Is there a right or wrng way to apply lead flashing? My builder has simply stuck my flashing to the wall with lead mastic – surely this will not last very long!

  • Mark Brinkley


    People do stick flashings to walls with mastic but when they do they rarely go to the expense of buying lead to use as a flashing. Duct tape would be more common!

    The "correct" way to do it is to chisel or grind out a mortar course and then fold the top edge of the lead into it. You hammer home a few bits of lead above the flashing to hold it in place and you neatly "dress" the lead underneath. Finally, you "point up" (i.e. place mortar in and trowel off to a neat finish) the empty gap above the lead to match the existing mortar. That makes a good lasting waterproof detail.

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