IS 1642:1989 Part 2 is the Indian Standard (BIS) for fire safety of buildings (part 2: details of construction). This code establishes the detailed construction practices required to ensure adequate passive fire safety in buildings. It specifies fire resistance ratings for various structural elements, compartmentation rules to prevent fire spread, and construction requirements for walls, floors, roofs, and staircases.
Specifies construction details for fire resistance of building elements, including walls, floors, and roofs.
Key fire resistance ratings, minimum element thicknesses, reinforcement cover, and construction details for steel, concrete, and masonry structures.
| Reference | Value | Clause |
|---|---|---|
| Min dimension, RC Column (4h)— Minimum dimension for a 4-hour fire resistance rating. | 450 mm | Cl. 5.2.1 (Table 5) |
| Min dimension, RC Column (2h)— Minimum dimension for a 2-hour fire resistance rating. | 300 mm | Cl. 5.2.1 (Table 5) |
| Min thickness, RC Slab (2h)— For solid reinforced concrete slabs. | 125 mm | Cl. 5.2.3 (Table 7) |
| Min thickness, RC Slab (1h)— For solid reinforced concrete slabs. | 95 mm | Cl. 5.2.3 (Table 7) |
| Min cover, RC Beam (SS, 2h)— For simply supported beams to achieve 2-hour fire resistance. | 45 mm | Cl. 5.2.4 (Table 8) |
| Min cover, RC Beam (Continuous, 2h)— For continuous beams to achieve 2-hour fire resistance. | 35 mm | Cl. 5.2.4 (Table 9) |
| Min cover, RC Slab (SS, 1h)— For simply supported slabs to achieve 1-hour fire resistance. | 20 mm | Cl. 5.2.4 (Table 10) |
| Min cover, RC Slab (Continuous, 1h)— For continuous slabs to achieve 1-hour fire resistance. | 15 mm | Cl. 5.2.4 (Table 11) |
| Concrete encasement, Steel Column (2h)— Minimum thickness of solid concrete protection. | 50 mm | Cl. 4.2.1 (Table 2) |
| Concrete encasement, Steel Beam (2h)— Minimum thickness of solid concrete protection. | 50 mm | Cl. 4.2.1 (Table 3) |
| Plaster protection, Steel Column (1h)— Thickness of gypsum plaster on metal lath. | 20 mm | Cl. 4.2.2 (Table 4) |
| Min thickness, Solid Brick Wall (4h)— Assumes plaster on at least one side. | 200 mm | Cl. 7.2.1 (Table 15) |
| Min thickness, Solid Brick Wall (2h)— Assumes plaster on at least one side. | 100 mm | Cl. 7.2.1 (Table 15) |
| Min leaf thickness, Cavity Brick Wall (2h)— Minimum thickness for each brick leaf. | 100 mm | Cl. 7.2.2 (Table 16) |
| Max gap, Fire Door (Bottom)— Maximum permissible gap between door bottom and floor/threshold. | 15 mm | Cl. 8.2.3 |
| Max gap, Fire Door (Sides/Top)— Maximum permissible gap at jambs and head. | 3 mm | Cl. 8.2.3 |
| Max gap, Fire Door Frame to Wall— Gap to be filled with non-combustible material. | 10 mm | Cl. 8.2.2 |
| Max panel area, Wired Glass (1h)— For 1-hour fire-resisting doors and partitions. | 1.2 m² | Cl. 9.2 (Table 18) |
| Max cavity dimension before barrier (Wall)— Maximum height or length for concealed wall spaces. | 20 m | Cl. 10.2.1 |
| Max cavity area before barrier (Floor/Roof)— Maximum area for concealed floor or roof/ceiling spaces. | 100 m² | Cl. 10.2.2 |
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
| Parameter | IS Value | International | Source |
|---|---|---|---|
| Min. thickness for 1-hour rated reinforced concrete slab | 100 mm | 89 mm (3.5 inches) for siliceous aggregate concrete | IBC 2021, Table 722.3.2(1) |
| Min. concrete cover for a 2-hour rated restrained RC beam | 40 mm | 25 mm (1 inch) | IBC 2021, Table 722.2.1(1) |
| Min. dimension of a 3-hour rated reinforced concrete column | 400 mm | 356 mm (14 inches) | IBC 2021, Table 722.2.2.1 |
| Min. thickness for a 4-hour rated solid clay brick load-bearing wall (unplastered) | 200 mm | 178 mm (7 inches) nominal thickness | IBC 2021, Table 722.3.2 |
| Min. thickness for a 2-hour rated solid concrete load-bearing wall (siliceous aggregate) | 160 mm | 152 mm (6.0 inches) | IBC 2021, Table 722.3.2(1) |