electrolysis | General Discussion | Archive | Ask The Experts Forum

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Hi, I know it's ok to install metal roofing over existing roof (asphalt shingles) and I'm considering do just this. I understand that eloctrolysis occurs when dissimilar metals contact each other. Do I have to remove the old drip edges and flashings because they are aluminum? My embedded flashing in the chimney is lead. Will water runoff from the lead cause corrosion on the painted galvalume roofing? Thanks for all you help.	Guest User 7/3/2009	Share Or copy this URL: https://www.metalroofing.com/spirit/comment/13536/find/
I think the lead runoff should be okay but probably wise to check with your metal roofing manufacturer pertaining to the paint finish they use. As far as the aluminum flashings, I always suggest a layer of underlayment over old shingles. This underlayment would also serve to separate the aluminum flashings from the steel roof.	Todd Miller Isaiah Industries, Inc. 7/3/2009	Share Or copy this URL: https://www.metalroofing.com/spirit/comment/13537/find/
Great. I was planning on doing that anyway. I'll just be sure to run it up under the siding far enough to separate the two. Thanks again	Guest User 7/3/2009	Share Or copy this URL: https://www.metalroofing.com/spirit/comment/13538/find/
All best.	Todd Miller Isaiah Industries, Inc. 7/3/2009	Share Or copy this URL: https://www.metalroofing.com/spirit/comment/13539/find/