacturing issue is found to be present that the warranty will be honored.  No idea if it coincided with the acquisition of Natural Polymers an Illinois based manufacture of spray applied foam insulation but the science is clear, foam does not impact the longevity of your roof and it dramatically impacts the monthly cost of heating and cooling as well as the required tons of cooling/ Btu’s needed to heat/ cool your home and the overall comfort of your home.

CertainTeed lists unvented/ hot roofs created with spray foam insulation applied to the roof deck as acceptable in its warranty. The company goes on to warn of insulation materials that allow air to flow and moisture to condense as the growth of mold and mildew is not covered under the warranty.