“Floating” gets stuck in front of any staircase that looks visually light. That creates a real problem when a homeowner brings in a reference photo, asks for a quote, and the image shows three different structural systems mixed together. Before we can price anything, we have to figure out what is actually being asked for.
This post is a direct, fabricator’s comparison of mono stringer staircases and cantilevered floating staircases. Same goal, a clean, modern stair with no visible bulk. Different structure, different cost, different code path.
Start with the definitions
A mono stringer staircase uses one steel beam up the centre of the stair. Treads mount to brackets welded off that beam. The beam is visible from the underside and from the sides of the treads. The visual effect is open, you can see through the stair, light passes under it, but the structural logic is obvious.
A floating staircase hides its structure. The most common version is a cantilevered system: each tread is anchored independently into a reinforced wall, and from the room you see only the tread projecting from a flat wall surface. A second version uses a concealed central stringer buried in a drywall bulkhead or a recessed floor channel, with treads emerging through a slot. Both read as “floating” because nothing below the tread is visible.
The confusion comes from marketing. Most custom homebuilders will call any open-riser stair a floating stair, and that includes mono stringers. In the fabrication trade, the distinction matters because the engineering scope, the wall prep, and the price are different.
Structural principle: beam versus cantilever
A mono stringer acts as an inclined beam. The combined dead load (steel, treads, railing) and live load (people on the stair) travel down the stringer and land at two connection points, one at the top, one at the bottom. The engineer sizes the beam for bending and deflection across the full span. The tread brackets are relatively small because each one only carries the load of one tread over a short cantilever off the main beam.
A cantilevered floating stair works in reverse. There is no spanning beam. Each tread is its own small cantilever, anchored into the wall at one end and projecting out into space at the other. The vertical load at the tread tip tries to rotate the tread downward, and that rotation pulls hard on the wall connection. The engineer has to design for the moment force at every bracket, and the wall itself has to carry the combined rotational forces from every tread that hangs off it.
That difference drives almost every other difference between the two systems.
Wall and floor requirements
A mono stringer only needs two strong connection points. At the top, the beam ties into the floor structure or a header, typically with a steel bracket bolted through the rim joist or embedded in a concrete edge. At the bottom, it lands on a base plate anchored to concrete or a reinforced framed floor. Everything in between is structurally independent of the surrounding walls. You can put a mono stringer in the middle of an open room with no adjacent wall at all.
A cantilevered floating stair needs a structural wall along its full length. That wall has to carry concentrated rotational loads at every tread. In new construction, we spec a continuous steel channel or plate that runs the height of the stair, with the framing built around it. On a recent North Vancouver project, the engineer specified a 10 mm continuous steel channel behind the drywall with every bracket through-bolted to the channel. That channel had to be installed during framing, months before we showed up with treads.
This is why floating stair retrofits are hard. Opening an existing wall, adding structural steel, and closing it back up is a real construction project on its own, and if the existing framing can’t accept the loads, sometimes the answer is no. A mono stringer retrofit avoids that problem because it only touches the floor at two points. See the installation guide for more detail on what retrofits actually look like.
Engineering scope and stamps
Both systems are structural steel elements under the BC Building Code, and both require a P.Eng. stamp before a permit gets issued. BC Building Code - https://www2.gov.bc.ca/gov/content/industry/construction-industry/building-codes-standards/bc-codes. That part is the same.
What differs is the complexity of the engineering package.
For a mono stringer, the engineer sizes the beam (typically an HSS section in the 8x4 to 12x6 inch range for residential), specifies the two end connections, details the tread bracket geometry, and confirms deflection stays within L/360. Straightforward scope. Two to three weeks from brief to sealed drawings.
For a cantilevered floating stair, the engineer designs the wall reinforcement, calculates bracket forces at every tread, specifies the fastener schedule into the backing steel, and coordinates with the framer on the wall build-up. Two to four weeks of engineering, plus ongoing coordination during framing. More steel fabrication, more drawings, more site coordination.
Welding on both systems has to be done by a C.W.B. certified shop under CSA W47.1 - https://www.csagroup.org. Our Burnaby shop is certified and every structural weld on every stair we build is traceable.
Cost tiers
We will not invent numbers, but here is the honest tier breakdown:
| System | Tier | Notes |
|---|---|---|
| Mono stringer, straight run, hardwood treads, cable railing | Baseline | Most common residential scope |
| Mono stringer, L-shape with landing | Mid-range | Landing platform and direction change |
| Cantilevered floating stair, new construction, hardwood treads, glass railing | Mid-range to Premium | Wall reinforcement included in framing |
| Cantilevered floating stair, retrofit | Premium | Wall reconstruction adds meaningful scope |
| Curved mono stringer or curved floating | Top-tier | Specialty fabrication, rolled steel |
Structural engineering fees are billed separately by the engineer in both cases. Request a quote for pricing on your specific project, we will not give you a number without seeing the space.
For a deeper side-by-side, the mono stringer comparison guide breaks down the trade-offs against other stair types in more detail.
Code minimums, same for both
A common misconception is that floating stairs get code relief because they look minimal. They do not. Both systems have to meet the same BC Building Code requirements:
- Minimum tread run: 235 mm nosing to nosing
- Maximum riser height: 200 mm, with riser variation inside a flight capped at 5 mm
- Minimum stair width: 860 mm clear between handrails in residential
- Minimum guard height: 900 mm from the nosing line
- 100 mm sphere rule on guard openings and between open risers
- Minimum headroom: 1,950 mm vertical from nosing line
- Concentrated live load on any tread: 1.5 kN
These are constraints you design around, not around. Our design guide walks through how these numbers shape tread thickness, spacing, and rail detail on mono stringer projects.
Tread detailing
Mono stringer treads usually sit 40 to 60 mm thick. Solid white oak, walnut, or engineered hardwood over a steel plate subframe. Each tread bolts to a pair of brackets welded off the stringer with countersunk stainless fasteners from below. The bracket stays hidden under the tread, you see a clean wood step floating off a steel spine.
Cantilevered treads usually go thicker, 60 to 80 mm, because the tread section has to resist the rotational load and because a thin tread on a cantilever reads as fragile. The tread slides over a hidden steel pin or blade welded to the wall bracket, and then locks in place with hidden fasteners. The blade geometry has to be exact, 3 mm off vertical and the tread tilts visibly.
Glass treads are possible on both systems but more commonly detailed on mono stringers because the steel bracket underneath is already part of the design language. On a cantilevered stair, a glass tread makes the whole assembly read as all-glass, which is striking but expensive.
Railings
Both systems work with cable, glass panel, and minimal steel rod railings. The detail changes:
On a mono stringer, railing posts usually weld directly to the stringer or to the outer edge of each tread bracket. Cable infill runs horizontally between posts with the 100 mm sphere rule driving spacing.
On a cantilevered stair, the railing typically anchors into the wall on the closed side (if there is one) or into the tread itself on the open side. Frameless glass panels mounted between treads are common. Cable railing is possible but needs careful detailing at the wall anchor to avoid telegraphing cable tension into the drywall.
Which system fits which project
Mono stringer makes sense when:
- The stair sits in the middle of an open-plan space with no adjacent wall
- You are retrofitting into an existing home and cannot easily rebuild walls
- Budget matters and the goal is visual openness rather than total invisibility
- The scope includes L-shape, U-shape, or curved geometry (mono stringers handle these more cleanly than cantilevers)
Cantilevered floating stair makes sense when:
- The stair runs along a structural wall in new construction
- The framing schedule allows for coordination with the backing steel install
- The visual priority is a clean wall with treads projecting and nothing else visible
- Budget has room for the engineering, wall steel, and tighter installation tolerances
For most Metro Vancouver residential projects, custom homes, laneway builds, loft renovations, the mono stringer path is the more practical answer. The cantilevered floating stair is a specific architectural move that needs the right space, the right wall, and the right schedule. When it works, it is striking. When it does not, it is an expensive lesson.
If you are trying to figure out which one your project actually supports, send us the floor plan and a couple of reference photos. Request a quote and we will tell you honestly which system fits the space and the budget.
