vinyl siding (cupping) 1

[PSUengineer1]

Looking for a cause of the cupping in the siding at the inside corner (double J-channel), please see attached pics (cupping marked with chalk). I have ruled out heat-related damage, this is under a covered porch and no neighboring windows within hundreds of yards. Also no grill nearby.

The siding panels are approximately 8 inches long. When I shifted the siding to one side, an approximate 1-inch end clearance is at the single-piece siding runs. Tight nailing of the fasteners is not an issue as I can slide the pieces of siding back and forth with ease. Bottom edges of the siding panels are not popped loose, suggesting that there is a sufficient allowance for thermal expansion at the end of the panels. The panels were not removed.

Is observed cupping a manufacturing defect, or something else? Siding about 10 years old.

Pics attached. Any assistance is much appreciated. Thanks.

 

[Compositepro]

The cupping indicates that the siding is in compression in the vertical direction. It appears that the planks on one wall do not align perfectly with the rows on the adjacent wall, as they should. It appears to be an installation problem. The siding pieces in this area are very small and therefore light. With so little weight they may not have rested on the nails properly when being installed so the clearances to allow for expansion were not correct.

 

[MotorCity]

I would guess that its due to thermal contraction and expansion. The siding will expand and contract with temperature in both directions. Perhaps because the pieces are so short and stubby, expansion in the up and down direction is more pronounced than compared to longer pieces. The opposite wall (which probably consists of longer pieces) does not appear to have the same issue. As long as the pieces are able to move slightly without much resistance, it sounds like they were nailed correctly, otherwise I might suggest that it is buckling between the nails which act as restraints. Not likely a manufacturing defect.

 

[jayrod12]

My bet is they were installed too tight vertically in cold whether and are therefore buckling outward from heat expansion in the vertical direction. Loose nails and adequate gap allow for horizontal expansion, but it doesn't appear the same was provided in the vertical direction. Is it possible the starter strip at the bottom was installed too high, and therefore the installer tried to get the bottom of panel to line up to the adjacent paneling by pushing these down tightly on top of the next piece.

 

[oldestguy]

Why most buckling at the end and in the corner? My guess is there are tight nails and incomplete fitting of the vertical slot connection. At the inner end that part is weaker vertically. Thus an installation problem.

 

[TGS4]

Oddly enough, that vinyl siding pattern and color looks identical to what was on my home. And I had multiple instances of warpage - both on sun-facing and shade-facing sides - and in multiple lengths from short like yours to full 20' lengths. My siding was 2001-vintage - yours is a little younger.

Based on my experience, I would say that it's a manufacturer's defect.

(BTW, got my house completely re-sided in the claim.)

 

[PEinc]

Two Opinions from Siding Executives for a Major Siding Manufacturer (I have my sources!)

Opinion 1
The cause of this damage is heat distortion. This is caused when the material heats to a temperature too fast and expansion takes place causing the wavy buckling look. This can be caused by sunlight reflection or other heat sources. After seeing that one section is in a very short run and next to a door into the house, I suspect it was caused by a gas grill. If this can be proven incorrect, then look for reflection. The fact that the pieces are so small (siding pieces) and this has happened means that the heat had to be high.

Opinion 2
The course is very short so I would be surprised if it was expansion/contraction and, based on comment, looks like they left room for expansion/contraction (based on the picture).
I agree with Opinion 1. It looks like heat distortion and, because of the direction, looks like more grill damage.

http://www.PeirceEngineering.com

 

[dik]

Some vinyls have very high coefficients of thermal expansion.

Dik

 

[PEinc]

Dik, the vertical width of each siding slat is so small that there should not be that much cupping due to normal temperature variation. Length variation would be the bigger problem but that would not cause the cupping shown.

http://www.PeirceEngineering.com

 

[dik]

PEinc: I gathered that... but with the irregular shape, under compression I'm not sure how it will deform.

Dik

 

[PEinc]

Have we really confirmed there is vertical compression?

http://www.PeirceEngineering.com