Replies

1. GBA Editor
   Martin Holladay | Mar 30, 2012 09:39am | #1

   Daniel,
   Unfortunately, the problem you describe is fairly common, and the number of reported incidents like yours is increasing. I suggest you read this article: Window Reflections Can Melt Vinyl Siding.

   After reading the article, if you have further questions, feel free to post your questions here.

2. 
   user-723121 | Mar 30, 2012 10:13am | #2

   Vicat Softening Temperature of PVC is quite low, a google search will give a temperature range.

3. GBA Editor
   Martin Holladay | Mar 30, 2012 10:17am | #3

   Doug,
   That information is in my article. Vinyl siding starts to soften and distort at 160 to 165 degrees F.

4. 
   puZz6sBjXg | Mar 31, 2012 01:24pm | #4

   Please take a look at this to understand how damage is being done TO vinyl siding, not BY vinyl siding --- and to other products in the path of this unnaturally concentrated beam of sunlight: http://www.vinylsiding.org/aboutsiding/cleanmain/solarandheat/index.asp

   Anything in the path of the beam that can't take 200+ degress can be damaged.

5. 
   4eWF9dpiWi | Apr 09, 2012 08:41am | #5

   The problem is as others have stated, the neighboring glass is being concentrated & focused on your siding. Your best defense against reflected light is placing a screen over the windows in question. Vinyl can start softening at the temperatures noted, though if the vinyl siding is actually a CPVC (cellular PVC), chances are the reflection won’t damage it as CPVC can withstand temps around 210F. That’s slightly higher than anything I’ve recorded while studying this condition. I’ve not found any type film that could be applied to the exterior of a window that would defuse the reflection as well. As the VSI information suggests, other ways of dealing with the reflection include placing trees or other foliage in line with the reflection, though if the sun is concentrated on them, they will likely be damaged as well. Other options are to replace that area with a material with a higher tolerance, like CPVC or polypropylene. Today’s architecture, with an ever increasing number of windows and spectrally selective coatings, has resulted in the increased regularity of reflected sunlight damage.

6. GBA Editor
   Martin Holladay | Apr 09, 2012 09:35am | #6

   Rick,
   Other investigators have recorded temperatures as high as 219 degrees F on siding that is receiving reflected light from nearby windows.