Moisture entry through basement walls

Cause

Ground moisture, seen as efflorescence or internal paint damage, moves through the basement wall because of:

  • failure of or missing damp-proof membrane
  • no perforated drainage pipe at the base of the wall for groundwater removal
  • no drainage gravel above the drain, resulting in the drainage pipe becoming blocked with silt
  • no filter fabric between the drainage gravel and drain, resulting in the drainage pipe becoming blocked with silt

Repair

  • if possible dig out and expose the basement wall:
    • check the drainage pipe for blockages; clear by flushing out with high pressure water
    • install a perforated drainage pipe at the base of the wall if necessary; place pea gravel around the pipe and lay a geotextile filter fabric over the gravel
    • seal the exposed wall with a waterproof coating or membrane
    • protect the waterproof membrane with sheet material such as polystyrene
    • line both excavated face and face of basement wall with B19 grade geotextile fabric.