Lead flashing stains on a concrete tile roof


Postby pmcb » Thu Feb 17, 2011 5:44 pm

Hello folks. I am in the process of completing a self build house project and have discovered a problem with the lead flashing trays which were built into the chimney.

The builder did not coat the trays with patination (think that is how it is spelt) oil and after having completed the roof it is now leaking down the tiles and staining them. All exposed lead is coated but the leakage is coming out from between the chimney blockwork.

Any ideas for removing lead stains from tiles or suggestions on how to remedy this eyesore? :cry:
pmcb
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Joined: Thu Feb 17, 2011 5:40 pm

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Postby bethesdaslate » Fri Feb 18, 2011 10:18 am

Hello
Unfortunately the best remedy is going to be to replace the stained tiles, if they are run-of-the-mill concrete tiles then this is quite easy and cheap to do.
Lead DPC trays should be coated with bituminous based paint, this would avoid staining and prevent corrosion of the lead.
Patination Oil is for using on exposed lead, and should be used on the underside of aprons and cover flashings too.
Lead staining is likely to continue if the chimney is porous/semi-porous and not being rendered? due to the reaction of the moisture and mortar on lead, which would have been avoided by the bituminous paint.
Either replace tiles and render the chimney or rebuild the chimney installing the DPC's to LCA recommendations or expect the staining to continue.
Sorry!
Jon
bethesdaslate
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Joined: Fri Feb 18, 2011 9:47 am


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