Stain below vinyl siding.

[Dennis R. Goudreau]

did you see the type of nails used,in any of the applications

[David C. Macy]

No,

But it sounds like you are hitting the nail on the head.

Another inspector friend of mine that has been in business for about 20 years stated he thought it may be the type of nails used.

That makes sense!!

[Carl Brown]

Would the nails be causing stains if they are dry?

[Mark Sylvester]

Looks to me like the foundation bolts probably were exposed to rain storms during construction causing the rust stains.

That's my guess.

[Eddie P. Chatterton]

Is there alot of snow in those parts. At any time was snow making contact on the foundation wall and siding?

[David C. Macy]

Originally Posted by echatterton

Is there alot of snow in those parts. At any time was snow making contact on the foundation wall and siding?

It really depends on the season and area. I would not say a lot, but we get enough. Not located in the snow belt.

[Scott E. Green]

Being in the vinyl siding business for years , here's another likely possibility. Abundance of decaying insects (cluster flies & bee's are common) behind the siding. Acids eating at galvanized roofing nails , and maybe galvanized starter strip. Will cause stains to come out weep holes in siding. In your case , I would guess galvanized or steel starter strip. Or , maybe just galvanized nails in starter strip of any material. When vinyl siding first come out , We were told we had to use aluminum nails , and we did. Somewhere along the line the aluminum nails were no longer an issue. Most contractors switched to roofing nails. No problems useing roofing nails unless they started to rust really bad , which was caused by wet decaying insects. In most cases , it was not just a rusty nail head alone.

[Charlie D. Zornes]

Are stains matalic in nature? I believe the plates or shoe was bolted down and nailed. Along came a rain during construction and rusted them. Another rain came prior to dry in and started the stains. If no sill seal is used we have found this to be true. Try an acid wash and see if it comes off.