Plaster after waterproofing. How to waterproof gypsum plaster in the bathroom

In most modern domestic houses, the walls do not protect against moisture. It is believed that traditional surface cladding with ceramic tiles or a cheap analogue - painting with oil paint is enough. How to make waterproofing of walls and whether it is really needed in the bathroom, whether funds are spent in vain - our article is about this.

Everyone knows that it is necessary to insulate the floor in order to prevent moisture from entering the building structures and, as a result, to the neighbors living below. As for the walls, building codes are silent. However, we advise you to do so. In areas where water flows will fall directly on the wall, we strongly recommend that you waterproof the walls with high quality. These are places behind the bath and shower, if it does not have airtight back walls.

Bathroom areas in need of waterproofing

In most cases, there is no need to specifically protect against water walls that remain dry or where only individual splashes will reach (for example, behind a washbasin). It is enough to tile, paint with waterproof paint and even stick waterproof wallpaper on the appropriate adhesive. But this is provided that the walls and partitions are built from materials that are resistant to moisture: concrete, brick, effective wall blocks. There is one more condition - good ventilation. If your bathroom is small enough and the ventilation is poor, then not only drops of water, but also steam will settle on the walls and ceiling. As a result, this will lead to the formation of fungus and, at a minimum, damage to everything in the bathroom.

The choice of plaster is an age-old question that citizens face when carrying out repairs, but this article will not discuss the choice. In our case, preference has already been given to gypsum plaster, but it so happened that the owners wanted to lay tiles on such a base. Is it possible or not? Opinions here are diametrically opposed, we will try to understand the problem.

The core of the dilemma
Gypsum plaster is elastic, does not contain large sand grains, like cement-sand, so it can be used to create a coating close to the finish. Such a base is well suited for painting or wallpapering. Gypsum has a pleasant white color and dries quickly. At the same time, it is believed that such a coating does not fit very well under the tile and there are reasons for this:

• High hygroscopicity is a mysterious word that often comes up in discussions related to gypsum. Hygroscopicity refers to the ability of a material to absorb water. In a humid environment, gypsum plaster can absorb the smallest particles of water, as a result of which it loses its strength, and pathogenic flora (fungi and mold) can develop inside.

The main reason for the hygroscopicity of gypsum lies in its porous structure.

• Low strength - everyone who has dealt with gypsum knows that the material does not tolerate mechanical damage. For this reason, heavy tiles on gypsum plaster should be laid with great care.

Gypsum plaster does not have a grainy texture, so they give the walls a finished look.

• Promotes corrosion - this disadvantage of gypsum does not apply to tiles, but to metal fasteners in general, on which the material has a destructive effect.

If it is planned to lay a heavy finish coat, then it is recommended to abandon gypsum plaster at the planning stage. If there is no choice, and the walls are already plastered, then you should use a few tricks to mitigate the negative features of the gypsum base.

How to prepare gypsum plaster for tiles?
The question of whether it is possible to glue ceramic tiles on gypsum plaster can be answered positively, but with certain reservations.

Tile adhesive is applied in a thin layer so as not to create an extra load.

• The layer of plaster should be twice the thickness of the tile, including the tile adhesive.
• Do not use tile adhesive to fix uneven plaster. Because of this, the thickness of the adhesive increases and the weight of the finish coating, which is already significant. For leveling, it is best to use gypsum plaster and wait for it to dry. The protrusions on the old coating must be ground off.

The trowel mesh is used to correct minor irregularities.

• The tile should be as light as possible, it is not recommended to use heavy varieties of stone or marble.
• Antiseptic treatment is an important stage in the preparation of the room, especially when it comes to a wet room (bathroom, toilet or shower room). The compositions are applied to the surface and protect the gypsum from mold growth.

A heat gun will help dry damp rooms.

When working in the bathroom, it is recommended to pre-dry the room. To do this, you can use a heat gun.

Priming is a mandatory procedure for strengthening the gypsum base.

• The primer partially corrects the shortcomings of gypsum plaster, so this procedure should not be neglected. For this, deep penetration compounds are suitable that impregnate the base, improve the adhesion of the plaster with the finish coat, increase the waterproofing properties of the material, and protect the gypsum from subsequent shedding under the weight of the tile.

For gypsum plaster, a special primer is used for surfaces with high hygroscopicity.

• Waterproofing is not used simple, but special, which is designed for laying tiles. Coating mastic and latex compositions are used as waterproofing. When applying the composition, follow the manufacturer's recommendations. Some waterproofing is applied in two layers.

Layers of mastic waterproofing can have different colors to immediately notice unpainted areas

Waterproofing is applied to the junction of walls with the floor, and waterproofing tapes are also laid in these places. These tapes are glued at the junctions to pipes and other communications.

• If it was not possible to refuse heavy tiles, then the surface must additionally be covered with a reinforcing mesh. As stated, gypsum contributes to rust, so it is recommended to use a plastic mesh.

Work progress
Installation of tiles on a gypsum base is practically no different from laying tiles on cement-sand plaster.

• Marking is done before starting work. The approximate location of the tiles can be applied to paper, and then to the wall. At this stage, beacons can be installed. Do not forget about the presence of seams between the tiles. To beat off even horizontals and verticals, you can use a plumb line and level.

Marking the lighthouse under the tile.

Marking is conveniently carried out using a laser level or a thread-chopping.

• When calculating the tiles in height, do not leave the halves to join the ceiling, this will spoil the appearance of the room.
• It is important when choosing a tile adhesive to choose a composition on a gypsum binder. The adhesive should have an elastic consistency and provide good adhesion. Avoid using cementitious compounds, as the tile may fall off in the future.

Mixing tile adhesive with a mixer.

• Glue is applied to the wall in a small layer. If you apply the solution also on the tile itself, then the weight of the finish coating will increase, and this is fraught with consequences. To minimize the thickness of the adhesive layer, a notched trowel is used to make grooves.
• Gypsum plaster should not be loaded, so all procedures for sawing or drilling tiles should be done before fixing to the wall. The tile is mounted on the wall according to the markup. After completion of work, the surface should be washed from adhesive residues.

Tile adhesive is diluted in a container with the addition of water. It is convenient to use a drill mixer for stirring. After that, you need to give the solution time so that it has time to acquire the desired consistency.

A few words about the bathroom
With all the bold recommendations of manufacturers of various building mixtures, it is better to refrain from using gypsum plaster in bathrooms and other wet areas. Only the application of gypsum compositions to the ceiling for painting justifies itself, since such a coating will be lighter than cement plaster, while it will have a smooth, pleasant surface.

Conclusion
Thus, we can conclude that it is possible to lay tiles on gypsum plaster, but only this must be done, observing all the preliminary procedures for preparing the base. Still, more natural finishes for gypsum compositions are paint or wallpaper.

The operational resource of construction objects depends on many factors. Excess moisture has a significant effect on the condition of the building. Protecting the walls of the house with your own hands from moisture, which leads to destruction, is quite within the power of everyone. And we will talk about the most effective way to protect your home from excessive moisture in this article.

Varieties of waterproofing plasters and their features

Plaster waterproofing is the best solution. It is able to prevent the penetration of moisture into the thickness of the bearing walls. Such a finish can be applied to low-rise residential construction projects. At the same time, with the same success - and on large buildings of a public type. ().

At the moment, two types of waterproofing finishing materials are widely used:

• asphalt plaster;
• cement-sand plaster.

Cement-sand waterproofing mortars

Waterproofing plaster based on cement and sand is a durable coating. It is resistant to the negative effects of environmental factors. Unlike conventional cement-sand coatings, the waterproofing finish has a high density. It is also characterized by an extremely small number of pores in the thickness of the finishing layer.

A cement-sand waterproofing mortar is made by mixing non-shrinking Portland cement, seeded river or quarry washed sand and water. All of the above components are used subject to certain dosages. This is done to achieve optimal performance of the plaster mixture.

The most popular mixtures are waterproofing cement-sand mortars. But only produced with the addition of ferric chloride. (In a ratio of 1:16, 1:22, 1:26 relative to the mass of cement.)

This type of plaster mortar is characterized by short setting times. This is due to the addition of sulfate-yeast brew in the amount of 0.2% of the total mass of the material. In order to prevent the possibility of unauthorized setting, the solution is stored in hermetically sealed polyethylene containers.

For the treatment of plinths and buried structures, solutions with the addition of ferric chloride can be used. Such plaster compares favorably with a high degree of hydrophobicity.

Cement-colloidal plaster mortar is made in special mixers using dry finely ground sand and cement. Water with sulfate-alcohol mash is added to the prepared mixture. Such modifications of the plaster are suitable for finishing structures that are not subject to uneven shrinkage. (Whose foundation is laid on solid ground.)

Application of cement-sand waterproofing

Cement-sand waterproofing for gypsum plaster is applied with a layer of mortar no more than 25–30 cm thick.

As an example, consider what is the instruction for self-plastering.

• Preparing the surface for plastering. We clean the walls before applying the plaster from dust, dirt and grease stains.

If the surface is not rough enough, we make notches with an ax to ensure greater adhesion. If you have sandblasting equipment, the work is greatly simplified. After all, since it is possible to cover the entire wall with small notches not only quickly, but also with minimal labor costs.

Important: Cement-sand waterproofing can only be used on rigid surfaces that are not subject to vibrations. In addition, the application of enclosing plaster is allowed only after the complete settlement of the building object.

When deformation (sedimentary and temperature) joints are formed during sedimentary processes, we fill their cavity with bituminous elastic mastic.

• We fill the reinforcing mesh. After the surface to be insulated is prepared, we attach a metal corrosion-resistant mesh netting to it. The main purpose of the mesh is to compensate for sedimentary processes and maintain the integrity of the plaster layer.

The grid is selected with a wire diameter of 2-4 mm with a cage side of 10 to 40 mm. We roll the mesh roll along the wall, lift it up and fix it with construction nails or dowels. We fix the grid in increments of no more than 40 cm.

• We prepare the solution. At this stage, it is necessary to prepare a solution that, when applied, will provide not only the required adhesion, but also demonstrate optimal strength qualities.

A guarantee of the quality of the plaster solution is the observance of proportions. For example, the combination of cement and sand should be one to two. (In contrast to the preparation of conventional plaster). Water and other components are added with the expectation that the consistency of the material was homogeneous. And the density resembled thick sour cream.

Important: Mixing of all components must be mechanized. That is, you need a concrete mixer. For insulation work on the walls of a low-rise building, a stirrer with a drum volume of 100 to 200 liters will suffice. Such equipment can be purchased or rented.

In the photo - a sketch of cement

• Applying the solution to the surface. To carry out waterproofing work using plaster, you will need a medium-sized trowel and a plaster rule.

The surface to be insulated is sprayed with water from a spray bottle before finishing work. Then we become to the wall with the left side. And, picking up the solution from the container in medium portions, with an effort we throw it on. The movements of the trowel should resemble the movements of a ping-pong racket.

Periodically spray the surface of the wall with water. This is done to ensure better adhesion of the outline. We throw the solution from the bottom up to a strip width of up to 1 meter. Then we take the rule. Smooth out the sketch with smooth movements from side to side.

Important: After the plaster has been applied, the surface must be kept moist in order to prevent cracking. To do this, periodically water the surface of the wall with water from a hose with a sprayer during the week.

Composition of cement-sand insulation

In the photo - an example of manual application of insulation

For a long time the use of plasters has accumulated considerable experience in the use of waterproofing coatings. As already mentioned, modern insulating plaster is prepared from dense cement-sand mortars in a 1: 2 ratio.

In the manufacture of waterproofing plaster solutions, various chemical additives are used:

• responsible for filling pores and voids in the solution;
• responsible for the formation of neoplasms of a colloidal or crystalline nature in the process of chemical reactions with cement.
• ensuring the water resistance of the solution (plasticizing additives);
• giving the plaster mortar additional resistance to mechanical stress;
• providing additional adhesion to the surface of the walls.

Various components are used as sealing additives. Such as ground sand, cerolite, ceresite, ground coal, stone flour, bituminous emulsions, pure bitumen, etc. In addition, plasticizers are necessarily integrated into the solution. Namely, soap naphtha, abietic and rosin soap, oleates or saponified wood pitch.

The most reliable are waterproof plasters with a layer thickness of 250 mm or more, applied from the side where water enters. The pressure of water and its tearing action are those characteristics that must be taken into account in the manufacture of plaster and in the selection of chemical additives.

Shotcrete as waterproofing

Shotcreting is another way to protect concrete pavements.

Statistics and repeated studies show the following advantages of using shotcrete:

• high mechanical strength;
• increased adhesion and, as a result, reliable adhesion to the concrete surface;
• high water resistance of the finished coating;
• resistance to sudden temperature changes during the operation of the finished coating;
• possibility of application on the coverings laid mechanically.

The disadvantages of using shotcrete on insulated coatings include a high probability of cracking in the process of uneven settlement.

Asphalt waterproofing

Asphalt waterproofing is a protective coating consisting of several layers of hot asphalt mastic or a solution of emulsion mastic and a viscosity enhancing paste.

This type of waterproofing is applied with equal success to both vertical and horizontal surfaces. Asphalt plaster is recognized as the best solution for waterproofing basements and basements.

Methods for applying such plaster depend on the type of composition used. For example, hot plaster asphalt insulation is heated to +180°C before application.

This method of application guarantees a high degree of hydrophobicity of the treated surface. But it is not always convenient due to the need to use special heaters. In order to simplify the application of waterproofing, cold mixtures prepared in the form of mastic are used. (Or emulsion paste.) Such a finish can be applied for its intended purpose only after complete drying.

Asphalt plaster is applied to vertical surfaces by two methods: manually and mechanized. In the first case, special coating brushes are used.

In the second case, a special device is used - an asphalt thrower. The mechanized method of applying asphalt makes it possible to process large sections of walls in a short time, evenly distributing the plaster material.

Application of asphalt plasters

The preparation of hot asphalt plaster is carried out using mixtures of increased viscosity. As a result, they can be applied to horizontal, vertical and inclined surfaces.

The supply of the mixture in the asphalt machine is carried out by means of compressed air. Asphalt throwers on the market, in addition to the blower and working tool, are equipped with a mastic heater. As a result, the application of an insulating material can be carried out both in the warm and in the cold season.

Application of bituminous mastic is carried out in layers with a thickness of up to 7 mm. The movement of the nozzle is arbitrary, that is, the coating can be sprayed both from the bottom up and from side to side.

During operation, the nozzle of the asphalt thrower is held perpendicular to the treated surface at a distance of 50 cm from it. The total thickness of asphalt plaster is usually between 10 and 20 mm. Plastering works are carried out only in dry weather. Or when using weather protection.

Cold asphalt waterproofing is a bituminous emulsion mastic. It is applied in several layers. Cold mastic is made directly on the object or shortly before application. In the process of preparation, bituminous paste is mixed with mineral powder with the addition of a small amount of water. Until a single-consistency mass is obtained.

On large covers, cold asphalt mastic is applied using a diaphragm pump in combination with a compressor, agitator, hoses and nozzles.

The advantage of mechanized application of plaster is the possibility of processing the surface of building objects at a height of up to 15 meters. Laying of cold mastic is carried out at a general temperature of at least +15°C.

Conclusion

Now you know what waterproofing plaster is and how it is applied. It remains to figure out whether waterproofing is needed for low-rise residential buildings. Or should such a finish be used exclusively on large public or industrial facilities?

Of course, high-quality waterproofing is necessary for most structural elements. Regardless of the purpose of the building. Despite the fact that the price of professionally carried out waterproofing work is high, it is fully justified by the durability of the protected structural elements. (

Many suburban residents dream of making a full-fledged basement in a cottage. On the basement floor, you can place engineering equipment, equip a workshop or store things and household items you need in the household. But, unlike the above-ground part of the cottage, a fully or partially underground room is subject to the negative influence of groundwater and the formation of condensate due to excessive humidity. These features must be taken into account when choosing a material for plastering the internal walls of the basement and the technology of work. From this article you will learn:

• Why are the walls damp in the basement and in the basement.
• How to solve the problem of excess moisture in the basement.
• How to choose a material for plastering walls in the basement.
• How to prepare basement walls for applying cement plaster.
• How to plaster the walls of the basement with high quality.
• Recommendations and life hacks.

Why are the walls damp in the basement and basement

Reasons for this problem:

Alexey NikolaevLafargeHolcim Specialist

The ground floor is an exploited room under the cottage, the floor mark of which is located below the planning mark of the ground around the house to a height of no more than half the height of this room. If the floor level is lower, then the room is called the basement. The walls in rooms buried in the ground become damp due to the ingress of moisture from the soil or its precipitation in the form of condensate due to the lower surface temperature of the walls.

The main reason for this problem is the developer's refusal to conduct engineering and geological studies of the soil and erroneously accepted engineering and technical solutions during the construction of the house.

If there is no or poor ventilation in the basement or basement, then condensate accumulates abundantly on the walls and ceiling of the premises.

How to get rid of excess moisture in the basement

Before equipping the basement or basement, for example, finishing the walls with cement plaster, it is necessary to identify the cause of excess moisture and be sure to eliminate it. In each case, a whole range of measures is carried out - pumping out water in case of severe flooding of the basement, additional waterproofing of the floor, walls and seams, arrangement of drainage and ventilation, drying the room with heat guns.

Alexey Nikolaev

Plastering walls in the basement is not only a way to level their surface, but also one of the measures to protect wall materials from constant or periodic moisture penetration and increase indoor comfort. For this, special types of plaster are used, containing various chemical compounds and complexes of mineral additives, which make it possible to reliably isolate the basement or basement from the negative effects of excess moisture.

Criteria for the selection of materials for plastering basement walls and basement floors

AStor FORUMHOUSE user

I built a house with a basement. The basement walls were built from FBS blocks. Outside waterproofing. The basement is residential, heated with underfloor heating. I want to finish the walls. Builders say it's best to use a simple sand-and-cement plaster. I would like to know how to properly plaster basement walls? What preparatory work should be done? Even at the bottom of the walls, in some places, a white coating similar to efflorescence appeared, how to remove it?

Before answering these questions, let's talk about:

• In what cases in the basement should special - sanitizing and waterproofing plasters be used.
• How do they differ from ordinary cement plaster.

Sanitizing plaster

Sanitizing plaster is also called draining or restoring. Due to the porous structure of the material, moisture is evenly distributed over the entire layer of plaster, and does not go deep, which contributes to its active evaporation. Hydrophobic additives prevent the reverse movement of moisture.

Due to the increased pore area, moisture evaporates faster, and the base (plastered walls) remain dry. Therefore, such plaster is called draining. In addition to the drying effect, sanitizing plaster prevents the formation of efflorescence by retaining the salts dissolved in water in its pores.

The effect of the sanitizing plaster only appears if the subsequent layers are vapor-permeable.(ideally, the vapor permeability coefficient is greater than that of the plaster itself), i.e. system: wall-finish "breathes".

Waterproofing plaster

This is the name of cement-based plaster mixtures for waterproofing basement walls and recessed rooms. The composition of such plaster includes special additives and minerals that provide a high degree of water resistance after the mixture has hardened.

In addition to damp basements, waterproofing plasters can be used to finish bathrooms, swimming pools, underground structures, etc.

Alexey Nikolaev

Waterproofing plaster is suitable for all types of stone walls, but has some limitations in application. Waterproofing plasters are not recommended for active shrinkage of the building, as well as on structures prone to deformation, because. in case of violation of the integrity of the plaster layer, namely the formation of deformation cracks and other defects, the waterproofing effect of the material is lost.

Waterproofing plaster only prevents the penetration of moisture from the ground into the basement, but moisture still remains in the walls.

General construction cement plaster

In the case when all the necessary measures have been taken at the construction stage to prevent the penetration of groundwater into the basement or basement, and it is also equipped with an effective ventilation system, then the best solution would be to use it from a reliable manufacturer. The use of cement plaster will help reduce financial costs, and will also create a reliable base layer for further finishing work.

Preparing basement walls for applying cement plaster

The preparation of the walls of the basement for plastering is divided into a number of successive steps:

1. The walls are cleaned of dirt, dust, grease and oil stains, traces of old finishes, easily separable inclusions, paint, etc.
2. The walls are visually inspected. If there are cracks or open seams on the surface through which water can penetrate into the basement, then they should be repaired: jointing and subsequent “caulking” of defective places with special repair materials.
3. If there are pockets of mold in the basement, then they must be removed mechanically, cleaning the surface to the ground, and then pickling the place of infection with antifungal agents. If there are efflorescences on the surface of the walls, then the surface is also treated with special chemical compounds (often these are solutions of weak acids).
4. The walls are primed.

Even if there is no mold in the basement, then the use of primers containing antifungal substances will not be superfluous.

If necessary, measures are taken in the basement to create an additional waterproofing layer.

The technology of plastering the walls of the basement

At this stage, we adhere to the following sequence of work:

• We determine the required thickness of the plaster layer.

Alexey Nikolaev

With a plaster layer thickness of more than 15 mm or at the junction of dissimilar materials, for example, concrete and brick, it is recommended to use a plaster mesh. The plaster mesh is mounted in such a way that after applying the mortar mixture, it is located in its volume by at least 2/3 of the thickness. This condition can be met by pre-fixing the plaster mesh by organizing an indent from the wall by a given value. The mesh will reduce the likelihood of cracks and minimize the width of the opening in the event of their occurrence.

• Setting up beacons.
• We mix the composition of the plaster strictly according to the manufacturer's instructions. Usually the finished solution resembles thick sour cream in consistency.

For plastering basement walls, a common set of tools is used.

• First, we fill the irregularities and seams with a solution, after which we apply the first layer of plaster.

Subsequent layers are applied based on the type of plaster and the recommendations of the mixture manufacturer.

During the first 7-14 days after applying the plaster, it is necessary to ensure the care of the coating, that is, do not allow the material to dry out. To do this, the temperature in the room is maintained within + 5-30 ° C and, if necessary, the plaster layer is moistened. This minimizes the risks associated with the appearance of cracks and provides the plaster composition with a set of strength characteristics laid down by the material manufacturer.

If there is excess moisture in the basement, and there are no obvious signs of why it appeared, then you can identify it like this: we tightly attach a transparent plastic bag to the wall. We leave it in the basement for a few days.

If excess moisture is formed due to condensate, then drops of moisture on the package will be from the side of the room, and if due to infiltration of groundwater - from the side of the wall.

Also, portal users are interested in the question: “Is it necessary to use special chemical additives to improve the waterproofing properties of ordinary cement plaster?”.

Alexey Nikolaev

The main condition when choosing a plaster mixture is the correct assessment of the tasks facing it.If you buy cement plaster from a reliable manufacturer, then you do not need to add chemical additives to the solution. The components included in the product are selected in such a way that it is guaranteed to obtain all the characteristics declared by the manufacturer with minimal labor costs for the consumer. The main points that you need to pay attention to are the appropriate preparation of the base, compliance with the manufacturer's recommendations for the preparation and application of the mortar mixture, and proper care of the coating during the curing period.

Summarizing

The premises of the basement or basement floor can and should be effectively used, equipping it for your own needs. If groundwater lies below the basement basement, or a set of waterproofing measures has been carried out, the developer can successfully apply ordinary cement plaster without spending money on special mixtures. In this case, ordinary cement plaster is the most affordable and budget solution.