Bathroom waterproofing: layers, tapes and the order of work

07.10.2026

Tiles and grout are not waterproofing: water passes through the grout lines and reaches the substrate. That is why bathroom waterproofing is done under the tiles, before they are fixed. This guide shows where water gets in, which substrate belongs in the wet zone, which tapes are needed and in what order the work is done. The products mentioned come from the Fermacell and Crocum ranges offered by Ymalko Montenegro.

1. Where water gets in

Corners. Wall-to-wall and wall-to-floor junctions move slightly, so a waterproofing coat without tape can crack there.
Board joints and screws. Every joint and every screw head is a break in the board surface.
Pipe penetrations. Around the connections for the tap, the shower and the WC there is a gap through which water gets behind the lining.
Shower area and floor. The walls behind and above the bath and the shower, and the entire floor, are directly exposed to water.

2. Substrate: cement boards for bathrooms or gypsum-based boards

Fermacell Powerpanel H2O is a water-resistant building board developed for wet rooms: bathrooms, showers, toilets and kitchens. According to the manufacturer, in a domestic bathroom it is enough on these boards to additionally seal the joints and the fixing points.

Gypsum fibre boards can be used on surfaces that get brief, moderate splashing. On these boards, waterproofing a shower area means a waterproofing layer over the whole wall surface in the shower zone and over the entire floor.

For the floor there is Fermacell Powerpanel TE, a floor element made of two factory-glued Powerpanel H2O boards 12.5 mm thick. The manufacturer names it for a floor-level shower, for which the prefabricated Powerpanel H2O Linear Shower Outlet 2.0 element is also intended.

3. Waterproofing tapes and collars

Corner tape. Fermacell Flexible Sealing Tape is a polypropylene tape with a special coating, alkali-resistant and permanently elastic, for the corners of interior rooms.
Pipe collars. Fermacell Pipe Penetration Patches are collars made of elastic, alkali-resistant polypropylene, for connections and pipe penetrations.
Preformed corner pieces. CROCUM L 130 for internal corners and CROCUM V 130 for external corners are elastomeric tapes 120 mm wide, shaped into a 130 x 130 mm corner.
Joint tape. CROCUM RSK 120 is a safety tape for construction joints and cracks, for polymer-cement and acrylic waterproofing systems and for ceramic tiling systems.
Fabric instead of a liquid coat. CROCUM AS 60 is a waterproofing fabric fitted with tile adhesive on dry, flat and firm surfaces. Tiles are laid on the fabric straight away, with no drying time to wait for.

4. Order of work before tiling

With the Fermacell sealing system the order is as follows:

Substrate. The boards are fixed, the joints glued and the screw holes filled.
Primer. Fermacell Deep Primer is applied to the whole board surface and left to dry.
Corners and pipes. The first coat of the Fermacell Waterproofing Application liquid membrane goes into the corners and the tape is pressed into it. Collars are fitted at the pipe penetrations.
Further coats. After drying, further coats of membrane are applied over the tape and beyond its edge. Where stronger protection is required, the membrane covers the whole surface. Take the number of coats and the drying time from the manufacturer's current instructions.
Tiles. They are fixed on the dry membrane with Fermacell Flexible Tile Adhesive, which is part of the same system.

5. Common mistakes

Waterproofing only the shower area, leaving out the floor and the floor-to-wall junction.
A liquid coat in the corners without tape, and pipes without collars.
Tiling before the coat has dried.
Powerpanel H2O boards glued directly to a wall: the manufacturer only permits a metal or timber substructure.

Checklist before ordering

Floor and wall area in m²
Shower with a tray or floor-level shower
Substrate: cement boards, gypsum-based boards, plaster or concrete
Length of corners in metres and number of pipe penetrations

Bathroom waterproofing in Montenegro

See the range for bathrooms:

Waterproofing tapes and membranes
Fermacell Powerpanel cement boards
Fermacell dry construction accessories
Article: Powerpanel H2O for bathrooms and showers

Models mentioned in this guide:

Send us the bathroom dimensions, the shower type and the substrate, and you will get a material recommendation and a quote.

Contact Ymalko Montenegro for a quote