Thread: Rust spots on stucco (EIFS)

At todays inspection of a 28 year old townhouse the exterior walls showed rust spots, they were present on every wall.

Any ideas as to the cause? I am thinking since the spots are rust coloured there is iron present in the stucco finnish?

Thank you for any assistance rendered.

Normally rust spots like that are caused when the finish coat ends up with some type of iron in its mix. Could be some little sand flex's of iron oxide or a sand mix with small amounts of iron in it.

About the only cure is to scratch/sand out the areas and refinish. More cosmetic than anything.

Thanks very much Scott, thats reassuring. I am sure my client will be relieved.

In Arizona this issue turned into a major lawsuit against a large builder and the sand supplier. I would caution you not to under estimate/report this problem. Rust is an expansive process and these spots can develop into ever-worsening cracks down the road. Lawyers can easily line up experts to testify that the stucco must be removed and replaced.

I bowed out of a case as an expert witness where I would have assisted in defending the builder. You definitely do not want to be named in a lawsuit on this matter. Protect yourself with cautionary language.

Originally Posted by David Swartz

In Arizona this issue turned into a major lawsuit against a large builder and the sand supplier. I would caution you not to under estimate/report this problem. Rust is an expansive process and these spots can develop into ever-worsening cracks down the road. Lawyers can easily line up experts to testify that the stucco must be removed and replaced.

I bowed out of a case as an expert witness where I would have assisted in defending the builder. You definitely do not want to be named in a lawsuit on this matter. Protect yourself with cautionary language.

True with stucco, but this is on EIFS.. I guess if you had enough in the mix it could cause a problem but with my experience it is more of a cosmetic issue with EIFS. The lamina on the EIFS is more elastic than a hardcoat or western one coat stucco.

Thanks guys.