Floor gradient: the fall to the drain that keeps water where it belongs

A wet-room floor is never meant to be level. It's built with a continuous, measured slope so every drop runs to the drain — and GVK is exact about it, because incorrect fall is one of the most common bathroom defects.

Why it matters, in law

In rooms with a floor drain, the parts of the floor (and its waterproof layer) regularly exposed to water must slope to the drain, so water can't reach adjoining rooms and cause damage. Boverket's building regulations require it directly: floors often exposed to liquid water must have a drain and a fall towards it, and backfall must not occur in any part of the room (BFS 2024:8, ch. 7, §11).

The exact tolerances

GVK sets measurable limits:

• In shower places (or equivalent), the fall to the drain must be at least 1:150 (7 mm/m) and at most 1:35 (30 mm/m).
• The fall between the drain and adjacent walls may be at most 1:25 (40 mm/m).
• No backfall anywhere in the room.
• The fall requirement applies to both the substrate (when the membrane is installed) and the finished surface layer.

Too little fall and water pools; too much and it's uncomfortable and tiles are hard to lay flat. The window between 7 and 30 mm/m is where a floor both drains and works.

Thresholds

At door openings the detailing (with a threshold height of around 20 mm) is arranged so water is contained and can't run out into the adjoining room.

What M5 brings to Dubai

We build the fall into the whole floor — not just a dip near the drain — check it on the substrate before the membrane and again on the finished tiles, and never allow backfall. It's the detail that decides whether your bathroom floor quietly drains or quietly floods.

Official source: this is M5's plain-language summary, not the official text. For the full rules see GVK — gvk.se.