Reaction With Pressure Treated Cedar Roof Shingles

Kenneth Holzberg
2/18/2011
I have a galvalume roof on my one-story wrap around porch. Above it, on the second story roof, my contractor installed pressure treated cedar shingles. With the first rain, the galvalume roof immediately appeared to rust/corrode from chemicals leeching from the cedar shingles. It continues to worsen. Is there any way to remove this corrosion? My contractor wants to try a product called CLR, but I'm concerned that such a strong chemical will cause further damage to the galvalume. Is there any way to prevent further damage from the leeching? There is a gutter on the second story roof, but it is ineffective as a barrier in the winter months when it is filled with ice and snow; when the snow is thawing, the runoff just bypasses the gutter.
Todd Miller
Classic Products, Inc.
3/3/2011
There probably is no way to stop this. It will lessen over time but the damage will be done. I think that CLR will create additional damage. A quality paint system on the galvalume roof would be one option. You could even stay with the silver or mill finish sort of color.
Info @windowsonwashington.net
An informed customer is our best customer.
3/3/2011
+1 The CLR is designed to remove oxidation and mineral content via a chemical interaction. It is likely that this chemical would further strip the roof of any protective finish.
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