warped vinyl siding

Being in the vinly siding business from day one of vinyl siding, I’ll give all you inspectors a little tip. I notice many home inspectors spend a lot of time scratching your heads on why the vinyl siding is warped. You all have your opinions, and some good opinions at that. You can all agree that it is heat, right? And you all know of the barbaque grill, right? Beyond that, you’re guessing heat reflecting off this, and heat reflecting off that. Good guesses, but still guesses. Well, I can tell you that you’re right. The suns rays reflect off roofs, windows, metal chimneys, shields, etc, and on to the siding. The rays of the sun also create excess heat build up at inside corners/indents of house where air doesn’t seem to move. Other heat sources are dryer vents, air conditioning units, etc, which can add heat on top of suns rays. But, the big culprit is ALUMINUM BACKING on the insulation behind the siding. The suns rays are heating the siding from the front, and also reflecting off the aluminum behind the siding, and heating the back side of the vinyl siding, which causes the warping. So, the next time you see warped vinyl siding, go to a siding joint, and take a look under the siding for aluminum. Years ago, the sales reps for vinyl siding came around to job sites, telling everyone NOT to use foil, or foil faced insulation behind the vinyl siding. It was too much heat, and would distort the siding. Yet, I still see contractors to this day, useing foil faced insulation behind vinyl siding. (By the way, prior to vinyl siding, aluminum behind siding was common practice.) Now-a-days, the suns rays are more intense than ever. I’m seeing more and more warped vinyl siding. As a rule, I find aluminum behind the siding. The post below shows a variety of pictures of melted/warped siding. One picture is melted siding on the chimney. I can tell you from experience, it’s not heat from the chimney flue. It’s heat reflecting off the little roof below the siding. More than likely aluminum is behind the siding.

Thanks for the tip Scott. I never knew that, and I’m sure there are many here that will find that to be new for them too.

Good info…

got pics?


Hey Scott. Thank you for the extensive information on warped siding. I saw my first warped house last week. I really appreciate explaining the warping on the chimney. Excellent. Good J.O.B.

Not trying to pat myself on the back but, am I on the money, or what??? For the first time, I watched a You Tube clip below on melted siding. The man actually pulled up the corner of a melted siding panel. And sure enough, THERE"S THE ALUMINUM!!! Some things the man said about materials was brief. When I get a chance, I’ll go more into details/evolution of the vinyl siding as I remember it.

I have seen it regularly happen over OSB and OSB with house wrap. The windows that were reflecting the sun had glass that was curved inward, creating a “satellite dish” effect, focusing the suns rays into a concentrated (and very hot) beam.

No aluminum foil involved… just good old basic science.

Andrew Constantine
InspectPro Home Inspections
Serving NC and SC :roll:
Fort Mill Home Inspections](http://inspectprohomeinspections.com)