Wood vs Steel Framing — GTA Construction Guide

Steel is roughly 4x stronger than wood per pound but costs 2-3x more per linear foot of beam. The choice usually is span and load, at certain span lengths, no wood beam is large enough, and steel becomes the only option.

Wood is the default for residential single-family construction across Ontario for good reasons:

1. cost, wood framing is 30-50% cheaper than equivalent steel for typical residential spans
2. every framing crew in the GTA is trained on wood, unlimited labour pool
3. cheap and abundant, every lumber yard stocks 2x4, 2x6, LVL, and parallam
4. easy to modify, homeowners and renovators can re-cut, re-nail, and re-attach without specialized trades
5. better thermal performance, wood has lower thermal conductivity than steel, reducing thermal bridging
6. excellent in residential spans, engineered LVLs handle 18-24' beams which covers most residential needs
7. lighter, wood requires less crane time on site and lighter foundations.

For new builds, additions, garden suites, and basement framing, wood is correct.

Steel is necessary when:

1. span exceeds 24 feet, open-concept main floor with no interior walls, large family rooms, or basement renovations removing multiple bearing walls all push beyond LVL capacity
2. load exceeds wood capacity, second storey above two-bay garage, heavy roof systems, or commercial floor loads
3. commercial or industrial fit-outs, non-combustible framing is often required by code or insurance
4. multi-storey buildings, high-rises and most multi-unit residential above 4 storeys require steel or concrete
5. tight ceiling height, steel beams achieve the same load capacity in less depth than wood, preserving headroom
6. point loads from columns above, steel concentrates load better than wood at column-to-beam connections.

Most GTA custom homes have 2-4 steel beams in them, typically opening up the main floor or supporting the second storey above the garage.

Steel premium gets quoted as a percentage of total framing cost. For typical residential projects, steel usually adds 8-15% to the framing line item, concentrated on a few high-demand structural elements rather than the whole building.

Both wood and steel are approved framing materials under the Ontario Building Code. Standard residential wood framing falls under Part 9 with prescriptive sizing tables, no engineer required for typical assemblies. Engineered wood (LVL, parallam, glulam) and all structural steel require a P.Eng-stamped design.

For any beam over 12 feet of clear span, any column carrying more than one floor of load, or any composite wood-steel assembly, an engineer's stamp is required and the City building department will not issue a permit without it. CWB (Canadian Welding Bureau) certification is required for any welded steel connection in Ontario.