Guide

Mono stringer vs double stringer vs stringerless vs floating

Four stair typologies show up over and over on modern Metro Vancouver residential and commercial projects: mono stringer, double stringer, stringerless, and fully floating cantilever. They look different, they cost different, and they solve different architectural problems. This page is the honest comparison from a fabricator who builds all four, what each one is good at, where each one falls down, and how to pick the right answer for your project.

The short version: mono stringer is the modern default for residential projects where the stair is on display but a supporting wall is not available. Floating is the premium answer when a wall is available and the budget supports it. Stringerless is a close cousin of floating with slightly different visual intent. Double stringer is the workhorse for traditional, industrial, and commercial egress contexts. Most modern Vancouver homes pick between mono stringer and floating.

What each stair type actually is

Before the comparison makes sense, the definitions need to be clean. These terms get used loosely by architects, suppliers, and homeowners, and the wrong word on a drawing can mean the wrong stair gets quoted.

• Mono stringer: A single central steel beam runs the full length of the stair. Treads cantilever off both sides of the beam through welded brackets. The stringer is typically HSS tube or a built-up plate section sized for span and deflection. See our mono stringer overview for more detail.
• Double stringer: Two parallel beams, one under each side of the treads. Treads sit on top of the stringers or between them. Simpler engineering, more visual bulk, lower fabrication cost per step.
• Stringerless: No visible stringer at all. The structure is hidden inside the wall pocket or in concealed brackets inside the treads. Visually similar to a floating stair but usually has risers or a solid wall closing one side.
• Floating (cantilever): Treads project from a wall with no visible support underneath or on the open side. Each tread is a structural cantilever anchored into an embedded wall beam. The most demanding engineering of the four. See floating stairs.

Decision matrix

Side-by-side view of where each stair typology lands on the decisions that actually drive fabrication cost and installation risk. "Tier" labels describe the typical cost relationship, not absolute pricing.

Where mono stringer wins

Mono stringer is the most-built modern residential stair we fabricate out of our Burnaby shop. The reason is that it delivers 80 percent of the visual effect of a floating stair for roughly half the cost, and it does not require the supporting wall that a floating stair needs. For a stair sitting in the middle of an open-plan main floor, mono stringer is almost always the right answer.

It also wins on renovation projects. A floating stair is functionally impossible to retrofit into an existing finished wall because the structural beam has to be embedded during framing. A mono stringer can be engineered to anchor into whatever structure is already there, a concrete slab, a steel beam, an engineered header, with connection detailing worked out during shop drawings. The Burnaby homes we build in are a mix of new construction and substantial renovations, and mono stringer works across both.

Where double stringer wins

Double stringer is the right answer when the design intent is traditional, industrial, or unapologetically structural. A steel double-stringer stair with checker plate treads and a pipe rail in a warehouse loft is an honest piece of architecture, trying to force a mono stringer into that context usually looks overwrought. Commercial egress stairs are almost always double stringer because the BC Building Code live load for commercial stairs is higher and the structural robustness of two parallel stringers makes the detailing simpler.

Double stringer also wins when cost is the dominant constraint and the visual result is acceptable. Basement stairs, service stairs, and stairs inside closed stair shafts are almost always double stringer because nobody sees them and the price difference over mono stringer is meaningful.

Where floating wins (and where it doesn't)

Floating stairs are the right answer when the stair is the single most important architectural element in the room, a supporting wall is available and can be engineered for the cantilever load, and the budget supports the top-tier cost tier. In that narrow window, no other stair comes close visually. Frameless glass railings disappear, treads appear to grow from the wall, and the stair becomes a sculpture.

They are the wrong answer when the project is a renovation, the available wall is not structural enough to support the cantilever, the schedule is tight, or the budget is mid-range. Forcing a floating stair onto a project that does not support it produces either a compromised stair that doesn't deliver the effect or a budget overrun that hurts the rest of the build. The floating stairs page has the full detail on what it takes to do one right.

Where stringerless sits in the picture

Stringerless is the least common of the four, and the term itself is loose. Some projects use it to mean a floating stair with a solid side wall; others use it to mean a stair where the stringer is completely inside the tread. In practice, stringerless shares the engineering demands of a floating stair because the load still has to travel from each tread back to the building frame, it just gets there through concealed structure inside the tread or wall.

Stringerless makes sense when the visual intent is maximum minimalism, a stair that looks like nothing more than a stack of treads emerging from the wall. The engineering and fabrication cost sits at or above floating because the concealed structure has to be precision-built into every tread. Most clients who start out asking for stringerless end up at floating with a wall pocket because the practical difference is small and the floating detail has more precedent.

Cost tier breakdown

Rough cost tiering for a 14-step residential stair with similar tread material and similar railing treatment:

• Baseline tier, double stringer, steel treads, steel picket rail: The cost-effective workhorse. Used in basement stairs, service stairs, commercial egress, and exterior applications.
• Mid-range tier, mono stringer, oak treads, steel picket rail: The typical modern residential main stair we build. Mono stringer in matte black powder coat with 2-inch solid white oak treads.
• Premium tier, mono stringer, walnut or stone treads, cable or glass rail: Upgraded materials with the same mono stringer structure. Walnut treads or stone treads plus a tensioned stainless cable rail or glass rail.
• Top tier, floating or stringerless, premium treads, frameless glass rail: Wall pocket stair with walnut or stone treads and frameless glass railing. The architectural centrepiece of the house.

These tiers describe the cost relationship, not absolute pricing. Every project is quoted specifically for its span, tread count, tread material, rail system, finish, and site conditions. For numbers on your project, request a quote. Our full cost breakdown by component is in the stair cost guide.

Quick picks by project type

• Modern single-family home, open-plan main floor, stair is the centrepiece, no structural wall available: Mono stringer.
• Modern single-family home, stair against a feature wall, top-tier budget: Floating.
• Renovation where the existing stair is being replaced: Mono stringer, unless the wall is already being opened up.
• Basement or service stair where nobody sees it: Double stringer.
• Commercial egress stair: Double stringer with concrete-filled pan treads.
• Restaurant or retail interior where the stair is a brand element: Mono stringer or floating depending on available wall.
• Industrial or warehouse loft conversion: Double stringer, deliberately honest.
• Exterior stair in Metro Vancouver climate: Double stringer, hot-dip galvanized. See exterior galvanized stairs.

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