Rust on Metal Valley

Hey Guys-

Is rusting on the metal valleys a material defect? Is it just a surface cosmetic issue or will it continue to eat away at the metal and eventually cause problems?


Rust is permeable to air and water, therefore the interior metal continues to corrode.

Permeable and roof are two words that shouldn’t be mentioned in the same sentence.

Also, an old narrative I might use in this situation:

  • Minor amounts of rust observed in one or more areas of the metal flashing. Rust is permeable to air and water, in which the interior metal continues to corrode therefore could cause subsequent leaks. Recommend corrective action as necessary. One option would be to: While the rust is minor (at the time of inspection): Wire brush the rust then prime and paint the metal. If rust is prevalent, it can be removed using Rust-Away® Oxidation and Corrosion Remover. Manufactured by Hocking International, 2121 Hoover Ave., National City, CA 91950. Ph: 619/474-8457 Fax: 619/477-5630. It works very well. Paint the valley with Rustoleum® or similar product afterward.

Hope this helps.

the shakes will be gone before the metal ever gives up…I have done over 10k roof inspections and I dont see that being a big deal…I have also torn off about 2000 shake roofs so I feel pretty good in sayin that… now on some tile roofs I have seen them rust so bad that the metal was gone and the ply wood was exposed.

Looks as if the shakes are failing, anyway. (cupping and lifting) see pic #1. Some of them have a good inch or more of lift. (either that, or a really screwed up install, but should still be corrected.).

The fire retardant in some shakes are corrosive.

I would have probed those areas and report my findings.

Sorry guys, I’ve been away from the boards for a few days. I agree and called out the wood roof.

Jeff, could you explain further the process you’d use for probing? I’m assuming you mean with a moisture meter? Sorry if that’s an elementary question but I just never thought of that. Thanks.

look rust is never a good thing and shows deterioration ,simple.The Vally is wearing away.I would note as fixable and minor issue.I am owner of small facade restoration business and roofing was my first trade and did so for 14 years.Also brick and cement finishing.
Any water markes under the roof deck any-ware near the Vally.
Can fix problem using rust paint and should be done using Ariel platform.
Do not walk on shakes can be dangerous.
I am only going off the pictures you have sent us to make an observation.:roll: