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Melting Vinyl Siding? Here's Why and What You Can Do

Vinyl siding on a home that has been melted and bowed by relfected light from low-e window

Thousands of homeowners across Virginia and the U.S. are seeing their vinyl siding melting, bowing, and bubbling up, and they don't know why. Is it global warming? Is the vinyl defective? The answer is probably no to both questions, it's your neighbor's home that's causing the problem.

Randy Scarth is one homeowner who can't believe what is happening to his home.

"It's almost like a waving action as you look at the entire siding," Scarth says.

So what is causing the problem? Concentrated sunlight from a neighbor's energy-efficient windows, is often referred to as "thermal distortion."

Energy-efficient (low-e) windows are coated to reflect more light than standard windows. The heat and light that hit the vinyl siding is actually worse in winter because the sun is lower in the sky.

Low-e windows act like a magnifying glass, concentrating the sun's energy onto a small area. Temperatures in these hot spots often exceed the melting temperature of the vinyl siding, causing thousands of dollars in damage. Most vinyl siding products will start to melt and warp when they reach 160 to 165 degrees Fahrenheit. On darker siding, temperatures have reached as high as 220° F.

How to prevent damage

The only way a homeowner can stop the reflection from damaging vinyl siding is by blocking and diffusing the reflection.

Here are three ways to do this:

Ask your neighbor to (or purchase them for him yourself):

  • Install insect screens on his windows.

  • Install Exterior window shades on the windows.

  • Purchase awnings to go over the window.

  • Plant bushes or trees to block the reflection.

What about the damaged siding?

According to Matt Dobson, VP at the Vinyl Siding Institute, once you've been able to block the light reflection, you may or may not be paying out-of-pocket for new siding.

If your homeowners insurance or home warranty won't cover the repairs, the siding manufacturer may supply replacement siding to take care of the damage. This is probably the best first place to start, and the easiest solution.

If you cannot remedy the reflection issue, however, you are better off installing a non-flammable material such as Hardy Plank.

Can other things be damaged by these reflections?

Artificial turf, garbage cans, trash bags, vinyl fencing, plastic parts of cars, and even the vinyl based paint on wood siding can all melt when exposed to the reflected light from low-e windows. The Consumer Product Safety Commission has confirmed that four house fires in the U.S. were caused by low-e window reflections. In these cases, sun room roof glass and skylights ignited nearby cedar shingles or wood siding.

Some plants may also suffer from reflected light and heat, particularly if they are in the shade loving plants like hostas. Some turfgrass can also get burn spots.

Homes are not the only things damaged by these reflections. The windows in a newly built hotel in Las Vegas purportedly gave off reflections hot enough to burn guests using the hotel's pool.


Sources:, GBA Prime, EZ Snap, St. Louis Dispatch


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