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What guard height is required for a deck in Ontario?

Last updated: June 2026

Short answer: Guards on elevated walking surfaces typically require 900 mm (36 in.) minimum height when the drop exceeds 600 mm; some locations require 1,070 mm (42 in.) — always verify the latest OBC and local amendments.

Detailed explanation

Guards are required where the difference in elevation exceeds 600 mm in Part 9. Height is measured from the adjacent walking surface to the top of the guard.

On stairs, guard height is measured from the line of nosings and may differ from guards on flat surfaces. Infill openings must not allow passage of a 100 mm sphere.

Load requirements apply to guards and handrails. Cable and glass guard systems must be designed and installed to meet structural and opening limits.

Relevant OBC sections

  • Ontario Building Code

    Section 9.8.8. — Guards

  • Ontario Building Code

    Section 9.8.7. — Handrails

Example scenario

Your deck surface is 30 inches above grade. You install a 36-inch guard, but your municipality enforces 42-inch guards on decks — check local amendments before final inspection.

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