You have picked frameless glass for your deck, balcony or staircase. The design is settled and the quote looks fair. Then someone asks a question you did not expect: has an engineer signed off on it?
Glass railings are safe and long-lasting when they are specified correctly. The rules behind that are easier to follow than they first look. This guide covers what homeowners in the Greater Toronto Area should know about glass type, railing height, gaps, top rails, engineering and permits before signing a contract.
Rules differ between municipalities and change over time. Use this as a planning guide, and confirm the details for your address with your local building department.
Why glass guards get extra attention
A guard is the Building Code’s word for a railing. Its job is to stop a fall. With wood or metal, the way a guard fails is easy to predict. Glass can be very strong, but the wrong type can fail all at once if it breaks. That is why Ontario’s rules for glass guards look at the type of glass, how it is held in place and how the whole system is designed, not only how tall it is.
Which glass is allowed
For houses and dwelling units, the Ontario Building Code calls for tempered or laminated safety glass that meets the Canadian standard CAN/CGSB-12.1-M. In plain terms:
- Tempered glass is heat-treated to be much stronger than ordinary glass. When it breaks, it crumbles into small, blunt pieces.
- Laminated glass has a tough clear interlayer between two sheets. When it breaks, the pieces stay stuck to the interlayer, so the panel tends to stay in place.
Ordinary annealed glass is not an option for a guard. Laminated glass is often chosen where a failure would be serious, because a broken panel stays up instead of falling away. Ask your installer which type is in your quote and why.
How high does a glass railing need to be?
Height depends on where the railing is. For exterior decks, the Ontario Building Code sets the guard rules, and the same Code applies in every GTA municipality. In summary:
- A guard is needed where the walking surface is more than 600 mm (about 2 ft) above the surface next to it within 1.2 m. The City of Markham explains this 600 mm trigger in its Builder Tip on guard locations.
- The guard must be at least 900 mm (about 35 in.) high where the deck surface is less than 1.8 m (about 6 ft) high.
- The guard must be at least 1,070 mm (about 42 in.) high where the deck surface is above 1.8 m.
Guard height is measured up from the walking surface. Interior stairs, landings and balconies have their own height rules, so confirm those with the Code or your building department before you order.
The 100 mm rule and gaps between panels
Guards in houses are generally not allowed to have an opening that a 100 mm (4 in.) sphere can pass through. Glass itself has no gaps, but frameless systems have spacing between panels and between the glass and the floor or stair. Ask your installer to show how the layout keeps every opening within the limit, especially on stairs.
Top rail or no top rail?
Systems where the glass is held only at the bottom give the cleanest look. They also get the most scrutiny, because the glass is the only thing between a person and a fall. Building officials look closely at how these systems are designed and anchored, so ask for the engineering behind the exact system you are considering.
If you want a rail-free look, ask who has reviewed that design and how it satisfies the Code. A good installer will answer this without hesitation.
Engineering and permits: the step people miss
In the GTA, a glass guard is normally treated as an engineered system, and your city will want to see the details. The City of Vaughan asks for a copy of the pre-engineered guard or railing details with your drawings, which usually come from the railing supplier. The City of Richmond Hill requires drawings to show guard height, spacing, connection details and type, with an engineer or architect stamp where applicable. The City of Toronto asks for an Assumption of Responsibility form when drawings carry an engineer’s seal. Requirements differ by city, so check with yours.
Whether you need a permit depends on the project and the city. In Vaughan, any deck attached to a building needs one, while an uncovered detached deck up to 18.6 m² and no more than 0.6 m above grade does not. In Richmond Hill, a permit is required if the deck is attached to a building, is more than 600 mm above average grade, or is larger than 10 m². Even when no permit is needed, zoning setbacks still apply. For replacing a railing on an existing deck, ask your local building department.
Ask whether engineered drawings are included in your quote or priced separately, and how long they take. They can add time to your schedule.
Built for GTA weather
Ontario winters are hard on exterior railings: freeze-thaw cycles, road-salt spray near driveways and heavy snow. For outdoor posts and hardware, 316-grade stainless steel is the best choice for corrosion resistance. A protective glass coating such as Diamon-Fusion makes both sides of the glass easier to clean and helps resist staining and corrosion. On residential glass railings it is backed by a lifetime warranty. You can read more in our post on the benefits of a protective glass coating.
Seven questions to ask before you sign
- Is the glass tempered or laminated, and what thickness?
- What guard height is the design based on, and is it measured from the finished walking surface?
- Does the layout have any opening larger than 100 mm?
- Does the system have a top rail? If not, who has reviewed it?
- Are engineered drawings included in the price, and who provides them?
- Does my municipality require a permit for this work?
- What hardware grade is used outdoors, and what warranty covers the glass and the coating?
Frequently asked questions
What type of glass is used for railings in Ontario?
For houses and dwelling units, the Ontario Building Code calls for tempered or laminated safety glass that meets CAN/CGSB-12.1-M. Laminated glass holds together better when it breaks.
How high does a glass railing need to be on a deck?
A guard is needed where the deck surface is more than 600 mm above the ground. It must be at least 900 mm high where the deck is under 1.8 m, and at least 1,070 mm high above 1.8 m. Confirm the figures for your municipality.
Do glass railings need an engineer in Ontario?
In the GTA, glass guards are normally submitted as engineered systems. Vaughan asks for pre-engineered guard details and Richmond Hill asks for an engineer or architect stamp where applicable. Check with your local building department before you order.
Do I need a permit to install a glass railing?
It depends on the work. A deck attached to a house needs a permit in Vaughan and Richmond Hill, and smaller detached decks may not. For replacing a railing on an existing deck, ask your local building department.
Can I have a glass railing without a top rail?
Some designs allow it, but glass held only at the bottom gets close review. Building officials look closely at how these systems are designed and anchored. Ask who has reviewed any rail-free design.
Planning a glass railing?
Glasswise designs, makes and installs custom glass railings across the GTA, including Toronto, Vaughan, Markham and Mississauga. Book a free consultation and bring your questions. We will go over what to expect for your address.
Sources: City of Vaughan, decks and porches · City of Richmond Hill, residential deck checklist · City of Toronto, decks and porches · City of Markham, Builder Tip No. 64
