A carpentry foreman is reviewing a scaffold setup on a large commercial construction site. The scaffold has a platform width of 1.2 metres and is 9 metres high. The crew reports that the scaffold feels stable, but the foreman notices that the scaffold is not tied into the building structure. What is the maximum height a scaffold can typically be before it legally requires tying into an adjacent structure in Canada (as per CSA Z797 or provincial regulations)?

Question: A carpentry foreman is reviewing a scaffold setup on a large commercial construction site. The scaffold has a platform width of 1.2 metres and is 9 metres high. The crew reports that the scaffold feels stable, but the foreman notices that the scaffold is not tied into the building structure. What is the maximum height a scaffold can typically be before it legally requires tying into an adjacent structure in Canada (as per CSA Z797 or provincial regulations)?

Answer options:

• 3 metres (10 feet)
• 4 metres (13 feet) ✅ The height-to-width ratio exceeds 3:1 or 4:1 (depending on type/jurisdiction).
• 6 metres (20 feet)

Correct answer: The height-to-width ratio exceeds 3:1 or 4:1 (depending on type/jurisdiction).

Explanation: In Canada, scaffolds generally must be tied into the structure when their height-to-base width ratio exceeds a certain limit, often 3:1 for non-rolling scaffolds and 4:1 for rolling scaffolds, to prevent overturning. This ratio is more critical than an arbitrary height limit, though it translates to specific heights based on the scaffold's footprint. The given scaffold is 9 metres high with a 1.2 metre width, resulting in a ratio of 7.5:1, well past typical tie-in requirements.