Skip Navigation

Deck Cross-section Requirements

Use the following checklist to ensure your drawings are complete and provide enough information to verify Building Code requirements and Zoning By-law requirements. A sample drawing is shown below.

Your cross-section must show:

  • Top guardrail size and type - see mandatory requirements below (shown as A on the drawing below)
  • Baluster size, type and spacing - see mandatory requirements below (B)
  • Deck surface, size and type (C) 
  • Anchorage to house, if applicable (D)
  • Joist attachment, i.e., hangers (E)
  • Joist size and spacing (F)
  • Beam size and type (G)
  • Post size and type (H)
  • Post and beam support, if the deck is not attached to the house (I)
  • Railing height (J)
  • Deck height above grade (K)
  • Post depth in ground – see requirements below (L)
  • Pad type and size, or flared concrete sono tube, if used (M)
  • Joist overhang (N)

 Sample cross section drawing for residential decks

Guardrail requirements:

  • Guardrails must be provided if the deck is 0.6 metres (23.6 inches) higher than the adjacent surface or grade.
  • Wooden guardrails must be either the “cantilever picket systems” or the “post and rail system” (click here for more information).
  • Any other type of guardrail must be approved by a professional engineer registered in the Province of Ontario.
  • Perimeter seating requires backrest heights and construction based on the guardrail requirements. The guardrail height will be measured from the seat surface.
  • Minimum guardrail heights are shown in the following table:

 Deck Height  Req'd Guardrail Height
 Below 0.6m (23 5/8)"  No guardrail required
 Up to 1.8 m (5'11") 0.9m (36") guardrail
 Above 1.8m(5.11") 1.07 m (42") guardrail

Balustrade requirements:

  • Balustrades must be vertical, non-climbable, with no openings of more than 0.1 metre (4 inches)
  • Balustrades must meet the structural requirements of the Ontario Building Code

Foundation requirements:

  • Decks attached to a building with a full foundation usually require support from a foundation extending at least 1.5 metres (5 feet) below grade.
  • Decks that are not attached to a building may be built with on-grade structural supports.