[Home](https://garde-corps-fer-forge.fr/en/) / Standards & safety Standards & safety # The rules governing a wrought-iron guardrail Regulatory heights, baluster spacing and NF EN ISO 1461 galvanizing — the French NF P01-012 standard and building regulations explained and sourced. Legal framework ## NF P01-012, a voluntary standard backed by a legal obligation The NF P01-012 standard is a voluntary AFNOR standard — not directly binding by itself. The real legal basis is French building regulations (Code de la Construction et de l'Habitation, articles R.111-15 and R.134-59): the standard details and technically complements these requirements, which makes it in practice the reference professionals follow to size a compliant guardrail. A guardrail becomes mandatory once the fall height exceeds 1m or the slope exceeds 45°. Heights ## Minimum height by context 1m (0.80m if the element exceeds 50cm thick) Balcony, terrace, gallery, loggia 0.80m to 1m Stairs (from the stair nosing) Protection required if sill + frame < 0.90m Window / low sill Spacing ## Maximum infill spacing ≤ 11cm Vertical balusters, full height < 11cm Horizontal rail, anti-climb zone (0–45cm) ≤ 18cm Horizontal rail, above 45cm > Worth watching, not confirmed with AFNOR: a single source reports a standard revision (low zone raised to 60cm, T1/T2/T3 sphere gauges, mandatory from 1 January 2026). We don't present it as established until corroborated by an official source — this page will be updated if it's confirmed. Outdoor protection ## NF EN ISO 1461 galvanizing For a guardrail exposed to the weather, the steel is hot-dip galvanized (immersed in a molten zinc bath) before powder coating. The NF EN ISO 1461 standard (2022 edition) sets the minimum zinc thickness depending on steel thickness: > 6 mm 505 g/m² / 70 µm Local minimum 610 g/m² / 85 µm Mean minimum > 3 to ≤ 6 mm 395 g/m² / 55 µm Local minimum 505 g/m² / 70 µm Mean minimum ≥ 1.5 to ≤ 3 mm 325 g/m² / 45 µm Local minimum 395 g/m² / 55 µm Mean minimum < 1.5 mm 250 g/m² / 35 µm Local minimum 325 g/m² / 45 µm Mean minimum An 85 µm thickness gives an average maintenance-free lifespan of roughly 40 to 70 years depending on environment (more in low-corrosivity settings) — worth nuancing by the tier actually reached: many decorative balusters are under 6mm thick and therefore sit in the lower tiers (35 to 70 µm), not the maximum tier. Fabrication ## A check that starts before the zinc bath The steel's actual section (measured before galvanizing) determines which zinc-thickness tier applies — checked in the workshop before every batch goes into the bath, not just on paper against the standard. Frequently asked questions ## What we're asked most often Is the NF P01-012 standard mandatory? Not directly as a regulatory obligation: it's a voluntary AFNOR standard. The binding legal basis is French building regulations (Code de la Construction et de l'Habitation, articles R.111-15 and R.134-59), which the NF P01-012 standard details and technically complements. What height does a balcony guardrail need? 1m minimum, with a tolerance to 0.80m only if the guardrail itself is a massive element over 50cm thick — a rare case for a classic wrought-iron structure. What is the maximum spacing between two balusters? 11cm maximum over the full height for vertical balusters. For a horizontal rail, under 11cm within the first 45cm (anti-climb zone), up to 18cm above that. Does every window need a guardrail? No — only if the combined height of the sill and window frame is under 0.90m. Above that, no additional protection is required under French building regulations. Is galvanizing enough for outdoor use? Hot-dip galvanizing protects steel from corrosion for decades, but many decorative balusters are under 6mm thick and therefore sit in the 35 to 70 µm tiers, not the maximum 85 µm tier reserved for thicker pieces — powder coating then adds further aesthetic protection. Quote ## A project to size? Describe your structure — the workshop replies with a first compliant estimate within 48h.