Lally columns and steel I-beams are the primary structural support systems in most Ontario post-war homes. Deteriorated or improperly installed columns and beams are a structural safety concern requiring prompt attention.
Types of Support Columns in Ontario Basements
Lally columns (steel pipe columns): Hollow or concrete-filled steel pipe, typically 3.5" or 4" diameter. Common in Ontario post-war construction. Lifespan 50-75 years in dry conditions. In wet basements, base corrosion is the primary failure mode. Signs of failure: visible rust scale or pitting, deflection or lean, concrete pad deterioration.
Wood posts (pre-1950 homes): Susceptible to rot and insect damage. Wood posts in contact with concrete must be replaced with steel or treated lumber with proper isolation membrane.
Adjustable steel teleposts (modern standard): Allow height adjustment during installation. Must be locked (welded or pinned) after installation — adjustable columns are not designed for permanent use.
Steel I-Beam Assessment
Surface rust is normal. Active pitting rust reducing web or flange thickness requires structural engineer assessment. Temporary shoring cost while beam is replaced: $500-$1,500.
Replacement Costs (GTA 2026)
- Single lally column replacement: $800-$2,500 (including temp support, new column, base/top plates, concrete pad)
- Full beam and column system (3 columns, 20m beam): $6,000-$15,000
- Structural engineer assessment: $500-$1,200
- Municipal permit: $200-$500
Related guides on home.renovation.reviews
Most lally column problems we see in GTA basements show up alongside water issues, so it pays to read these together:
- Wet Basement This Spring? What GTA Homeowners Should Do First — first-week triage when you find moisture at the column base
- Toronto Basement Flood Subsidy Jumps to $6,650 on May 1 — funding that can offset waterproofing tied to a structural fix
- Ontario Spray Polyurea and Waterproofing Membrane Guide 2026 — what we spec on the foundation side after a beam or column replacement
- What it actually costs to pull a permit in the GTA in 2026 — realistic permit timelines and fees for structural work
- Most Commonly Asked Questions — community FAQ for homeowners new to the forum
If you have a column or beam concern in your basement, post a photo and a quick description of the symptoms (lean, rust, deflection, water staining) below and we will weigh in.
Full structural guide: https://telegra.ph/Ontario-Lally-Column-and-Steel-Beam-Replacement-Guide-2026---Costs-and-Structural-Requirements-04-26