Steel Staircases & Multi-Storey Steel Structures — Vertical Circulation and Vertical Expansion
A staircase is the most code-governed, detail-loaded, and schedule-forgiving element in a steel building — until it is wrong, at which point it stops a certification and embarrasses a handover. And a multi-storey addition is the fastest way to double a plant's useful floor area without buying land. We design, fabricate and deliver both to the geometry and load rules of the governing code — AISC 360 for the steel design, IBC 1011 for egress stair geometry, GB 50017 and GB 50352 for Chinese projects — pre-drilled and test-assembled so the stairs bolt into level flights and the frames stack without site persuasion.
Staircases Are Code Geometry, Multi-Storey Frames Are Load Paths
Two products, one discipline: geometry and connections decided on paper before steel is cut.
A steel staircase earns its place in a building the way everything else does — it must pass inspection, on the numbers. The dimensions that inspectors check — tread run, riser rise, clear width, headroom, handrail height, opening size — are set by code, and they are not negotiable. This is why we treat stairs as shop-fabricated assemblies rather than site-welded improvisations: the stringers are cut with the riser-tread geometry programmed, the treads are jigged and welded at the exact module, and the two flights of a landing arrive with matching bolt holes. Erection is placing pre-built units, not interpreting a drawing with a grinder.
Multi-storey steel frames follow the same philosophy at a larger scale. The column grid, story height and bracing arrangement define the load paths; the composite floors provide the diaphragm; the connections — moment-resisting at the frame joints, pinned where the bracing takes the lateral load — are pre-engineered, and the beam-to-column joints are either full-penetration welded or high-strength bolted per the analysis. Our fabrication line welds the built-up columns and beams, drills the connection holes by CNC, and the erector's bolts do the final assembly — the same controlled path whether the project is a 3-storey office extension over a factory or a 6-storey car park.
The two products meet at the egress stair: a fire-rated stair tower is simultaneously the vertical circulation of a multi-storey building and one of its most load-governed components. Its fire-resistant enclosure, its landing-to-frame connections and its geometry all come from the same design report — which is the argument for buying the staircase and the frame from one engineer who has already decided how they meet.
Four Stair Systems, Four Geometries
Each type follows its own governing dimension set; the values below are our standard scheme ranges, verified against the project's code and occupancy.
Fire-Rated Egress Stairs
The building code staircase: 280 mm minimum tread run, 180 mm maximum riser rise, and 1.1 m minimum clear width, enclosed and protected to the required fire rating, with landings sized to the door swing and handrail extensions beyond the opening.
- Tread run ≥ 280 mm, riser rise ≤ 180 mm
- Clear width ≥ 1.1 m (occupant load dependent)
- Fire enclosure per IBC/GB 50016 rating
- Shop-fabricated flights with matching bolt holes
Industrial & Plant Stairs
Working stairs for plant access with 250 mm treads and 200 mm risers — steeper than egress geometry because they serve workers carrying tools, not crowds — with 1.05 m high handrails and open-grid or chequer-plate treads.
- Tread run ≥ 250 mm, riser rise ≤ 200 mm
- Handrail height ≥ 1.05 m
- Open-grid treads shed oil and mud
- Straight, dog-leg and alternating-tread forms
Spiral Stairs
Space-saving spiral access with a 1.5 m minimum inner diameter and 220 mm minimum tread width at the outside edge — the geometry that makes a spiral usable and code-passing rather than scenic but useless.
- Inner diameter ≥ 1.5 m
- Outside-edge tread width ≥ 220 mm
- Central column or open-riser cantilever construction
- Prefabricated as one or two-piece shop units
Catwalks, Platforms & Galleries
Service walkways and viewing platforms with a minimum width of 0.8 m, a live load of 3.0 kN/m², and 1.05 m handrails — the standard access furniture of process plants, warehouses and industrial facilities.
- Width ≥ 0.8 m, live load 3.0 kN/m²
- Handrail 1.05 m, mid rail and kickplate
- Anti-slip grating or chequer plate decking
- Bracket or torsion-tube connection to structure
Stair Geometry Limits — The Numbers Inspectors Read
Applicable limits depend on the governing code and occupancy; we detail to the strictest relevant value and table the governing code per project.
| Parameter | Maximum Riser Rise | Minimum Tread Run | Minimum Clear Width |
|---|---|---|---|
| IBC 1011 (egress stairs) | 178 mm | 279 mm (11 in) | 1,118 mm (44 in) |
| GB 50352 (civil building design) | 175 mm | 280 mm | 1,100 mm |
| EN 1991-1-1 / common practice | 190 mm | 250 mm | Per stair design standard |
The comfort and safety of a stair is governed by the riser-run combination, not just the individual limits: a rise of 175 mm with a run of 280 mm sums to the classic 455 mm module that human stride fits comfortably, while a steeper combination pushes people's weight onto the toes, which is why egress codes draw the line where they do. For every stair we check the two-rise-plus-tread rule (2R + T) against the code's band, dimension the nosing projections, and verify headroom — at least 2.0 m above the nosing line — and the landing geometry where the door swing and the occupant flow meet. Where the architectural plan forces a non-standard stair, we say so in the drawing set with the code reference, instead of delivering a stair that the inspector rejects at handover.
Multi-Storey Steel Frames: Four Engineered Answers
Frame, floor, fire and connection — the four decisions that define a multi-storey steel building.
Frame & Bracing System
Steel frame with braced bays or moment frames, story heights of 3.6–4.2 m and column grids of 6–9 m — the grid chosen so beams, composite floors and facade modules all span economically without a redundant column line.
Composite Floor System
Profiled steel deck plus reinforced concrete topping, 110–150 mm total depth, with φ19 mm headed shear studs welded through the deck — the floor that provides stiffness, fire separation and the lateral diaphragm in one element.
Fire Protection
Thin-film intumescent coating rated 1.5–2.0 hours per GB 14907, or board enclosure where the occupancy demands it — the protection thickness calculated from each member's section factor, not applied as a uniform guess.
Connection Standards
Beam-column joints rigid (moment-resisting) or pinned per the frame analysis, connected with grade 10.9S high-strength bolts with friction-grip installation, and column splices welded with full-penetration groove welds at the designated floors.
Handrails and Guarding — The Details People Touch
The handrail is the part of the building everyone touches and the code parts that get inspected with a tape measure. Our standard railing system: guard height 1.05–1.20 m measured from the walking surface (the height follows the code and the fall hazard), posts at ≤1.5 m spacing anchored to the floor or stringer with a base detail that resists the code's required horizontal load without prying the plate, a mid rail exactly centered between the top rail and the floor so the opening rules are satisfied, and a 100 mm high kickplate where open decks can shed objects. For egress stairs the system adds the handrail extension: the rail continues horizontally at least 300 mm past the top and bottom risers, so a person reaching for the rail in a hurry finds it before the first step — the detail that is easiest to skip on site and hardest to defend in an inspection.
All railing components are fabricated and welded in the shop — posts, rails, gussets and kickplates jigged and drilled together — so the field work is bolting pre-assembled segments and aligning them on the grout line. The surface treatment matches the environment: hot-dip galvanized for industrial stairs and plant access, painted to the building's palette where the railing is part of the architecture, with the coating system stated on the shop drawing and the fastening torque values in the erection manual.
Adding a Storey, a Stair, or Both?
Send us the building geometry, the code that governs your jurisdiction, occupancy and fire-rating requirements. We return stair geometry, framing layout, connection details and a quotation — with the shop drawings following in the same submission cycle.
Design Steel Staircase & Multi-StoreyEmail: market@permanentsteelstructure.com | WhatsApp: +86 18621689980 | Phone: +86 516-83269982