IS 6494:1988 is the Indian Standard (BIS) for waterproofing of concrete roof slabs. This code of practice provides guidelines for the waterproofing of flat and sloped concrete roof slabs in buildings. It covers various waterproofing systems including bitumen felts, mastic asphalt, and plastic sheeting, detailing material requirements, surface preparation, application techniques, and protective finishes. The standard emphasizes the importance of proper drainage, detailing at junctions, and maintenance for long-term effectiveness.
Lays down the recommendations for waterproofing of various types of concrete roof slabs using different materials and techniques.
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
| Parameter | IS Value | International | Source |
|---|---|---|---|
| Minimum Roof Slope (Fall) | 1 in 100 (for bitumen felt) | 1 in 80 (minimum finished fall at any point) | BS 6229:2018 |
| Minimum Upstand Height | Not less than 150 mm above finished roof level. | Minimum 150 mm (6 in.) above the finished roof surface. | ACI 222.3R-11 / BS 6229:2018 |
| Bitumen Primer Application Rate | 0.27 L/m² to 0.3 L/m² depending on surface. | Typically 0.2 - 0.4 L/m² (1 gal/100-150 sq ft) or to manufacturer's specification. | ASTM D6622 / General Practice |
| Hot Bitumen Application Rate (per coat) | At least 1.2 kg/m² per coat. | Typically 1.0 - 1.5 kg/m² (20-30 lbs/100 sq ft) per mopping. | ASTM D6622 / General Practice |
| Protective Layer | Prescribed options: Graded screed, brickbat coba, tiles. | Options include: cementitious screed, pavers on pedestals, ballast, asphaltic concrete. | ACI 222.3R-11 |
| Membrane Elongation at Break | Not specified; performance is based on the composite system. | >300% (typical for EPDM/TPO single-ply membranes). | ASTM D4637 / D6878 |