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Spanish Wet-Room Waterproofing: What CTE DB-HS1 Doesn't Cover

CTE DB-HS1 governs building-envelope damp — ground, façades, roofs — not shower or wet-room membranes. Those run on UNE product norms and manufacturer ETAs, which this page names but doesn't reproduce.

CTE DB-HS1 (consolidated text, RD 450/2022) Clause ES CTE DB-HS 1

The requirement

CTE DB-HS1 sets no shower or wet-room membrane rule. It covers damp from the ground, from façades, and from roofs. That is the shell of the building, not the bathroom. Wet-room membrane rules come from the product side instead: UNE-EN 14891 and each product’s approval papers.

DB-HS1 is short for Documento Básico HS1, “Protección frente a la humedad”. That means protection against damp. It sits in the CTE’s Salubridad (HS) set. Unlike the UK’s Approved Document C or Ireland’s TGD C, DB-HS1 is free to read and truly official. But its scope is like theirs: the outside of the building.

A direct read of DB-HS1 confirms the gap. It has no shower recess, bath surround or wet-room floor detail. There is no table for how far a membrane must reach. There is no wall-height figure for a bathroom in it.

What CTE DB-HS1 coversWhat it doesn’t cover
Ground moisture through floors and foundationsBathroom, shower or wet-room waterproofing
Damp resistance of façades (driving rain, cladding)Internal tanking membranes
Roof weathertightnessWall/floor junctions inside a wet room

So has someone told you “the CTE says” a shower wall must be tanked to a set height? That rule is not coming from DB-HS1. Spain leaves wet-room detail to other standards. The UK, Ireland and France do the same.

Where the actual numbers live

Spanish wet-room waterproofing runs on UNE norms in practice. These are the national standards from UNE (Asociación Española de Normalización). Many of them mirror European (EN) standards. The big one here is UNE-EN 14891. Its full name: “Liquid applied water impermeable products for use beneath ceramic tiling bonded with adhesives”. In plain words, liquid membranes that go under tile. Products are tested and classed against it.

A membrane system gets certified to UNE-EN 14891. It then carries a European Technical Assessment (ETA), or a like approval. That paper spells out how that exact system goes in, and how far it must reach.

One catch: UNE-EN 14891 is a paid standard. UNE sells it, and CEN sells the base EN text. This page names it and explains its job. It does not copy the classes or test detail. That is fine, because the numbers you need on site are not in there anyway. Membrane thickness, coverage rate, cure time and upstand height all sit in the product’s ETA or data sheet. Each maker writes their own and hands it out free.

What this means on site

DB-HS1 stays silent here, so the product papers carry the job. The route looks like this:

  1. Pick a membrane certified to UNE-EN 14891, or a locally recognised equal. Check its ETA or Declaration of Performance. Do not assume any liquid membrane makes the grade.
  2. Follow that product’s data sheet and ETA exactly. Coats, coverage rate, cure time, mesh at the joints, upstand height at drains and junctions. That paperwork is the spec you build to. DB-HS1 gives you none.
  3. Check your region and council. Some autonomous communities layer their own guidance or habitability decrees on top of the CTE. Room height and floor area work the same way. See the ceiling-height page below. Confirm what your region adds.
  4. Keep the paperwork. Save the ETA or Declaration of Performance, plus proof the job went in right. There is no DB-HS1 clause to cite, so that file is your record.

Sources

  • CTE Documento Básico HS1, “Protección frente a la humedad” (consolidated text, Real Decreto 450/2022) — confirmed by direct read to cover ground, façade and roof moisture only, with no shower or wet-room waterproofing clause. Freely published. Read it at codigotecnico.org.
  • UNE-EN 14891, “Liquid applied water impermeable products for use beneath ceramic tiling bonded with adhesives” — the harmonised European/Spanish product standard wet-room membranes are certified against. Paid, published by UNE/CEN; not reproduced here. See une.org.

Read this first. DB-HS1 is freely published and official, but its scope is the building envelope, not internal wet-room detail — always check the specific membrane product’s ETA or Declaration of Performance, and confirm whether your autonomous community layers any additional requirement on top of the national CTE, before you rely on any waterproofing detail. (Verified against DB-HS1 as at 2026-07-31.)

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