IS 12251:1987 is the Indian Standard (BIS) for drainage of building basements. This code of practice outlines methods for the investigation, design, and construction of drainage systems for building basements. It addresses sources of subsurface water, methods for its exclusion (waterproofing) and removal (gravity or pumped systems), and provides guidance on system components like drains, sumps, and pumps.
Code of practice for drainage of building basements
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
| Parameter | IS Value | International | Source |
|---|---|---|---|
| Minimum Gradient of Perimeter Drain | Not less than 1 in 150 (0.67%) | Shall be drained by gravity or mechanical means. A slope of 0.5% (1 in 200) is common practice. | IBC 2021 (1805.4.2) / General Practice |
| Perimeter Drain Location | Invert to be at least 150 mm below the top of the basement floor slab. | The top of the drain tile shall be at or below the level of the slab or area to be protected. | IBC 2021 (1805.4.2) |
| Minimum Sump Pit Size | 0.5 m x 0.5 m and 0.5 m deep | Not less than 750 mm in diameter or 500 mm square, and not less than 600 mm deep. | NBCC 2020 (9.14.5.1) |
| Protection of Waterproofing Membrane | 115 mm brick wall or 40 mm thick cement concrete (1:2:4) layer. | Protected from damage by a protection course, drainage panel, or insulation board. | BS 8102:2022 |
| Filter Media for Drains | Prescribed graded filter of coarse sand and gravel around porous pipes. | Gravel or crushed stone covered with an approved filter membrane (geotextile fabric). | IBC 2021 (1805.4.2) |
| Design Performance Levels | Not formally defined; provides a single code of practice. | Grade 1 (some seepage tolerable), Grade 2 (no water penetration), Grade 3 (totally dry environment). | BS 8102:2022 |