Exterior Stairs — OBC Requirements
Last updated: June 2026
Weather exposure, drainage, guards, and landings for outdoor stairs.
Detailed explanation
Exterior stairs must resist weather and frost heave where supported on grade. Treads should shed water and remain slip-resistant. Part 9 requirements for rise, run, width, handrails, and guards still apply.
Landings are required at doors and at the top and bottom of stairs depending on configuration. The landing depth must accommodate the door swing and safe standing space.
Guards are required where the drop exceeds the threshold in OBC Part 9 — commonly at deck and porch stairs. Guard height and opening limitations differ from interior guards in some cases.
Ontario Building Code references
Ontario Building Code
Section 9.8.4. — Stairs
Stair construction including exterior applications.
Ontario Building Code
Section 9.8.8. — Guards
Guard requirements at elevated walking surfaces.
Examples
- Rear deck stairs to the backyard need guards if the drop exceeds the code threshold.
- A landing at the patio door must be large enough for safe egress with the door open.
Common mistakes
- Omitting landings at exterior doors.
- Using interior-rated materials without accounting for freeze-thaw and wet conditions.
- Guard height measured incorrectly on stairs versus flat surfaces.
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