Moisture-resistant plaster for the bathroom

Due to their constant exposure to moisture, bathrooms are among the hardest spaces to finish. Water can cause serious damage to walls that aren’t adequately protected, whether it comes from steamy showers or splashes near the sink.

Moisture-resistant plaster can help with that. This particular kind of plaster is perfect for bathrooms because it is made to withstand high humidity and direct contact with water. It offers a strong, water-resistant coating that keeps your walls looking new and free of damage or mold.

This post will explain the various types of moisture-resistant plaster that are available, go over their advantages, and provide application advice for optimal results.

Which plaster to choose for the bathroom

Because there could be a variety of uses for the plaster composition, there is no definitive answer to this query.

Bathroom wall plastering is done for the following reasons:

• leveling wall surfaces for subsequent finishing;
• creating a finishing coating.

These objectives line up with compositions that have different characteristics. When asked how to level the bathroom walls in the first instance, several plasters meant for technical finishing will be recommended. Consider a widely used, easily available, and reasonably priced cement-sand mixture (CSM). There is an even greater variety of plaster compositions available for finishing.

For instance, façade compositions work well in restroom settings. They adapt well to temperature fluctuations, high humidity, and chemically aggressive airborne substances.

In addition, manufacturers make waterproofing plaster, specialized sanitizing mixtures, and moisture-resistant plaster for bathrooms.

There are three types of compositions used in high-humidity rooms:

• moisture-resistant (those that can withstand a large percentage of moisture in the air);
• hydrophobic (water-repellent compounds that form a hydrophobic film on their surface when hardening);
• sanitizing (unidirectionally passing water from the base to the outside).

Which requirements should a plaster mix fulfill?

Features of mortar mixtures:

• ability to keep water out;
• vapor permeability (important, since there is no free air circulation in bathrooms);
• unattractiveness for fungi, microorganisms, mold (heat and humidity conditions here are favorable for the creation of their colonies);
• durability;
• strength;
• adhesiveness;
• plasticity;
• repairability;
• environmental friendliness;
• possibility of repeated washing
• affordable price;
• decorativeness (for finishing compounds).

The plaster materials that are listed below satisfy these requirements.

Cement plaster for the bathroom

Conventional bathroom cement plasters. Sand is used as the filler in simple solutions that are made on a cement base. This is a leveling mixture generally speaking. It has always been finished by painting with oil paints and using ceramic tiles.

Numerous businesses produce ready-made SS (dry mixes). You can write and prepare solutions on your own as well.

Cement-lime and cement-polymer mixtures are used as bases less frequently.

Is it possible to use gypsum plaster in the bathroom

When beginning a renovation project or finishing a newly purchased home, novices often wonder if they can use a gypsum mixture to plaster the bathroom’s walls and ceiling. Gypsum compositions are tenacious, easy to lay, long-lasting, and very simple to apply. The problem lies in the fact that gypsum is a material that actively draws water from its surroundings.

Gypsum becomes weaker when it gets saturated with water. As a result, bathrooms did not use the common use of gypsum-based compositions for interior decoration. Only cements are recommended as plaster binders for bathrooms in the Technical Recommendations for Moscow.

With the advancement of building materials, this scenario has evolved, and gypsum plaster in bathrooms is now more typical.

Consequently, there is uncertainty in the response to the query, "Is it possible to use gypsum plaster?" For leveling, gypsum with modifying additives is appropriate (with a hydrophobic coating applied later). Not for the heavy tile cladding substrate.

If you choose to use a gypsum composition, it is preferable to buy gypsum plaster from reputable companies, such as Unis Teplon or Rotband from Knauf.

Silicone plaster in the bathroom

A silicone mixture works well for ornamental cladding. It is hydrophobic, strong, sticks to any kind of coating well, and "long-lasting" (it can operate for up to 60 years). Mold and fungi are examples of bioaggressors that do not like silicone composition. Plaster coating made of silicone is simple to clean. Ready mixes are simple to tint, and manufacturers offer a wide variety of composition colors. Drawbacks: too expensive, not suitable for leveling.

Sanitizing mixtures

Low-porosity sanitizing compositions that are vapor-permeable can hold on to salts that readily escape the wall materials when water passes through the capillaries. As a result, they stop wall materials from leaching and stop efflorescence from developing on the surface. They work well as a waterproof plaster for walls in bathrooms as well.

They are used to sanitize and level walls. Sanitizing concoctions are flexible. This material won’t crack when it dries if it is applied thickly. A gradual increase in strength is the drawback. Only seven days after plastering can the sanitizing coating be finished with the finishing finish applied.

Suitable types of decorative plaster

There is a wide range of compositions available for bathroom wall plastering because many decorative mixtures are made using silicone, acrylic, silicate, cement, and polymer bases. They are all unafraid of direct contact with water and high humidity. Thus, all the prerequisites for developing any design style are present.

However, there are some limitations. For instance, there’s no need to coat the bathroom in excessive embossment. Numerous bacteria and other microorganisms may be drawn to the nooks and crannies where moisture builds up. Furthermore, washing a wall with excessively "furrowed" walls—like a bark beetle—is incredibly difficult. However, "flat" finishes like Moroccan or Venetian appear to have been created especially for bathrooms. The genuine Moroccan plaster is used to make even bathtubs, sinks, and shelves.

Waterproofing compounds

Coatings can be made completely waterproof by adding water repellents into plaster compositions.

The plaster compositions listed below are utilized to waterproof bathrooms:

• cement-sand;
• cement with liquid glass;
• cement-latex;
• asphalt.

Gypsum tongue-and-groove slabs, which are frequently used to create bathroom partitions, are particularly well-suited for covering with waterproofing coatings.

Make your own mortar

There is a wide variety of plaster mixes available on the construction market today. A lot of artisans would rather create the compositions themselves. As a result, the components’ combined cost is nearly multiple times lower. The preparation of basic cement compositions is doable even for a novice. You must mix the solution in the proper order, prepare the ingredients, and pay attention to the dosage in order to accomplish this.

For cement grades 400 or 500, the volume ratio of the cement-sand mixture is assumed to be 1:3 or 1:4, respectively. It is best to use quarry-sourced sand. But river sand works just as well. Detergent or liquid soap is added to the water used to prepare the composition to increase its plasticity.

The majority of the water needed is put into a revolving container if the solution is made in a mortar and pestle. Next, use a shovel to add sand and liquid soap. Next, cement is added. Little amounts of the remaining water are added while the plaster dough’s consistency is being watched. Stop adding water to the dough as soon as the desired consistency is reached.

If the solution is made by hand, start by combining cement and sand (dry components). Once the mixture is homogeneous, stir and add water (along with a plasticizing agent) until the right consistency is reached. Use a trowel or mixer (based on volume) for mixing.

It is essential to use moisture-resistant plaster when plastering a bathroom in order to guard against moisture exposure and humidity. This kind of plaster is designed specifically to withstand moisture, mold, and mildew, guaranteeing that the walls will remain strong and attractive for a long time. Selecting the proper moisture-resistant plaster will give you a long-lasting, durable finish and prevent expensive repairs.

Installation of beacons

The bathroom walls need to be of the highest caliber because all of their curves and imperfections will affect how well the tile cladding is laid and make the job much more difficult later on. Beacons are used during the plastering process in the bathroom to ensure wall alignment. The mixture that will be used to plaster the room can be used to make them. Plastic and metal beacons are also in use.

The installation process is completed in the following order:

1. Examine the geometry of the walls.
2. Make a markup of the installation location of the beacon strips (the distance between the strips is taken from 100 to 150 cm).
3. Along the line of the beacons, spot “patches” of gypsum dough are applied to the wall.
4. Beacons are attached to the wall using gypsum “patches” according to the level, creating a vertical plane for the future surface of the plaster coating.
5. Clean the upper surface of the strips from dried gypsum deposits with a spatula (while moving, place the sharp edge forward).

Eliminating Extra Plaster

Plaster leveling technology

When repairs are needed, old buildings are typically the target because the bathroom walls need to be leveled. New construction frequently has uneven or flooded walls. As a result, leveling the bathroom walls is a "popular" task with several possible solutions. Plastering is easier.

• Ladle;
• trowel;
• rule;
• spatula;
• level;
• mixer;
• grater;
• chisel;
• punch;
• container;
• ind.protective equipment.

There are steps involved in plastering:

1. Preparing the wall surface for plastering.
2. Installing beacons.
3. Preparing the dough.
4. Applying the plaster mortar.
5. Grouting.
6. Drying.

Conditions of work:

• temperature +5 — +35оС;
• humidity no more than 60%.

Preparing the walls for work

1. The leveling plaster in the bathroom, intended for tile cladding, will not stick to oil paint, whitewash. Old, peeling or crumbling plaster is also unreliable. All this is removed by cleaning the walls down to the concrete or brick base.
2. Brickwork (old or new) will better hold the plaster coating if the seams are deepened by 1 cm, and the surface is cleaned with a wire brush.
3. Protrusions on the concrete base are knocked down. Large cracks are expanded, dust is removed, moistened, filled with mortar. For reliability, as well as to prevent cracking of the finish in the future, a reinforcing mesh is attached over the cracks. Large chips are covered with mortar, which must dry well before plastering. Nots are applied to smooth concrete surfaces.
4. Stains of various origins (oil, grease, bitumen, mold foci, rust, efflorescence) are cleaned with appropriate means, or chipped off to clean wall material.
5. Remove excess metal objects (nails, dowels, staples). The remaining parts are covered with insulating agents.
6. Openings for communications are completely cleaned of mortar, dust is removed, moistened. Gaps that are too large are filled by laying pieces of broken brick with cement mortar. Seal with cement paste on top.
7. Protect utility outlets from mortar. Wrap them with masking tape.
8. Prime the base surface (some bases – twice). Dry.

The caliber of preparation determines the overall finish’s quality and longevity.

Preparation of the solution

The method for making plaster dough with a cement base was previously discussed. If you choose to use a premade gypsum mixture, you must carefully dilute it in accordance with the directions. On other bases, this also holds true for pre-made dry mixtures. To lift the settled heavy components, ready-made purchased mixtures are stirred before being applied to the wall. Add a little water or another thinner (as directed in the instructions) if the composition gets thicker.

Plastering that self-levels is applied in three layers: splash, primer, and cover. Every layer has its own set of solutions. The cement and sand mixture is thinned for splashing. The primer (base layer) solution has a typical fat content and viscosity. Use fine sand with grain sizes up to 1.5 mm for the cover, or add a little extra cement to increase the fat content. As long as paint or thin-layer decorative plaster will be used for the final finish, the cover can be applied.

Applying splashing and base layer

Note general. The degree of wall irregularity determines how many layers are plastered.

Cement plaster base layers are only made up of one centimeter. There may therefore be two or more base layers in areas where the space between the wall and the beacons’ surface is greater than 15 mm. Once the previous layer has started to solidify, each subsequent layer can be applied. It is given a day to dry if this window of opportunity is missed and the applied layer has solidified. It is moistened before the next layer is applied.

The wall must be sprayed when applying cement mortar (gypsum does not require this step). Using a ladle or trowel, the splash is thrown onto the wall, spot by spot, leaving no gaps, and working from the bottom up. The splash layer has a thickness of roughly 5 mm. In order to improve adhesion with the next layer of primer, it is not leveled. Allow the layer to harden for two to three hours after application.

A collapsing wall requires reinforcement. A reinforcing mesh is used for strengthening; it is fixed to the wall and monolithed with the first coat of plaster mortar.

Over the splash, a primer base layer (10 mm layer) is applied. Using a trowel or spatula, do this. Application is done in segments up to 120 mm high, in between the beacons. A rule is used to level the solution if the layer rises above the beacons, pushing it up and up against the beacons. The rule is used to create zigzag movements simultaneously.

Where there is not enough solution, the excess composition gathered on the rule is moved with a spatula to the wall or thrown into a container. Run the rule once from the top down after running it two or three times from the bottom up. In this manner, the mortar can’t slide down the wall.

The primer is made in multiple layers if the wall is excessively piled up. Upon application, the first layer is leveled right away. The following layer is applied after waiting for the setting to start. After the mortar starts to set, the beacons are removed and the top layer of soil is leveled along them. The groove that results is then filled with mortar. With a float or spatula, the mortar is leveled.

The traditional method calls for drying every layer of soil for a minimum of one day. In this instance, a sharp spatula corner is used to mark the surface of the laid layer for improved adhesion. More horizontal or diagonal lines are preferable. Using stainless steel beacons or mortar beacons that don’t need to be removed makes more sense for this technique.

Surface leveling

The standard calls for the plaster on the bathroom walls to be exceptionally even and smooth before painting. The surface quality required for Venetian plaster is the same. They do a cover because of this. The plastered surface is then polished, smoothed, and rubbed.

Using a spatula or trowel, apply the cover solution in a thin layer (2–3 mm) while maintaining a 15-20 degree angle with the tool. After the cover has somewhat solidified, it is leveled using a float that moves in circles. Convex regions are compressed, applying additional pressure to the moving float. The float is not removed, nor is it compressed over the depressions. We refer to this process as grouting "in a circle." On a regular basis, the solution gathered on the float is removed.

Grouting is done "in acceleration" right after circular grouting. These are pressure-free, straight-line movements of the float up and down. Additionally, you can smooth for "shine-chic" looks. You either use a rubber or stainless steel float, or you wrap it in felt. Similar motions occur when rubbing "in acceleration." That being said, you can bypass this step.

Finishing

In order to provide an outlet for the moisture that was not used for chemical reactions, this stage is only initiated after the rough finishing has fully dried.

Painting is the easiest and most affordable way to finish. The ceiling and walls can be painted. Tiles are an option for decorating the space; however, experts recommend waiting three weeks for the cement to solidify. Decorative plastering is a more involved and costly option.

Feature	Description
Water Resistance	Moisture-resistant plaster is specially designed to withstand humidity, making it ideal for bathroom walls.
Mold Prevention	This plaster often contains additives that help prevent mold and mildew growth.
Durability	It"s more durable than regular plaster, ensuring a longer lifespan in wet environments.
Application	Can be applied to walls and ceilings in bathrooms, providing a smooth, water-resistant finish.

Selecting the appropriate plaster for your bathroom is essential to preserving its durability and aesthetic appeal. Where ordinary plaster might crumble in places subjected to excessive humidity, such as bathrooms, moisture-resistant plaster provides a workable alternative.

This kind of plaster offers a smooth, long-lasting finish that is resilient to the everyday rigors of a bathroom, in addition to aiding in the prevention of mold and mildew. If you want to make sure your bathroom walls last a long time, it’s an investment well worth making.

It is crucial to take into account the unique requirements of your bathroom, such as ventilation and the frequency of water exposure, when choosing moisture-resistant plaster. Making well-informed decisions will help you create a resilient and aesthetically pleasing bathroom.