Pop quiz... - Certified SoftWash Roof Cleaning

Ray Burke · Community Member

Pop quiz...

Jeff Thompson · Junior Member

Maybe at one time that concrete was sealed and that is the old sealer showing ?....

Ray Burke · Community Member

Jeff:
the metal on the sign pole is leaching out metals that are killing the growth on the concrete.

Jesse Bracken · Junior Member

Galvanic coating is a process where Zinc is applied to metal to protect it from corrosion. Zinc is added to algae resistant shingles (used to be copper, but it got too expensive) There fore the Zinc is killing the what ever is growing on the concrete as it leaches off the sign post.

Jesse Bracken · Junior Member

oops sorry I didn't see Ray's response till after i posted...

Jeff Thompson · Junior Member

Ray Burke wrote:
Jeff:
the metal on the sign pole is leaching out metals that are killing the growth on the concrete.

Interesting. I was focused on all the spots away from the pole. They are everywhere. Didn't think they could have spread out like that from the pole.

Troy Layman · Lead Tech

Yay me! I knew the answer. Good info Jesse. I didn't realize that about the AR or stain guard shingles using zinc instead of copper due to the cost. I guess I haven't read every post on these forums yet.