Why Is My Siding Melting?

Energy-Efficient Windows

• Your siding may be melting because surrounding homes have energy-efficient windows designed to lower the heat flow through the windows. "LBM Journal" and the “Green Building Advisor” website note complaints from homeowners who replaced vinyl siding that melted or warped due to sunlight reflecting off a window. The problem may occur when nearby windows have low-emittance, or low-E, coatings that block radiant heat transfer, causing the sun's heat to reflect back onto a nearby home and melt a portion of its vinyl siding.

Roofs

• Heat transferred from dark-colored roofs also can melt vinyl siding, according to an "LBM Journal" article by Steve Easley. According to Easley, vinyl siding might absorb the sun's heat that radiates from a dark, sloping roof to an extent that causes the siding to melt. Easley reported this situation could occur if the slope of the roof intersects a vertical wall with vinyl siding. He noted the amount of solar energy that strikes a surface can be 250 to 300 British thermal units or BTUs, per square foot per hour.

Warranties

• The manufacturer's warranty on your vinyl siding probably doesn't provide coverage if your siding melts due to heat transferred from windows or roofs. In fact, according to “Green Building Advisor” writer Martin Holladay, all major vinyl-siding manufacturers have changed their warranties to exclude that type of damage. Manufacturers' warranties for building materials often only cover damage that the manufacturer can control, such as defects in a product related to a faulty manufacturing process.

Landscape Barriers

• The Vinyl Siding Institute acknowledges that sunlight that windows reflect onto vinyl siding can create surface temperatures that exceed temperatures produced by direct exposure to the sun. According to the institute, energy-efficient glass can become concave, creating a mirror that concentrates sunlight on one area, and that area can reach temperatures higher than vinyl siding and other building materials are designed to withstand. Trees, bushes and landscaping products can block the path of reflected sunlight to prevent damage to siding and other materials, according to the institute.