Melting vinyl siding is getting its share of media attention in Charlotte, N.C.
That's where homeowners have experienced warped and melted vinyl siding, which caught the attention of Charlotte's WCNC NewsChannel 36.
WCNC's investigative team was asking viewers to contact the team if they, too, had melting vinyl siding. Reporter Stuart Watson did not respond to an e-mail request for comment.
The homes were built by Pulte Homes Inc. of Bloomfield Hills, Mich., whose spokesperson said by e-mail March 9 that the incident in Charlotte is not isolated to that city.
The culprit in the melting vinyl siding situation is, in fact, low-E (energy-efficient) windows, according to Pulte's Eric Younan.
He said the problem is occurring in areas where low-E windows are used.
This melting is a result of a system problem where the windows and the siding sometimes do not work well together, Younan said. It's not that widespread of a problem and represents a small fraction of the total homes with low-E windows. The fix is going to be comprised of a solution where the siding has a higher melting point, and the windows have lower reflectivity.
Officials from the Vinyl Siding Institute confirmed that by e-mail March 9.
This issue is not limited to vinyl siding, VSI President Jery Huntley said. There have been some reports of reflected sunlight damage to other materials as well. Occasional wood discoloration and charring, and damage to paint, roofing and other plastics such as decking, window lineal and trim, have all been reported.
The National Association of Home Builders of Washington has even issued a report on the phenomenon. In the science of window glass, the glass may slightly warp or deflect because there is a difference in barometric pressure between the interior of the glass panes and the outside air pressure, according to the report. The resulting concavity of the glass may focus sunlight reflected from the window, similar to what happens when light goes through a magnifying glass. The heat generated by the focused, reflected sunlight has proved sufficient to visibly damage and distort vinyl siding on nearby houses, NAHB said.
NAHB has issued recommendations for remediation, which include use of screens over the windows to diffuse the light; use of awnings; and planting shrubs or trees to offset the effect of the sunlight.
Officials also have said that replacing the vinyl siding with another exterior cladding material is an option, although expensive and it may lead to other issues, including color matching. Low-E windows also could be replaced by clear glass, but local building codes often can be an obstacle. Low-E windows often are requested by the building codes.
NAHB officials also have suggested equipping the windows with capillary tubes. This allows for the gradual equalization of barometric pressure, according to the NAHB document, and decreases the possibility of concavity. The tube solution was used in a development in Tacoma, Wash.
After replacement, there has been no reported recurrence of vinyl distortion from reflected sunlight, NAHB said.
For its part, Washington-based VSI is watching the issue.
The issue of heat distortion from reflected sunlight is a relatively new and infrequent phenomenon, Huntley said. However when it does happen, because it can be a striking visual image, it tends to garner media attention.
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