Waterproofing a Bathroom – Step by Step Guide

The shower is not only a place for hygiene procedures; we relax there and relieve stress from a busy day. But bathing won’t be as pleasant if there’s a knock from below. Residents of apartment buildings should remember such an important aspect of bathroom renovation as waterproofing. A disregardful attitude threatens conflicts with neighbours and compensation for losses.

This article will discuss the step-by-step guide for waterproofing a bathroom/shower.

bathroom waterproofing

Complex works

You need to understand that waterproofing a bathtub includes a whole range of work that begins with preparing the base. Before starting the main activities, several important issues must be resolved: choose a topcoat and decide on the waterproofing material.

Of course, there are different types of finishing in the bathroom (painting, self-levelling floors, etc.). Still, the most common is ceramic tile, so we will specifically consider waterproofing.

Common Waterproofing Options in Melbourne Australia

Many varieties of modern waterproofing materials can cause difficulties even for experienced builders; we will give a general overview of the most common materials on the market.

If your home has yet to have a bathroom waterproofed previously, then the room most likely has standard waterproofing in plastic film. This material is unsuitable for wet rooms, as it has poor vapour permeability, resulting in condensation under the coating.

Coating waterproofing

Coating waterproofing is available as a paste or liquid solution, applied to surfaces using a brush or spatula. After polymerization, the coating hydro barrier forms a protective layer on the surface of the base. Elasticity prevents rupture due to mechanical damage or due to changes in the geometry of the building.

Rolled waterproofing

Rolled waterproofing is rolled out on the floor. Materials with a self-adhesive base are convenient to attach to vertical surfaces. If there is no adhesive base, then a layer of mastic should be spread under the canvas.
Rolled material is quite challenging to roll out in a small room; part of the web will inevitably go to waste.

Penetrating waterproofing

Penetrating waterproofing (Penetron) is used for concrete bases. It reacts chemically with lime and water, filling capillary cracks and pores with crystals. The polymerization process takes considerable time (2 weeks); the presence of large cracks and joints hampers the use of this type of waterproofing.
When installing rolled material, it is essential to overlap adjacent sheets correctly; they are secured with mastic. In this case, the edges of the sheets are melted using a burner to join. Using this method in a confined space poses specific difficulties. In addition, holes must be made in the canvas for communications (pipes and taps).

Coating compounds waterproofing

Coating compounds are the most optimal material for do-it-yourself waterproofing. Coating compositions are distinguished depending on the design and consistency.

Other Methods

The other most popular methods for waterproofing showers and balconies waterproofing in Melbourne and other parts of Australia are caulking, grouting and epoxy grouting.

Which coating waterproofing to choose for the bathroom?

Based on consistency, coatings are divided into paste and liquid. The choice depends on the application method and location. Liquid waterproofing can be applied using a roller or spray, which allows you to complete the job quickly; paste-like compounds are applied using a spatula.

In terms of composition for the bathroom, designs based on latex, acrylic, oxidized bitumen, and cement are well suited. Cement waterproofing interacts well with the concrete base, allowing you to level the floor surface further.

Do I need to cover all the walls and floor?

The answer to this question depends on the plumbing equipment you plan to use. There are several standard bathroom designs.

Only the floor – the bed base is covered with waterproofing. At the same time, an overlap of 20 cm is made on the wall to cover the seams between the wall and the floor, and the places where communications enter the bathroom are also additionally coated. This option is suitable for rooms where showers with a cabin are used, which does not involve water getting into the plumbing units.

Floor and wall with wet wall areas – this scheme is used when a frame does not cover the bathtub and is adjacent to the wall. In this case, coat the entire vertical surface 50 cm from the bathtub in both directions and cover the shower and sink area with waterproofing.

This scheme is the most optimal in terms of price and leakage protection.

All walls and floors – this method allows for maximum protection from water, but at the same time, it will require the highest costs for waterproofing material. A water barrier is made on all walls if the shower is installed without a tray and the water is drained through a drain in the floor.

Stages of work

For example, we will use coating waterproofing with an application pattern when only the floor and wall around the plumbing units are covered.

Even in new buildings, the old layer of waterproofing is under the screed, so before starting work, it is necessary to remove the old screed and the old layer of waterproofing.

Dust, dirt and screed residues must be swept up; before starting work, it is recommended to carry out wet cleaning. If bitumen waterproofing is used, then the base must be dried. On the contrary, the surface must remain wet for a cement water barrier.

A layer of primer must be applied to all surfaces to which waterproofing will be used. Any deep penetration composition will do; some primers create an additional film with hydrophobic properties. Some varieties have an antiseptic effect; they do not allow mould to multiply.
Carefully read the instructions for the primer composition; some varieties must be applied in several layers.

The joints between the wall and the floor are taped with waterproofing tape. Rubber seals must be installed on the pipes.

The primer layer must dry; only then can you begin applying waterproofing. The substance is applied using a brush. It is necessary to make an overlap of 20 cm on the wall, 50 cm around the bathroom, and 10 cm near the pipes.

Mastic waterproofing is applied in two layers; the second layer is laid after the first has dried. Some manufacturers make special two-color mastics. The first layer is grey, and the second is pink. This makes it difficult to miss an area without waterproofing.
Processing of joints. PhotoTreatment of joints with a coating composition

To waterproof the wall, it is better to use cement mortar; after application, it is recommended to reinforce the waterproofing layer with mesh. Compositions that contain bitumen adhere less well to vertical surfaces.

After the waterproofing, you can pour the screed and create the finishing coating.


Thus, the easiest way to waterproof a bathroom is to use a coating waterproofing method. The material allows you to obtain a seamless base that does not allow water to pass through and prevents the proliferation of fungal microflora under the screed.


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