On an Ontario construction project a scaffold must be able to support four times its maximum load (O. Reg. 213/91 s. 126(1)(b)), sit on a firm foundation with no makeshift supports (s. 128), and carry a guardrail on every open side where the fall is 2.4 m or more — top rail 0.9–1.1 m, toe board 89 mm (s. 26.3). A professional engineer must design any scaffold over 15 m, or over 10 m if it is a tube-and-clamp system (s. 130(1)); suspended swing stages need an engineer at any height (ss. 136.1–142.06). A competent worker must inspect the scaffold before each shift and after any event that could affect its stability.
The requirements below come from Ontario Regulation 213/91 (Construction Projects) under the Occupational Health and Safety Act (OHSA), specifically Part II (General Construction) — Access at Heights, Scaffolds and Work Platforms, and Suspended Work Platforms, sections 125 through 142. These are the rules a Ministry of Labour inspector enforces when they see a scaffold on your construction project.
Scaffold collapses and falls from scaffolds are among the leading causes of serious injuries and fatalities on Ontario construction sites. A scaffold is not permanent infrastructure — it is a temporary structure that is assembled, modified, and dismantled repeatedly over the life of a project. Every time a scaffold is changed, the risk profile changes. A brace left out, a pin not inserted, a plank that has cracked under repeated loading, a base plate sitting on frozen ground that thaws in the afternoon — any of these can cause a catastrophic failure. The inspection requirement exists because scaffolds degrade. They get hit by equipment. Workers remove planks to pass materials through and forget to replace them. Wind loads shift components overnight. The regulation requires inspection by a competent person before each shift and after any event that could affect structural integrity. This is not a formality — it is the last line of defence between a functional scaffold and a collapse that sends workers to the ground.
Sections 125 and 127 of O. Reg. 213/91 require that scaffolds be designed and erected under the supervision of a competent person. Under OHSA, “competent” means a person who is qualified because of knowledge, training, and experience to organize the work and its performance, is familiar with the Act and regulations that apply, and has knowledge of any potential or actual danger to health or safety in the workplace. For scaffold work, this means someone who understands the manufacturer’s instructions for the specific scaffold system being used, knows the load capacities of each component, can identify defective materials, and understands the tying and bracing requirements. A labourer who has never been trained on scaffold erection is not a competent person — even if they have watched others do it for years. The constructor and employer are liable if they allow an incompetent person to supervise scaffold work and a failure occurs.
Section 128 requires that every scaffold be erected on a firm foundation. This sounds simple but it is where the majority of scaffold collapses originate. A firm foundation means mudsills (typically 2x10 or 2x12 lumber) under the base plates, distributing the scaffold load over soft ground. Concrete, compacted gravel, and asphalt are adequate — but freshly backfilled soil, thawing ground, and rain-softened clay are not. The regulation explicitly prohibits makeshift supports — concrete blocks, stacked bricks, scrap lumber — under scaffold legs. Base plates must be in full contact with the mudsill and the scaffold must be plumb and level. A scaffold that is 2 degrees out of plumb at the base can be 150 mm or more out of plumb at working height on a 10-metre scaffold, and that eccentricity multiplies the lateral forces on the structure. Inspectors carry levels.
According to O. Reg. 213/91 s. 126(1)(b), a scaffold must be designed and constructed to support at least four times the maximum load or force to which it is likely to be subjected, without overturning. This is not 4 times the weight of the workers — it is 4 times the total of workers, tools, materials stored on the platform, and any dynamic loads from work activity (pouring concrete, lifting materials, wind). A standard frame scaffold bay with two 10-inch aluminum planks can typically support 75 pounds per square foot, but that capacity drops dramatically if a plank is cracked, a frame leg is bent, or cross-bracing is missing. The safety factor exists because real-world conditions are never ideal — components wear, loads are estimated, and workers sometimes stack more material on a platform than planned. When a scaffold is loaded to its rated capacity with a 4:1 safety factor, it has a 75% reserve. When workers pile extra material and reduce that factor to 2:1, the scaffold is one unexpected load away from failure.
Under O. Reg. 213/91 s. 26.3, a guardrail is required on all open sides of a scaffold platform where a worker may fall 2.4 metres (7.9 feet) or more. The guardrail must include a top rail between 0.9 m and 1.1 m above the platform, a mid rail midway between the top rail and toe board, and a toe board at least 89 mm high. Per s. 26.3(5) the top rail must resist a 675 N lateral load, the mid-rail 450 N, and the toe board 225 N. Section 135 requires that platform planks be at least 460 mm (18 inches) wide and laid tightly side by side, with the platform fully decked across the working area. A gap between planks is wide enough for a tool to fall through and strike a worker below — or for a worker’s foot to catch during movement. Fully decking the platform and securing planks against displacement are not optional — they are regulatory requirements with serious consequences when ignored.
O. Reg. 213/91 s. 129 covers rolling or mobile scaffolds. The most dangerous moment in a rolling scaffold’s use is during movement. Section 129(3) prohibits a worker from being on a platform more than 2.4 m above the base while the scaffold is being moved. This rule exists because even a small bump or crack in the floor surface can cause a sudden stop, and the resulting lateral force at platform height — amplified by the scaffold’s height — can throw a worker off the platform. Casters must be rated for the full scaffold load and wheel brakes must be engaged whenever work is being performed. Under s. 129(2), when the platform height exceeds three times the least lateral dimension of the base, guy wires, outriggers, or stabilizers must be deployed to prevent tipping. The floor surface must be smooth, level, and free of holes, drop-offs, or debris.
Sections 136.1 through 142.06 govern suspended work platforms (swing stages). These are among the most dangerous scaffold types because the entire structure hangs from the building by wire ropes, and a single rope failure can be catastrophic. Every suspended work platform must be designed by a Professional Engineer, regardless of height or size. The PE drawings must be on site. Wire ropes must have a 10:1 safety factor — far higher than the 4:1 required for frame scaffolds — because dynamic loading, rope wear, and environmental degradation (UV, chemicals, abrasion over parapet edges) reduce rope strength over time. Each worker must have an independent safety line connected to a separate anchor from the scaffold suspension system. If the scaffold fails, the worker’s independent lifeline catches them. The roof rigging must be inspected by a competent person before each use. The platform must remain level within 3 degrees — a tilted swing stage means uneven loading on the suspension points and worker instability.
Under O. Reg. 213/91 s. 130(1), any scaffold taller than 15 metres (about 49 feet) — or taller than 10 metres (about 33 feet) if it is a tube-and-clamp system — must be designed by a Professional Engineer licensed in Ontario. This is a common trap: a tube-and-clamp scaffold at 12 metres needs an engineered design even though a standard frame scaffold at the same height does not. The PE must produce drawings specifying the scaffold configuration, component types, bracing intervals, tie-in locations, and maximum load capacity. Those drawings must be on site and the scaffold must be erected per the PE’s specifications exactly — field modifications by the crew are not permitted without the PE’s approval. The 15-metre threshold exists because the engineering complexity of a tall scaffold increases non-linearly. Wind loads, eccentric loading, thermal expansion, and the cumulative effect of component tolerances all become significant at height. A 6-metre scaffold can often be designed from the manufacturer’s standard tables. A 20-metre scaffold requires site-specific engineering that accounts for the building geometry, wind exposure, soil conditions, and the specific work being performed.
Scaffold violations are among the most common orders issued by Ministry of Labour inspectors on Ontario construction sites. An inspector who finds a scaffold with missing braces, no guardrails, workers without Working at Heights training, or a scaffold over 15 metres without PE drawings will issue a compliance order — and in most cases, a stop-work order under OHSA section 57 that halts all scaffold-related activity until the violations are corrected. Fines under OHSA section 66 (as raised by the Working for Workers Act, 2023) can reach $500,000 and 12 months imprisonment for an individual, $1,500,000 for a director or officer, and $2,000,000 for a corporation. In 2023, scaffold-related violations accounted for hundreds of Ministry of Labour orders across the province. Beyond fines, a scaffold collapse that injures or kills a worker triggers a WSIB lost-time claim. Under WSIB’s current premium-rate-setting model, an employer’s rate is set within their class using six years of claims-cost and insurable-earnings history, so a serious claim can push a business into a higher risk band and raise premiums over that window — though WSIB notes that for a small business with few claims, the class rate influences the premium more than any single claim. The cost of proper inspection — 10 minutes per shift by a competent person — is negligible by comparison.
Working through a full site inspection? Pair this with the Fall Protection Requirements checker, the Ladder Safety tool, and the Critical Injury Reporting guide — all in the WSIB & OHSA tools hub. If you run a crew and want scaffold inspections, timesheets, and job records logged in one place instead of on loose paper, the Ontario contractor workspace keeps the signed daily records an inspector asks for.
Source & edition: Clause references above are drawn from O. Reg. 213/91 (Construction Projects), Part II, as amended to O. Reg. 157/25 (2025), and OHSA, R.S.O. 1990, c. O.1. Regulations change — confirm the current section text on Ontario e-Laws (ontario.ca/laws) before you rely on it. This page is an educational checklist, not legal or engineering advice, and does not replace a competent person’s judgment or a professional engineer’s design.
A scaffold must be inspected by a 'competent worker' — defined in OHSA s. 1 as a person who is qualified by knowledge, training, and experience, familiar with the Act and regulations, and aware of any actual or potential danger.
By the ToolFluency team · Updated September 2026
Free Ontario scaffold safety inspection checklist. Select scaffold type, check compliance items per O. Reg. 213/91 Part II (ss. 125-142) — frame, rolling, suspended, mast climbing, pump jack scaffolds. Flags violations with clause references.
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