Ontario Structural Beam and Header Guide 2026 - Sizing, Engineering and Costs

Structural beam and header installation is required for any wall opening in Ontario — whether removing a load-bearing wall or installing a new window or door in an exterior wall. This guide covers engineering requirements, OBC sizing rules, and 2026 GTA costs.

Load-Bearing vs Non-Load-Bearing Walls

In Ontario residential construction, load-bearing walls run perpendicular to floor joists and carry the weight of the structure above. In a typical two-storey home, all exterior walls are load-bearing. Interior load-bearing walls typically run parallel to the ridge (perpendicular to joists).

How to identify: look at the floor joists in the basement — load-bearing walls are directly above beam/post systems supporting the joists. A structural engineer can confirm in 1-2 hours for $300-$600.

OBC Header Sizing

Ontario Building Code 9.23 provides prescriptive header sizing tables for standard residential spans and loads. Examples for a two-storey structure with one floor above:

1.8m (6 ft) opening: 2 x 2x10 or 1 LVL 1.75x9.25 minimum.

3.0m (10 ft) opening: 3 x 2x12 or 1.75x14 LVL engineered beam minimum.

Beyond OBC prescriptive limits (over 3.5m or non-standard loading): structural engineer specification required.

Temporary Support During Beam Installation

Removing a load-bearing wall requires temporary shoring while permanent beam and posts are installed. Shoring typically uses LVL beams or fabricated wood cribbing at 1.2m intervals. Remove bearing only after new beam is fully supported on posts and footings confirmed adequate.

Costs (GTA 2026)

Structural engineer assessment and beam sizing: $600-$1,500.

Load-bearing wall removal with beam installation (3-4m opening): $8,000-$18,000 including engineering, temporary shoring, beam, posts, drywall, and finish.

Building permit for structural work: $300-$800 in GTA municipalities.

Ontario structural renovation resources: home.renovation.reviews