Flat roof flashing - leak

Discussion in 'Roofing and Guttering' started by mmaatt, 10 Dec 2020.

  1. mmaatt


    10 Dec 2020
    Thanks Received:
    United Kingdom
    We moved in to this house in May. The garage is a flat roof extension and joins the external wall of the house, which is pebble dash rendered.

    Looks like it was done on the cheap as it's just mortar flashing and while the felt has been recently been redone, they've just gone over the old stuff.

    Anyway, it leaks down the wall where it joins the house. A roofer came out and supposedly sealed it by painting on a load of lead mastic (or something like that) over the mortar. That hasn;t worked.

    I know (now) that a proper job would involve raking into the render, feeding in lead flashings and then sealing that. But I'm reluctant to spend more money as I kind of want to see what else crops up and anticipate having to replace the whole roof in the next few years.

    Is there anything I can do as a low-skilled but willing to try DIYer to improve the seal of the flashing, even if it's not perfect?
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  3. ^woody^


    3 Sep 2006
    Thanks Received:
    West Mids
    United Kingdom
    Assuming that the "roofer"(?) did a proper job with suitable material and it has not worked .....

    You need to at least cut a slot into the render and insert a barrier to stop water running down the face and within the render if its in poor condition.

    A mini grinder, some Flashbland and some mastic (Leadmate) are the minimum for a quick fix for several years life. Less than £50

    Otherwise if the render is sound and a suitable sealer such as Acrypol or bitumen is used, it could be fine for a while.
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