A steel railing for a balcony, deck or terrace in Ontario is a guard under the building code, so it has to be high enough, closed enough and strong enough before style comes into it. For most balconies and raised decks that means a guard at least 1,070 mm high, openings that stop a 100 mm sphere, no climbable footholds between 140 mm and 900 mm, and posts anchored to resist the code's guard loads. Within those rules, steel gives you more freedom of design than most off-the-shelf systems, as long as it is protected from Ontario winters.
This guide covers what changes when a railing goes outside and up high: the rules that apply, the infill types, how posts attach to slabs and deck framing, finishes, and what drives the price.
What a balcony or deck railing has to do
The Ontario Building Code requires a guard on any open side of a walking surface where there is a drop of more than 600 mm to the surface within 1.2 m. On a deck, measure to the lowest ground within that 1.2 m, not straight down at the house wall; yards often slope away, and a deck that starts low can be well over the limit at its outer edge.
For exterior guards, the key numbers from Section 9.8. of the 2024 OBC are:
| Requirement | What the code sets |
|---|---|
| Guard height, most locations | At least 1,070 mm |
| Exterior guard serving one dwelling unit (or a house with a secondary suite), walking surface no more than 1,800 mm above finished ground | At least 900 mm |
| Openings through the guard | Must stop a 100 mm sphere |
| Climbability | No member, attachment or opening between 140 mm and 900 mm above the walking surface that makes the guard easier to climb |
| Horizontal load at the top of exterior guards serving up to two dwelling units | 0.5 kN/m or a 1.0 kN point load, whichever is more critical |
A balcony on a second storey or a deck more than 1,800 mm above grade needs the 1,070 mm guard. Our guide to OBC guard and handrail rules for steel railings explains each rule in more detail, including the loads for other buildings.
Balconies in larger buildings (more than three storeys or more than 600 m² of building area for residential use) fall under Part 3 of the code. Exterior guards serving a single suite there still follow the Section 9.8. geometry, but their loads have to be checked under Part 4, which is the structural design part of the code. In practice, condo and apartment balcony railings are engineered.
Types of metal deck and balcony railing
| Infill type | How it performs outside | Notes |
|---|---|---|
| Vertical steel pickets | Durable, easy to galvanize and recoat | The simplest way to meet the opening and anti-climb rules |
| Flat bar pickets | Clean modern look | Spacing must still stop a 100 mm sphere when bars are pushed apart |
| Framed mesh or perforated panels | Reads as one plane, good for privacy | Panels add wind load to the posts |
| Glass panels between steel posts | Keeps the view open | Glass must be safety glass; see steel railings with glass |
| Cable or horizontal bars | Popular in catalogues | Generally fails the anti-climb rule on required guards |
Horizontal styles deserve a warning because they are everywhere online. Many railing products are designed for markets without Ontario's anti-climb rule. On a required guard, horizontal rails or cables in the 140 mm to 900 mm zone generally don't comply, so a design that looks fine in a catalogue can fail inspection here.
If you're still deciding between materials, our comparison of steel vs aluminum vs glass railings goes through the trade-offs.
How the posts attach
The infill is rarely what fails on an outdoor railing. The posts, the welds at their base and the anchors are. How the post attaches depends on what you are building on.
Concrete balcony slabs and terraces
- Surface (top) mount: a base plate anchored into the slab. Simple and adjustable, but anchors close to a slab edge can break out the concrete, so edge distance matters.
- Fascia (side) mount: posts fixed to the face of the slab edge. Keeps the walking surface clear and keeps anchors out of the membrane on top.
- Core-drilled and grouted: posts set into holes in the slab. A clean look, but water at the post can damage the concrete if the grout and slope aren't right.
On a terrace or balcony over living space, the walking surface usually sits on a waterproofing membrane. Every anchor through it is a potential leak, so fascia mounting or a raised curb is often the better detail. Talk to your designer or roofer before drilling.
Wood decks
Ontario publishes Supplementary Standard SB-7, "Guards for Housing and Small Buildings", and guards built to it are deemed to meet the code's load requirement. SB-7 covers wood guards. A steel post bolted to a wood rim joist isn't one of its details, so the connection has to be shown to work: solid blocking, through-bolts sized for the load, and a rim joist that is itself tied back to the joists. A steel railing on a weak deck frame will still move.
Steel frames
Posts welded or bolted to steel beams or channel give the stiffest result and are the norm on steel-framed balconies and decks. See embedding steel posts in concrete vs base plates for how the two main post details compare.
Finishes that survive Ontario winters
Outdoor steel railings face rain, snow, freeze-thaw cycles and, near driveways and walkways, de-icing salt. Plan protection from the start:
- Hot-dip galvanizing is the standard protection for exterior steel. Galvanizing is done by a specialist galvanizer after fabrication, so the railing is designed for it, with vent and drain holes in closed tubes.
- Duplex systems (galvanized, then painted or powder coated) give colour on top of galvanized protection and usually last longest.
- Paint over primer alone is a maintenance commitment outdoors. Expect to touch up chips and rust at the base of posts.
Detailing matters as much as coating. Water inside a hollow post or rail can freeze and split it, and standing water at a base plate attacks the welds and anchors that carry the load. Good railings drain, keep base plates off wet surfaces where possible, and use caps or welded closures that won't trap water.
What drives the cost of a balcony or deck railing
"How much is metal railing for a deck" is one of the most common questions, and the honest answer is that it depends on the layout and the details more than on length. The main drivers are:
- Total length and number of runs. Short runs broken by corners cost more per metre than one long straight run.
- Posts, corners, ends and gates. Each post is cut, fitted, welded and anchored.
- Height. A 1,070 mm guard uses more material and often stiffer posts than a 900 mm one.
- Infill. Pickets, panels and glass all price differently, and glass is a separate supply.
- Mounting. Fascia mounts on a slab edge or a designed connection to deck framing take more work than base plates on solid concrete.
- Finish. Galvanizing, duplex coatings and colours each add a step.
- Stairs. Sloped sections down from a deck need every picket and rail cut to the stair angle.
- Site access and installation. A third-storey balcony is a different install from a ground-level deck.
For a fuller breakdown, see what drives steel railing cost per foot.
Before you order
- Confirm the guard height you need from the drop at the outer edge, not at the house.
- Check what the posts attach to: concrete slab, membrane, wood rim joist or steel.
- Pick an infill that meets the anti-climb rule for your guard.
- Decide on the finish for outdoor exposure.
- Finish the decking or topping first, or tell the fabricator its thickness. Heights and gaps are measured from the finished walking surface.
- Ask about permits. Railings on a new deck or balcony are part of that permit; replacement rules vary by municipality.
Getting a balcony or deck railing made
We fabricate custom steel railings, gates, stairs and ladders in our shop in Erin, with CWB certified welding and shop drawings prepared in-house, and deliver across the GTA and Ontario. Engineering services are available for projects that need them, which helps when a balcony guard or deck connection has to be designed.
Send us your measurements, photos or drawings for a free quote. We can prime or galvanize your railing to suit the job, and installation is by your installer or contractor. See our steel products for the other miscellaneous steel we make.
Frequently asked questions
How high does a balcony railing need to be in Ontario?
Under the 2024 Ontario Building Code, most guards must be at least 1,070 mm high. An exterior guard serving a single house can be 900 mm where the walking surface is no more than 1,800 mm above finished ground, so most high balconies and raised decks need the full 1,070 mm.
Can a deck railing have horizontal bars in Ontario?
Not on a required guard. The code says nothing between 140 mm and 900 mm above the deck may make the guard easier to climb, which generally rules out horizontal bars and cables in that zone. Vertical pickets, glass and tight mesh panels are the usual choices.
Are steel railings good for outdoor use?
Yes, if the steel is protected. Exterior steel railings are normally hot-dip galvanized, often with paint or powder coat over it, and detailed so water drains out of posts and rails instead of sitting inside and freezing.
What types of metal deck railing are there?
The common types are steel or aluminum picket railings, flat bar railings, framed mesh or perforated panels, glass panels held by metal posts, and cable systems. Cable and horizontal styles run into Ontario's anti-climb rule on most required guards.
Do I need a permit for a new balcony or deck railing?
A railing built as part of a new deck or balcony is usually covered by that project's building permit. Rules for replacing an existing railing vary by municipality, so check with your local building department before you order.
