PVC/galvanized

Bob Howard rmhoward at omninet.net.au
Wed Dec 12 02:30:01 EST 2001




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









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