Guideline for Municipalities: How to maintain Green Roofs?

As public entities takes steps to adopt clean technology across their buildings and communities, green roofs have become increasingly popular. Green roofs offer many environmental benefits, such as reducing water run-off, removing water pollutants, and promoting energy efficiency. Additionally, they can provide other benefits, such as temperature regulation, aesthetic appeal, and common space for patrons to socialize and connect with others.

When public entities look to design and maintain green roofs atop their buildings, they need to consider a wide range of risks. However, many of these risks can be addressed through the implementation of targeted measures that will help to prevent or mitigate injury while accessing the green roof and its common space.

The following guidance highlights key areas of considerations for public entities as they look to design and maintain green roofs atop buildings across their communities. It should not be seen as an exhaustive list and should be used in conjunction with internal policies and procedures, as well as in compliance with local laws and regulations.

Design

Public entities should consider the following design elements as they look to install green roofs atop their new and/or existing buildings:

Green roof components:
- Adopt the appropriate design and installation of the following structural elements:
- Structural layer (deck support)
- Protection layer (waterproofing membrane, thermal insulation, and root protection layer)
- Drainage layer (roof drainage)
- Vegetation layer (growing medium)
- Plant layer (hardy drought-resistant plants)
- Consider the requirements and implications of the following:
- Local building codes and standards
- Local fire codes and regulations
- Local occupational health and safety standards
New buildings:
- A new installation of a green roof will require structural and architectural consultations to include the green roof as part of the overall design and construction of the building.
Existing buildings:
- A retrofit installation of a green roof will require structural and architectural consultations to assess the additional loading that will be placed on the building due to the additional vegetation, material, structure, and water.

Safety

Public entities should keep safety top-of-mind when designing green roofs and adopt appropriate measures to help ensure a safe space for employees, contractors, and patrons. Specifically, public entities should consider the following safety measures:

Fire safety:
- Adopt and enforce a no smoking policy while on the green roof
- Adopt and enforce a no hot work (for example, welding, grinding, and soldering) policy while on the green roof
- Implement firebreaks at the perimeter of green roof system
- Implement a safe distance between plant holders and walls
- Use substrates that will absorb and retain water
- Use drought-tolerant plants
- Use high water content plans
Water penetration:
- Use a shallow growing medium to prevent plants from growing large and developing a deep root system
- Use of a hardy and drought tolerant plant that does not establish a deep root system
- Use of a plant that has ability to limit transpiration and store excess water.
- Install waterproofing membrane at the base and junctions of green roof system
- Install electronic water leak monitors
- Perform flood and leak tests immediately after installation to identify water leaks
- Perform flood and leak tests at regular intervals
Fall prevention:
- Adopt an appropriate fall prevention system for staff and/or contractors that may need to access the green roof during installation and maintenance:
- Lifeline and anchors (freestanding systems and attached systems)
- Guardrails (freestanding rails and attached rails)
- Warning line system that is a minimum of two metres/six feet from the unprotected edge of building
- Safe access to the roof via elevators and/or vertical wall-mounter ladders
Wind exposure:
- Analyze exposure to wind and wind gusts
- Adopt measures to resist uplift of plants/equipment and control debris
- Snow exposure:
- Analyze exposure to snow and snow drift loads
- Adopt measures to address snow accumulation if it surpasses a safe threshold
Common space:
- Ensure all entry and exit points are well lit and well marked during hours of use
- Ensure that all walkways are free of debris and other safety hazards

Maintenance

Public entities should establish an inspection and maintenance program for their green roofs. Specifically, this program should enable the public entity to implement appropriate measures to identify, rectify, and document safety hazards at green roofs across its communities.

Inspection:
- Establish an inspection policy, which should outline the required frequency and scope of inspections taken to identify safety hazards throughout the green roof that require remedial actions.
- Conduct regular inspections of the green roof to:
  - Assess any fire hazards
  - Assess any water penetration hazards
  - Assess any slip, trip, or fall hazards
  - Assess any uplift hazards
  - Remove any garbage, broken glass, and other debris
  - Remove any protruding objects (for example, chain link fencing and fence screens)
Maintenance:
- Establish a maintenance policy, which should outline the remedial actions, timelines, communication, and documentation associated with the repair and/or removal of any safety hazards identified during the inspections.
- Conduct preventative and demand maintenance to the green roof to help ensure that all identified safety hazards are rectified:
  - Inspect all areas prior to use
  - Dispatch safety hazards to be repaired or replaced
  - Post signage advising patrons if an area is unavailable for use or under repair
Establish a centralized documentation repository to house the inspection reports and work orders

Signage

Public entities should have the appropriate signage throughout their green roofs to inform patrons of essential information as they use the space. Specifically, public entities should consider the following information as part of their signage:

Restricted activities:
- No smoking
- No use of any flammable or combustible sources or materials
- No walking on designated vegetation and plant layer
- No littering — all debris must be placed in designated secured garbage/recycling containers
- No horseplay
Safe Use of Green Roof
- Patrons to maintain safe distance from the edge of the green roof
- Patrons to ensure that all children are supervised
- Patrons to ensure their pets are leashed and under control at all times
Contact information:
- Emergency services
- Maintenance services

Summary

Green roofs have become a popular way for public entities to adopt clean technology across their buildings and communities, due to their ability to deliver sustained climate and social benefits. Through the development and implementation of a comprehensive risk management plan, public entities can put in place appropriate measures to address any risk exposures during the design, maintenance, and use of green roofs.

If you have questions, please contact your Marsh representative.

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