Compatability of Zinc with Cedar Cladding

keyplan

Hi all,
I am working on an extension that has a zinc roof with red cedar parapet walls above. The roofing contractor has advised me that, even though both materials don't come in contact with one another, the rainwater run-off from the cladding may damage the zinc. I have spoken to a timber consultant who disagrees and has told me that this will not be an issue. I have googled this and cannot find any information that is in agreement with the consultant. Has anyone had any experience using these materials together and what was the outcome? Also if there is a potential problem is there a suitable treatment for the cedar to alleviate the problem?
Thanks in advance.

Alun

I had an inkling it might have something to do with acidity since IIRC cedar wood is slightly acidic, so I Googled 'cedar acidic' and found this reference. It refers to copper roofs but the principle is the same.

http://fourseasonsroofingandsiding.com/Environmental%20Effects%20on%20Copper.html

Spannerman7

I clad my house but not cedar and had it pressure treated, some builders think it's fine to use either zinc coated or galved nails but the pressure treatment has copper salts in it, this reacts with the zinc coating and removes it, this is why black lines appear, I went for stainless and not an issue. This info may be of some use to you.

keyplan

Thanks for your replies. I have decided to put a small aluminium channel at the base of the parapet cladding to catch any run-off from the cladding and direct it to the gutter. This should go a long way to protecting the zinc - hopefully!