| Primary value | 1.0 m |
| Applies to | Residential buildings |
| Exceptions | Hotels, hostels, dormitories → 1.5 m |
| Educational, assembly, business, mercantile, industrial, hospital → 1.5 m | |
| Buildings up to 15 m height (residential) → 1.0 m permitted | |
| Buildings with very low occupant load (max 20 persons) → 0.75 m | |
| Spiral stairs (not a primary exit for >10 people) → 1.5 m minimum diameter | |
| Measured as | Clear width between stair handrail / wall — exclusive of handrail projection (max 90 mm). |
| Source | NBC 2016 — Part 4, Clause 4.10.1 and Table 5 ✓ Verified |
Stair width is critical for orderly evacuation during emergencies. NBC 2016 mandates minimum widths to ensure a calculated flow rate of people and to allow for contraflow movement, where firefighters with equipment can ascend while occupants descend, a crucial factor in high-rise incidents.
While 1.0 m is the minimum for apartments, many developers provide 1.2 m to 1.5 m for better comfort. For institutional (hospitals) and assembly buildings, the mandatory 2.0 m width is non-negotiable to allow for stretcher movement and rapid mass evacuation.