ᐅ Stains on Gutters and Downpipes

Hello building professionals,

we are fully renovating a single-family house of the EW65 type.

In October 2021, the entire roof was replaced, including reinforcing the roof structure and installing Steico® boards for insulation. All zinc gutters and downspouts were also replaced.

However, only a few weeks after installation, heavy stains appeared on these gutters and downspouts – see attached pictures. The bends and elbows are particularly affected.

I reported this issue immediately to the contractor. The response was not very satisfactory: “It’s true that downspouts develop patina at different rates, which is not very attractive […] but it will eventually even out.”

Winter weather conditions prevented any action at the time, but now in early summer I would like to address this again. I have a newly replaced roof with a roof exit, heating boiler vent, etc., but these really unsightly gutters and downspouts remain – for me, this is unacceptable since I have never seen this with a newly replaced roof.

Now my question(s): Is this a material defect, or what is causing these stains?
Is this issue covered under the roofer’s warranty?

Best regards.

This is a natural oxidation of zinc.

Completely normal for zinc. It oxidizes… take a walk through new housing developments and have a look around.

Completely normal... There's nothing you can do, or you could replace it with plastic.

HilfeHilfe schrieb:

Completely normal....... There’s nothing you can do, except replace it with plastic.

Or paint it after oxidation.

Or have them pre-coated beforehand. Or use pre-weathered zinc pipes.