Across Ontario and beyond, rooftop safety installations face great pressures as winter approaches. Snow drifting against rooftop equipment and gusting winds across parapets will pile on forces that will test their limits, posing a serious question to building owners and managers. Ahead of the season, we’re putting that question to you: are your safety systems engineered and verified to resist environmental loading in your jurisdiction?
If you cannot answer ‘yes’ to this question confidently, you face inherent risks to your people, company and brand. In order to assist property managers and owners, we’ve created this comprehensively detailed learning resource explaining Ontario law, Canadian codes and the current risk data that should shape your winter-readiness plan.
Your Legal Responsibilities
Ontario’s Occupational Health and Safety Act (OHSA) requires employers to “take every precaution reasonable in the circumstances for the protection of a worker.”
This is a duty that applies to rooftop work and to the safety equipment workers depend on. Failing to plan for environmental loads such as snow accumulation, drifting and wind uplift can breach this duty.
At a federal level, the Westray Law (Criminal Code s.217.1) adds a legal duty on those who direct work to take reasonable steps to prevent bodily harm; criminal negligence findings have referenced this section when safety systems and supervision fail.
The key takeaway here is that in the event that your teams experience an accident or injury due to compromised safety installations, you may be held criminally liable.
Ontario-Specific Regulations
On construction projects in Ontario, O. Reg. 213/91 lays out guardrail requirements: use guardrails where workers are exposed to a fall, with a top rail 0.9–1.1 m above the surface, an intermediate rail and a toeboard. Industry guidance summarizes load and dimensional criteria and points you back to the regulation for full specification.
Don’t neglect this regulation – even if your elevated workspace doesn’t qualify as a construction site. Even on completed buildings, this is a practical baseline for maintenance set-ups and temporary works. 
Ontario’s Building Code also sets minimum loads on guards (e.g., vertical and horizontal line loads) that manufacturers and designers reference when selecting or engineering permanent systems. When you install ballasted, non-penetrating guardrails or modular walkways, those components must resist the specified loads in the Code as well as site-specific wind actions. 
National Building Code (NBC) on Structural Design for Snow & Wind
Permanent rooftop safety systems are small compared with primary structure, but they still need to withstand NBC Part 4 environmental actions. Before you create a winter-readiness plan, you should be aware of your obligations.
In Ontario, that means using NBC climatic data to determine specified snow load on roofs and design wind pressures for the site, exposure and building geometry. The NBC and its Structural Commentaries describe how to calculate roof snow including drifting around discontinuities and equipment and how to determine wind pressures and uplift on parapets, guards, panels and appurtenances.
How National Building Codes Should Inform Your Approach
These provisions should inform both the base design of safety systems and the anchorage or ballast that keeps them in place during storms. Here are some of the key elements of what this means in practice:
- Guardrail posts and connections should be checked for combined lateral wind and unbalanced snow drift actions near edges and large units.
- Ballasted systems must be verified against sliding and overturning under site wind; ballast quantities often increase on tall or highly exposed buildings.
- Walkways and platforms should be evaluated for additional snow accumulation caused by wind drifting around the walkway itself and adjacent equipment.
- Fasteners, anchors and substrates require pull-out and shear verification for the design wind pressures in NBC Part 4.
Why This Matters Now
Weather risk data in Canada shows a clear escalation. Insured losses from severe weather reached a record C$8.5B in 2024, driven by clustered catastrophic events.
Environment and Climate Change Canada listed 2024 as the most expensive year on record for weather disasters, with multiple billion-dollar events. For Ontario and Quebec, windstorms historically account for the majority of catastrophic insured losses; the 2022 derecho alone produced about $1B in insured losses.
For owners and managers, this translates into greater scrutiny from insurers and higher expectations for engineered rooftop systems that account for snow and wind.
The Human Cost of Inaction
Falls remain a major source of harm. The CCOHS notes that 67% of falls are on the same level (slips/trips), while falls from height make up most of the remainder.
In Ontario, workplace falls are associated with thousands of lost-time injuries and about 20 deaths annually, underscoring the need for winter-ready access routes, anti-slip surfaces and protected edges around hatches and equipment.
Taking Action: A Practical Compliance Roadmap for Winter Loads
Confirm the regulatory framework for your site: Identify whether work falls under O. Reg. 213/91 (construction project conditions) or routine maintenance under OHSA general duties. Either way, guardrail and opening protection principles still apply. Align permanent systems with the Ontario Building Code loads on guards and the NBC wind and snow criteria.
- Get the right climatic data and exposure: Ask your engineer to use NBC climatic data for your municipality and confirm your building exposure category. Corner zones and roof edges experience higher wind pressures; equipment clusters increase drift. The Structural Commentaries provide guidance on localized effects.
- Check ballasted systems for uplift and sliding: For non-penetrating guardrails and free-standing walkways, ballast must be sized for site wind pressures and friction conditions, not just manufacturer “typical” tables. Tall parapets, high elevations and open exposures raise demands; snow accumulation around base weights changes friction and overturning checks.
- Verify anchors & substrates: For penetrated systems, evaluate pull-out, pull-through and shear in the actual substrate, including membrane and deck system. Wind suction on rails and screens can exceed intuitive values.
- Design for snow drift at discontinuities: Changes in elevation, large units and screens produce unbalanced snow. Walkway treads and platform stringers can trap snow and ice if poorly detailed. Your engineer should apply NBC drift provisions and consider drift surcharge on posts, bases and connections.
- Maintain anti-slip performance: Specify serrated or textured treads, seasonal de-icing plans and routine clearing at ladder bases and hatch landings. Pair hatches with guardrails and self-closing gates to eliminate open-hole exposures during winter work. Align details to guardrail requirements and OHSA duty of care.
Expert Support for Complex Compliance
Navigating requirements for snow load and wind compliance can be challenging. Building layouts, roof materials and environmental exposure vary widely across facilities, creating unique design demands. Understanding how multiple codes interact – OHSA, the Ontario Building Code and the National Building Code – requires technical insight that many property managers do not have the time or resources to maintain internally.
Our engineers design, test and certify guardrails, walkways, ladders and crossover bridges to meet site-specific load requirements. Each installation is supported by engineered drawings and documentation, confirming that it performs safely under real Ontario conditions.
With expert guidance and a complete understanding of the codes, Skyline helps building owners and managers achieve compliance without uncertainty.
Don’t Wait for Winter: Act Now
Winter is unpredictable, but your safety systems shouldn’t be. A free consultation provides practical insight into compliance, risk reduction and the right solutions for your facility’s design. Schedule your consultation today and take the first step toward a safer, fully compliant rooftop.
