How Prevalent is Melted Vinyl Siding—and are Windows and Glass to Blame?

June 12th, 2012 by DWM Magazine

The industry has heard it before: a local newspaper will report on a case of melted vinyl siding and fingers are often pointed at low-E windows. The news will then die down until another case arises. However, some in the industry believe the issue of vinyl siding melting due to low-E windows is truly an isolated one. Yet the topic continues to draw interest. In fact, a discussion thread in the Linkedin group for the Insulating Glass Manufacturers Alliance (IGMA) posed the question: “We are hearing a lot more about melted vinyl siding from the window industry. Do you believe this is something that IGMA and other fenestration associations should look into further?” The thread generated a fair amount of response but some of that was misinformation, so DWM went to the sources in a few cases to set the record straight and to explore the issue further.

First, representatives of the Window and Door Manufacturers Association (WDMA) and the American Architectural Manufacturers Association (AAMA) tell DWM they do not have a task group looking into these issues. IGMA’s executive director Marg Webb says the discussion was posted to gauge how many in the industry deem this to be a real issue and there are no plans at the present time to research the matter—either alone or in conjunction with other industry associations.

Research has been performed on the topic, however. Lawrence Berkeley National Laboratory (LBNL) published a white paper on the subject in July 2011.  Titled “Research Needs: Glass Solar Reflectance and Vinyl Siding,” the research showed that, “The spectral reflectance, angle of incidence to the sun, and surface distortion properties of insulating window glass will determine the shape and concentration of reflected solar radiation from the glass. Recent media reports have pointed to these concentrated solar reflections as the primary contributor to vinyl siding distortion; however, all the factors involved in vinyl siding distortion are not yet fully understood.

Investigation directly into the causes of vinyl siding distortion has been limited, and a majority of test results from those investigations have been kept confidential by their sponsors. Further studies are needed to fully characterize the conditions associated with siding distortion, the scope of the problem, and possible mitigation or prevention strategies.”

“The intervention methods now are to put a screen on the window—anything that block the rays of the sun,” adds Webb. “But the reality is it can happen when sun is reflecting off roofs, driveways and even by direct sunlight with no adjacent buildings. You have to have the right parameters for this to occur. It doesn’t happen a lot but it can be dramatic when it does.”

Phil Lewin, vice president, technical marketing at Vinyl Window Designs in Ontario, says he has never personally seen a case of melted siding beyond those documented in magazines.

“So, one would have to assume that it is the exception and not the rule unless there is more documentation to the contrary,” he says. “However, it is clearly a real phenomenon and, if it does occur, needs to be treated seriously by the contractor.”

But that leaves a question: who is liable?

“The vinyl siding industry is being aggressive and pointing fingers without taking responsibility for their product,” says Webb.

“Should it be the siding company that is liable for making a product that might melt?” asks Lewin. “Maybe it’s the window company for not disclosing the possibility that a reflection could create excessive heat? How about the contractor for not checking every window for all possible angles of the sun?”

He adds that no one should be blamed.

“It should be treated as an ‘act of god’. One would hope that all parties, including the customer, would resolve the issue in a professional and intelligent manner and move on,” says Lewin.

So where does the industry go from here? When the LBNL white paper was published, Table 6 listed proposed research topics and actions to further understand and characterize this issue. “Collaboration with industry would be required to develop research protocols and methodologies to address the proposed research topics,” reads the report.

LBNL’s Stephen Selkowitz was not available for comment at press time so no word yet on whether that further research is in the works.

“I’ve never had one question about this issue,” adds Webb.

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  1. RE:

    Hi, I just found this article and wanted to pass along that not only is vinyl siding being melted but my patio furniture was destroyed by the “magnifying glass” affect of our windows.

    What has been the industry’s response?

    I am emailing some photos to


  2. The siding on our four year old home is seriously warped. Both the builder and the vinyl manufacturer have denied our request for help, stating solar distortion was caused by reflection from our neighbor’s windows. This distortion occurred after three years in our home and while we were still under warranty from the manufacturer. We are trying to get information regarding the type of screening that could be applied to the neighbor’s window and have gotten an estimate for landscaping that might help the situation; however, we cannot proceed until the damaged siding is replaced. We feel that the responsibility for the “act of God” should be shared by everyone involved and not just by the unsuspecting buyer who bought a home in a 55 and over community built by a very reputable builder.

    Any help or suggestions you can provide will be greatly appreciated. We are a retired couple on a limited income and cannot afford to replace an entire wall of the home we thought would be our last.

  3. I don’t think there is any way that you can hold the vinyl siding manufacturer liable for sun glare warping, melting or burning the siding. That would be like holding them liable because the siding caught on fire because a kid was playing with matches and started the siding on fire.

    If it was a big enough issue some member of congress would have poked there noses in the issue and started a witch hunt against siding manufacturers.

  4. I am a realtor and have run into this in more than one community in our service area. Several homes have severely warped sections of vinylin the last one I saw. The vinyl is medium weight, which may be less resistant than the heavier weights, but that is a guess.

    It is consistently true that suppliers, architects, developers and builders throw up a product then walk away saying, “Not my problem” after their obligatory year or so is over for warranty on their structures. It is truly disgusting to see the industry blaming one another and saying it “isn’t a big enough problem to warrant MY attention” or “I will wait until someone MAKES me do something about it”. Sadly, no one has pride in their work. It’s all get the quick buck and run.

  5. I have a feeling this is happening to my neighbors house from my low-e double-paned windows. It’s been a process within the last year or so and it has gotten worse. It started off with about 4 feet, then spread to about 12-15 feet. He does not believe this can happen, because it hasn’t happened to anyone else’s home in the neighborhood. Nobody else’s home has the thinner vinyl siding, paired with neighboring low-e windows. There are many articles out there on this and I really wish he would read them! It’s very frustrating knowing we have not placed a heat source near his home, but he thinks that we did. Now, as time goes on, I plan on taking many photos of where the sun reflects for proof. I just hope he doesn’t replace the 5 or 6 planks of siding before I prove my point!

  6. This happened to me. We had newer windows installed and a year later in the summer I noticed warping starting to happen. I came to the conclusion that it depends on so many variable. The manufacturing process, type of window, amount of sunlight etc… I replaced the affected areas and it hasn’t happened again. I wasn’t happy about it but it’s fixed now so my wife is happy.

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