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Damp 9" solid wall - will Thompson's waterseal help?

Discussion in 'Plastering and Rendering' started by MeldrewsMate, 22 Dec 2018.

  1. MeldrewsMate


    27 Jan 2010
    Thanks Received:
    Buckinghamshire, Darn Sarf
    United Kingdom
    I got a call from the gf yesterday, a large damp patch had appeared high up on her bedroom wall, and I can't confess to being the culprit...it's been a long time since that was possible.

    Her flat is the ground floor of a converted 1910 (ish) semi house with solid 9" walls. The bedroom affected spans the south and west faces.

    The immediate cause was found to be a blocked gutter downpipe, now cleared, but further inspection revealed damaged brickwork, with several brick faces eroded, and poor pointing.
    The lower 1.4m of the entire house has been externally rendered.

    The ultimate plan is to have the entire gable end (including the upper flat's west face) re-rendered to (I assume) prevent water permeating to the brickwork, but that won't happen until summer 2019. In the meantime I plan to mitigate the water ingress by coating the external wall with something like Thompson's Water Seal.

    My question is simply this: Will use of a waterproofing substance now cause or compromise the adhesion or performance of the cement render next summer?

    Regards, MM
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  3. footprints


    21 Sep 2011
    Thanks Received:
    United Kingdom
    Spraying silicone could well cause problems in rendering, you have fixed the gutter issue. Leave it till you decide to do a full repair, the wall will stand more chance of drying out if untreated.
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