How Hot Can Vinyl Windows Withstand?

Thermal Expansion

• Vinyl windows can expand in hot weather, but so can any other material if it gets hot enough. This is called thermal expansion, and the “Journal of Light Construction” notes vinyl windows do have a greater rate of expansion than do other types of windows. In an interview with the journal, window consultant Karl Kardek notes you could see an increase of as much as 7/16 inch -- almost half an inch -- in windows that are 8 feet wide. The expansion can actually crack some building materials, notes the journal. However, builders and window installers should already be aware of this and plan for it when installing the vinyl window. They accommodate possible thermal expansion by leaving a gap between the edge of the window and the siding of the building. The journal places this gap at 1/4 inch.

Established Use

• Vinyl windows are used on homes in areas like Phoenix, Arizona, where summer temperatures of over 100 degrees Fahrenheit are normal. The National Weather Service in Phoenix notes that an average of 18 days per year have temperatures at or above 110 F. There are companies in the area, though, that are actively trying to discourage installing vinyl windows because they claim the windows warp too badly in the heat, overcoming any allowances included by the installer. However, the use of vinyl windows in central Arizona indicates that they are able to withstand temperatures that are at least a few degrees over 110 F. Vinyl windows do have a limit, though; while the exact hottest temperature it can withstand isn't known -- it would vary with the quality of the window and the installation -- vinyl can't hold up to temperatures nearing 200 F.

Considerations

• Temperatures can climb that high and possibly destroy a vinyl window when sunlight reflects off another window. ABC15.com notes that homeowners in different parts of the United States, including colder climates like Ohio, have noticed melting vinyl even if the object in question had never had a problem before. It turns out that these vinyl objects were in the path of reflected sunlight from a newly installed window, which created spots where the temperature reached over 200 F. This is something to take into account when installing vinyl windows. If a reflection from another window hits the vinyl frame, the window would not be able to withstand the increased temperature.

Word of Mouth

• It is possible some companies are biased against the material because they sell another type of window, just as positive reports about vinyl could have a basis in bias against other window materials. If you want to install vinyl windows in an area that regularly sees very hot temperatures, speak to neighbors who you see have vinyl windows. Find out how long they’ve had them, what the sun exposure has been like and if they’ve noticed any problems.