Private vs Multi-Family vs Commercial Staircase in Switzerland — Classification & What Changes

U-shape central spine staircase suitable for multi-family Treppenhaus (common stair) — 1.0 m clear width, both-side handrails, SIA 500-compatible 17 cm riser specification.

The single most important question that drives Swiss staircase specification is not "what does it look like?" or "what does it cost?" but: what is the building's classification? The answer determines almost everything else — dimensional rules, fire safety enclosure (Brandschutz), accessibility obligations (SIA 500), inspection process and Baubehörde dossier requirements. The same villa can sit happily within the residential framework while a project across the street with shared common stairs falls under tighter multi-family rules; a boutique commercial space adjoining the same block follows a third, stricter framework again.

This guide is the practical decision framework for Continox Switzerland projects across the three classification tiers — covering when each applies, the dimensional and structural differences, fire safety implications, and the documentation pack needed for each. For the broader regulatory framework see our SIA standards guide. We supply floating cantilever, central spine and fully bespoke configurations across all three classifications, along with matching glass balustrades, balcony railings and external staircases.

The Three-Tier Classification Framework

Swiss staircase classification operates on three tiers — each with its own dimensional rules, structural loading, accessibility obligations and Brandschutz requirements:

Wohnbau privat — Private Residential

Wohnbau privat covers single-family villas (Einfamilienhaus) and the staircase inside an individual apartment in a multi-family building. The defining characteristic is that the staircase is used exclusively by one household and is not shared with neighbours.

Wohnbau privat applies when: (a) the staircase is inside a single-family villa, (b) the staircase is inside an individual apartment unit (e.g., duplex insertion within a single Wohnung), or (c) the staircase serves the private rooms of a residential property without giving access to areas shared with other tenants.

Wohnbau privat allows the most generous dimensional latitude: riser up to 20 cm (steepest of the three categories), tread minimum 24 cm, width minimum 80 cm. Step formula 2R + T = 600–630 mm. Headroom minimum 2.00 m. Maximum flight 18 risers without intermediate landing. One handrail sufficient (both sides only if width exceeds 1.20 m).

Brandschutz requirements minimal — typically only a smoke detector in the staircase area as part of household fire safety. No fire-rated enclosure (Brandabschnitt) required for the staircase itself within a single-family or single-apartment context. SIA 500 accessibility not mandatory but voluntary. Inspection: standard architect sign-off plus the cantonal Baubehörde Schlussabnahme at project completion.

Floating cantilever staircase in a Swiss single-family villa — Wohnbau privat classification with dimensional latitude and minimal Brandschutz requirements.

Treppenhaus mehrfamilienhaus — Multi-Family Common

Treppenhaus mehrfamilienhaus covers the shared staircase in a multi-family residential building (Mehrfamilienhaus, MFH) — the staircase that gives access to multiple separate apartments. This is a fundamentally different regulatory beast from the private staircase inside an individual apartment.

The Treppenhaus is the shared vertical circulation in a multi-family building — connecting the entrance lobby (Eingangshalle) to multiple apartment doors on each floor. Used by all tenants, visitors, postal workers, deliveries. Acts as the primary fire escape route for the entire building. Subject to Stockwerkeigentum (condominium law) for shared maintenance and modifications.

Tighter dimensional framework: riser maximum 18 cm (vs Wohnbau privat 20 cm), tread minimum 26 cm, width minimum 100 cm clear between handrails and obstructions. Step formula 2R + T = 610–630 mm. Headroom minimum 2.10 m. Both sides require continuous handrails. Maximum 16 risers per flight without intermediate landing.

Treppenhaus must be a fire-rated Brandabschnitt (fire compartment) per BSV/AEAI Brandschutzvorschriften. Typical specification: R 90 fire resistance for structure, EI 30 fire-rated apartment doors opening into the stairwell, natural or mechanical smoke ventilation (Rauch- und Wärmeabzugsanlage, RWA), and fire-resistant materials on stairs and handrails. Continox supplies structural elements; the Brandabschnitt enclosure is the responsibility of your appointed Brandschutzplaner.

SIA 500 barrier-free requirements typically mandatory in most cantons for new-build multi-family buildings (≥ 4 apartments threshold common). This adds: handrail extensions 30 cm at top and bottom, tactile warning strip at flight head, contrasting nosings, riser-tread relationship within accessible 620–640 mm step formula range. Renovation projects sometimes exempted; new builds nearly always covered.

U-shape steel plates configuration — typical Treppenhaus mehrfamilienhaus specification with 100 cm clear width, both-side continuous handrails and SIA 500 accessible riser/tread proportions.

Öffentlich zugängliche Bauten — Commercial & Public

Öffentlich zugängliche Bauten (publicly accessible buildings) cover commercial and public-access spaces — offices, retail, hotels, restaurants, healthcare, education, cultural institutions. The strictest of the three classifications, with full SIA 500 + Brandschutz BSV/AEAI compliance plus elevated structural loading.

Any building or part of a building open to the public — whether continuously (retail) or by appointment (medical, professional services). Subdivided in Switzerland by occupancy density and risk: Versammlungsstätten (assembly buildings — theatres, churches, schools, conference halls) carry the strictest rules; Verkaufsräume (retail) and Beherbergungsbetriebe (hotels) sit slightly lighter. Continox typical clients: boutique commercial fit-outs, medical practices, hotels and serviced offices.

Riser maximum 17 cm — significantly shallower than Wohnbau privat 20 cm. Tread minimum 28 cm. Width minimum 120 cm clear between handrails and obstructions (some assembly applications require 140 cm or more depending on occupancy density). Headroom minimum 2.20 m. Step formula 2R + T = 620–640 mm — within SIA 500 accessible range. Maximum 16 risers per flight without intermediate landing.

Full compliance with the Brandschutzvorschriften (Swiss fire protection regulations) administered by the BSV/AEAI (Vereinigung Kantonaler Feuerversicherungen) — including escape route certification, smoke ventilation, fire-rated materials, and where applicable Rauchabzug (smoke extraction) and emergency lighting. Specific requirements scale with occupancy density and floor area.

Full SIA 500 mandatory: handrails on both sides with 30 cm horizontal extensions at top and bottom, tactile warning strip at flight top (bande d'éveil de vigilance equivalent), contrasting nosings on every tread leading edge for visually-impaired users, step formula within 620–640 mm accessible range, handrail height 0.85–0.90 m above nosing line continuous through landings.

Commercial-spec central spine — 120 cm clear width, double handrails with 30 cm extensions, contrasting nosings and full Brandschutz BSV/AEAI compliance for Swiss public-access fit-out.

Side-by-Side Comparison Table

Fire Safety — Brandschutz BSV/AEAI

Swiss fire protection regulations are administered by the Vereinigung Kantonaler Feuerversicherungen (BSV/AEAI) — a cross-cantonal body that publishes the unified Brandschutzvorschriften. The framework is technically separate from the SIA standards but applied in parallel for any project beyond Wohnbau privat.

When SIA 500 Accessibility Triggers

SIA 500 (Hindernisfreie Bauten) is mandatory when the building is publicly accessible or accommodates a public-equivalent function. Specific triggers vary by canton but typical thresholds:

Decision Framework — Practical Walkthrough

Three questions the architect should answer before sending the project brief to Continox:

If only one household (single-family villa or inside one apartment) → Wohnbau privat, lightest framework. If multiple households share the staircase (Treppenhaus MFH) → mid-tier framework with Brandabschnitt and SIA 500. If members of the public (commercial, hotel, retail, office) → strictest framework with full Brandschutz and SIA 500.

If yes → Brandabschnitt is non-negotiable. The staircase becomes a fire compartment with R 90 structural fire resistance, EI 30 doors opening into the stairwell, and Rauchabzug provisions. Architect coordinates with appointed Brandschutzplaner. If no (alternative escape route exists) → Brandabschnitt provisions can sometimes be relaxed; verify with the Feuerpolizei.

Cross-check the cantonal accessibility law and the building type. If SIA 500 mandatory → max 17 cm riser, min 28 cm tread, both handrails with 30 cm extensions, tactile warnings, contrast nosings. If voluntary → owner can elect either way; many architects voluntarily apply for future-proofing.

Frequently Asked Questions

This guide is produced by Continox Technical Team for Swiss architects, Bauingenieure and Brandschutzplaner specifying bespoke staircases. Final regulatory compliance verification, Baugesuch acceptance, BSV/AEAI Brandschutz sign-off and cantonal Baubehörde Schlussabnahme remain the responsibility of the project's appointed Swiss architect or Bauingenieur.