Waterproofing

Waterproofing is the application of water-resistant barriers and membranes to building surfaces to prevent water penetration into the structure. In residential construction, waterproofing is most critical in wet rooms (bathrooms, showers, laundry rooms) and on foundation walls and basement floors. The waterproofing system works in conjunction with floor drains and proper surface slopes to manage water safely.

In wet rooms, waterproofing typically consists of a liquid-applied or sheet membrane that is applied to the floor and walls before tiling. The membrane must be continuous, with all joints, corners, and penetrations (pipes, drains) sealed using reinforcing fabric and compatible sealants. Finnish building codes specify minimum requirements for wet room waterproofing, and the work must be performed by a certified waterproofing installer.

Foundation waterproofing protects below-grade walls and floors from ground moisture and hydrostatic pressure. Methods include bituminous coatings, drainage boards, bentonite clay sheets, and cementitious waterproofing systems. Foundation waterproofing works in tandem with the foundation drain and proper surface grading to keep basement spaces dry.

Failed waterproofing is one of the leading causes of moisture damage in homes. Signs include peeling tiles, discolored grout, soft or spongy flooring, and musty odors. If you suspect waterproofing failure, especially in a bathroom, a professional moisture survey should be conducted promptly to determine the extent of the damage before repairs are planned.