A steel staircase kit is a set of standard stringers, treads and railings that you adjust to your space; a custom fabricated stair is drawn and built to your exact floor-to-floor height, opening and landings. Kits make sense for straightforward straight or spiral stairs that fall inside the kit's range and whose railings meet Ontario rules. Custom stairs make sense once there's a landing, a turn, an unusual height, a tight opening or a design you can't buy off the shelf. Either way, the finished stair has to meet the 2024 Ontario Building Code, and that's where many kits sold online fall short.
Kits vs custom at a glance
| Steel stair kit | Custom fabricated steel stair | |
|---|---|---|
| Fit | Adjustable within a range of heights and widths | Made to your measured floor-to-floor height and opening |
| Layouts | Straight runs, spirals, some L-shapes with a standard landing | Anything: switchbacks, winders within code limits, mono-stringers, floating stairs |
| Code check | You or your designer verify the kit against the OBC | Designed to the OBC on shop drawings before fabrication |
| Railings | Usually included, often in US-market styles | Designed with the stair to meet Ontario guard rules |
| Finish | Fixed options from the manufacturer | Primer, paint, powder coat or galvanizing to suit the location |
| Installation | Often bolted together on site | Delivered in one piece or bolted sections designed for your access |
| Changes | Limited to what the kit allows | Built into the drawings before steel is cut |
Types of steel stair kits
- Spiral stair kits. The most common steel kits, with a centre column, pie-shaped treads and a railing. They save floor space and suit lofts, secondary access and exterior decks.
- Straight stair kits. Pairs of steel stringers with treads, sometimes adjustable in pitch, used for basements, mezzanines and exterior steps.
- Modular stair systems. Stringer sections, landings and railings that bolt together into L- or U-shaped stairs, often used for industrial access.
- Outdoor steel stair kits. Galvanized or coated straight stairs for decks and rear entrances.
Checking a kit against the Ontario Building Code
The OBC doesn't care whether a stair came in a box. Once installed, it has to meet Section 9.8. (for houses and small buildings) like any other stair. The checks that catch kits most often:
| Item | 2024 OBC requirement (Part 9) |
|---|---|
| Rise, private stairs (within or serving a single dwelling unit) | 125 mm to 200 mm |
| Run, private stairs | 255 mm to 355 mm |
| Rise and run, public stairs | Rise 125 mm to 180 mm, run at least 280 mm |
| Width, stairs within or serving a single dwelling unit | At least 860 mm |
| Headroom, stairs serving a single dwelling unit | At least 1,950 mm |
| Spiral stairs | Handrails both sides (outer one at least 1,070 mm high), at least 660 mm clear between handrails, risers no more than 240 mm, treads at least 190 mm deep measured 300 mm from the narrow-side handrail, headroom at least 1,980 mm |
| Guards | Generally 1,070 mm, or 900 mm within a dwelling unit; openings must stop a 100 mm sphere |
| Anti-climb | No climbable member between 140 mm and 900 mm above the walking surface of a required guard |
| Loads | Designed for 1.9 kPa (stairs serving one dwelling unit) or 4.8 kPa (other stairs) |
Our guide to Ontario Building Code rules for steel stairs explains each of these, including uniformity tolerances and landings.
Three problems come up again and again with kits:
- Railings with horizontal bars. Many kits are designed and marketed for the US, and their railings use horizontal rails or cables. On a required guard in Ontario, those generally fail the anti-climb rule. You may need a different railing, which is often a custom job anyway.
- Spiral stairs used as the main stair. A spiral stair can only serve as the sole means of egress where it serves no more than 3 people, and a kit's clear width between handrails has to meet the 660 mm minimum. Check both before ordering.
- Rise outside the range. Kits are sold by a range of floor-to-floor heights. If your finished height falls between sizes, risers end up too tall, the top or bottom step comes out uneven, or the kit is cut. Risers must be uniform within 5 mm between adjacent steps and 10 mm across the flight, so a short or tall last step fails.
If a building permit covers the stair, the inspector will check it against these rules regardless of where it came from.
Where kits fit, and where they don't
A kit is a reasonable choice when:
- The stair is a simple straight run or a spiral in a secondary location
- Your measured floor-to-floor height sits comfortably inside the kit's range
- The kit's railing meets Ontario guard rules, or you plan to replace it
- The opening and landing space match the kit without changes
- You or your installer are comfortable assembling and anchoring it
Custom is the better route when:
- There's a landing, a turn, or the stair connects to a balcony or mezzanine
- The floor-to-floor height or opening is unusual
- It's the main stair in a house, a commercial stair, or a stair that must meet public stair rules
- You want a specific design: plate stringers, a single spine, wood treads on steel, glass guards
- The stair needs to fit through a narrow door or be installed in a finished space
- An engineer or the specification calls for shop drawings or a sealed design
Outdoor steel stair kits
Exterior stairs are where kits are most tempting, and where they need the most care in Ontario:
- Finish. Look for hot-dip galvanized steel, or galvanized plus a coating. A painted-only kit will need regular maintenance through winters with snow and salt.
- Footings. A kit is only as stable as what it sits on. Exterior stair footings need to resist frost movement, and the depth depends on your soil and location, so confirm it with your designer or building department.
- Connection at the top. Attaching to a deck rim joist or a house wall needs a designed connection, not just the brackets in the box.
- Treads. Grating sheds snow and water; solid treads need a slip-resistant surface.
For exterior stairs designed from scratch, see exterior steel stairs.
How the costs compare
We don't publish prices, but the pattern is predictable. A kit's price is mostly material and manufacturing at volume, and it looks low on the box. What it doesn't include is site work: adapting the kit to your opening, replacing a non-compliant railing, footings, anchors, finishing and installation. A custom stair puts more cost into drawings, fitting and welding, and less into on-site adjustment.
The fair comparison is a kit installed, inspected and finished against a custom stair installed and finished, for the same layout and railing. Our guide to what drives steel stair cost in Ontario covers the custom side in detail, and steel stairs vs wood stairs compares materials if you're still deciding.
A middle route: custom stair, standard parts
You don't have to choose all or nothing. Common combinations:
- Custom steel stringers made to your height, with standard steel or wood treads
- A kit stair with a custom steel railing that meets Ontario guard rules
- Custom landing framing that lets a standard straight kit work in an L-shaped space
Getting a custom steel stair quoted
We fabricate custom steel stairs and railings in our shop in Erin, with shop drawings prepared in-house and CWB certified welding, and deliver across the GTA and Ontario. If you're weighing a kit against custom, send us the kit details along with your measurements and we'll quote the custom option for the same layout.
Send your floor-to-floor height, opening size, photos or drawings for a free quote. We fabricate and deliver the stair, and installation is by your installer or contractor. See our steel products for the other miscellaneous steel we make.
Frequently asked questions
Are steel stair kits up to code in Ontario?
Some are and some aren't. A kit has to meet the 2024 Ontario Building Code once installed: rise, run, width, headroom, guards and handrails. Many kits are designed for US codes, and their railings often use horizontal bars that don't meet Ontario's anti-climb rule for guards, so check before you buy.
Is a steel staircase kit cheaper than a custom stair?
For a standard straight or spiral stair that fits the kit's range, a kit can be the cheaper route. Once you add cutting, adapting, replacing railings or a custom landing, the gap narrows. Compare a kit installed and inspected with a custom stair installed, not the kit's box price.
Can you buy outdoor steel stair kits?
Yes, there are galvanized or coated steel stair kits for decks and exterior entrances. They work best for straight runs within their adjustable height range, on level, solid footings, with a railing that meets the Ontario guard rules.
What is the difference between a steel stair kit and a custom stair?
A kit is a set of standard parts that you adjust to fit your space. A custom stair is drawn and fabricated to your exact floor-to-floor height, opening, landings and finish, so it fits without on-site modification.
