Spanish Stair & Barrier Rules: Riser, Going, Handrails, Guarding

The requirement

A Spanish dwelling’s internal stair is built to DB-SUA 1, the Documento Básico for “Seguridad de Utilización y Accesibilidad” — safety in use and accessibility. Before you read off a single number, though, get the classification right: the CTE’s own glossary (Anejo A) classes the interior of a single-family or attached dwelling as “uso restringido” — restricted use. That matters, because DB-SUA 1 also sets out a separate, stricter “uso general” class for shared and public stairs, with different (and in one case, extra) rules. This page covers uso restringido — a house’s own stair.

• Riser (contrahuella) — how tall each step is.
• Going (huella) — how deep each step is, measured in the direction of travel.

For a restricted-use dwelling stair, each riser can be no more than 20 cm and each going must be at least 22 cm — DB-SUA 1, §4.1. Keep every step in a flight the same. On a curved stair under 1 m wide, measure the going on the stair’s own axis; at 1 m or wider, measure 50 cm in from the narrow side, with the going never dropping below 5 cm at the narrow end or exceeding 44 cm at the wide end. The same clause sets a minimum clear width of 0.80 m per flight — DB-SUA 1, §4.1, point 1.

No 2C+H formula for a dwelling stair. DB-SUA 1 does carry a comfort formula — twice the riser (C) plus the going (H), kept between 54 cm and 70 cm — but §4.2.1 states it only for uso general stairs, the shared or public class. A house’s own restricted-use stair isn’t checked against it; the riser and going limits above are the whole rule.

Headroom is set separately, in DB-SUA 2 (§1.1) — the impact-risk section, not SUA 1. It’s 2.10 m minimum in restricted-use circulation zones (a dwelling’s hallways and landings), 2.20 m in other circulation zones, and 2.00 m at a door threshold. The Ministry’s own comment on this clause confirms the 2.10 m figure applies to circulation zones only — not to a living or sleeping room, so a sloped ceiling over a stair doesn’t fail this test just because it’s low somewhere else in the room.

Handrail & guarding

The handrail (pasamanos) sits 90–110 cm above the pitch line. Read this one carefully: the 90–110 cm figure is stated explicitly in §4.2.4, the uso general clause. The restricted-use clause that actually governs a dwelling’s own stair (§4.1, point 4) only requires a handrail on any open side, without restating a height. In practice, the 90–110 cm figure is applied to a house stair by common cross-reference, but the code doesn’t independently restate it for the restricted-use case.

Guarding (barreras de protección) protects a drop, and DB-SUA 1 uses one rule for every kind of edge — stair, landing, floor or balcony alike — driven only by how far the drop is, not by what’s dropping:

The gaps in the guarding matter too:

• No opening should admit a 10 cm diameter sphere — the residential/ school-zone and public-use-commercial-or-assembly figure — or 15 cm in other public-use zones.
• The open triangular gap formed by a tread, riser and baluster’s lower edge is exempt only if it’s 5 cm or less from the stair’s line of inclination — §3.2.3.

Work it out on site

Say your floor-to-floor height is 2.80 m and you’re setting out a restricted-use dwelling stair.

1. Pick how many risers. 2.80 m ÷ 0.20 m (the tallest a riser can be) = 14. That’s a clean number — 14 risers, each exactly 200 mm, right at the 20 cm ceiling.
2. Set the going. Try 220 mm, the minimum. Fourteen risers means 13 goings, so the stair runs 13 × 220 = 2860 mm along the floor. Check it fits the space — Spain sets no 2C+H comfort check to satisfy for this class, so a shallower or deeper going is your own call on comfort, not a compliance one.
3. Check headroom and guarding separately. Confirm 2.10 m clear above the restricted-use stair, and that any open side is guarded to 0.90 m (or 1.10 m past a 6 m drop).

The calculator does the riser rounding for you and flags if you’ve gone past the 20 cm riser or under the 22 cm going.

Do it in 5 seconds

Related

• Spanish Building Regulations hub — how the one national CTE and its Documentos Básicos work.
• Irish stair & barrier rules — for anyone comparing riser/going conventions across countries.

Sources

• CTE DB-SUA — Seguridad de Utilización y Accesibilidad, §4.1 (riser, going, restricted-use classification), §4.2.1 (2C+H formula, uso general only), §4.2.4 (handrail height, uso general), §3.2.1 (guard heights), §3.2.3 (guard-opening sphere rule), and DB-SUA 2 §1.1 (headroom). Read it at codigotecnico.org.

Read this first. These figures are from the current DB-SUA articulado (Real Decreto 450/2022, de 14 de junio, corrected BOE 02/02/2023). A further partial revision of the CTE affecting DB-SUA was in public consultation at the time these figures were checked (not yet adopted) — always confirm the current DB-SUA text at codigotecnico.org before you build to it.