Cracks in the walls, their types and causes of appearance, methods of elimination and preventive measures. Cracks in the walls are a diagnostic sign of a change in the stress state of the enclosing structures. The reasons for the appearance of these shortcomings can be very different, but their overwhelming number is associated with deformations of the foundations that exceed the maximum permissible values for load-bearing walls. Such damage can reduce the structural reliability of the building and its performance. If cracks are found in the walls, they are inspected, the nature, place and cause of deformation is established. Based on these data, planning and implementation of the necessary technical measures are carried out.
Types and causes of cracks in the walls
Wall cracks can be classified by dividing them into groups:
- Due to: shrinkage, deformation, temperature, structural, and also caused by wear or weathering of walls.
- Destruction: cut, crush and rupture.
- Directional: oblique, vertical and horizontal.
- By outline: curved, straight and closed (not capturing the edges of the walls).
- By depth: through and surface cracks.
- According to the degree of risk: dangerous and not dangerous.
- Time: stable and unstable cracks.
- By the size of the opening: large - more than 1 mm, small - up to 0.3 mm, hairy - up to 0.1 mm, developed - up to 0.5 mm.
The main causes of wall cracks can be:
- Uneven soil compression … At the same time, the cracks on the walls are inclined and reach their edges. By the size of the opening of cracks and their direction, it is possible to determine the type of settlement and deformation of the building, as well as to find the place of the cause of the defect. In addition, precipitation can occur from uneven loading on foundations, soil leakage into old pipes, damage during construction, and for other reasons.
- The presence of add-ons or add-ons … They cause a change in the state of the foundation: an additional compressive stress appears in the ground under the building, as a result of which the foundation settles. In this case, the adjoining walls can have inclined cracks in the "downward" direction, and opening - "up". The same phenomenon often occurs when a partial superstructure occurs along the length of the building.
- Uneven load on the foundation along the length of the building … Longitudinal walls of buildings often have glazed areas of significant size, passing into blank parts of aboveground structures. All of them create different loads on the foundation, making its settlement uneven. Under heavy floor loads on the longitudinal internal walls, settlements can also occur. In this case, cracks appear in the corners of the transverse walls.
- Construction of a pit near an existing building … In this case, the building is located near the slope or on it. Soil displacements take over the area of the foundation, and oblique cracks appear in the walls from the side of the pit. Sometimes the slope of the adjoining wall is associated with the threat of its collapse.
- Interaction of adjacent foundations … In this case, the stressed sections of the foundations are mutually superimposed and increase the local compression of the soil. They have a tilt to each other, provided that buildings are erected simultaneously, if buildings are being built at different times, the tilt occurs in the direction of the building that was erected later. An existing building on piles, for example, can get settlement and inclined cracks in the walls when a new building is located close to it on a natural foundation.
- Impact of surface loads … They can arise from storage near walls of industrial raw materials, building materials or products. From the impact of such loads, soil compression and foundation settlement appear, causing cracks.
- Dynamic influences … These include the movement of loaded vehicles, pile driving, the operation of compressors and hammers in production shops, etc. Such influences affect the soil of the foundations and can lead to the formation of cracks in the aboveground structures. At the same time, sandy soils are compacted, and clayey soils soften. As a result of such processes, foundation settlement occurs.
- Freezing of soils and their thawing … Freezing of the foundations can cause the foundations to rise by heaving forces. This process is especially dangerous for buildings under construction, when their walls are lightweight and have low bending stiffness. The walls on which all other floors need to be erected receive numerous cracks, which negatively affects the further production of work. The settlement of foundations during thawing of the soil is greater than during its freezing, while the walls may receive new cracks. The presence of basements often aggravates the situation: it is possible for the outer walls to separate from the transverse partitions. In this case, cracks occur along the entire height of the structures and can cause a violation of their stability.
- Thermal deformations … They can cause cracks if the building is long and free of expansion joints. Damage in this case occurs in the middle of the structure, cracks have a vertical direction.
- Shrinkage deformations … Cracks arising from their impact usually appear in the corners of wall openings of large-panel buildings and have a radial direction. Such damage is not dangerous. On plastered walls, small closed, chaotically located or oriented cracks sometimes appear that do not reach the corners. They are caused by the shrinkage of the high-fat solution.
- Overloading the walls … It leads to crushing of the masonry and is accompanied by the appearance of cracks in the supporting structures, pillars and walls. In this case, the cracks are closed and have a vertical direction. They are the initial sign of wall collapse and are extremely dangerous. Local deformations during overloading of structures of old buildings are manifested by cracks in the places of supports of beams and trusses.
- Material wear … Periodic changes in temperature and humidity affect the integrity of brick walls. Due to weathering, small cracks may appear on them over time. They are shallow and are not dangerous for massive structures.
In addition to the above reasons, cracks can appear at the junctions of old and new walls, depend on the sequence of masonry, etc. Such cracks are straightforward, open along their entire height and are not dangerous. Sometimes cracks may also appear at the joints of the partitions and the ceiling. They indicate beams deflection, floor settlement, or wall material shrinkage.
Before repairing cracks in the wall, you should study them carefully. During visual inspection of cracks, the depth of their opening, age, location and direction are determined. When wall damage appears at different times and for various reasons, their analysis becomes much more complicated.
For him, you need to have documentation on the history of design, engineering geology, operation of the structure, the location of underground communications and a working project. For a visual representation of the results of the survey, cracks are indicated on the drawings of the internal walls, facades, then they are numbered indicating the beginning of their opening at a given moment in time.
Wall crack elimination technology
After carrying out the diagnosis of wall cracks and eliminating the causes of their appearance, the sealing of problem areas can be carried out in various ways.
Sealing stable cracks in the wall
Shallow cracks can be repaired by plastering with mortar. When mixing, cement putty or PVA glue should be added to it. Plastering must be carried out on a previously prepared area of the defective surface. To do this, before eliminating the crack in the wall, the problem area and the area adjacent to it must be cleaned of destroyed fragments and dust, primed, and a special reinforcing tape must be applied to the gap.
Medium-sized cracks are repaired with a metal mesh. In this case, the destroyed wall covering must be removed, and the resulting solid base must be primed. Then, along the crack, drill holes in 30 cm increments for mounting the dowels, insert them and fix the mesh with screws equipped with wide washers.
The size of the mesh of the metal mesh is 5x5 cm. If several strips of mesh are to be applied to a large emergency area, they should overlap at least 10 cm. The plaster should be applied to the wall through the mesh. After that, the surface should be slightly leveled, wait until it is completely dry and apply a finishing layer of plaster.
It is possible to effectively eliminate cracks in the walls with polyurethane foam. During polymerization, it somewhat increases in volume, so its dried excess must be cut off with a knife, and then the problem area should be covered with any suitable finishing material: plaster, paint, etc.
Elimination of unstable cracks in the walls
It is not difficult to identify a progressive crack. This requires strips of paper to be pasted in the middle, bottom, and top across the crack. If after a while the strips break, you will need to look for and eliminate the causes of the defect.
It is possible to stop the development of large cracks with significant opening by installing a channel (anchor) or metal plates. The work is done in this way:
- First, it is necessary to knock down the plaster from the emergency section of the wall, focusing on the length of the selected plate. If it is 1 m, then the surface should be cleaned 50 cm on each side of the crack. The depth of the resulting groove should be equal to the thickness of the plate.
- Its fastening is carried out, depending on the material and wall thickness, by means of dowels or long bolts. For the latter option, through drilling of the structure is performed.
- The crack and grooves should be cleaned and filled with foam, and then the anchor should be inserted into the recess and fixed with fasteners. The screed system is recommended to be installed in three places of the problem area: across the end and beginning of the crack, as well as in its middle. After that, you need to fix the reinforcing material in the emergency area and perform plastering.
A similar operation can be performed using staples instead of plates:
- They can be made from fittings. After selecting the rods of the required length, their ends should be bent at a right angle by 15-20 cm.
- Then, across the crack in several places, it is necessary to make grooves so that the staples sit in them deeper than the level of the existing wall surface. For example, with a reinforcement diameter of 10 mm, the depth of the grooves should be 13-15 mm.
- The ends of the staples must be inserted into the pre-drilled holes. Plugging of staples is excluded, as this process can lead to the expansion of the crack.
- After installing the required number of brackets, you need to follow the standard procedure: surface cleaning, priming, reinforcement and plaster.
How to remove cracks in a drywall wall
Such coatings are characterized by small cracks. Defects in the form of a cobweb indicate that when decorating the walls, an excessively large layer of gypsum putty was applied to the gypsum board sheets or the thermal regime was violated when it dries with the use of heaters and hair dryers. Vertical or horizontal cracks usually occur at the joints of the sheets. The sources of the appearance of such defects may be the weakening of the metal frame of the wall or the absence of a reinforcing tape at the seams of the gypsum board.
You can get rid of the "cobweb" only by removing the damaged layer and applying a new one, its thickness should not exceed 2 mm. If you need to apply another layer, you need to wait until the previous one dries.
When the frame is weakened, sealing cracks in the gypsum plasterboard wall is very problematic. And with reliable fastening of the coating, its defects can be easily eliminated:
- Cracks need to be cut at a 45-degree angle with a sharp knife.
- The resulting grooves should be filled with plaster mix.
- Apply a reinforcing serpentine tape on top of the closed crack, then level the surface with a putty and sand with an abrasive mesh.
How to repair wall cracks in plaster
Before covering the cracks in the wall, peeling plaster must be completely removed, and then primed and re-coated. Before doing this work, you should read the instructions on the packaging of the material. It indicates the mixing ratio and the recommended layer thickness.
You can hide the existing cracks in the plaster with the help of fiberglass. It will resist the expansion of old cracks and the formation of new ones. Before starting work, deep recesses should be repaired with gypsum plaster and a penetrating primer should be applied to the wall.
How to remove cracks in the walls of log cabins
Cracks in the walls of wooden buildings arise from the influence of moisture in the inner layers of a log or timber. The formation of such cracks can be minimized by means of a compensation recess, which is cut along the entire length of the log to a depth of no more than 1/5 of its diameter.
The formation of large cracks in old wooden buildings is not a cause for panic. These defects do not pose a danger and do not at all affect the performance of the walls. An example of this is the cracked log cabins erected in remote villages decades ago.
Therefore, the repair of cracks in the walls of log cabins is only aesthetic in nature. You can use various materials for this, but none of them differ in durability.
The sealant does not provide long-term adhesion to wood, cracks in it will have to be repaired every 2 years, applying new layers on top of the old ones. Wood, absorbing and releasing moisture depending on the season, periodically changes its volume. For this reason, any sealing material will flake off.
The optimal solution for filling cracks in timber or logs is to caulk the cracks with linen hemp braids or moss.
Preventing the appearance of cracks in the wall
As mentioned above, the main reasons for the appearance of dangerous cracks are the deformations of the foundations. Therefore, when designing them, it is necessary to comply with a number of requirements:
- Columnar foundations located in heaving soils must be fastened with lower straps or grillages.
- In houses with basements or technical basements, it is better to make recessed walls in a monolithic design. At the same time, it is not recommended to connect them with reinforcement into an integral structure with a slab foundation.
- The foundations of heaving soils should not freeze under the slab foundations when the box is built at home.
- The broadening of the drill supports should be located below the freezing level of heaving soils.
To prevent the appearance of cracks, the following measures can be applied:
- Dismantling of emergency walls and installation of new block or brickwork;
- Manufacturing of a monolithic concrete reinforcing belt;
- Replacement or strengthening of supports;
- Restoration of the blind area;
- Increasing the length of the load-bearing walls and strengthening the walls.
How to remove cracks in the walls - watch the video:
Most of the cracks appearing on the walls of houses are caused by violations of technical conditions, rules, building codes, lack of supervision over their observance or low qualifications of performers. Therefore, when erecting buildings, it is important to avoid all this. Good luck!
