What French Building Codes Say About Stair Dimensions in Public Buildings
The latest French regulations governing stairways in ERP (Établissements Recevant du Public) impose precise measurements to ensure safety and accessibility, and the updated diagram released in 2021 clarifies the minimum widths, riser heights, and tread depths required for every type of public venue.
Why Stair Dimensions Matter for Every Business Owner
Whether you run a restaurant, a school, or a shopping centre, the stair design you choose can affect compliance costs, insurance premiums, and the daily flow of patrons. Non‑conforming stairs can trigger mandatory upgrades, cause costly legal disputes, and, most importantly, endanger users.
Key Measurements Set by the 2021 Standard
The diagram 
outlines three critical parameters:
- Riser (hauteur de marche): 140 mm ± 5 mm is the maximum allowed height. Anything steeper makes the stair harder to climb, especially for elderly visitors.
- Tread (giron): Minimum 300 mm without a nosing, or 280 mm with a nosing, ensures each step provides a safe foothold.
- Width (largeur de passage): At least 90 cm for public stairs, increasing to 120 cm for emergency routes serving more than 200 occupants.
How to Audit Existing Staircases
Start with a simple measurement sweep: use a laser level to verify riser uniformity, then check tread depth with a ruler. If any step exceeds the 140 mm limit, plan a retro‑fit. For commercial sites, a professional “accessibility audit” often uncovers hidden issues such as missing handrails or inadequate lighting, both of which are also mandated by the ERP code.
Practical Checklist for Facility Managers
- Record the dimensions of each stair run in a spreadsheet.
- Compare findings against the 2021 standards highlighted above.
- Identify non‑compliant steps and prioritize those in high‑traffic zones.
- Engage a qualified contractor to redesign or rebuild offending sections.
- Schedule a follow‑up inspection after remediation to obtain a compliance certificate.
Implications for Future Renovations
When planning extensions or modernisations, embed the latest ERP criteria from the start. Choosing modular stair components that match the prescribed dimensions can shave weeks off the approval process. Moreover, investing in wider handrails (minimum 42 cm apart) and non‑slippery treads not only satisfies the code but also reduces the risk of slip‑and‑fall claims.
Bottom Line for the Everyday User
Compliance with stair dimension rules isn’t just a bureaucratic hurdle—it directly influences how comfortably and safely people move through public spaces. By measuring, auditing, and updating staircases according to the 2021 ERP standards, owners protect their patrons and avoid costly retrofits. The clear visual guide provided by the French authorities makes it easier than ever to stay within the law while delivering a user‑friendly environment.