Odd markings on vinyl siding

[Matt Fellman]

This siding is installed over plywood T1-11.... the picture is on the south side of the house and gets a lot of direct sun. The pattern makes me think the fasteners from the original siding or the foam siding underlayment are, for some reason, showing through. Maybe they're touching the siding and causing different temperature conditions at those points? I'm just guessing here... any ideas?

[Jim Luttrall]

Not a clue.

[John Dirks Jr]

In a case like that I might have lifted a piece at one of the overlaps to see if it was a bleed through pattern or what might have been underneath.

[Scott Jarvis]

Matt,

I had the exact same thing on a home where newer vinyl siding and foam underlayment had been installed. The spots were only on the south and west sides. On this house they were consistently spaced both horizontally and vertically. The buyers had a contractor come out and look at it prior to the inspection, and the contractor came up with the same conclusion you did. In some way the underlayment fasteners appeared to be causing the spots.

[Rolland Pruner]

Possible past cleaning Or past bushes rub? somthing leaning against sideing. Hard to say!