Spanish Minimum Roof Pitch (CTE DB-HS1): By Material

The requirement

There is no single national minimum in Spain. The code sets a minimum slope for each roofing material instead. The figures sit in Tabla 2.10 of DB-HS1. Curved tile needs 32%. Slate needs 60%. Zinc needs 10%. Every figure is a percentage slope, not degrees.

Roof pitch is how steep a roof plane is. The CTE calls it the pendiente. Lay a material flatter than its limit and rain works back under the laps instead of running off. Spain’s national code is the Código Técnico de la Edificación (CTE). The rule lives in Documento Básico HS, Sección HS1 “Protección frente a la humedad”, at §2.4.3.1.

Each material and profile gets its own minimum. A deep tile profile sheds water differently to a flat sheet. Here is the full list:

These are percentage slopes, not degree angles. DB-HS1 states every figure as a pendiente. That means rise divided by run, times 100. A degree figure from another country’s code is a different kind of number. Convert before you compare.

The table has limits. Tabla 2.10 covers a roof plane (faldón) under 6.5 m, at normal exposure. It also assumes the climate zone is unfavourable, the safe worst case. Go past any of those limits and the code hands the minimum to a UNE product standard. That means UNE 127100 for concrete tile and UNE 136020 for ceramic tile. So the table figure is a starting point. On a long or exposed roof plane it is not the final answer.

Flat roofs are a separate table

Flat roofs (cubiertas planas) get their own table, Tabla 2.9, right next to Tabla 2.10. It gives ranges, not single figures. Gravel, self-protected membrane, and fixed or floating paving sit at 1–5%. A green roof (ajardinada, with a soil layer) runs 1–15%. This page covers pitched roofing. If you are detailing a flat roof, work from Tabla 2.9’s ranges.

Worked example

You have framed a roof plane. The rafter climbs 1 m over a 4 m run. What is the pendiente, and is it steep enough?

1. Get the rise and the run. The rise is how far the roof climbs: 1 m. The run is how far it travels flat to get there: 4 m.
2. Turn it into a percentage. Divide rise by run, then multiply by 100. That gives 1 ÷ 4 × 100 = 25%. The roof-pitch calculator does this bit for you. It can also convert to degrees if that is what you are used to.
3. Check it against your material’s minimum. Laying zinc? Its minimum is 10%, so 25% is well clear. Laying flat interlocking tile (teja plana con encaje)? Its minimum is 50%. The same roof is far too flat for that tile, even though it was fine for the zinc sheet.

Related

• Spanish Building Regulations hub explains how the one national CTE and its Documentos Básicos work.
• NCC minimum roof pitch (Australia) fixes pitch in degrees rather than percentage slope, for comparison.

Sources

• CTE Documento Básico HS, Sección HS1 “Protección frente a la humedad”, §2.4.3.1, Tabla 2.10 (pitched-roof minima by material) and Tabla 2.9 (flat-roof ranges) — edition of 14 June 2022, Ministerio de Vivienda y Agenda Urbana. Read it at codigotecnico.org.
• UNE 127100 (concrete roof tile) and UNE 136020 (ceramic roof tile) — the standards DB-HS1 defers to outside Tabla 2.10’s scope (roof plane over 6.5 m, or outside the assumed exposure/climate case). Paid AENOR standards, not reproduced here.

Read this first. These figures are from the current DB-HS1 articulado. Always confirm the current edition at codigotecnico.org before you build to it, and check whether your roof plane, exposure and climate zone actually fall inside Tabla 2.10’s stated scope before using its percentage directly.