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 comes down to 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.