If the plaster has moved away from the wall after repair in some places or cracked, what could be the reason, and is it possible to eliminate the defect without new puttying. The basics of repairing plaster on interior walls and facades Repairing old plaster on a wall in separate places

All connections, including those used in furniture production, can be divided into two categories: detachable and one-piece.

The latter constitute a special category, since they are subject to special requirements. They work in conditions of temperature and humidity differences, which affects their durability and stability. And if detachable connections can be tightened or sorted out, then you cannot carry out such a procedure with one-piece connections.

A little about the characteristics of adhesives glue D4

In the manufacture of furniture, glued one-piece joints are mainly used. Since furniture is usually made from wood-based materials or their derivatives, appropriate adhesives are used. One of the most important criteria characterizing the adhesive is its water resistance. So, glue D4 considered the most water resistant compared to the rest. This is all the more important since polyvinyl acetate dispersions, widely used as furniture adhesives, work even in tropical climates.

About gluing

The drying parameters of the adhesive during application are affected by temperature, humidity and the pressing force of the elements to be glued. Higher temperatures shorten the time required for compression, while humidity increases it.

Another point is the humidity of the surfaces to be glued. For most moisture-resistant adhesives, it should be between 7 and 10%. That is, the surfaces must be dry.

A bit of physics

The physics of the process is such that in the process of absorbing moisture, the adhesive layer swells, and during evaporation and recoil, on the contrary, it dries up and loses in size. Such fluctuations lead to the fact that the glue line "dries out" and loses its strength and geometric stability. In fact, these cyclic fluctuations lead to the destruction of the connection and the furniture as a whole. That is why the moisture resistance of the glue is of such importance.

ABOUT THE PROCESS OF GLUING WITH THE USE OF ADHESIVE D4

When gluing, it is desirable to reduce the gap between the parts to a minimum, since a large tolerance and an increase in the adhesive layer reduce the strength of the seam and increase the drying time. Glue is applied to one of the surfaces and the surfaces are pressed against each other. It also does not hurt to clamp them with a clamp. The seam gains its final strength and water resistance after 7 days. As a rule, glue does not change the color of wood, but contact with metal should be avoided, since together with the tannic acids of the tree itself, it can change its color. The adhesive layer itself can also be painted.

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The plaster is crumbling, what should I do? It happens that saving on cement, builders make plaster practically from sand. And such material is used indoors and for exterior wall decoration of any structure.

Plaster increases the strength of the wall by almost 30 percent, which is very important, and only then the owners decide for themselves: paint the walls, tile them or glue the wallpaper. In addition, such a coating helps to level the walls, hide the defects on them and ideally prepare surfaces for applying liquid or gluing ordinary wallpaper.

The plaster can crumble from high humidity in the room if the technology was violated during its application or a poor-quality mortar was used. In order for the plaster to hold firmly, it is better to entrust the work to an experienced craftsman.

If the walls of the dwelling are plastered with an old cement-sand mortar (see. Let's consider how to plaster with a cement-sand mortar), which starts to crumble at the touch of a spatula, or there is no certainty whether it is possible to putty on the old coating without damaging the mortar, the plaster should:

Strengthen. This method is used if the coating is only crumbling. In this case, it is enough to apply a deep penetration primer to the old plaster before starting puttying or treat the wall surface with concrete contact, which should fix the surface well in cases where the primer cannot cope with this.
Use a more radical method - completely remove the coating. This method is used if the plaster is crumbling. This usually happens due to non-compliance with the technology during its application or from the wrong temperature regime, when the temperature in the room is very low.

For this you need:

peel off all the old plaster (see How to remove old plaster from walls without problems);
treat the walls with a primer;
putty everything in a new way.

After that, you can apply the finish coat. In this case, the price of work will be higher, but the result will be better and more reliable.

Which method to choose, everyone decides for himself, the main thing is to determine when the plaster becomes unusable. Plaster, in principle, should not have high strength - it is just a finishing material, and not a supporting element of the building.

How to repair plaster

Tip: If you are not confident in your own abilities or have not had to plaster walls before, you should trust the professionals. They will complete the whole process faster and better than a self-taught amateur.

Repair of plaster is carried out in several stages. To isolate the surface of the wall from moisture, you will need to apply a protective compound, and then proceed to further operations.

The repair procedure is as follows:

The wall is carefully and carefully scraped off with a metal brush from all the remnants of the old plaster.
A special primer mixture is applied in two layers.
The stains remaining after the primer has dried are lightly washed with a stream of water.
The wall dries for about three hours.

Tip: If the coating defects are very serious, the damaged areas should be reapplied with putty mixture or plastered.

The applied coating should be about three centimeters thick.
When puttying the wall, the powder dissolves in water and is applied in a small layer.
The first layer is performed to level the wall (see Leveling the walls with plaster according to all the rules).
After one hour, a second layer is superficially applied.

How to fix plaster

For work you will need:

Primer.
PVA glue.
Wallpaper glue.

Instructions for strengthening cracked, peeling or crumbling plaster:

To avoid such defects, the plastered surface must be strengthened with a primer. Such a coating is an important condition for the performance of finishing and repair work of good quality. It is used to finish the surface of walls and ceilings before applying paint, wallpapering and tiling. A primer is a mixture of a solvent, a binder component and various additives that determine its properties. The dried material creates an opaque film of one thickness, which increases the adhesion or adhesion of the following layers of the coating.
According to the purpose, primers are divided for application to:

metal surfaces;
wooden surfaces;
universal, having an acrylic base. Acrylic is used for concrete, cement and gypsum plaster, for wood and fiberglass wallpaper. Such compositions dry quickly, they do not have a strong odor.

The impregnating composition is applied with a roller, in one layer or with a wide paint brush.
When finishing rooms with high humidity: bathrooms, showers, special compounds are used, they create a layer of waterproofing. For example, Aura Primer is suitable for dry rooms and high humidity. The mixture is diluted with water immediately before use in a ratio of 1:4. The dilution ratio can be reduced to 1:6, this will increase the protection against moisture.
Cheaper strengthening of plaster can be carried out with wallpaper glue. This method is often used before wallpapering. With high-quality glue, the adhesion is strong, the wallpaper, together with the putty, will not lag behind. But this option does not apply to vinyl heavy wallpaper.
Unjustified savings is the use of PVA glue for the primer, especially in rooms where there is high humidity. The glue contains dry components in its composition, they are able to absorb moisture, which after staining can contribute to the appearance of matte spots, due to the uneven absorption of paint.

How plaster is strengthened with impregnations

Today, manufacturers produce high-quality "strengthening" impregnations in plastic containers. Before use, the liquid is poured into a convenient container, then applied to the plaster with brushes or rollers.

Some types of compounds penetrate into plaster and concrete by more than a meter. At the same time, they close the pores even at the chemical level, transform the material, bind even microscopic particles together.

After strengthening the plaster with impregnations, cracks will not form, the coating will stop crumbling. Using this method with your own hands, to strengthen the surface is quite simple.

In addition to the use of special impregnating compounds, plaster can be strengthened using a reinforcing mesh, and then puttyed. The option of strengthening the plaster is selected depending on the situation and goals.

How to reinforce plaster with reinforcing mesh

In more complex cases, a reinforcing mesh is used to strengthen the plaster. In this case, the plaster layer is very badly destroyed, as can be seen in the photo.

Tip: To strengthen the plaster, you must use a metal mesh, preferably stainless steel. After it rusts, traces of rust can break through a thick layer of coating, which will lead to additional costs for rust control.

With this method:

The grid is attached to the wall in any way: dowels or nails, depending on the material of the wall.
A new layer of coating is applied on top, not too thick layer. The main thing is that the grid is closed.

Details of strengthening the plaster shows the video in this article.

When overhauling walls, first of all, you should think about plaster. It can be completely dismantled and replaced, or you can just patch it up. Let's look at how to repair the plaster of old walls.

Replacement

Repair of plaster begins with its inspection. After all, it is necessary to redo not only the fallen areas, but also those where greasy spots or fungus have appeared:

After you determine the site of work, it will be necessary to dismantle the old plaster layer from it;
After that, the seams of the masonry are cleaned for two meters and everything is washed with warm water;
Plastering is carried out in three steps. First, the wall is wetted, then primed, and after that a new layer of mortar is applied with their own hands. With large areas, masonry is done using beacons. The beacons are located from each other, at a distance of the rule you have, as shown in the photo. In this case, it is necessary that the edges of the rule lie on the surface of the beacons when editing the solution. If the treated area is not too large, then the edges of the old layer can serve as beacons.

Given the season in the yard, plaster has its own nuances. At high temperatures outside the window, fresh mortar must be moistened from time to time, otherwise everything may crack. If defects are found, they can be removed with a scraper or a piece of brick.

For plastering wooden surfaces, lime mortar is used, but rooms with high humidity require the use of cement mixtures. For protruding corners, a gypsum-based mortar is used. It has a fast setting effect. The corner is cleaned of dust and dirt, moistened with water, a pre-mixed solution is applied and the corner is given the correct shape.

A mallet or wooden mallet is used to locate a loose area. The entire surface is tapped, and a dull sound will indicate exactly where the finish has moved away.

Restoration

In addition to peeling and destruction, the plaster layer may have other defects, due to which it is necessary to repair the plaster of the internal walls. Over time, stains of grease and soot appear on the wall:

Before applying paint or sticking wallpaper, they must be removed. Grease stains are removed with a 2% hydrochloric acid solution;
But for rust, a 3% solution of the same acid is needed. In addition to it, copper sulfate will help get rid of rust;
If the stains are too deeply ingrained and cannot be removed, they can be painted over with whitewash or special dyes.

In addition to spots, holes also belong to defects and, of course, they must be repaired before cladding with any materials. To do this, the hole is given the shape of a rectangle, cleaned of dust and smeared with a solution.

Any surface on which restoration is carried out must first be cleaned in separate places from dirt and dust. After that, it must be treated with a solution of soda.

If you decide to do the restoration of the wall under the tiles, then:

at first, the entire tile is tapped with care and its poorly fixed parts are immediately removed;
sometimes the tile is not removed by a simple tapping method, then you have to break it in separate places. This must be done very carefully, starting from the middle and slowly moving to the edges so as not to damage the adjacent tile;
if a rather strong layer of the old mortar remains in place of the tile, then it is better not to touch it. A new tile can be glued onto it using special glue, as shown in the photo. This glue is based on casein-cement mastic and is added to the solution in a certain proportion - 1 to 3 to 1 to 2.5. Where one part is occupied by glue and sand, three parts are cement, and two and a half are water. At the connection with the window, double-sided foam tape is used under the plaster layer.

cracks

The wall with cracks is cleaned of the remnants of facing materials and covered with a primer layer. After a few hours, when the primer is completely dry, the surface is cleaned to perfect smoothness.

We knead the cement mortar and apply it in a thin layer to the surface, after which it is leveled by the rule, as shown in the video. If the crack is very large or there are a lot of them, then you can resort to a plaster mesh. It will give strength to the plaster layer.

alignment

Wall alignment can be achieved in three ways:

using special panels for decoration;
applying a layer of plaster;
combination.

Drywall can also be used for leveling. The most ideal option for any surface is the use of plaster and drywall at the same time.

Hanging the wall, you can find out how it deviates from the norm. To do this, a nail is hammered at a distance of 30 cm from the ceiling. A plumb line is attached to it and a second nail is driven in from below. The same is done on the other side. Cords are stretched between the nails from the upper right nail to the lower left. Similarly, the cords are stretched between the second pair of nails. If the distance between the wall and the cord is more than 5 mm, then the surface must be leveled.

Summing up

Before any cosmetic work, the old plaster must be checked. Its restoration will not take you much time and effort, but it will save you from a complete redo of the repair and unnecessary financial costs.

But due to certain factors, such as dampness or an initially incorrect composition, it can fall off in places, crumble, crack, swell, move away from the surface.

In this case, the removal of old plaster is simply necessary.

Depending on the lesion, the removal of plaster can be:

partial
complete

To determine the strength of the old plaster and how well it adheres to the walls, you need to examine the entire area and then decide on its complete and partial replacement.

If cement or lime plaster begins to crumble along with the removal of paint from it, then it is impossible to “cure” it, in which case it must be completely removed.

The strength test is carried out with a scraper or spatula. If the plaster crumbles only in individual places, then you can cover it with a solution on fine-grained sand or putty weak areas, having previously cleaned them with sandpaper and primed them.

To determine how strong the plaster of slopes, walls or ceilings is, you need to tap the entire surface with a wooden mallet, hammer or spatula handle.

In places where the plaster is weak, a void has formed under it, so a dull sound will be heard. In these places, the old plaster must be removed.

Tapping the wall with a hammer

If dampness has appeared in certain places (from below, from above) and weakened the plaster, then the old plaster must be removed not only in these places, but also by 50 cm more than the level of moisture.

Cracks in old, but durable plaster are sealed with cement mortar and carefully rubbed. In this case, the cracks are pre-expanded to a V-shape and moistened with water.

The solution is applied in several stages: first to the very bottom of the recess, then after drying by 2/3, and only then they begin to completely seal the crack.

If there are grease stains on the old plaster, washing the surface alone will not be enough. It is necessary to prepare the walls for plastering as follows - cut down the oiled places, after which they are repaired with a new layer of plaster.

Removal of old plaster can be done in different ways, the tool depends on how firmly it adheres to the base.

Tools for removing old plaster:

putty knife
scraper
axe
hammer
scapula
perforator
Bulgarian
plaster remover

Precautionary measures

Use a respirator or gauze bandage to prevent dust from entering the lungs;
Wear safety goggles and gloves;
Before starting work, determine the location of the electrical wiring, if necessary, turn off the power supply.

Methods for removing old plaster

First, you can use a hammer and tap the entire work surface with a sharp protrusion of the head. Weak patches of plaster will immediately crack and fall off. Then clean the walls with a scraper or spatula.

Durable areas should be moistened with water using a rag or brush; abundantly moistened plaster falls off more easily from hammer blows.

Coarse-grained crumbling plaster can be gradually cleaned with a spatula layer by layer, but this process is very long and tedious. In addition, it requires a lot of strength and frequent change or sharpening of the spatula.

For these purposes, a special mesh is also used for cleaning uneven surfaces, which is mounted on a holder or a special grater.

Surface cleaning device

Advice! To reduce the amount of dust, spray the walls periodically with water using a water sprayer.

When it is difficult to knock down old plaster with manual methods, you can use a perforator with a “blow” function.

How to remove plaster with a perforator? To do this, fix one of the special nozzles in the tool socket, for example, a lance or a chisel, and by switching the switch to the “hit” position, get to work.

Well, if you have the opportunity to remove the plaster grinder. Having fixed a cutting wheel with a diamond edge on it, make longitudinal and transverse cuts on the surface, and then use hand tools such as a spatula, scraper.

When repairing, the question often arises of how to remove plaster from the ceiling around heating risers or between floor slabs.

As a rule, in old apartments these places are plastered very sloppily, there are bumps or depressions on the ceiling. To level the ceiling, it is necessary to knock down irregularities with a hatchet and grind off with a grinder.

Often, at the joints of the floor panels, the cracked plaster itself falls off and it only needs a little help in this, using a hammer, less often a perforator.

Advice! Scrape plaster off the ceiling with a trowel or long-handled scraper so you can work with both hands.

Special power tools make the work much easier - grinders (LShM, angle grinders, PShM) or special machines for removing plaster (such as Flex, AGP).

The use of a particular tool depends on the thickness, density, type of plaster and the required surface finish.

To remove plaster from facades of a large area, high water pressure units (HPA) are used, which can only be used by professionals.

If, after removing the old plaster, you plan to lay a new one, then the surface must be thoroughly cleaned with a metal brush, then primed and treated with an antiseptic.

Now you know how old plaster is. Those who have already encountered this work understand how difficult and unpleasant the process is, but, unfortunately, it is almost impossible to perform high-quality repairs to walls and ceilings without it.

Plaster repair

In the process of repairing an apartment, such a phenomenon as minor damage to the plaster is very often observed. They are formed due to various mechanical damage, as well as shrinkage of the walls.

Repair of plaster is carried out as follows: the old damaged plaster is removed by scraping with some sharp tool, also grabbing some of the undamaged plaster. It is necessary to scrape everything down to the main layer. In the event that either the spray is still strong, it is allowed to leave them and apply patches only to the finish.

After the damaged part is scraped off and the surface is cleaned, it is necessary to apply some substance as a binder (for example, PVA) to the surface that remains, while grabbing the edges of the whole plaster.

It will be possible to continue repairing the plaster in about one hour, when the binder has already dried. Now it will be possible to finish the layer using standard technology.

When the main layers are damaged, they must be removed in order to exclude the option of peeling the repaired surface from the very base of the wall. You can assess the damage by the sound if you tap your knuckles on the wall. A dull sound is always made by peeling plaster.

Repair of plaster is carried out similarly to the plastering of still bare surfaces. Places where new plaster is superimposed on the old one must be carefully smoothed out to avoid various bulges or, conversely, depressions. To do this, the surface must be constantly moistened with water. Lastly, use a damp brush to run along the entire repaired surface to achieve a perfectly smooth and clean finish.

The repair of plaster also includes its grinding. This is done in order to remove various minor defects and finally level the surface. If the cover requires grinding, it must first be cleaned of whitewash, residues of paste or paint. After that, a solution is taken on lime dough with the addition of sand sifted on a millimeter sieve (proportions 1: 1), water is poured into this mixture until the density of sour cream is reached.

Do not use a lime-gypsum mortar, as in the process of prolonged mashing, this solution may lose its strength by frostbite. Also cement paste is not suitable. You can not use clean sand, as well as clean lime dough.

The next step in repairing plaster by grinding is to wet the wall with water. After that, it is necessary to apply a thin layer of the solution with a brush, which is then rubbed in a circular motion with a grater. If it (the grater) is covered with felt, then the quality of the grout will improve significantly.

If there are cracks, then they are cut 3-5 mm deep using a special plaster spatula. After that, moisten them with water and fill with a solution. It is better to fill with a spatula, the movements of which should be perpendicular to the crack itself. After that, align everything completely, moving with a spatula along the cracks.

When the smeared places dry up, they must be sanded with fine sandpaper. You can also level these places immediately after applying the prepared solution: use a grater for this.

By following these simple guidelines, you can repair the plaster yourself.

Repair of old plaster

List of articles

Determining whether or not there is a need to remove the old layer of plaster is very easy. If the plaster is easily separated from the walls along with a layer of paint or wallpaper, it should not be left, even partially. If the destruction is not very noticeable, you need to test for strength by tapping on the surface of the ceiling or wall. If there is a dull sound, it means that the layer of plaster has lagged behind the wall in this place, and a complete void has formed there.

These defects, provided they are few in number, can be “cured” by cutting out empty spaces and then filling them with a new solution. This work is also carried out when installing windows and doors. For example, on ital-on.ru/catalog/ you can purchase high-quality doors, but whether they will serve faithfully depends on their correct installation in a well-prepared doorway.

How is the old layer removed? At the beginning, it is better to moisten the surface: this reduces the amount of dust, and wet plaster peels off more easily. If there is not much work, then you can use a spatula, hammer and chisel. But it is better to fully mechanize such a laborious process and arm yourself with a conventional puncher. A suitable nozzle and the "blow" function will relieve you of memories of the old finish in half an hour. If there is no puncher, you can use the grinder. It is necessary to apply a grid of cuts, and after that return to manual labor.

If the plaster layer is quite strong, but there are cracks on it, then it will be enough to fill all the recesses with mortar. Having slightly widened the edges of the cracks, they are well cleaned and moistened with water. After that, they can be filled (for this you can use a "syringe" from a plastic bag).

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Plaster in such places is beaten off with light blows of a hammer, a chisel or a blunt axe. Stains are removed from the remaining plaster. Rusty spots and soot are washed off with a 3% hydrochloric acid solution, and greasy stains are washed off with a 2% soda solution. To remove rust stains, a solution prepared from copper sulfate and water is also used. For 1.0 liter of boiling water, take 50-100 g of copper sulfate. The solution is used in a hot state, since the cold one gives a smaller effect. If with the help of these means the stains cannot be removed, they are painted over with oil varnish or whitewash.

After that, cracks in the plaster larger than 1 mm are cut with a knife to a width of 3-4 mm, the thinnest cracks are not touched, they are filled at the first primer. If the surface is smooth and previously puttied, it is enough to seal individual cracks and small potholes. The cleaned surface is washed with water. A rough and not previously puttied surface needs a solid putty.

Before plastering, the old plaster is well moistened with water so that the fresh mortar clings to the old one more firmly. Insufficient wetting between the old and new plaster may cause cracks. The mortar is carefully leveled with a long rule so that it is in the same plane with the old plaster. Pay great attention to the lapping of new plaster to the old one. With poor grinding, even a well-leveled and wiped solution will stand out from the general plane.

The gaps between the wall and the plinth are cleared, well moistened with water and densely filled with mortar. The solution that comes out is cut off, leveled and rubbed with a grater.

When repairing plastered walls, special attention should be paid to the junctions of partitions and walls. As a result of the precipitation of the house, cracks and crevices often form here. In such areas, it is necessary to clear cracks, beat off weak plaster and attach a metal or fiberglass mesh with small cells (usually 2x2). The mesh is installed in the corner of the junction of the wall and the partition in such a way that half of it adjoins the wall, and the other - to the partition. The metal mesh is reinforced with nails, and the fiberglass mesh is embedded in the plaster.

When repairing old plaster, the same solutions are used as for new plaster. Wall plastering in dry rooms can be carried out with lime mortar, and in wet rooms - with a complex one. If you want the repaired surface to be harder, add one part of gypsum dough to six parts of lime mortar. The gypsum mixture is prepared at the rate of 1.0 kg of gypsum per 1.5 liters of water. Gypsum dough is added to lime mortar immediately before use.

Damaged corners are best repaired with gypsum mortar, which hardens quickly. To do this, the remains of the solution are removed from the bare masonry, the seams are scraped to a depth of 20 mm, moistened with water, the gypsum mass is applied and it is well leveled. Plastic and metal corners are also used (to give strength to the corners). The joints between the old and new plaster are rubbed with a plastic trowel and a wet brush.

A certain difficulty is the repair of surfaces lined with dry plaster (for example: plasterboard sheets). Sheets of such plaster do not adhere tightly to the walls and sometimes break through in some places. In these cases, the damaged areas are expanded in the form of a rectangle or square. Then a patch of the same shape and size is cut out of a piece of plaster. After that, it is applied from the mastic and the prepared patch is glued onto it flush with the old lining. When the mastic sets, the seams are filled with the same mastic or putty and overwritten.

Surfaces lined with dry plaster sheets can also be repaired with lime-gypsum mortar. To do this, cut out the damaged area and tightly lay along the entire perimeter in the gap between the wall and the lined surface with an indent from the edges of the edges by 10-20 mm paper rollers-limiters. Then prepare the solution and apply it to the area to be repaired. Thanks to the rollers, the solution does not spread on the sides. It is leveled and rubbed so that the new plaster is flush with the previously finished surface.

With high-quality work, the surfaces of wet and dry plaster will turn out to be even. You can start painting or gluing wallpaper or sheets of flexible stone.

Do-it-yourself apartment renovation - repair of old plaster

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The article describes the reasons for the formation of cracks in the plaster on the wall, swelling of the surface, its delamination. It also describes in detail how to repair a wall with cracks, how to prevent a plastered wall from cracking immediately.

Causes of cracks

Blisters can occur due to the wrong composition of the solution. If unseasoned lime was used, in which there were unslaked particles, then after covering the walls, small swellings may appear on them. After a while, the coating will completely deteriorate. To prevent this from happening, it is required to clean off the plaster with bubbles, and then spread a better composition on the surface. Other reasons:

Cracks may appear when poorly mixed or greasy solutions are used. Fatty solutions are those in which there is an excess of astringents.
Cracks also occur due to too rapid drying of the surfaces. To prevent this from happening, it is required to prepare the plaster strictly according to the instructions, carefully stir the composition before applying it to the walls.
May move away from the walls due to excessive moisture on the wall or too dry surface.
It is also advised to wait until each applied layer dries, and apply the finish on a completely dry wall.
On a new wall in a built-in building, it is worth applying concrete contact before each new layer of plaster, this will ensure adhesion, which is absent without surface pretreatment.
Do not plaster the walls in an unheated room before frost.

Why walls crack after plastering

If you cover the wall with the composition of the plaster, not observing the technology, then it will definitely crack:

Aerated concrete is vapor-permeable, because of this, the plaster that is applied to aerated concrete must also be vapor-permeable. It is even better if it has a stronger vapor permeability than aerated concrete, otherwise the steam will accumulate in the coating and it will crack.
You also need to remember that finishing should be carried out in one day. Otherwise, the next day there will be a different air temperature, humidity, they will change the conditions for the solidification of the mixture, and the wall will crack.
If moisture gets on and under the plaster during work, it may crack.

What to do?

If it has moved away from aerated concrete on the basis of cement, then it is required to completely clean it off and reapply it.

First, it is advised to finish the walls inside the room, and only then finish the facade.

Plaster may come off due to constant changes in humidity. You need to find the source of the increase or decrease in humidity and fix it.

If this happened due to a mixture of poor quality or an old composition, then you can only completely remove the old finish and apply a new one.

The problem should be carefully studied, perhaps this was due to subsidence, which appeared due to the fact that the plaster preparation time indicated by the manufacturer was not maintained. Then just redo everything.

When applying the mixture in the heat, it is necessary to slow down the drying of the walls. To do this, they are moistened from time to time.

But if cracks nevertheless arose, then the walls are rubbed with mortar or gypsum dough. If the gaps are too large, then they are expanded, cleaned, moistened and plastered.

Try sticking a piece of paper tape over the peeling area of the plaster. If the tape breaks, you will have to start all over again.

Repairing cracks in plaster has its own algorithm of actions, filled with some subtleties that must be carefully studied.

Subtleties of sealing cracks:

It is advised to buy a mixture of the same brand that was previously used.
It is impossible to work at air temperature below +5°C and at humidity more than 80%.

What to do if the wall cracked again?

cement must be carefully but thoroughly cleaned using a hammer and chisel. Any place that looks unreliable should be cleaned.
Then scrupulously rinse the crack from the remnants of the material, dirt, dust. Wait until everything is completely dry. At the same time, you can prepare the solution. Before application, the crack should be moistened from the inside and covered with a new solution.
Next, attach a reinforced paper tape and wait to see what happens.
Then you can plaster the tape. After it should be sanded, and then do the finish.
A crack, which is less than 5 mm wide, is covered with assembly adhesive before applying the finishing putty.

How to repair cracks in the wall if their cause has been eliminated, but many small cracks remain on the surface?

First you need to close up each crack, and then attach a reinforced mesh. Sealants can be used, but the sealant must be of such properties that it can be applied to the lime wall.

If the wall is made of concrete, then initially it is required to lubricate the crack inside with PVA glue, and then cover it with a mixture of cement.

Why plaster falls off the wall after repair

The plaster falls off the wall after repair due to non-compliance with the plastering technology.

Make the mixture strictly according to the instructions, knead it correctly. If you did everything right, then you will need 9 kg of gypsum-based composition or 20 kg of sand-cement composition per 1 cm layer of 1 m². It is required to stir the composition in clean buckets, use a clean tool.

How to properly prepare a mixture based on gypsum and based on cement?

If you are making a gypsum composition, then slowly pour the entire composition from the bag into cold water, wait a short time, and then mix it again. Do not mix old and new compositions.
If you pour a lot of water into the sand-cement mixture, then in the end it will shrink a lot, this will lead to cracks in the wall.

If the wall is swollen at the site of the crack

It may still flake off. This is due to the fact that the solution was smeared with an overly dry surface. Or this solution was applied to another solution having a lower strength. To correct the situation, peel off the peeling plaster, moisten the wall and reapply plaster on it.

Do not forget that before work, you should carefully examine the wall and understand where else the material can peel off. When creating a mortar and spreading it on a wall, do not forget that the strength of the mortar should change in descending order. That is, the first layer of plaster must be stronger than the rest.

Swelling also occurs due to the plastering of an excessively damp wall. To correct the situation, you should clean off the material, dry the surface and apply the solution again.

You need to follow these tips and recommendations when puttying walls:

Before applying putty, moisten the wall with plain water. This can be done with a spray bottle.
The temperature in the apartment must be less than +24°C, but more than +5°C.
It is impossible for the direct rays of the sun to fall on the wall and there was a draft.
The solution with a layer of more than 2 cm should be fixed with beacons.
Before applying the next layer, carefully inspect the previous layer so that there are no cracks on the wall.
Plaster based on gypsum is applied with a layer that is less than 1.5 cm, and based on cement, a layer is less than 2 cm.
We must not forget that on the surface of brick, concrete, stone plaster is spread with a layer of less than 0.5 cm, and on wood - less than 0.9 cm.
It is required to read the instructions written on the bag of dry plaster.
You should mix the components in a certain order.
The walls are reinforced.

So that later cracks do not appear on the walls, you must strictly observe. Keep drafts and direct sunlight out of the room.

If cracks still appear, then they need to be cleaned and the walls puttied again.