There are no heat sources behind that wall besides a toaster oven that sits on the counter top and is seldom used. I would think any heat source from inside would have caused some damage to the cabinet directly above. This is new housing so the walls are insulated.
I haven't used any chemicals on the deck since the spring of '06.
It's not a manufacturer defect, or it wouldn't all be in the same spot like that.
My guess is that you had something on the deck or the railing that reflected the sun on that spot. Maybe a snow shovel leaning against the railing, depending on which direction that wall faces. Or maybe something dark leaning against the wall?
It not only looks melted, it looks burnt. Scary. What is peculiar is that the melt doesn't look like it goes straight up, as if something hot was set there and the heat would radiate and rise. Does the light fixture have curved lenses that could concentrate and focus the sunlight? Might take an alignment of all the planets for that to happen :o) Kids been experimenting?
Wow, that had to be heated over 200 degrees. Given the location, was anything on the deck rail? Leaning against it? Could the wires behind the light and receptacle have been shorted and started a fire?
Something like a grill too close could do it, but the location seems unlikely for that.
Here is a pic of the deck, the damaged area is on the far left. My grill is under that striped cover on the right.
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There is an outlet behind that area. It is a GFCI that controls half of the kitchen outlets. I have put my hand all over that wall on the inside and out, I feel no heat and see no damage on the inside including the outlet.
I think we have a winner here- that looks chemical, not heat-related. My first thought was that whoever did the last stain job on rail got a glob on wall, and wiped it down with the wrong solvent to clean it off. Even if the solvent didn't cause immediate visible damage, it could have made the plastic more sun-sensitive.
That's what I was thinking, seeing the outlet right there, and possibly a wire path.
I don't think it would be chemicals, vinyl is pretty inert stuff. But I don't know I've never applied mineral spirits or thinner to it - both would be used to clean up the finish on that railing.
Did the builder leave any siding scraps in garage ceiling, crawlspace, or similar? Sounds like time for a test. For that matter, since you will be replacing that area of siding anyway, just test it next to the current damaged spot. By the way- time to start looking for the matching siding to do the repairs with. Colors and surface textures change from year to year, so the place only being a couple years old is in your favor. A good siding guy should be able to piece in replacement strips with no problem, but he probably won't wanna hunt down matching material for you. If the builder still has a local office, they can probably pull up the file and tell you the make and color number. I'd buy a whole bundle, and keep the extras in garage attic or similar. You, or the next owner, will need them at some point.
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