Every year we get more and more calls about the increasing concerns and issues with window reflection causing siding to melt. New construction homes are on the rise and so is the melting of siding with window reflection.


So what does cause the melting of siding?


While no scientific testing has been done, it has been discovered that Low-E glass (energy efficient windows–which are mandated in a lot of new builds) tend to be the big culprit. Low E glass acts like a magnifying glass and enhances the sun’s intensity in certain weather conditions. Depending on how close neighboring houses are, it is suggested that 20 feet is usually what triggers damage.

So what are Low-E Windows?

Low-e windows limit heat transfer (keeping the cool in and heat out and vice versa depending on the season.) While the glass does tend to have more of a green hue to it, it also reflects 30-50% more of the sun’s energy compared to clear glass that reflects roughly 10%. In fact, the National Association of Home Builders (NAHB) believes the cause of melting siding is due to changes in barometric pressure causing the low-e glass to bow inwards creating the magnifying glass effect.

Figure 26_06_02

The reflection creates a beam of light and heat so intense it bounces onto the siding and causes it to melt. Crazy, huh? Most vinyl siding withholds heat of up to 160-165 degrees Fahrenheit. But with the sun bouncing off the low-E glass, temperatures are reaching around 200 degrees causing the siding to melt, ripple, warp and distort.

This has been problematic for many homeowners across the nation. In many cases, homeowners insurance, home builders, and siding and window manufacturers are refusing to cover the replacement costs. Leaving the costs up to the homeowners. It has been a circling issue as to whom is left to pay for the bill.

So, how can you stop window reflection from melting siding on homes? Can you prevent your siding from melting?


While there is no guarantee that anything will stop it 100%, there are a few options that can help.

1. 3M Window Film. 3M Exterior Prestige 40 works by redirecting the light. See more benefits listed below.

**Multi-layered Construction disperses IR & Solar Energy

**Reduces direct Magnification of solar energy off of Low-E coated Glass

**7 Year Warranty by 3M on product

**Medium tint shade provides Fading Protection, up to 97% IR rejection & moderate glare reduction to interior environment

**Applied to exterior of glass

**Window film was not designed for this issue – But it has been used successfully for this issue – However, there is no guarantee this product solves      this problem.

2. Add in landscaping/screening. Try to cover up the problem areas.

3. Install an awning
4. Change out the low-e glass to clear glass. While it may be expensive, it certain extreme cases, it might be the best option.

We’d love to chat if you need more information regarding window films.

-Sun Control MN