Ladders are one of the most commonly used pieces of equipment on construction sites, and one of the most commonly misused. Ministry of Labour figures show that 13% of the critical incidents reported to the ministry between January 2006 and April 2017 (279 of 2,075) were falls from ladders. Many of these incidents involve experienced workers who simply got complacent with a tool they use every day.
This guide covers the rules, standards, and habits that will keep you safe every time you climb a ladder on a job site.
The 4-to-1 Setup Rule
The single most important rule for setting up a straight or extension ladder is the 4-to-1 ratio. For every four feet of ladder length up to the point where it contacts the upper support, the base should be one foot out from the point directly below that support. Ontario's rule, for a ladder that is not securely fastened, allows a base distance of one-quarter to one-third of the ladder's length (O. Reg. 213/91, s. 81(2)).
Here is how to check it quickly on site:
The arm test: Stand at the base of the ladder with your toes touching the rails. Extend your arms straight out in front of you. If your palms rest flat on the rung at shoulder height, the angle is close to the correct 75.5 degrees.
Why it matters: Set the ladder too steep and it can tip backward. Set it too shallow and the feet can kick out. Both scenarios cause serious falls. The 4:1 ratio gives you the safest balance between stability and usability.
On uneven ground: Never stack lumber, bricks, or other materials under one leg to level a ladder. Use a ladder leveller or choose a different access method. An improperly levelled ladder is an unstable ladder.
The 3-Point Contact Rule
Three-point contact means maintaining two hands and one foot, or two feet and one hand, on the ladder at all times while climbing or descending. Ontario's construction regulation does not spell this rule out, but treat it as non-negotiable: it is the most basic habit of safe climbing.
Face the ladder: Always face the ladder while climbing up or down. Never climb with your back to the rungs.
No carrying tools in your hands: Use a tool belt, tool lanyard, or hoist line to get materials up and down. The moment you carry something in one hand, you have lost your third point of contact and your ability to catch yourself.
Do not skip rungs: Climb one rung at a time. Skipping rungs shifts your centre of gravity and increases the chance of a slip.
Keep your belt buckle between the rails at all times. If you cannot reach something comfortably, climb down and reposition the ladder. Overreaching is one of the most common — and most preventable — causes of ladder falls.
Extension Ladder Overlap and Extension Rules
Extension ladders have specific overlap requirements that many workers ignore. The overlap is the section where the upper (fly) section overlaps the lower (base) section. Too little overlap weakens the ladder.
Up to 36 feet extended length: Minimum 3-foot overlap required.
36 to 48 feet extended length: Minimum 4-foot overlap required.
48 to 60 feet extended length: Minimum 5-foot overlap required.
Top extension: When using a ladder to access a roof or elevated platform, the ladder must extend at least 3 feet (0.9 m) above the landing surface. This gives you something to grab onto as you step off the ladder.
Secure the top and bottom: When the ladder is your access to a roof or another level, O. Reg. 213/91 requires it to be secured at both the top and the bottom to prevent movement.
CSA Z11 Standard and Ladder Ratings
In Canada, portable ladders must meet the CSA Z11 standard (Portable Ladders). This standard sets requirements for design, construction, testing, and labelling. Every ladder on your site should have a legible duty rating label.
Grade 1 (Industrial): Rated for 250 lbs. This is the minimum you should be using on a construction site.
Grade 1A (Extra Heavy Duty): Rated for 300 lbs. Recommended for construction work, especially if workers carry tools and materials.
Grade 1AA: Rated for 375 lbs. The highest duty rating available for portable ladders.
Weight rating includes you and everything you carry: Your body weight plus tools, materials, and clothing all count toward the rated load. A 220-lb worker carrying 40 lbs of tools needs at least a Grade 1A ladder.
Never use a household-grade (Grade 2 or 3) ladder on a construction site. They are not built for the loads and conditions of construction work.
Pre-Use Inspection
Ontario's Occupational Health and Safety Act (OHSA) requires that equipment be maintained in good condition. For ladders, that means inspecting before every use. Here is what to check:
Rails: Look for cracks, bends, dents, or corrosion. Fibreglass rails should not show signs of blooming (a fuzzy, white deterioration of the fibreglass).
Rungs: Must be tight, level, and evenly spaced. Loose or missing rungs take the ladder out of service.
Feet: Anti-slip pads must be present and in good condition. Worn-out feet dramatically reduce the ladder's grip on smooth surfaces.
Hardware: Locks, rung locks (dogs), pulleys, and ropes on extension ladders must all work properly. If the fly section does not lock securely in place, do not use it.
Labels: The duty rating label and manufacturer information must be legible. If you cannot read the rating, you cannot verify the ladder is suitable for the job.
If anything fails inspection, tag it "DO NOT USE" and remove it from the work area. Do not lean it against a wall where someone else might grab it.
Common Ladder Accidents and How to Prevent Them
Most ladder accidents follow predictable patterns. Knowing these patterns helps you avoid them:
Base kick-out: The ladder feet slide on a smooth or wet surface. Prevention: use proper anti-slip feet, set the correct angle, and place the base on firm, level ground.
Overreaching: The worker leans too far to one side instead of moving the ladder. Prevention: keep your belt buckle between the rails at all times. If you cannot reach it comfortably, climb down and reposition.
Top of the ladder: Standing on the top two rungs of a stepladder or the top three rungs of an extension ladder. Prevention: never stand higher than the manufacturer's recommended top standing level.
Electrical contact: Metal ladders or wet fibreglass ladders contacting overhead power lines. Prevention: use fibreglass ladders near any potential electrical hazard and maintain the minimum approach distances required by Ontario Regulation 213/91.
Unexpected movement: Doors opening into the ladder, vehicles driving past, or wind gusts. Prevention: barricade the area around the base, lock or guard doors, and secure the ladder at the top and bottom.
Ontario OHSA Requirements for Ladders
Under Ontario's construction projects regulation (O. Reg. 213/91), there are specific legal requirements for ladder use on construction sites:
Section 80: Portable ladders must meet the Grade 1, 1A or 1AA requirements of CSA Standard Z11-12, Portable Ladders, apart from custom-built single ladders that meet the section's own specifications.
Section 81: Portable ladders must be free from defective or loose rungs, placed on a firm and level footing, and used according to the manufacturer's instructions.
Section 82: A ladder used for access between levels must extend at least 900 mm above the landing and be secured at the top and bottom to prevent movement.
Section 83: A step-ladder's legs must be fully spread with the spreaders locked, and no worker may stand on its top cap, top step or pail shelf.
General duty clause (Section 25): Employers must take every precaution reasonable in the circumstances to protect workers. This includes providing proper ladder training and enforcing safe ladder practices.
MOL inspectors can and do issue orders and fines for ladder violations. Penalties under the OHSA can reach $500,000 per offence for individuals, $1,500,000 for directors and officers, and $2,000,000 for corporations.
Expect ladders to get particular attention for now. The set-up and use of ladders is one of the named focus areas of the ministry’s 2026–27 construction campaign, which runs on residential sites until March 31, 2027. Ontario’s updated Working at Heights program standard, in effect since April 1, 2024, also added content on ladder hazards.
The Bottom Line
Ladder safety comes down to choosing the right ladder, setting it up correctly, inspecting it every time, and maintaining three points of contact. None of these steps are difficult. None of them take more than a couple of minutes. But skipping any one of them can put you in the hospital or worse.
If your crew works at heights — even just climbing ladders to access elevated work areas — proper Working at Heights training covers ladder safety along with harnesses, anchors, and rescue planning. It is a legal requirement for construction workers in Ontario who may use a travel restraint, fall restricting or fall arrest system, a safety net, or a work belt or safety belt, and it could save your life.
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