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How To Fit Cavity Drain Membrane For Above Ground Damp Proofing - Preservation Shop
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How to fit cavity drain membrane – above ground damp proofing

How To Fit Cavity Drain Membrane For Above Ground Damp Proofing

  1. Wall to be worked on.

    Identify areas of damp and exceed by minimum 250mm either side and above, usual heights for hacking off are 1000mm, 1200mm and 1500mm. Please note we now supply 1200mm high rolls of membrane too!

  2. Carefully remove skirting board.

    2. Carefully remove skirting board- How to fit cavity drain membrane – above ground damp proofing

  3. Carefully hack off plaster back to stone, brick or blockwork.

    3. Carefully hack off plaster back to stone, brick or blockwork.- How to fit cavity drain membrane – above ground damp proofing

  4. Drill 12mm holes 150mm over external ground level and inject DPC cream.

    4. Drill 12mm holes 150mm over external ground level and inject DPC cream- How to fit cavity drain membrane – above ground damp proofing

  5. Apply primer sealer to wall.

    5. Apply primer sealer to wall- How to fit cavity drain membrane – above ground damp proofing

  6. Affix membrane to the wall .

    (see pic 12 – Floor Type Detail for the bottom edge of the membrane) finishing).
    PB2 is Isola Membrane from Sweden and CM3 Membrane is Wykamol membrane made in the UK, both do the same job.
    Depending on the area of damp you may need one of the following sized membranes,
    PB2 Membrane 1000mm high x 10 metres long roll
    PB2 Membrane 1000mm high x 20 metres long roll
    PB2 Membrane 2000mm high x 20 metres long roll
    OR
    CM3 Membrane 1000mm high x 10 metres long roll
    CM3 Membrane 1000mm high x 20 metres long roll
    CM3 Membrane 1200mm high x 20 metres long roll
    CM3 Membrane 2000mm high x 20 metres long roll
    The membranes are fixed by drilling an 8mm hole through it into the wall behind, Membrane fixing plugs are then wrapped with sealing rope and hammered into the holes to hold the membrane on the wall.
    6. Affix membrane to the wall - How to fit cavity drain membrane – above ground damp proofing

  7. Affix sealing rope around perimeter of membrane and squash onto primer.

    7. Affix sealing rope around perimeter of membrane and squash onto primer.- How to fit cavity drain membrane – above ground damp proofing

  8. Affix Overtape around the perimeter of membrane half on membrane and half on primer.

    8. Affix Overtape around perimeter of membrane half on membrane and half on primer.- How to fit cavity drain membrane – above ground damp proofing

  9. Bond the membrane to blend with the wall.

    You can either Bond the membrane to blend with the wall if thin coat required or dot’n’dab with board adhesive castled to the required depth to blend with the existing wall, ensure dabs go onto plugs to get a good mechanical fix. 9. Bond the membrane to the wall - How to fit cavity drain membrane – above ground damp proofing

  10. Check skirting for rot etc. If okay stick skirting back on with saves nails or similar.

    10. Stick skirting back on with saves nails or similar- How to fit cavity drain membrane – above ground damp proofing

  11. Skim the plaster boards to blend with remaining old plaster.

    11. Skim the plaster boards to blend with remaining old plaster- How to fit cavity drain membrane – above ground damp proofing

  12. Floor finishing detail.

    12. Floor finishing detail - How to fit cavity drain membrane – above ground damp proofing


Article by Mike Davison CSSW, M.Inst.SSE.

Mike Davison - Managing Director of the Preservation Shop

Mike is the Director of the Preservation Shop and also works as a freelance surveyor. Mike is a member of the Institute of Specialist Surveyors and Engineers and a certified surveyor in structural waterproofing (CSSW) registered with the PCA. Mike has over 30 years’ experience in the construction industry and specialises in Building Pathology, remedial works and structural repair.

Got questions??? – Ask our in-house expert Mike questions related to damp, condensation, black mould, timber preservation and treatment, basements etc.


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