Wet-Room Floors: Falls, Drains and Slip Resistance

How to build falls in bathroom and shower floors, point versus linear drains, the link with waterproofing, and choosing slip-resistant tiles.

In a bathroom or shower, the main job of the floor is to carry water quickly and completely to the drain. If puddles remain, grout darkens, mould appears around the tiles and, in the worst case, water finds a weak point in the waterproofing and leaks to the floor below. Almost all of these problems come from not planning three things together: the falls, the drain and the tiles.

Falls are formed in the screed

For water to reach the drain, the floor is built with a slight fall in one or more directions. This fall is not created with the thickness of tile adhesive; it is formed at the screed stage. Trying to build falls with adhesive leads to uneven beds, voids and water collecting under the tiles.

How steep the fall should be depends on the type of drain, the tile size and the manufacturers' recommendations. Too shallow, and water stands; too steep, and you feel it underfoot and standing in the shower becomes uncomfortable. That is why falls are calculated in the design and marked on the walls with level lines before the screed is poured.

The direction of the fall must relate to the rest of the room. If the bathroom floor slopes towards the hallway, water can escape through the door. So the entrance is the highest point of the floor and the drain the lowest.

Point drain or linear drain

A point drain is the traditional solution. It usually sits in the middle of the shower area, with the floor falling towards it from four sides. This requires an "envelope" cut: tiles are cut along diagonal lines. Small tiles and mosaics adapt to this shape easily, while large tiles end up with many noticeable cuts.

A linear drain is a long channel along a wall or at the edge of the shower area. The floor then falls in only one direction, and large-format tiles can be laid without cutting. A linear drain also suits a step-free shower level with the rest of the floor.

In both cases, the height of the drain body and the fall to the waste pipe must be checked in advance. Where the floor build-up is too shallow for the drain, the floor has to be raised or a low-profile drain chosen.

Connecting the drain to waterproofing

The drain is the most critical point of the waterproofing. Water passes through the tiles and joints to the waterproofing layer and must flow from there into the drain. For that, the drain needs a clamping flange or a factory-bonded collar to which the waterproofing membrane is sealed.

The basic rules are:

the drain is fixed firmly in the screed and its height adjusted to the finished tile level;
waterproofing tape is applied around the drain and at wall-floor corners;
the waterproofing layer is joined to the drain flange or collar without breaks;
a flood test before tiling is advisable;
dedicated collars are used where pipes pass through.

Choosing slip-resistant tiles

A wet floor is slippery, and a fall in a bathroom can cause serious injury. When choosing tiles for a wet room, look not only at colour but at the surface's slip-resistance rating. Manufacturers state this in their catalogues under various standards; ask the supplier how suitable a particular tile is for bare wet feet.

Practical tips:

do not use polished or glossy tiles on a shower floor;
choose matt, lightly textured or specifically slip-resistant surfaces;
with small tiles and mosaics, the joints add extra grip;
in a step-free shower, the same tile range can be used throughout, with a rougher version in the shower area;
remember that a very rough surface is harder to clean.

Grout and care

In wet rooms, grout should be water-repellent and mould-resistant. Wall-floor corners, the area around the drain and the edge of the bath are sealed with sanitary silicone rather than rigid grout, because small movements occur there and a rigid joint cracks.

In daily use, squeegeeing water towards the drain after a shower and ventilating the room greatly extend the life of the joints. The drain grate and trap should be opened periodically and cleared of hair and sediment. Dealing with dark joints promptly and renewing silicone when needed prevents leaks.

The most common mistakes

Typical faults found on bathroom and shower floors:

falls built with adhesive, leaving voids under the tiles;
the drain set higher or much lower than the finished tile level;
waterproofing not connected to the drain flange;
large tiles laid with many cuts around a point drain;
glossy tiles in the shower area;
poor ventilation causing joints to darken quickly.

Zaferoğlu İnşaat plans bathrooms and showers at the design stage together with the fall layout, drain position and tile setting-out. Show us the shower dimensions and where the waste pipe is, and we will fix the drain type and fall direction on the plan with you.

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