Sound technical content, curated with aloha by
Ted Mooney, P.E. RET
Pine Beach, NJ

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Rheinzinc roofing & siding issues

Q. I recently built a house and used Rhinezinc metal panels on portions of the exterior. This house is located near the Beach in NJ and is subject to Attack from Seagull crap. I wash it off as soon as I can if I am there, but sometimes I am not there for a week or two, and it seems the excrement starts to pit and corrode the metal. What is the best way to clean the panels, and what can I do to repair the damage? I would appreciate any help.

Thanks,

John Pewitt
homeowner - Hoboken, New Jersey
2004

A. Your problem isn't a metal structural problem, it's more esthetic. As rain and moisture wash down the roof it will remove the Seagull mess, the more rain the quicker the removal. The nature of Rheinzink material as a regenerative metal is what makes it so special. Your roof will last from 50 to 100 years depending on your climate. Feel secure that you have bought a long term roofing solution.

Nils Simonsen
Metal Tech -USA - Peachtree City, Georgia, USA

Reaction between zinc wall cladding and aluminium rivets

Q. I have a fairly old beach cottage about 20 meters from the sea and exposed to heavy winds. About a year ago we had the walls cladded with titanium zinc sheets (Rheinzink) which carries a warranty of 30 years. The contractor made extensive use of aluminium rivets to join or fix some sheets. Within less than a year holes appeared in the sheets around some of the aluminium rivets. The titanium zinc appears to be crumbling or disintegrating around the holes (now 20 to 50 mm in size). Thus far it is only on the sea side of the house.
My question: Will there be some kind of galvanic action between the aluminium rivets and the titanium zinc sheets? And why do the holes grow bigger?
Also, a very coarse white layer forms on the sheets only on the sea side. Is this the normal protective layer that forms through oxidation? It seems excessive. It is not salt as it cannot be washed off.
Hope you have answers. Thank you.

Willem Malherbe
Home owner - Stellenbosch, Western Cape, South Africa
September 17, 2018

A. Hi Willem. Aluminum is supposed to be compatible with Rheinzink according to
https://www.rheinzink.us/technical-info/compatible-building-materials/

I think you'd better contact them or your contractor and try to figure out what's happening. Perhaps there is copper in the galvanic loop somewhere?

Regards,

Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

Q. Thank you, Ted. I am aware of what Rheinzink claims and they sent someone for an inspection. According to them it is caused by vibration around the rivet. But then why does the metal continue crumbling?

Willem Malherbe [returning]
- Stellenbosch, Western Cape, South Africa

A. Hi Willem.

It is important to clarify whether the rivets consist only of aluminum.
There are aluminum rivets with a copper pin or steel pin.
Especially the rivets that contain copper are not good in contact with aluminum.
Would ask the manufacturer what kind of rivets were used.

If the problem has started on the sea side it could also be delayed in time on the other sides as well.

Joerg Beerli
AluSolutions - Hallau, SH, Switzerland

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