Newly plastered walls cracking: Hairline cracks appearing in new plastering work.

Why cracks appear

Before you blame the craftsmen, the material or start a new repair, you need to understand what causes cracks in principle. Often these causes are beyond our control at all:

• Natural shrinkage of the house – this usually happens with new buildings, and this fact cannot be prevented;
• Exposure to sunlight – do not work at temperatures above 25 degrees, and direct sunlight quickly evaporates moisture from the mixture;
• Moisture ingress – the plastered surface is no longer permeable to moisture, but the foundation of the house, on the contrary, is highly moisture permeable. It turns out that at the junction of two materials, moisture has nowhere to go and it accumulates. In this case, the plaster begins to flake off and cobwebs of cracks appear;
• Incorrect work – this includes both the master’s flaws and the wrong selection of composition.

It is believed that all surface plastering work must be completed in 1 day. We must not forget about the weather conditions – they can harm the coating.

How to get rid of cracks

Since it is impossible to foresee the appearance of cracks in plaster, it is worth knowing how to repair them – carefully and quickly. Depending on the depth and width of the crack, one of 2 options is selected:

• Small and shallow cracks can be sealed with sealant. It is important to pay attention to the composition of the sealant – it should be similar to the composition of the finishing mixture. After the sealant has hardened, the surface can be treated with a layer of plaster;
• Repair deeper cracks with mortar. To do this, the hole is first cleaned and dried, then coated with a primer and the mixture is spread into the crack. On top of the dried layer of the mixture, you need to apply fiberglass, and then apply the plaster again.

It is important to remember that before eliminating cracks, they need to be “worked” with – cleaned and dried well. Otherwise, the new material may not “adhere” to the surface. If a crack appears in the decorative plaster, you will have to select the appropriate shade so that the repair site does not stand out too much.

Video cracking plaster Who is to blame and what to do

How to check: Hidden defects in wall and ceiling decoration – Interior Design Ufa

How to avoid problems, identify defects in time and correct already made mistakes?

There is never enough time to do everything right,

But for some reason there is always time for rework.

A mysterious story happened recently that can happen to anyone. In one new apartment, the renovation was already coming to an end. The walls and ceiling were completely sanded and sanded. The owner checked the quality and was satisfied – all that remained was to prime and paint the surfaces. We started, as usual, from the ceiling. Primed, painted – beautiful! But when they were going to paint the walls, the owner could not believe his eyes: yesterday even walls were covered with furrows that no paint could hide. I had to re-putty the walls. But where did these flaws come from? The answer is at the end of the article.

Visible defects are easy to identify based on the results of work, if you know the technology, and in order to prevent the appearance of hidden ones, you will have to control workflows. It takes time. But if this is not done, the alteration will take you even longer. The insidiousness of hidden defects is that they manifest themselves at the later stages of repair or at its completion, when the price of alterations rises many times. The wallpaper is covered with mold, the paint peels off the walls and ceiling, ceramic tiles fall off, cracks appear on the ceiling, etc.

How to avoid this? Take it as a rule: during the work of the team of finishers, conduct operational control and, at the end of the next stage of work, carry out acceptance quality control.

Acceptance quality control in finishing involves checking surfaces for curling and peeling. If you tap the surface, the gypsum layer should make a clear sound, the cement-based layer should be sonorous. A dull sound indicates that a layer of plaster may soon fall off. As the plaster dries, we check that cracks do not appear on the surface. Bubbles should not form on the surface of the paint and wallpaper.

Flaking, flaking, cracking can be due to various causes. But all of them ultimately come down to a violation of the technology of plastering and finishing works. Let’s take a look at the points on how to control processes in order to prevent this.

High material consumption.

What’s the problem? Consumption rates of the plaster mixture – for a layer 1 cm thick with an area of ​​​​1 sq. M, 9 kg of gypsum mixture or 20 kg of sand-cement will be required. When the flow increases, the reason is most likely a violation of the instructions for preparing the mixture. Incorrect kneading gives a bad mixture, flaws and bumps appear on the surface, the mixture quickly loses its working properties and freezes. Workers have to throw away a quickly solidifying or poor-quality mixture. The preparation of a high-quality gypsum mixture has its own subtleties and consists of several stages. The bag of mix is ​​closed at once entirely. The composition is gradually poured into cold water, then wait for time and re-mix. Be sure to use clean buckets and tools. You can not add an old mixture to a new mixture, and even more so mix different compositions. A mixture with additives can behave unpredictably (dries quickly, cracks or peels off). If you add a lot of water to a cement-based mixture, it will shrink a lot and this will almost always lead to cracks.

How to control? Read the instructions for working with the plaster mix in advance. You can ask the workers how they prepare it for work, but most importantly, watch how they work and correct the mistakes.

How to fix? Work exactly according to the instructions, keep the buckets, the mixer clean, with which the mixture is mixed.

The plaster, which was applied last autumn, will curl and fall off after wintering.

Gypsum plaster in cold weather dries for a long time and becomes moldy.

What’s the problem? Gypsum surfaces must not be left for the winter in an unheated room, only cement plasters can “winter”. For high-quality work, each plaster mixture has its own range of operating temperatures and air humidity. The temperature should not be lower than +5+10°C, the humidity should not exceed 60%. The base must also have a temperature of at least + 5 ° C. Under normal conditions, the gypsum mixture dries for about 5 days, depending on the thickness of the layer, and the cement mixture can dry for several weeks. When the temperature drops and the humidity rises, the plaster will take longer to complete. Gypsum plaster that has had to dry for a long time can become moldy. It is important that these parameters are observed while the mixture gives up moisture and gains strength. But if the frosts begin before moisture evaporates from the cement plaster (this is at least a month), it will freeze and swell the next year.

It is risky to speed up the drying process with heat guns – the plaster layer is covered with a dry crust, but moisture remains inside. The result is peeling, mold. Similarly, in summer the plaster layer must be protected from direct sunlight.

How to control? Check the weather forecast. Do not start plastering before the onset of frost. Control room temperature and humidity. Ensure good ventilation for fast drying.

Red spots appeared on the plastered wall . They can even show through wallpaper and paint.

What’s the problem? Gypsum plaster absorbs moisture from the surrounding air, it always retains residual moisture, so beacons left in the wall can simply rust. The same applies to any iron elements that have not been protected from corrosion.

How to control? Make sure that all beacons are removed from walls that are being prepared for wallpaper, painting or decorative plaster. All iron elements (pipes, fasteners, channels, fittings) must be coated with an anti-corrosion compound. For this purpose, it is better to use a primer on metal surfaces of the 3 in 1 type: rust converter + primer + paint. Galvanized perforated corners and profiles for the installation of plasterboard structures do not require processing.

How to fix: Forgotten beacons should be removed and the iron parts exposed, treated with a metal primer and re-plastered on top.

The layer of plaster curls, falls off the base.

What’s the problem? Poor adhesion of plaster to the substrate caused by dust, dirt, grease, foreign matter.

How to control? Before plastering, the base is subjected to a complete visual inspection. The surface must be uniform and clean – it must not contain dirt, efflorescence, grease, solution residues. All this is pre-cleaned mechanically. There is always a lot of dust at the construction site, it sits on all surfaces, including walls and ceilings. Especially a lot of dust is formed after sanding, and it remains in hard-to-reach places.

The primer removes dust from the surface and prepares it for plastering. The adhesion of the mixture to the base depends on its quality. Flat surfaces are treated with a roller, and in tight places the primer is applied with a brush. A good alternative is to apply an acrylic primer with a spray gun.

Before plastering, check with your hand for dust in corners, wall junctions, wall and ceiling. Pay special attention to the places where pipes, wires, sockets exit the wall.

How to fix? All areas with caulking must be ruthlessly removed, thoroughly cleaned and re-plastered.

The plaster layer becomes covered with a network of cracks as it dries.

What’s the problem? Cracks are caused by plaster drying too quickly. Materials such as expanded clay, gas and foam concrete blocks, bricks can rapidly absorb moisture from plaster, especially in hot weather.

How to control? Highly absorbent substrates must be treated with an acrylic primer before plastering.

Sometimes the appearance of cracks provokes an inhomogeneous base, when metal objects, wood, mortar splashes are not removed in time.

Cement-based plasters are more prone to cracking than gypsum plasters, therefore, in hot weather and in strong drafts, it is recommended to moisten them to reduce the drying rate. On thick layers, cement plaster is reinforced with a metal mesh.

How to fix? If the cracks are not accompanied by peeling, large cracks should be expanded, primed and covered with a plaster mixture. Small cracks, flaws and potholes are rubbed on top with a thin layer of plaster.

The plaster layer cracks and falls off difficult substrates: cast-in-place concrete, ceiling plates, iron structural parts (supports, angles, beams)

What is the problem? Non-absorbent substrates have poor adhesion to plaster mixtures.

How to control? Steel parts should be coated with an anti-corrosion compound and covered with a metal plaster mesh as a base for plastering. If gypsum plaster is applied to concrete, the surface must be treated with a concrete contact primer. Betonokontakt of different quality is offered by many manufacturers. It must be from the same manufacturer as the plaster. If the layer of gypsum plaster on the concrete ceiling exceeds 20 mm, it should be reinforced with a metal mesh.

Three rules must be observed when applying a plaster coat on old plaster. First, the bottom layer should be denser and harder than the top. This means that cement plaster cannot be applied on top of the gypsum base. The second rule is that old plaster must be carefully checked, all peeling areas and weak points must be repelled. Thirdly, a smooth base must be roughened – notches are made on the old plaster to provide the necessary adhesion.

How to fix? Dismantle the peeling layer and do it all over again, as expected.

Straight cracks in plastered ceilings and walls.

What’s the problem? On the ceiling, they appear at the border of concrete floor slabs (rusts), and on the walls at the border of different bases: brick, concrete, drywall, iron support or wooden base. Also, cracks appear with poor processing of drywall joints. Causes: different coefficient of thermal expansion, gradual subsidence of a new house, drywall vibration.

How to fix: the joints between the slabs must be expanded, thoroughly cleaned and primed with concrete contact. Next, the seams are filled with a special putty, for example, “Fügen Fühler” or “Uniflot”, glued with a serpentine tape. A covering layer of putty is applied on top flush with the ceiling surface.

The appearance of mold on the wallpaper, bubbles on the paint layer, swelling and flaking of putty, plaster curling.

What’s the problem? Such defects occur when the top coat is applied to a wet substrate. If wet plaster is putty, not dried fiberglass is painted, or wallpaper is glued on wet putty, wrinkles and cracks first appear, and then the top layer begins to fall off. If the wet spot does not dry out for a long time, mold will also appear. In this sense, wallpapers with poor vapor permeability, such as vinyl, are especially capricious.

How to control? The plaster must be applied to the concrete base in summer not earlier than one month after formwork removal, in winter – wait 2 months. Gypsum plaster dries on average 5 days, cement plaster even longer. There is a simple folk way to check the readiness of the base: stick a piece of transparent film on the area to be checked and seal its edges tightly with tape. After a day, see if there are drops of condensate on the film. If not, the surface is dry and the next coat can be applied.

How to fix: Remove the top coat and reapply after the base is dry.

Your bathroom was flooded by neighbors from above, and ceramic tiles fell off the walls. The plaster on the cold balcony swelled after a year. There was mold in the cold vestibule of the cottage.

What’s the problem? These are all the consequences of using water-soluble formulations in cold and wet areas. When water enters, gypsum plaster swells, and the tile falls off the softened gypsum base along with the cement adhesive. In cold areas, condensate settles on unprotected surfaces, which gradually destroys the gypsum layer. If the gypsum absorbs too much moisture, it creates favorable conditions for the development of mold. The exception is special gypsum mixtures with water-repellent additives.

If mold has appeared on the window sills, the problem may be that the window frames are not installed tightly, and therefore the plastered soffits are soaked with moisture from the street.

How to control? Avoid the use of gypsum plasters, acrylic sealants, conventional water-based paints in wet and cold areas.

How to fix: Replace gypsum mixtures with cement, acrylic sealants with moisture resistant ones, water-based paints with silicone or facade ones.

And finally, the end of the story described at the beginning of the article. Not all finishers know that an acrylic primer can corrode a thin layer of finishing putty like an acid. In our case, the ceiling was primed with a roller before painting, drops of primer fell on top of the walls, which, flowing down, blurred the layer of finishing putty.

To avoid this, the primer is applied to the ceiling with a spray gun. The junction lines are covered with masking tape. Carefully cover all finished planes, since the primer can leave an indelible mark on porous surfaces – these are all types of natural stone (including marble and granite), wallpaper, decorative brick, ceramic tiles (even glossy), walls covered with paint or decorative, parquet, etc.

What should I do if the plaster is cracked?

Despite the abundance of modern finishing materials that have appeared on the market in recent years, plastering of external and internal walls is still one of the most popular ways to protect building structures from external influences and give them an attractive appearance. For application on walls and ceilings, mixtures of various composition and properties are used, ranging from cement-sand mortars that are durable and resistant to moisture and shock to gypsum plasters, practical and aesthetic.

Unfortunately, even the highest quality coating eventually becomes unusable and may begin to crack. The reasons for this phenomenon can be different – violation of the technology of work, errors in the preparation of the solution, exposure to moisture, shrinkage of the building. Of course, if we are talking about deformations caused by the displacement of constructs, first of all it is worth thinking about solving this serious problem and contacting specialists who will help prevent further subsidence of the foundation. But if the appearance of cracks is not associated with an emergency, it is quite possible to get rid of them on your own, without resorting to outside help.

We repair plaster ourselves

The range of modern hardware stores makes it possible to choose ready-made solutions for repairing a plastered surface without resorting to self-preparation of the mixture. There are products on the market that are designed to repair both serious defects, such as large protrusions, depressions and chips, as well as to combat cracks and other small defects. Consultants and managers of manufacturing companies and retail outlets will easily select a composition suitable for sealing cracks, based on their nature and your financial capabilities.

So, you have purchased a dry mix for work, a spatula and stocked up with a powerful drill with a mixer attachment for mixing solutions. How to start troubleshooting? Oddly enough, but in order to get rid of a crack in the plaster, it needs to be expanded and deepened. Therefore, you will have to find a hammer and chisel in the toolbox, and also take care to protect the surrounding area from dust and fragments of material. Do not ignore your own safety – work gloves and goggles will protect you from injury.

To begin with, it gently deepens the crack by 1-1.5 cm, making accurate and accurate blows with a chisel. In the process of work, it may turn out that cracking is associated with such an unpleasant phenomenon as peeling of the coating from the base, and in this case the scope of work will increase somewhat – all fragments of plaster lagging behind the walls in the area of ​​cracks must be chipped off to the boundaries of a durable coating. As for the cracks, their edges should be, if possible, perpendicular to the surface of the wall, and the bottom should reach the base – a brick or concrete surface. When this most time-consuming stage of work is completed, it is necessary to carefully clean the prepared cracks with a wire brush, and then dedust using an industrial or ordinary household vacuum cleaner.

The next, no less important step will be the priming of the surface, in order to increase the adhesion of the material used for embedding to the existing plaster, which certainly differs in its physical properties. To do this, use a deep penetration primer, applying it with a wide brush so that it completely covers the working field.

While the soil impregnates the wall and dries, you can start preparing the solution. You should not experiment with proportions – manufacturers are well aware of their work and indicate on the product instructions the optimal ratio of water and dry mix. Mixing is done with a drill with a mixer, at medium speed, making sure that the mixture is homogeneous. Having prepared the mixture, you can safely proceed to the seal. We take a spatula and slowly begin to fill the cracks with a mixture. For wide and deep defects, metal spatulas 10-20 cm wide are suitable, and narrow rubber spatulas are suitable for working with thin cracks. An important rule: for a quality fight against cracks, you must achieve complete filling of the volume of the embroidered crack, so do not rush and carefully lay the repair mixture, making sure that no voids form in its volume.

After the cracks are completely filled with the mixture, you need to give it time to set. Despite the temptation to apply the finish on the repaired wall on the same day, it is worth waiting at least a day, and if the work is done on the facade of the building in wet weather, then 2-3 days.

Fixing small cracks

In addition to wide and deep cracks, thin defects often appear on the plastered surface, the width of which is 1-3 millimeters. To eliminate them, it is hardly worth resorting to “heavy artillery” and embroidering the edges with a chisel. It is also not advisable to purchase a mixture in a bag, from which you will hardly have to use more than 100-200 grams of material. To work with such damage, it is better to purchase acrylic in a tube designed to work with a special gun. Acrylic is a versatile material that is perfectly compatible with most finishing materials, durable and moisture resistant. In addition, the polymer has another important property – even when completely dry, it retains elasticity and securely fixes the crack even in cases where the coating is subjected to mechanical stress such as vibrations or shocks.

Small cracks must be cleaned of dust and other contaminants with a brush and a vacuum cleaner and be sure to prime. After that, we fill the voids with acrylic, also making sure that they are completely filled with material, and smooth them out with a narrow rubber spatula. Acrylic, unlike dry plaster mixes for repairs, hardens very quickly and the wall treated with it can be finished after 3-4 hours.

Finally, I would like to remind you once again that when eliminating wall cracks, not only the cosmetic aspect is important – in most cases, it is the determination of the cause of the problem that plays an important role, which may turn out to be more serious than it seems and lead to further destruction of the coating and its base.

Helpful Hints

Updated: 30.11.2020 16:13:11

why they appear in an apartment or house, and how to fix the problem

From the author: hello, dear readers. You know, you are very lucky. After all, wondering how to close a crack in the wall, you have come to our construction portal.

I saw several written requests on my mailbox, where people asked me to tell me why there are cracks in the walls and how to repair them. It turned out that everything they knew and did before did not work. No method saved them from new formations. That’s why I decided to write this article.

I haven’t talked about this topic with anyone for a long time, and I came across similar works about a dozen years ago, so I decided to update my knowledge and see what great minds had time to come up with something new in this regard. By the way, we always try to give you the latest information so that you keep up with the times. After all, something new is often invented, and it is often cheaper and more efficient to apply it.

Getting to the bottom of the problem

Article content:

Well, let’s start by defining the types of cracks. Yes, they are fundamentally different from each other, dividing into two types. The first is erosional cracks, which result from a process called erosion, although weathering can also be involved. So, erosion is a process of destruction that is associated with time, with the influence of mold, precipitation, wind or thermal expansion.

For example, we have a wall that was plastered with ordinary cheap cement, and even in a proportion of 1/3. Yes, the plaster holds and looks beautiful. But it absorbs moisture and crumbles due to insufficient molecular bonds. And as a result, water penetrates into it, washing out all our connecting elements from the top layer.

When the autumn rains come, they richly saturate and saturate everything around with moisture. Before winter, the wall does not have time to dry properly, and the moisture freezes, and at the same time it greatly increases in volume. Try filling a glass bottle with water and putting it in the freezer. You will see that as soon as it freezes, it will easily crack the bottle. And if it is a metal container, then it will simply be unbent or inflated.

So, the same thing happens in the thickness of the plaster, water breaks it from the inside. See how many there are? So, all these factors, of course, destroy the surface layer more and more over time. And what is the result? That’s right, microcracks appear. Each one is approximately 1 cm long.

If they are not sealed, then even more water will get into them, or some other factors will act doubly hard and increase the cracked places several times. If in this case they are not covered up, then after some time such plaster will completely fall off.

In general, you understand, we have just described an example of an erosion crack on the surface of the plaster of a building. Exactly the same can be indoors. For example, if the wrong cement composition was selected, then it may not react too quickly to thermal expansion and also crack.

There is another kind. For example, if we talk about a very old brick house, which was not finished with plaster, but just a brick was laid under the jointing. Yes, here erosion, even over a long period of time, cannot do anything to brick, that is, to pressed and fired clay.

Erosion will most likely wash out the joint cement, which may result in small cracks in the brick wall. If the cement from the joints is sufficiently washed out so that the main load is removed from it, then where will it fall? Of course, either to the remainder of the concrete in the seam, or it will go down a whole section, and then it will overcome it.

All this, it would seem, is nonsense. But tell me, what is the task of plastering? That’s right – to prevent harmful factors from reaching the main wall. And I will tell you that even plaster with minor defects copes with this. The cracks that appeared are the result of your savings, because the cement was not of the type that was needed. Or you did not know about the existence of another, or simply saved.

After all, cement mortars can be anything. For example, decorative, heat-resistant, structural, lightweight, dense, porous, astringent, straining, radiation-protective, polymeric, chemical, heavy, and dozens more different ones!

Yes, you won’t find them in ordinary building stores, because it is profitable for a buyer to buy only one type, the cheapest one, and sell it to you at the highest markup. But, as you can see, if you want, you can choose a special one for any type of work. Well, not about that now.

In general, the plaster described above does its job, that is, it protects the main walls from destruction. And if you saved on it on purpose or not on purpose, then be kind, patch it up a little, and everything will be fine. How to do this, we will describe later.

And now the most interesting part. I’m almost 100% sure that you asked for advice not because you need to fix a dozen tiny cracks, but because you have a real problem with the formation of large cracks. If you don’t have small cracks on your wall, but large ones, half a meter-meter long, and they appeared not just on the plaster, but in the body of the main, that is, the bearing wall, then you don’t have an erosion crack, but a real one deformation.

Remember for the rest of your life, a deformation crack never just appears, and you will never eliminate it with any coating. If you have such a thing, then you need to fight not with it, but only with the cause of its occurrence.

So, let’s figure out what are the causes of deformation cracks, list them.

Excessive one-sided foundation shrinkage

Worst kind of deformity. In addition, this is the most common situation, it occurs everywhere. If the foundation was not poured according to technology, if dozens of conditions for its pouring were not met, then it may crack. As a result, the wall on it will also crack. In this case, a cut will occur – not a shift, but a cut – of static loads, and the entire structure will begin to move relative to the axis, which will succumb to this movement.

Yes, it’s a bit difficult to understand. Let’s sketch what we’re talking about:

As you can see, part of wall “A” starts to move. This movement can be either vertical or horizontal. In any case, this is an extremely serious malfunction of the building. And in the event of such a nuisance, we will have to do global work.

Many people advise to foam the crack, cover it up, and that’s it. But if you think rationally, you can realize that on average a square meter of a wall weighs about a ton. Of course, there are also 500 kg, there are also 5 tons – it doesn’t matter. So, a part of the wall weighing 20-30 tons goes down, while also pushing through the foundation. To solve such a colossal problem with a simple putty is simply unrealistic. Well, nothing, more on that later.

Damage to the foundation due to damage to the blind area

The blind area is connected to the base and is an element that protects the foundation from water. So, if the blind area is damaged, water begins to flow into the foundation space. It liquefies the soil and accelerates shrinkage.

If the thickness of the freezing layer reaches the level of water in the foundation, then when it freezes, it similarly begins its destructive action. And when destroyed, we get, again, the consequence that was described above.

Thermal expansion

There is a problem with this, but quite rarely. The atmosphere inside the room does not change quickly. The house is like a thermos in which the temperature is constantly maintained. Inside, it is almost equal to the temperature of the walls of the room. If it is -10 outside, and +25 indoors, then there is a constant heat exchange. From heating devices to walls, from walls to atmosphere and vice versa. So, the temperature inside, as you know, does not change, and thermal expansion is either completely absent or extremely insignificant.

Now let’s imagine a house that hasn’t had a window for several years. For example, in your country house they broke it, but you didn’t see it or decided not to insert it. So what’s going on? The weather outside changes very quickly. In the autumn-winter period, it often happens that during the day the temperature is +2, and at night it drops to -8. As you remember, we have a broken window, and the temperature in the room is changing at exactly the same rate as it is outside.

The walls of the building, heated during the day, cool down very quickly at night, and vice versa. So they begin to play like an accordion: then they expanded, then they narrowed. Since the rate of temperature change is high, the speed of this “game” is also high. And concrete or brick walls are not an accordion, so they can’t stand it, they burst.

In this case, only the walls burst, while the foundation remains intact. It is difficult to fix such a malfunction, but it is possible. At the same time, it is realistic to make it seem as if it did not exist.

Structural changes

These also cause deformation cracks. To make it easier for you to understand, let’s use an example. Let’s say you bought a house, and there is a column in the middle of the hall, and you have it like an eyesore. Don’t like it, kill me. You, without thinking for a long time, demolish it, and six months later you start, perplexed, asking: why are the walls cracking?

Well, how can they not crack and burst if you demolished the support beam, on which the lion’s share of the load was located. The walls took on a load they were not designed for and began to burst. Everything is simple and sad. If you have a similar situation, now you have serious work ahead of you, which we will describe below.

Decay, damage to stiffeners or support beams

Cracks can also occur for this reason. If, for example, you have a two-story building, and the span above the window was built using not a channel, but a wooden bar, then when it can no longer carry the load, what will happen? That’s right, at this point the wall will burst, or something worse will happen.

The same applies to damage to stiffeners or concrete lintels. If, for example, there was a seismic beam in your apartment, but you didn’t like it, and you demolished it unauthorized, get ready for serious problems and punishment, because cracks are now inevitable. And they will arise not only for you, but also for all neighbors who will definitely call the BTI.

Overload

Let’s say you live in your private house, which you recently bought, you have one room upstairs empty, and you decide to put a lathe there. Yes, somehow you manage to put it in there, you are happy and everything is fine. A month later, they discovered that on the wall you have a crack as thick as a finger. Strange, yes, where did she come from?

Of course! You have placed a machine, the minimum weight of which is 3 tons, on an area of ​​​​three squares. And that slab, which took on the load, began to put pressure on a section of the wall with a huge mass, which as a result could not stand it and burst.

We eliminate erosion cracks

Let’s move on to the sweetest part of our story. I say this because everything is done very simply and does not require much effort. Understand that all your actions should be aimed only at preventing the damaging factor from entering the body of the crack, and nothing more.

If you pursue the goal of preventing their occurrence, then this is pointless, you still will not be able to do this. Unless, you can treat the surface with a strengthening primer, but the effect of this is minimal. So, in order to eliminate erosion cracks, do the work in the following sequence.

1. Since you still have to worsen the visual condition of the wall by applying a layer of putty or some other mortar on it, leaving stains, then treat the entire wall with a strengthening composition. It won’t be redundant. And if you do not want to do this manipulation with the entire wall, then apply it only on the crack and, preferably, in its cavity too. You can do this with a syringe or sprayer, which, for example, you have left from window cleaner.
2. Dilute the mortar, and it is better not to putty based on gypsum and not cement, but, for example, tile adhesive or a similar composition. Such products bind better to the surface, and in this case, your putty will definitely not fall out of the wall.
3. We draw glue or some other solution into a large syringe or similar device and press it into the crack. Sometimes I even took a tight bag, poured some glue into it, cut off a corner (a very tiny piece), and worked with it like with a pastry bag. Just do not press, otherwise the package will disperse along the seam.
4. We fill the crack until our solution starts to stick out of it.
5. We take spatulas and draw from above, leveling our solution along the plane of the wall.

That’s it. We carry out such manipulations with all our cracks. At the end of the work, it will be useful to prime everything again.

Repair of deformation cracks

And this is the most serious, hard and thorough work. We have to spend well and work physically. So, information for general understanding. If there has been damage to the foundation, it is useless to make a wall, you need to repair the foundation. If there was damage to the wall without damaging the foundation, then the wall must be sewn. If the seismic beam, stiffener or some other support was damaged, then it needs to be restored.

I won’t tell much about the restoration of beams and other supporting elements. Remember the main thing: you will not just have to restore this beam, weld it with reinforcement and concrete it. We will have to transfer the load that was there before, and this is done either molecularly or using jacks.

Now let’s talk about the first two types of work.

Restoring the foundation

In order to do this, work in the following sequence.

1. Break the blind area along the entire wall along which the crack has gone, as well as along the adjacent wall. You need to support the foundation and do it not only where it is destroyed, but along all the walls that were affected by the destruction. Usually, if there is one large crack on one wall, then the foundation should be strengthened with the letter “G”. That is, if you look at our first diagram, this is side “A” and the part that belongs to it and is, as it were, the leg of the letter “G”.
2. Is the blind area broken? Start undermining the foundation right down to its foundation, just don’t touch the clay that is under it. Make the trench width at least 20, and preferably all 30 cm, as much as possible. The new trench must be deepened at least 10 cm lower than the existing foundation, and even better, even 15–20 cm. Schematically, all this can be depicted as follows:
3. Once the trench is ready and you have raked all the earth out of it, move on to cutting the supporting tooth. This is a special recess about 15 cm in the existing foundation. It is done with the help of a grinder of the third number, that is, the largest, with a stone disk. It is necessary to produce two saws, the distance between which should be about 20-30 cm. Of course, 30 is better, but it all depends on the depth, more precisely, the width of your foundation. The distance from the top edge of the tooth to the top edge of the foundation should not be less than 15 cm. This also applies to the bottom side. The tooth needs to be done with the help of a grinder or, as it is technically called, an angle grinder. After the cuts are made, you need to hollow out the gutter. This is done using a puncher of the second or third number, an electric hammer is also suitable. And most importantly, remember: in no case should the impact load of a mechanical chisel be placed perpendicular to the existing foundation, it should be done as parallel as possible, that is, tangent. Because when applying perpendicular vibration-shock loads, there is a danger of splitting it. And yet, the corners, that is, the edges of your recess, should be as straight as possible, then they can take a large load. We will depict in the diagram how approximately it should be cut. The tooth is shown with a red dotted line.
4. We begin to reinforce, and this is required to be done with corrugated reinforcement with a minimum diameter of 16 mm. It is impossible to use smooth reinforcement, the effect of it is extremely doubtful. So, we take a puncher and make holes in a checkerboard pattern over the entire area of ​​\u200b\u200bthe foundation at a distance of 30 cm from each other. The depth should be such that at least 15 cm of reinforcement enter them, and another 15 remain outside. That is, the segment should be 30 cm long. This will connect two foundations, the old and the new. So, as soon as this work is done, we insert the reinforcement and begin to weld it together with jumpers. I repeat once again, weld with electrodes, and not tie with wire. And this must be done not only in the plane of the main wall, but also in the holding tooth.
5. We lay at least 6 longitudinal reinforcements along the entire diameter, simultaneously welding to an existing structure. From these 6 rods, you should get a kind of rectangle, from the walls of which to the ground will be about 10 cm, and to the wall of the main foundation about 5 cm. This is the armored belt of the new foundation, and everything that we did earlier was to connect the old and new.
6. We take a hose with a sprayer at the end and thoroughly wet the existing foundation. By the way, I forgot to say, but it should be clear anyway: the earth from the surface of the old must be completely removed.
7. We make a solution of sand and cement as large as possible, the proportions are better to take ½.
8. We fill our entire cavity with a solution, while simultaneously throwing in the bottle, which we have left from the blind area and the cut tooth.

That’s all, this is the end of the work. Now, as soon as the old foundation moves even a millimeter, the new foundation will take on its load, they are now tightly connected. All that remains for you is to plaster the crack. Only plastering should be done after at least two months. The whole structure must “play” and lie on a new foundation. If you plaster the next day, then in a month you will again see a tiny crack. This is just the distance that was necessary in order for everything to rest against the new foundation. And if you did everything right, then you will never remember about it again.

That’s it, friends are repairing cracks once and for all, and not just covered up and forgotten. Understand, if you smear it, it will not give anything at all. By the way, we once restored the building of a kindergarten that burst during an earthquake. So, we measured the shrinkage by gluing a ruler to one side of the crack and measuring the discrepancy. It was cosmic 2 mm per month, and this is critical.

We thus completely restored the emergency building, and then the quality of our work was checked by gluing glass strips on the control points of cracks. None of them burst to this day, since we always gave a guarantee, and every year we are interested in how our foundation stands there.

How walls are sewn

If there were cracks on the walls for any reason, you examined everything and did not find any damage to the basement, which means that the foundation is intact and you will have to sew up the walls. So, the necessary work depends on the type of damage, of which there are also two. The first is local damage, and the second is global.

In case of local damage, i.e. damage to a small area, small and uncomplicated work is required. And if the damage is global, for example, your entire building burst, then you have to do something more complicated.

So, local type of damage . These include small cracks one meter long, +/- 50 cm. These are repaired as follows.

1. Wall covering, wallpaper, lining or something else is removed, up to plaster.
2. The crack is trimmed so that its width is at least 1 cm.
3. At a distance of 15 cm from it, through holes are drilled along the entire length.
4. Using a grinder, cuts are made to the crack. And so on both opposite sides, and even on the other side of the wall. Let’s show in the figure how it should look approximately:
5. We cook the letter “P” from the ten reinforcement, so that the base of the letter, when we insert it into our holes, comes out literally 1 cm from the other side.
6. We put our letters in the holes and weld. And remember, this design must be made in such a way that it cannot be forced in and in no case hang out.
7. We do this with all our couples.
8. We pass the crack and all the cuts with a primer and plaster.

Global damage . They are eliminated in exactly the same way as local ones. But there, as you already understood, the crack is twice as large, and therefore we have to do something else.

We’ll have to throw a few reinforcing belts over the entire building. It is done like this.

1. We mark along the entire perimeter, at a distance of 50 cm from each other, lines. We make as many as we can fit. If the damage to the walls is not so strong, then we do it at a distance of 1 meter from each other.
2. Along the entire length of the marked lines we make grooves with a depth of 20 mm.
3. We put reinforcement along the entire length in one gate. And we grab it there with a few strokes of alabaster or putty – it doesn’t matter what exactly, the main thing is to hold on.
4. And now the most difficult thing, here you have to work as a team. So let’s get a cutter. As you know, this is an oxygen and propane cutting machine. So, we take a cutter and warm up all our fittings. We do it as hard as we can. If its length does not exceed 6 meters, then excellent, with a cutter you can heat it all red-hot, it will be ideal.
5. As soon as the reinforcement turns red, and it should be at least 16 mm in diameter, then we grab the other two segments close to the wall from both of its edges. And they didn’t just stick it with slag from the electrode, but made a high-quality solid seam. Because we are making a tight tightening hitch, and it will be constantly under load.
6. We proceed to the warm-up of the next one and repeat the same operations.
7. As soon as all the belts are welded, we plaster.

Well, in the end, as soon as the metal cools down, the entire circuit pulls our house together with great force. Heating the metal, the molecules expanded, and the length of the armature increased. Then she returned to her previous position, only there she already had fulcrum – other fittings, which were all pulled together, as if with a noose. And now your walls will never crack again, they will be constantly rigidly restrained by reinforcing belts. It is like a female corset that tightens the waist.

Well, friends, as you can see, things are not as simple as you expected. In another article, we will tell you how such serious problems could have been avoided. Because it is always easier to prevent than to fix what has already been damaged.

I hope you found our story useful. I want to tell you in the end that our goal was to write an introductory article, not a hard technical literature, so it should not be relied upon as an instruction for use. And as you understand, only you are responsible for all your actions. Therefore, approach all work with intelligence and caution, and you will never have any problems. Good luck!

why this happens and how to deal with it

Applying plaster is one of the most popular ways to decorate and insulate walls both outside and inside the house. It often happens that the plaster on the walls cracks after the first season. Today we will figure out why this happens and how to avoid the appearance of such shortcomings in the future.

Contents:

• 1 Why cracks appear on walls
  • 1.1 Processing of the wall with only one layer
  • 1.2 Disgrained with a primitive layer
  • 1.3 The use of a poor -quality or old mixture
  • 1. 4 Improper mixing of the solution
  • 1.5 Lack of reinforcing frame
  • 1.6 dust and garbage on the walls

  from clay

  • 1.8 Sun rays
  • 1.9 Moisture ingress
  • 1.10 Cracks due to damage to supporting structures
  • 1.11 Cracks due to deformation of the foundation
• 2 How to prevent the development of cracks?

Why cracks appear on the walls

A network of small cracks worries not only owners of buildings with a long service life, but also completely new houses with fresh repairs. If with old houses everything is more or less clear. The main reason is the wear of all structures, as a result of the subsidence of the walls, and hence the appearance of cracks.

Despite the fact that the updated base or a completely fresh building has such a drawback, it appears due to the assumption of one or a number of errors in the plastering process. Therefore, we will deal with all possible nuances, ignoring which, sooner or later, will lead to the appearance of cracks.

Wall treatment with only one layer

In order to achieve the highest quality plastering, it will be necessary to apply several layers of mortar of different consistency. Only in this case, the owner is sure that cracks in the plaster will not appear. A minimum of three layers is applied even when there is a very small thickness to level the surface.

Neglect of primer

Finishing walls with plaster begins with the preparation of the base. It is important not to skip the primer layer here. This is a special mixture that will help increase the adhesion of the base. There are also antiseptic and antifungal compounds. They will prevent the development of mold and mildew on the wall. The plaster mortar is applied only after the primer is completely dry.

But the primer layer is also called the first layer of plaster. By consistency, it is a little thinner than the main one, but at the same time it easily pounces on the surface of the wall and adheres well. At this stage, the applied mixture is not leveled, which will make it much easier to apply subsequent layers.

The plaster primer takes all the load, if the walls shrink a little and then the cracks will appear much later. In addition, this layer cannot be dispensed with when using cement-based mixtures. In the process of drying, such a solution changes, because the plaster on the walls cracks. The primer layer will protect against unpleasant “cobwebs”.

Use of poor quality or old mix

Expiration date for plaster is just as important as for products. If the mixture has been produced for a long time, then the components lose their positive qualities, which is why they suffer, and the ability to stay on the treated surface. In the case when the date of purchase coincides with the end of the period of use or is as close as possible, then it is better to refuse such products.

Do not forget about the composition of the mixture for plaster. It is important that the amount of cement does not exceed a third of the total weight of the components. If there is more of it, then for a long time the solution on the wall will not be kept in perfect condition. Cracks will appear very soon.

But a smaller number doesn’t work either. If there is little cement, then the solution will not cling to the base. Slipping is guaranteed even at the time of application, and if you still manage to process the surface, peeling is threatened in the future.

Incorrect mixing of the mortar

When buying a ready-mix, be sure that the manufacturer will provide instructions for preparing the mixture. Be sure to follow all the recommendations:

• control the amount of water;
• add dry mix in small portions;
• mix thoroughly;
• use a construction mixer or a drill with the appropriate attachment;
• let the solution settle, mix again and only then start working.

If you do everything by eye, in a hurry, the solution will turn out to be heterogeneous, which means it will be poorly applied. In addition, cracks will appear during the drying process.

No reinforcement cage

The use of reinforcing mesh is mandatory when applying plaster on drywall, under wallpaper and other surface decoration methods. Such an event will avoid the following troubles:

1. Peeling of the plaster.
2. Appearance of cracks after drying.

Depending on the thickness of the applied layer, as well as the risk of cracking, the following types of meshes are used:

• glass fiber;
• plastic;
• metal.

Previously used thin strips of wood – shingles, which were stuffed into the base.

Dust and debris on the walls

The presence of greasy stains on the wall, as well as fine dust, cause cracks in the plaster. Therefore, the preparation of the foundation should not be skipped. Dust will reduce the adhesive properties of both the substrate and the mortar itself.

Plaster may peel off after drying. To clean the base, you should walk on it with a damp cloth or simply spray it with a spray bottle.

From clay and sand

A mixture containing clay and sand is classified as fatty, since the main component is such. They are difficult to apply on the base, and besides, there are a number of nuances:

1. Surface with a large number of irregularities. On such a basis, the plaster will begin to crack very quickly. If the owner wants not to restore the decorative layer for a long time, then you need to take care of the even surface of the wall. and that means doing a rough alignment.
2. High humidity or regular jumps. This will definitely provoke the appearance of cracks. Clay mixtures do not tolerate moisture well, so they are not used to decorate walls in the bathroom or in the kitchen.
3. Too thin layer (less than 5 mm). In this case, the water from the solution evaporates too quickly. In order for the plaster to become as strong as possible, it is necessary that this process proceed slowly and evenly. Otherwise, the plaster on the walls will crack immediately during drying.

Sunbeams

In order for the mortar applied to the wall to acquire the desired strength and strength, it is necessary to maintain the correct temperature for uniform drying. It is recommended to carry out plastering inside the room at a thermometer value not higher than 25 degrees Celsius, and outside from 5 to 25 degrees Celsius. . The mixture does not have time to gain all the necessary qualities as a result of the appearance of small cracks.

Moisture

Too much moisture is just as dangerous as too much heat. At what there are several options for the influence of water:

1. Too much water was used to prepare the solution.
2. The substrate was thoroughly wetted before applying the plaster.
3. Works were carried out at overestimated (more than 75%) readings of ambient humidity.
4. Different vapor permeability of base material and finishing material.

Each of these moments will sooner or later lead to the appearance of cracks, and in the future, the peeling of the plaster.

Cracks due to damage to load-bearing structures

Most often, this situation is possible in buildings with a long service life. Therefore, if cracks appear in such a house, it is not worth doing cosmetic repairs, but it is better to check how intact the supporting structure is. If this is not done, then at one point you will lose your home.

If damage is found on the base material, then first assess the extent of the destruction, strengthen the walls, and then proceed to improve the appearance. When finishing the walls, they are guided by the fact that the base must be stronger than the decorative layer.

Cracks as a result of deformation of the foundation

If there are no visible defects on the walls, all the rules for plastering and preparing the base are observed, but cracks still appear, then it is worth considering if there is a problem with the foundation.