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Planning to tank a wall. How to deal with ducts?

Discussion in 'Building' started by a546345, 30 Apr 2021.

  1. a546345


    11 Feb 2011
    Thanks Received:
    United Kingdom
    I have a single skin shed that was built for me as a bit of an afterthought amongst other renovations. It is built on top of a patio. The other side of this block wall is soil. In between the shed wall and soil is a membrane, then another single skin wall about 1m height, then the higher ground of soil at 1m height. The exterior of the shed is rendered above ground using Weber monocouche.

    The membrane comes into the shed on the wall, and at floor level, so it probably doesn't do an awful lot.

    The inside lower section of the wall gets wet when it rains, and some water comes in presumably where the ducts enter. I'm now planning to tank the walls using KA tanking slurry with SBR, and a small section of the floor with a slot cut at the floor wall junction as per the instructions.

    The other wall shown is an existing retaining wall. It doesn't get wet.

    I know this isn't built correctly, but need to deal with what I've ended up with, ideally as DIY. I could screed the floor if necessary, but that won't fix the wall damp.

    2 questions come to mind, assuming my plan doesn't get shot down!

    1. Should I tank up to ceiling height, or just 300mm above the external ground level.
    2. How best to deal with where the ducts and cables come in? Pre coat with SBR, then pack the slurry in the gaps?

    The ducts are only about 10m long so not much pressure on them when pulling the cables.

    Afterwards, I'm planning to batten out using 2x4 studs with the long side against the wall without fixing the battens to the wall and line the walls with OSB. This is a shed, so the walls will remain accessible if necessary.

    Cheers for any advice.

    21-04-30 09-28-11 0226.jpg
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  3. Scarlet Pimpernel

    Scarlet Pimpernel

    9 May 2020
    Thanks Received:
    It sounds as if you have built in the problem. I suspect that ground water can seep into the gap, and accumulate, between the 1 metre high wall and the shed wall. That will put a positive pressure on the water entering the building.
    I would suggest that instead of trying to prevent the water coming in, (because that will require a total redesign and rebuild) that you spend your efforts in dealing with the water that does come in.

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