[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: PVC/galvanized
- To: permaculture <permaculture@franklin.oit.unc.edu>
- Subject: Re: PVC/galvanized
- From: Bob Howard <rmhoward@omninet.net.au>
- Date: Wed, 12 Dec 2001 15:30:01 +0800
- Newsgroups: permaculture
- References: <LISTMANAGER-106819-33860-2001.12.11-12.49.34--rmhoward#omninet.net.au@franklin.oit.unc.edu>
Michael Dean wrote:
> Howzit,
>
> Can somebody explain to me why --"Never use lead head nails as fasteners on such a roof; alternatives: stainless steel screws, also galvanized screws and nails with neoprene washers"
>
> Cheers Mike.
>
Corrosion is the short answer - Lead and zinc have different electrical potential and when water acts as a conductor between them an electric potential is set up and one will corrode
the other. This is a general problem with most metals. It is generally unwise for different metals to be in contact especially where there is a risk of water being involved. (Tho' I'm
not sure about why stainless steel is OK on galvanized roofs %-)
Bob