Floor, Waterproofing and Render

With the pipes in place, the bathroom is rebuilt from the bottom up: first the floor, then the walls and the ceiling. You won't see these layers again, but they decide whether water drains properly and whether the tiles sit straight.

A sloped floor

The new floor is laid with a slopeFalls (drainage slope)The gentle slope built into flat roofs, balconies and bathroom floors so water runs to the drain or gutter instead of pooling. towards the floor drainFloor drainThe outlet in a floor where water drains away on roofs, balconies and in bathrooms, with a grate on top and usually a trap below., so water runs away instead of pooling. In a bathroom with grey tiles, the floor was laid again around the drains and made ready for tiling.

In a walk-in showerWalk-in showerA shower with no tray and no step, level with the rest of the bathroom floor. The water drains through a floor drain or a linear channel drain. the slope matters even more, because there is no step and no tray to hold the water. In one bathroom, the floor was sloped towards a long, narrow channel drain under the window.

In a flat, nobody digs into the slab below, so the drain and the slope have to fit within the thickness of the floor. Often that can only be judged once the old floor is up. When they don't fit, a low built-up shower baseBuilt-up shower baseA low, built shower floor sloping to the drain and finished with tiles. An option when the floor isn't deep enough for a level shower. is one answer: in the small bathroom a shower base was built where the bathtub used to be, and in the bathroom with the grey tiles low sections of brick were built in the shower corner.

Waterproofing under the tiles

Tiles and groutGrout jointThe gap between tiles, slabs or stones, and the material that fills it. Grouting means filling these joints, which locks the surface together and keeps out water and dirt. are not watertight on their own. In the areas that get wet, mainly the shower floor and walls, a waterproofingWaterproofingThe work and materials that stop water getting through on flat roofs, balconies, bathrooms, basements, planters and tanks. layer is commonly laid under the tiles, reinforced at the corners and around the drain and the pipes. The material, and how high it goes up the walls, depend on the layout of the bathroom. Ask how the waterproofing will be done in your bathroom: once the tiles are down it can't be seen and is hard to fix.

Render for straight walls

The walls are renderedRender (plaster)A layer of mortar (sand, cement or lime, and water) spread over brick or concrete to give a wall a straight, sound surface ready for paint or tiles. again and made straight. In the bathroom with the green bathtub, a final coat of render left the walls smooth and straight so the tiles would sit properly. In the bathroom with the striped tiles, the surface of the render was scored in a criss-cross pattern so the tile adhesiveTile adhesiveA ready-mixed cement-based mortar, sold as a powder and mixed with water, used to stick tiles to walls and floors. It is spread with a notched trowel. would grip better.

Straight walls matter more than they seem. With large tiles or striped tiles, every bow in the wall shows in the finished result.

The ceiling

In some bathrooms the ceiling is closed in with plasterboardPlasterboardA sheet of gypsum faced with paper, screwed to a metal frame to make suspended ceilings and light partition walls. It hides cables and pipes and takes recessed lights., which hides cables and pipes and takes recessed lights. In the bathroom with the striped tiles, the plasterboard ceiling later took recessed lights. In wet rooms a moisture-resistant plasterboard is used, but good ventilation is still essential.