| Primary value | 2.20 m |
| Applies to | Headroom over treads · Headroom at landings · Headroom under stair soffit |
| Measured as | Vertical distance from the leading edge of any tread (or landing) to the underside of the stair or ceiling above. |
| Source | NBC 2016 — Part 4, Clause 4.4.3 ✓ Verified |
2.20 m ensures even tall users can climb without ducking. Below this, the under-stair zone becomes unusable for circulation and forces awkward design workarounds.
Designers usually provide 2.4–2.6 m for comfort. Headroom failures are most common where stairs land near doorways or under low slabs.