How waterproofing is done

Waterproofing is needed wherever water is present, constantly or from time to time: in the bathroom (under the floor tiles and on the walls up to a height of 2 m), in the toilet, in the kitchen (around the sink and on the floor), in the laundry area, on roof terraces and flat roof slabs. It is NOT done in ordinary rooms (bedroom, living room) – other systems do the job there.

Types of system. Waterproofing coating (polymer-based): applied with a roller or brush in 2–3 coats. Suitable for bathrooms and toilets. Price for labour and materials: €18–25/m². Cement-based waterproofing (two-component, flexible): for areas under heavier load and terrace slabs. Price: €25–35/m². Bituminous membranes: for roofs and below-ground areas. Price: €30–50/m², depending on the type.

Preparing the base (60% of the result). The old tiles are removed down to the concrete. The surface is cleaned of dust and oil. Cracks are filled with a cement-based adhesive mix. Waterproofing tapes and collars are laid along the junctions between floors and walls, around the floor drain and around the pipes – these are the critical points where leaks most often start.

Application. First, a coat of primer (to improve adhesion). After 2–4 hours, the first coat of waterproofing coating or membrane. After 6–12 hours, a second coat, applied at right angles to the first. Sometimes a third coat for areas under heavier load. Between coats, the surface is NOT walked on and no materials are placed on top of it.

Checks before closing up. Before the tiler starts, a water test is done: the area is filled with water for 24 hours (where possible), and the water level and the adjacent surfaces are checked. If everything is dry after 24 hours, the waterproofing works. If not, it is repaired before being covered with tiles. Once the tiles are down, a repair costs 10 times as much.

Red flags. A contractor who applies the waterproofing in just 1 coat is cutting corners. One who does not use waterproofing tapes at the junctions is cutting corners. One who does not do a water test is cutting corners. One who does not show you exactly which product they use (brand, product code) is cutting corners. These shortcuts often stay invisible until a leak appears 6–12 months later.

The price in a real example. A standard 5 m² bathroom, full waterproofing of the floor and of the walls up to 2 m (about 16 m² in total) with a two-component cement-based system: €380–560 for labour + materials. When you compare quotes, check this item specifically – very often it is ‘folded into’ the overall tiling price without being priced as a separate line.