Waterproofing and Damp-Proofing of Wet Areas in Building - Recommendations
1991 Edition

The IS 13182 standard identifies common causes of moisture and leaks in wet zones such as cracks and joints in concrete or masonry, improperly sealed expansion joints, damaged or insufficient waterproof membranes, leaks from plumbing fixtures and pipe penetrations, capillary moisture rising from the ground due to missing damp-proof courses, inadequate slopes leading to water pooling, and deteriorated sealants around wet area installations. It stresses the importance of thorough surface preparation, selection of appropriate waterproofing products, and meticulous detailing to mitigate these issues.

IS 13182 recommends that floor traps maintain a minimum trap seal depth of 50 mm to block sewer gases. Traps should be sized adequately to handle expected water flow without siphoning. Materials like PVC, cast iron, or stainless steel resistant to corrosion are preferred. Proper installation includes providing a slope between 1:50 and 1:100 on inlet and outlet pipes for smooth drainage, connecting traps to vent pipes to avoid siphoning, ensuring traps are accessible for cleaning, and sealing joints with appropriate compounds to prevent leaks.

IS 13182 advises using polymer-modified cementitious coatings, bituminous membranes (torch-applied or self-adhesive), liquid waterproofing membranes such as polyurethane or acrylic, polymer-modified bitumen sheets, and waterproofing admixtures in concrete or mortar. The process includes thorough surface cleaning and priming, applying at least two coats of waterproofing material, treating joints and corners with flexible sealants or tapes, and protecting the waterproofing layer with screed or tiles. Thickness typically ranges from 1.5 to 2 mm for liquid membranes and 3-4 mm for bituminous sheets to ensure durable protection.

For effective waterproofing of overhead tanks, IS 13182 suggests meticulous surface cleaning to remove dust and laitance, sealing visible cracks with polymer-modified mortars or epoxy injections, and applying a flexible cementitious or polymer-based membrane internally and externally with a minimum thickness of 2-3 mm over multiple coats. Pipe penetrations should be sealed using flexible sealants or waterproof tapes, and sleeves or collars embedded in the tank wall to prevent leaks. A protective screed or plaster layer should cover the membrane to prevent damage, followed by proper curing to ensure waterproofing efficacy.

IS 13182 recommends sanitary shafts be adequately ventilated with open tops and access doors for maintenance, coated with waterproof membranes, equipped with drainage to prevent water build-up, and have all joints sealed to stop water ingress. For external walls, the standard advises installing damp-proof courses at plinth levels, applying waterproof plasters or coatings, designing overhangs and drip edges to channel rainwater away, providing cavity walls or insulation to reduce moisture transfer, and ensuring proper site grading to prevent soil contact. These measures collectively help maintain dryness and structural integrity.