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Under One Roof

Canadian Roofing Reference Manual

12.1.2 Walls Accessible from the Exterior

For proper waterproofing installation, a space of at least 600 mm (24 in) is needed between the exterior face of the foundation wall and the surrounding earth. Sheeting and shoring must retain earth loads, and the excavation must be kept free of water. For best results, the waterproofing should be installed in lifts, typically 1.8 m to 2.4 m (6 ft to 8 ft) high, as backfill is placed and compacted. The following list of properties that waterproofing materials should possess when applied to the exterior side of foundation walls:

  • Be completely adhered to the wall. If the membrane is not fully adhered, water from a leak can migrate to other areas of the foundation, increasing damage and making location and repair of the leak more difficult.
  • Resist moisture. Waterproofing is exposed to conditions that can range from intermittently damp to constantly wet.
  • Resist the chemicals and minerals found in the surrounding soil.
  • Accommodate the shrinkage, settlement or other movement anticipated in the foundation wall.
  • Hold its position on the wall surface until the protection course and backfill has been placed.
  • Withstand backfill and compaction operations. Most waterproofing materials require some form of protection.