What is the foundation of any house, the element that is laid first, the support, the base, which, if done well and competently, will guarantee the stability and stability of the house for many, many years? The answer is obvious even to a person inexperienced in construction - of course, we are talking about the foundation. The foundation is such an integral and important part of the design of each building that it requires not only the highest qualifications when laying it, but also often the adoption of additional measures designed to protect it from aggressive environmental conditions. We will not go deeply into all the harmful effects on the foundation; in this article we will look at an element that is mandatory when designing any house, namely, the blind area.
This design is a special water-impermeable coating laid around the perimeter of the building and is intended mainly to protect the foundation from getting wet caused by rainwater and floods. As already mentioned, the installation of this element is necessary in any case, regardless of what type of foundation is used in the building’s structure. Our task is to find out what is most often used to reinforce the blind area, and, of course, all the advantages and disadvantages of various methods of reinforcement, as well as to hear the opinions of experienced builders regarding the installation and reinforcement of the blind area.
Features of reinforcing mesh
As a rule, mesh of various sizes is used to strengthen the structure.
Typical honeycomb sizes: 50x50 mm, 100x100 mm, 150x150 mm. This design is made of metal reinforcement, which has different diameters; there are two types of execution: heavy and light, respectively, having a diameter of 11 mm and about 4 mm. To solve reinforcement problems, of course, the heavy type is used, while the light type is mainly used for finishing work. Form of delivery of the material: in sheet (card) or roll form. Individual mesh elements are welded at the touching points. The reinforcement can be located longitudinally, transversely, or longitudinally-transversely. The shape of the cells in most cases is a square, in more rare cases a hexagon or some other shape. You should also divide the reinforcing mesh into two types based on the characteristics of the reinforced objects. In particular, a mesh with special deformations of reinforcing bars stands apart; its purpose is to reinforce structures exposed to impacts beyond the norm.
Advantages
The advantages of this type of reinforcement are the following types of its impact on the blind area:
- a significant increase in the strength of the blind area;
- uniform distribution of tensile and compressive loads inside the structure;
- the appearance of additional rigidity of concrete;
- leveling the likelihood of deformation and destruction of the blind area;
- increase in heat resistance and mechanical resistance;
- simplification of the work of designers due to the presence of normalization of the range of meshes;
- emergence of resistance to temperature fluctuations.
The main task
As should be clear from all of the above, the basic function of the reinforcing mesh for reinforcing the blind area is primarily to increase its service life, improve its functionality and, accordingly, in total, all this gives a synergistic effect, which consists in increasing the service life of the foundation of the building for which it is being constructed blind area.
Why is this necessary?
The blind area is a mandatory element of the building, which has a slight slope to drain moisture from the foundation. The detail often serves as a pedestrian zone around the house. The component gives the building architectural completeness, so it is often decorated (with tiles, stone).
According to building codes, reinforcement of the blind area is not a mandatory procedure. Strengthening the structure will improve the hardness parameters of the element and foundation. The use of technology helps to extend the operational life of the structure and facilitate repairs.
Reinforcements in the blind area strengthen floors of varying strength. When using the procedure, resistance to mechanical and thermal influences increases. The element is not destroyed by temperature changes. Due to the uniform distribution of load (tension, compression), the durability of the structure increases. The use of technology makes it possible to increase the rigidity of cement, which prevents deformation of the structure.
Strengthening the blind area helps reduce the time required to construct the element. Reinforcement cage is not needed when installing monolithic slabs around the building. Builders do not advise creating a structure only around the house, otherwise the fasteners will only affect longitudinal loads.
What types of mesh are most often used?
Currently, in the world there are various options for reinforcing mesh used for reinforcement, each of which is characterized by its own parameters, advantages and disadvantages, and application features.
Regular
An ordinary or classic mesh, in fact, is a set of wire wires welded to each other at right angles, as a result of which this mesh is somewhat lighter than a mesh made using a standard template. This mesh, as a rule, is supplied in the form of rolls and is used mainly when there is a need to strengthen brickwork or so-called asphalt concrete, for example, in the process of reinforcing parking lots or industrial facilities.
Standard
Unlike the usual one, it is characterized by an increased size of the rods, equal to approximately 6-8 mm in diameter, which are not welded, but woven perpendicularly. Accordingly, it is stronger and heavier, as a result of which the range of applications of this type of mesh is much wider than that of its classic “brother”. The standard mesh is used to reinforce foundation walls and floors; it is also used to tighten various surfaces, for example, when carrying out finishing work.
Metal
Metal reinforcing mesh is extremely durable, which allows it to be used for radical strengthening of objects and building materials. This design is characterized by high weather resistance and resistance to aggressive external influences, such as temperature fluctuations, the influence of air humidity and the corrosive effects of chemicals. Moreover, in many cases, during the manufacturing process, metal reinforcement is electrochemically treated with zinc, giving the resulting composite a number of undeniable advantages, presented in the list below:
- much longer service life;
- the ability to resist a wide range of external influences;
- a significant increase in resistance to mechanical impacts;
- providing a much more elegant appearance of the object;
- increase in strength.
Geogrid
In this type of mesh, in addition to metal, there are polymer and woven materials. The finished structure can be covered with geotextile or rubber. This type of mesh is used in a very narrow range, mainly when laying asphalt to strengthen the soil.
Stages
Is it worth strengthening the blind area with reinforcement?
Despite the fact that some companies refuse to use reinforcement when constructing a blind area, explaining that this aspect is not specified in SNiP, the First Dacha Company emphasizes that the concrete base is a movable structure, so the mesh must be used without fail , especially if concrete grade M150 is used. This significantly increases the coefficient of compressive and decompressive strength of the base, and at the same time the level of vandal resistance.
A full-fledged frame made of reinforcing mesh is not required only in the case of using monolithic slabs, because it significantly increases the cost of the object and makes it more expensive. It also makes no sense to use rod rods laid along the building. This is because the fastening elements in this case work exclusively on longitudinal mechanical loads, but not on transverse ones.
Reinforcement mesh: main characteristics
Metal rods with different diameters are used as the main structural parts when forming the mesh fabric. The fragments are structured by rods that are laid perpendicular to each other. Spot welds are used as fastening.
Depending on the complexity of the blind area, sections of various sizes, differing in weight and cell diameter, can be used:
In the light version, rods with a diameter of 3 mm are used, in heavy ones - 12 mm or more. It is produced in card (sheet) or roll formats.
Rods can be used to strengthen both monolithic and prefabricated types of building structures:
This method makes it possible to reproduce elements that are resistant to deformation and natural processes of destruction under the influence of precipitation, groundwater, and temperature changes.
Advantages of the method
In the classic version, mesh material with honeycombs of 100*100 mm is used to strengthen the construction site.
This sample significantly reduces work time, because has a fully assembled frame, with exact dimensions. Having chosen the method of arranging a blind area with a mesh, the structure acquires the following technical characteristics:
Combining all aspects together, we can say that this method significantly extends the service life of the foundation.
Selecting a mesh fabric
The reinforcing structure is divided into several types, differing in their characteristics:
Classical
The wire elements in this version are welded perpendicular to each other, and the weight is significantly less than the standard counterpart. It is sold in the form of rolls and is used to strengthen brickwork, asphalt concrete in parking lots or industrial premises, as well as for arranging drainage concrete screed laid around the building.
Standard
Mesh fabric with medium cell size and rods with a diameter of 6-7 mm, intertwined at an angle of 90°. It is used for reinforcing the walls of the base foundation and screeding any surfaces.
Metal
The surface increase in the load-bearing capacity of the structure with metal segments allows for high-quality strengthening of putty surfaces; it is used when pouring a cement floor. This material is indispensable when designing load-bearing concrete walls, building foundations, blind areas and ceilings.
The use of such samples makes it possible to achieve strengthening of objects or basic building materials due to the following characteristics:
Basically, metal reinforcement for concrete screeds goes through a galvanizing stage during the production process. The galvanization method has a number of advantages over other samples:
Geotextile
This sample consists of polypropylene and a special fabric, most often covered with rubber or geotextile. This material is mainly used to strengthen loose soil, as well as in seismically hazardous areas before laying asphalt.
The process of laying mesh fabric into formwork
The construction of the blind area begins with the construction of the formwork.
During this period, the reinforcing frame is laid. After determining the location for pouring concrete, a collapsible wooden form is formed in this area, secured from the outside with pins. The form-building structure provides for high-temperature seams with a pitch of up to 2.5 mm, including in corner joints. For sealing, wooden blocks placed on edge are used. They are covered with resin. Also, in the wall areas, an expansion joint of 10-20 mm is made, which is then filled with roofing felt.
When measuring the upper edge of the formwork, pay attention to the presence of a height difference to form a slope. If it is necessary to strengthen the object, metal rods are used, which are driven into the base of the building in increments of 70 cm.
To cut the mesh into fragments 1-2 meters in size, a standard tool is used - a grinder with disks 125-230 mm, up to 2 mm thick.
The sections are laid out in formwork with a distance from the crushed stone cushion of 20-30 mm. Thus, the reinforcement is located directly inside the concrete screed of the building. The end of one segment serves as the beginning of the next, i.e. The overlap method is used.
To arrange the corners, special corner segments are made. Their installation is no different from the described method. The following rules must be followed:
To remove protruding rods, use a grinder, large-sized or hydraulic shears.
When reinforcing a blind area, a sequence of actions is followed: initially the process is carried out on straight sections, then the internal and external corners are laid. There is no need for tying with mesh material attached to the reinforcement, and its laying is carried out in a single-layer mode, in contrast to the foundation of the base, where the tying is reproduced by two belts.
At the next stage, concrete mixture is poured to the upper boundaries of the formwork. The main task is to prevent air voids. To do this, a vibrator is used in the process.
Blind area reinforced with mesh from the First Dacha Company
Our specialists will help you choose the appropriate type and size of mesh fabric and will arrange the blind area in the shortest possible time, with strict adherence to all regulatory rules. Initially, the object is inspected by a specialized employee, and a soil analysis is performed. After this, you will receive professional recommendations for arranging a belt around the house, with a preliminary project estimate.
Stages of work execution
It is worth remembering that the drainage structure performs not only a protective role, protecting the foundation and basement from being washed away by water, but also a decorative element that gives the facade of the building completeness. The work algorithm for installing a sidewalk around the house looks like this:
Reinforced blind area: price
The price is determined based on several factors:
The price list also takes into account labor costs for certain processes, the number of employees involved, equipment and selected materials. In some situations, an increase in the concrete layer is required, which requires the use of additional materials and rods of larger diameter. You can view prices in more detail on the website.
Do not forget that high-quality work can only be done by a professional. How long a concrete structure will last depends on the correct construction of the internal pie. Contact us now, and we will do all the necessary work to design a high-quality reinforced blind area, because we have the most favorable conditions!
+7(499)-110-01-95 +7(903)-977-33-90 [email protected] All Moscow region Daily 9.00-20.00
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What materials are used for reinforcement
The mesh for the blind area is presented on the market in various versions. It differs in design. The cell size depends on the selected type. These nuances affect the quality characteristics of the material.
Classical
The classic version is lightweight, which reduces the load on the base. The mesh has the appearance of perpendicular welded wire. This material is universal and can be used when laying brick structures and when pouring concrete screeds.
Standard
A standard mesh with a medium cell size is used not only for the foundation. A blind area reinforced with such material is characterized by good strength, reliability and durability. The rods intertwine at right angles. The cell size is 6-7 cm.
Metal
The metal mesh is superior to the previous ones in strength characteristics and performance characteristics. The widespread use of metal reinforcement is due to a number of advantages:
- resistance to environmental influences;
- resistance to corrosion;
- resistance to chemical influence;
- ease of operation and storage;
- long service life.
The strength and reliability of the material is due to the use of high-quality metal, which is galvanized to improve performance parameters.
Geotextile
An innovative material that has become widespread in recent years is geotextile mesh. The cost of this option is considerable, so it is rational to use it only under certain conditions, for example, when carrying out work in seismically hazardous areas, as well as when arranging structures on loose soil.
Reinforced frame cell dimensions
The following sizes of reinforced frames are considered the most common:
- 50x50x5 mm. The small pitch of the mesh allows it to reliably strengthen the poured concrete layer by providing a large contact area. The weight of the material is 6.1 kg/m².
- 100x100x6 mm. The size of the cells is sufficient to form non-loaded blind areas. Mesh weight 4.5 kg/m².
- 150x150x8 mm. Durable and reliable frame, designed to withstand significant loads. Rarely used when laying blind areas, as it is aimed at wide structures and requires pouring a thick layer of concrete. Weight 5.5 kg/m².
The larger the diameter of the rods used, the larger the mesh pitch and its mass.
Builder tips
To be sure of the quality of the constructed structure, the following recommendations should be followed when arranging and laying reinforcing material:
- Arrangement of one layer of mesh. Overlay is allowed only at the joints.
- Laying the reinforcing material begins with straight surfaces. At the final stage, the corners are reinforced.
- Homemade fittings may differ in thickness, which will affect performance characteristics, so for greater reliability it is better to purchase ready-made products.
We recommend reading: Foundation anchor bolts: types and installation
Compliance with the listed recommendations and carrying out reinforcement according to technology will allow you to get an ideal result. A blind area equipped according to the rules will last longer, performing the functions assigned to it at the proper level.
Tools and materials for work
To install the blind area you will need the following tools:
- tamping;
- roulette;
- pegs;
- shovel;
- level;
- hammer;
- tool for cutting material;
- welding machine;
- hacksaw;
- twine.
In addition, it is necessary to prepare the following materials:
- concrete;
- reinforcing mesh;
- nails;
- boards.
Everything must be purchased in advance.
Possible mistakes
To ensure strength, beginners tie the blind area to the foundation, drilling the reinforcement to the base. This is a common mistake because cracks will form as the building shrinks.
Arranging a blind area is a guarantee of reliable protection of the house from the influence of negative factors.
Arranging a blind area is a guarantee of reliable protection of the house from the influence of negative factors. Correctly carried out reinforcement will make the structure strong and durable and save on repair work.
Requirements for the blind area and design rules
When starting the process of constructing a concrete blind area with your own hands, you need to make sure that it has the same width, 20-30 cm greater than the overhang of the cornice. In most cases, architects adhere to dimensions of about 1 m (this value can be deviated when placing strip foundations on subsiding soil). The encircling structure is buried to half the freezing point of the soil. Its thickness varies from 7-10 cm. If it acts as a path, a deviation of up to 15 cm is allowed.
The optimal slope of the blind area is 92-94 degrees from the load-bearing wall. The base can rise by 50 cm. The outer lower side is raised 50 mm above ground level to ensure effective drainage.
Sand cushion device
Everything is simple here: “take more - throw further.” The only thing is that the sand needs to be compacted. The most accessible way is to pour water; lovers of mechanization can use a vibrating plate.
If the farm has neither water nor equipment, then it is worth at least jumping or making a tamper from a pin and a metal plate. Such tampers are also sold in stores. In general, the matter is trivial, but it contains enormous creative potential. The result should be an even pillow, repeating the outlines of the future blind area, between the lace and the sand - 10 cm.
How to make a blind area
If you are interested in how to properly make a blind area around a house with your own hands from concrete, you should read the step-by-step instructions and mark the ground. You should also prepare the area by getting rid of the fertile layer of soil and laying out a sandy or clay layer.
Next, a geotextile covering is laid on the ground (in most cases, roofing felt is used as it), and formwork is also installed. The perimeter is additionally reinforced, and the concrete mixture, created in the appropriate proportion, is placed in the formwork.
Preparation of tools and materials
When starting the construction of a concrete blind area around a house with insulation, it is important to take care of all the necessary tools and materials. Excavation work is carried out using a shovel, pickaxe, twine, compactor, pegs and construction tape.
You also need to prepare the optimal amount of waterproof film for the water seal. Next you should find all the additives for mixing the concrete mixture, which include:
- Moistened sand.
- Water.
- Gravel.
- Crushed stone.
- Cement.
As an alternative, you can use a ready-made mixture labeled M400 and higher. Necessary tools include a mixer for diluting the mixture, shovels, stretchers, a measuring bucket and other containers. The underlying layer consists of clay or sand.
To arrange the tape formwork, boards are used, so the construction site must have a hacksaw, a building level, and a hammer with nails. For reinforcement, steel mesh, welding equipment and tools for cutting metal elements are used.
Marking
Before digging a trench along its perimeter, it is necessary to secure the pegs and stretch a string between them. The location where the blind area adjoins the plinth is indicated using special beacons with a permissible step of up to 1.5 m.
The top layer of fertile soil is removed taking into account the landscape design. Sand or clay is placed at the bottom of the recess and then compacted thoroughly. The maximum depth can reach 500 mm for heaving soil.
Creation and compaction of a sand cushion
The bottom layer of the recess is equipped with a drainage system, on top of which 10-20 cm of sand is poured. The exact thickness of this embankment is determined by the type of blind area and the depth of its placement. The sand is carefully leveled and compacted.
To reduce the time and effort required when performing such actions, you can fill the trench with water and wait until it soaks into the soil. In this case, the sand will be better compacted.
If groundwater lies close enough to the surface, installing a drainage system will be an obligatory step. It uses a tube with special holes, which is laid around the entire perimeter and connected to the general sewer system of a private house through a storm drain.
Waterproofing
To create effective waterproofing, you can use the following materials:
- Bitumen mastic or tar.
- Ruberoid and other rolled waterproofing materials.
- Available solutions in the form of geotextiles, rubemast, polypropylene and a number of other materials.
- Hydrocements and asphalt concretes.
- Mastered.
- All kinds of polymer products for placing a waterproofing layer between the blind area and the foundation.
When starting to waterproof the blind area around a concrete house, it is important to completely get rid of the fertile layer of soil around the entire perimeter at a distance of up to 1.5 m before construction. If there are no financial restrictions, all compacted clay must be covered with a roll of waterproofing material. To improve protection against moisture penetration, several layers of hot bitumen can be made. Next, backfilling with crushed stone and compaction is carried out.
Creating formwork
To extend the life of the enclosing blind area, it is important to provide high-quality formwork. It is made from boards 30 mm thick. The height is determined taking into account the dimensions of the blind area. Experts recommend applying markings to the boards to monitor the thickness of each layer.
Having secured the base, all that remains is to strengthen the structure with twine and corners. They are placed from the outside, and bolts are used to tighten them. If an individual section is damaged, it is enough to unscrew the bolt to carry out repair work.
The diameter of the fastening elements is 1 cm. If you do not have to restore the formwork, all wooden elements will need to be treated with an antiseptic. And to extend their service life, it is recommended to make an insulating layer based on roofing felt. Such a solution not only provides reliable protection of the formwork from rot and mold, but also increases the durability of the blind area.
Large formwork is reinforced with supports or blocks. Even at the stage of its installation, an expansion joint is created, it is placed near the junction of the blind area and the wall structure and is installed across the structure. The presence of an expansion joint will prevent possible consequences from temperature surges. If you do not do this, the blind area will become covered with cracks.
For error-free installation of transverse joints on the formwork, a distance of 2 m should be maintained. Wooden formwork is effective only for concrete enclosing structures. If the blind area is created on the basis of other materials without filling, a wooden base is not necessary.
Reinforcement and filling
To strengthen the structure, a metal mesh with dimensions of 50x50 (100x100 mm) and pieces of reinforcement are taken, fixed in the base in increments of 0.75 m. The mesh is raised above the crushed stone by 30 mm, and the concrete base is mixed and poured independently.
At the reinforcement stage, it is necessary to prevent the appearance of air pockets in the concrete. To do this, you should adhere to the proportions that are used in the production of concrete for laying roads. Cement grade M400 and higher is used as the finished mixture.
The composition may also contain various additives that give it increased strength and reliability.
Leveling and drying
To level the upper surface of the blind area, you must adhere to a number of rules and requirements. It is recommended to carry out the procedure of covering the screed with dry cement 1-2 hours after ironing. The top layer should have a thickness of 3 to 7 mm. After this, the coating is thoroughly rubbed, and an opaque polyethylene film is laid on top. The blind area can be called ready in 1.5-2 weeks.
Technology for constructing a blind area made of concrete with insulation
Preparing the base for the blind area
. To do this, the top layer of soil is removed, all roots, stones, etc. are removed. Using a blanket herbicide will eliminate activity under the substrate. For example, the drugs Agrokiller or Tornado.
Advice. Considering that the blind area must exceed the edge of the roof slope by 200 mm, it is recommended to use a plumb line to accurately mark the boundary of the blind area.
. To do this, we pull the rope onto the stakes hammered in the corners. To avoid sagging of the rope, you need to install intermediate stakes (at a distance of 5-6 m from each other).
Advice. How to determine the required angle of inclination of the blind area? Craftsmen install additional beacons (stretch a rope) on the base of the house. Fastening is done every 1-1.5 meters.
. To do this, lay fatty clay in a layer of 100-150 mm or cover the bottom with geotextiles (roofing felt, PVC film, advertising banner, etc.). Please note that to prevent the film from tearing, it is better to pour a layer of sand of 50-100 mm at the bottom of the trench. A layer of sand of the same thickness is also poured on top of the film. The sand is leveled, moistened and compacted. In the case of a clay hydraulic lock, there is only one sand layer. When laying the film, you should avoid tension. It must be able to move freely with the ground.
Note. Experts advise making high-quality drainage near the hydraulic lock. To do this, you need to dig a trench 100 mm deep and 200 mm wide and fill it with crushed stone or lay a drainage pipe in it, wrap it with geotextile and fill it with crushed stone. This will increase the rate of water drainage.
It is worth noting that many people ignore this stage of work. In practice, this attitude results in the fact that the water passing through the expansion joint goes directly under the foundation, and when it freezes, it leads to an increase in pressure on it.
. The layer thickness varies from 50 to 100 mm. The gravel is leveled and compacted. Since crushed stone is difficult to compact, some recommend using a special grid for laying it, which is used in landscape design for making gravel paths. We note right away that this will increase the cost of the blind area without much need.
Laying communication pipes
. To do this, a depression is made in the sand for pipes and storm drains.
. Expanded polystyrene or penoplex is laid on the compacted sand with which crushed stone and communications are covered. Only hard insulation is suitable for the blind area, but it is afraid of point loads, so it must be laid on a sand cushion.
Advice. Cold bridges can be eliminated by laying insulation in two offset layers.
Reinforcement of concrete blind area
. This is done by laying reinforcement mesh with cells of 50x50 or 100x100 mm or by knitting a reinforcement cage.
Advice. Chain-link mesh is not suitable for reinforcement - it is too flexible.
If insulation is not intended, the reinforcing mesh is laid directly on the crushed stone to a height of 20-30 mm. Which will contribute to better distribution of concrete.
. Boards or plywood are installed strictly according to level. To level out the pushing force of concrete, the formwork is reinforced with stakes that are installed on its outer side. During installation, do not forget that the formwork is removable, which means that all seams will be visible after its dismantling. In this case, the blind area will have an ugly appearance. Therefore, when installing boards, you need to ensure that the internal seams are invisible.
Construction of expansion joints
. To do this, we install wooden slats and boards (on edge), which are pre-treated with an antiseptic or tarred. The recommended distance between the expansion joints of the blind area is 2-2.5 meters. Expansion joints must be made diagonally in the place where the formwork turns (at the corners). The purpose of the expansion joint is to compensate for the thermal expansion of concrete during operation. They are installed level, taking into account the angle of inclination of the formwork, because When pouring concrete, they are guided by them. An alternative to wood can be Guerlain butyl rubber tapes (10 RUR/m) or a hydro-swelling elastic cord, for example, Penebar Rapid SW45 A/B.
How to seal the seams in the blind area?
According to reviews, those who ignored the formation of expansion joints had cracks after the first winter. Many people believe that wood swells and allows moisture to pass through. You can seal the resulting cracks with special sealants, such as TEKTOR 103 mastic (225 rubles/piece), ISOSEAL P-40 (280 rubles/piece).
Pouring a concrete blind area. When pouring concrete, you need to ensure that no air pockets are formed and that the cement mixture evenly fills the entire space. It is important that no bumps or depressions appear when pouring. Their presence will lead to stagnation of water in these places. If it is not possible to do the entire blind area at one time, part of it is poured, and then work is resumed.
Advice. When pouring a blind area, you can use a technique for uniform distribution of concrete - bayoneting. To do this, the concrete is “pierced” with a rod, and the solution fills the entire space.
How to properly pour a concrete blind area around a house - video
How to protect the blind area from destruction
Since concrete is used to construct a boundary strip around the perimeter of the foundation, it may be subject to damage and cracks. Most defects are a series of deep or superficial cracks, traces of crumbling and subsidence. Cases of tiles peeling off from the basement of the building cannot be ruled out.
We recommend reading: How to strengthen the foundation of an old wooden house with your own hands
Such phenomena are associated with the following factors:
- Failure to comply with installation rules. Often, builders ignore the importance of waterproofing, do not ensure optimal compaction and uniformity of backfill, do not comply with dimensional standards and make other primitive mistakes. Another problem arises when choosing the wrong recipe for a concrete mixture, when the composition contains an insufficient or excessive amount of binder additive. The first option threatens cracking of the surface, and the second - crumbling.
- The absence of an expansion joint that prevents damage to the supporting structure due to temperature changes or precipitation.
- Lack of reinforcement in the blind area. Some home craftsmen refuse to lay this layer, arguing that its presence is not specified in SNiP standards. However, the metal elements make the strip not only functional, but also durable.
To protect the blind area from any negative factors, it is important to monitor the width and density of filling expansion joints and restore them in time. Instead of wood, it is better to use 15 mm thick vinyl tapes. If the building stands on heaving soil, the blind area should not be connected to the basement part.
To increase the tightness of the concrete composition, it is treated with a deep penetration primer.
Tips for reinforcing blind areas
When performing work on pouring a reinforced blind area, it is recommended:
- Using a steel frame is beneficial only for industrial buildings and high-rise buildings. This is due to its significant weight and high cost.
- If the frame is assembled from separate steel rods, then it is better to tie them with wire, so the reinforcement will not lose its strength characteristics.
- If it is possible to abandon a homemade mesh in favor of a factory one, then it is worth doing. It will be guaranteed to meet the stated characteristics.
The service life of a properly laid reinforced blind area will be from 15 to 20 years without repairs.
Reinforcing the blind area allows you to protect it from negative external influences and improve technical characteristics. Despite the fact that the cost of the structure will increase significantly, the financial investment will pay off in several years.
Design requirements
To fill the blind area of a house with concrete, you need to familiarize yourself with the regulations and recommendations of SNiP:
- The width of the blind area should be 20 cm greater than the roof overhang (SNiP 2.02.01-83). If the structure has a drainage system, then its indicators are also taken into account. The optimal value is 1 meter. In this case, you can lay a tile path around the house.
- The length of the blind area around the house, made with your own hands, must correspond to the perimeter of the building. However, if you plan to install a concrete porch, then a “break” is allowed.
- Depth. The depth of the “tape” is half the calculated freezing depth of the ground.
- The thickness of the concrete blind area is also regulated by SNiP and, according to these requirements, should be at least 7-10 cm for the top layer. However, many people make concrete parking spaces for personal cars along with the blind area. In this case, the operational load increases, and the thickness of the concrete blind area can reach up to 15 cm.
The blind area must be built at a slope of 2-3 degrees
- Slope. According to SNiP III-10-75, the slope should be from 1 to 10 cm for each meter of width. Most often it is 2-3 cm per meter - this is approximately 2-3 degrees. The angle of inclination must be directed in the direction opposite to the foundation. It is not recommended to increase the slope, since in this case it will be difficult to walk along such a path in winter, when ice forms on the surface.
- Border. The installation of a blind area for a house does not include the mandatory production of a border, so in this case the decision is made by the owners of country property. However, experts recommend installing such “limiters” if trees and shrubs with an “aggressive” root system (blackberries, raspberries, plane trees, poplars and others) grow near the foundation.
- Base height. For a hard type covering (concrete), the base must be at least 50 cm.
- The recommended height of the blind area above ground level is 5 cm or more.
There are also several schemes according to which a blind area can be built from crushed stone, in the form of a monolithic concrete covering, both for normal soil types and for “problematic” ones.
Types of blind area, based on soil characteristics
Knowing the requirements of SNiP and the features of a suburban area, you can make a blind area with your own hands using the step-by-step instructions given below.
Marking work for the blind area
First, you need to mark the top of the future blind area on the base and, stepping back from the wall at a distance equal to the width, hammer beacons made of reinforcement into the ground. For accurate measurements you will need a level, but you can also use a hydraulic level.
To check the accuracy of the measurements, make a reverse move, its essence is as follows. Let's say you move the level marks from the starting point, going clockwise around the house. Having walked around the entire perimeter, you must return to the starting point at the same level. If there are discrepancies, take the same measurements, but now move counterclockwise around the building.
A cord stretched along the marked points will visually show at what height the blind area and its boundaries will be.
We make the blind area ourselves
The technology for constructing a blind area includes several stages that even a beginner in construction work can handle.
Preparation
To begin creating a protective coating around your home, prepare:
- pickaxe;
- twine;
- roulette;
- tamper;
- pegs for marking;
- waterproof film (geotextile);
- concrete mixture;
- boards for formwork;
- hacksaw;
- level;
- nails;
- reinforcement material, welding machine and wire cutters;
- usually a trowel, spatula;
- sealant for processing seams (it is better to purchase a polyurethane compound).
Marking
Arrangement of the blind area around the house begins with preparing the area for construction. At this stage, it is necessary to mark the perimeter of the future “tape”, or rather the trench for it, using pegs. There are several recommendations in this regard:
- The step between the beacons is 1.5 m.
- The depth of the trench will depend on the soil, but the minimum value is 0.15-0.2 meters. If the ground is “heaving”, then the depth increases to 0.3 m.
Marking for a concrete blind area using pegs
The easiest way to apply markings is to proceed in the following sequence:
- Drive metal or wood pegs into the ground at the corners of the house.
- Install intermediate beacons along the perimeter of the building.
- Stretch the cord or rope, connecting all the pegs.
Healthy! At this point, a sealant can be used to separate the sheeting from the foundation.
After this, the slope of the system is formed; for this, a trench is dug in which the depth of one of its sides will be greater. To compact the resulting ditch, it is enough to use wood. First, you need to place the log vertically, lift it and sharply lower it down with force. This will compact the bottom of the trench.
Formwork
Very often, recommendations for the construction of this type of coating do not contain a description of the creation of formwork, but beginners should not neglect such an “assistant”.
To prevent concrete from spreading, it is necessary to prepare the formwork
For formwork you will need boards on which it is better to immediately mark the height of the future cushion. At the corners, fasten the improvised “box” with metal corners (bolts from the outside).
Important! If you do not want to remove the formwork after the construction of the concrete blind area is completed, then be sure to treat the wood with an antiseptic compound and wrap the boards with roofing felt.
Scheme of formwork for blind area
Making a pillow
In order for a concrete blind area to be made according to all the “canons” of construction, it is imperative to prepare a sand or clay base for it. The thickness of the sand layer can reach up to 20 cm. It is best to lay the pillow in several layers, moistening and thoroughly tamping each subsequent layer. At the final stage, the surface needs to be leveled.
Waterproofing
The waterproofing device involves laying several layers of roofing material or other geotextiles on the pillow.
In this case, it is worth paying attention to the recommendations of experts:
- The material needs to be “wrapped” slightly onto the walls to create an expansion joint.
- Roofing felt must be laid overlapping.
- A thin layer of sand is poured on top of the geotextile, and then 10 cm of gravel.
- If you plan to install a drainage system, then it is laid close to the resulting “water seal”.
Waterproofing of the blind area is carried out using geotextiles or roofing felt
Reinforcement, pouring and drying
Above the level of 3 cm from the layer with crushed stone, it is necessary to lay a metal mesh in increments of 0.75 m. After this, you need to mix the concrete and pour it in equal portions into the resulting formwork sections. In this case, the poured composition should reach the level of the upper edge of the wooden “box”.
Reinforcing a blind area for a house using metal mesh
Healthy! After pouring, pierce the surface with an iron rod in several places to allow excess air to escape.
We recommend reading: FBS foundation blocks: what they are and where they can be used, installation technology
The composition can be distributed using a trowel or a rule. To increase the resistance of concrete, 2 hours after pouring, ironing is performed. To do this, the surface is covered with a layer of dry PC 400 3-7 mm thick.
Healthy! To prevent the composition from cracking, it must be moistened with water 1-2 times a day.
After pouring and leveling the mixture, it must be covered with polyethylene.
In addition to how to properly fill the blind area, you need to take care that it does not crack during the drying process. To do this, you need to protect the coating from precipitation and sun using plastic film. It is believed that the blind area dries completely in 10-14 days. However, according to the regulations, at least 28 days should be allowed for drying.
Knowing all these recommendations and the correct proportions of solutions, you can improve your home without the participation of specialists.
Work order
The DIY device involves performing actions in the following sequence:
- first you need to mark the blind area on the ground;
- digging a trench around the perimeter of the building to the depth of the blind area (depending on the thickness of the layers of bedding and concrete);
- compacting the base;
- installation of formwork panels and fastening them together;
- laying bulk materials (sand, crushed stone) with compaction;
- laying reinforcing mesh;
- installation of boards that will act as expansion joints that prevent concrete from cracking in winter) in increments of 2 meters;
- laying concrete and its compaction, leveling;
- ironing of the surface;
- waiting for time to gain strength, caring for concrete.
It is important to ensure a distance between the blind area and the wall of approximately 2 cm. This gap will allow structures with different weights to settle independently of each other and prevent the appearance of cracks. Concrete gains full strength in 28 days at an average daily temperature of 20 degrees Celsius. If the air temperature is lower, it will take longer. The formwork can be removed after reaching 70% strength.
Caring for concrete involves periodically wetting it. To prevent moisture evaporation, the blind area after pouring is covered with film or burlap. These measures will prevent the appearance of cracks during hardening.
An additional measure could be insulating the element. To do this, extruded polystyrene foam is used, which is placed under a layer of concrete on a bedding. Insulation is relevant when the depth of the foundation base is higher than the freezing depth.
How to protect the blind area from destruction?
The width and density of wall expansion joints and expansion joints filled with waterproofing should be controlled, and they should be repaired in a timely manner. For the latter, it is better to use vinyl tapes up to 15 mm thick rather than wood. On heaving soils, the blind area is not connected to the base of the house, and a storm drain and drainage system are created around the building, the structure of which effectively drains water into the external system.
The tightness of the concrete surface is increased by treating it with a deep penetration primer, a water repellent, a solution of liquid glass and cement. Additionally, the blind area around the building is decorated with stone, tiles (paving, clinker, etc.), and pebbles. Concrete acts as a solution.
If you don't have a blind area.
The editorial inbox receives letters with annoying regularity in which summer residents talk about loose foundations, cracks in the walls, and lopsided corners. As real practice shows, this problem often appears as a result of the influence of ground moisture on the “zero cycle” and the movement of heaving soils. But this disaster could definitely have been avoided if the foundation had been protected. This is precisely what the blind area is intended for. That is, it is a mandatory technological component for most types of foundations, and not an additional item of unforeseen expenses imposed by greedy builders in an already growing budget, as many summer residents think.
If the foundation is not protected by a blind area, the appearance of cracks in the walls is a matter of time
It becomes all the more offensive for inexperienced dacha developers, who very, very often do not pay attention to the obligation to implement it. And not only due, but not at all. As a result, the foundation is deprived of protection and becomes directly accessible to moisture, as a result... see above, where we talked about drops.
Repair of concrete blind area
Crack in the concrete blind area.
Most often, the installation of an expansion joint fails, which over time loses its tightness due to expansion. A common reason is a broken technology for forming the correct concrete solution and temperature and humidity conditions for strength development. A slight increase is “treated” with sealants and foam fillers. The wide gap is widened and filled with sand-cement mortar with fine crushed stone, maintaining the isolation of the blind area from the base.
Then the dry surface is primed. The same is done with cracks in the surface of sections of the blind area: small ones are spilled with liquid sand-cement mortar, large ones are opened deeper in the form of a cone and filled with bitumen mastic, covered with sand. Significant damage (splits) are concreted with a new mixture in the mode of long-term post-wetting and covering with film.
DIY concrete for the blind area of a private house
A poor-quality blind area manifests itself after winter: it simply disintegrates and splits into small parts, and in some cases completely. The reason is most often low-quality cement that was used to make concrete, and incorrect technology for preparing the concrete mixture.
You should consider how to make concrete yourself:
- For this, material of grade M200 is taken, higher grades are possible, because... The higher the brand, the higher quality the entire structure will be.
- The sand is taken purified, without any admixture of clay, limestone, or silt. Sand in buckets brought from a quarry or river is better suited for this.
- Crushed stone or gravel should be of a small fraction (from 5 to 20 mm).
- The more water, the lower the strength of the concrete structure.
- When selecting the composition of concrete for the blind area, the following proportions must be observed: 1 part cement, 4 parts crushed stone, 2 parts sand, 0.5 parts water.
Component quality
The service life will largely depend on the quality characteristics of the cement. The cement should not contain excess moisture and various particles, especially hard ones. Building materials should be purchased only from trusted suppliers.
When purchasing, be sure to look at the expiration date of the cement, because... It is of the highest quality in the first 3 months after graduation. After this period, strength indicators begin to decline.
It is better to fill the top layer of the structure with concrete of a higher grade: this will give additional strength to the entire structure.
Concrete marking
The grade of concrete is an indicator of its compressive strength. Regulations on technical characteristics - GOST 912897, 747394.
When choosing one brand or another, it is necessary to take into account the load, soil characteristics, and climate conditions. The blind area must meet the following requirements:
- brand M200;
- strength B 15;
- frost resistance F150.
The most popular mortar, M200, is most often used in construction; it is prepared from M400 cement. It can also be used to build the foundation of a house, pour screeds, and stairs.
When building in areas with frequent, large amounts of precipitation and sudden temperature changes, it is better to use the M250. This brand is most resistant to extreme heat and cold and is less likely to crack.
The larger the construction project, the larger the brand should be, because too low may be damaged by vibration.
Proportions for concrete m 200
M200 is the most popular mortar made from M400 cement. Before making concrete of this brand, it is necessary to determine the most accurate ratio of all components. For 1 m³ of product you will need:
- cement - 330 kg;
- gravel - 1260 kg;
- sand - 650 kg;
- water - 170-180 l.
Preparation
The finished solution for making a blind area must be of high quality, without lumps; for this, all steps in preparation must be consistent.
First, clean tap water is poured into a concrete mixer or container, with the manual method of preparation, then cement is added in a small amount, everything is mixed. The next stage is adding crushed stone and sand.
Laying
First, a bedding layer of clay and sand is formed. Then a drainage layer is made from crushed stone. For waterproofing, roofing felt or polyethylene film is suitable.
To form the blind area itself, you need a building level, with its help you can check the levelness, a 2 m lath, and tools for plastering and digging.
The area for the future structure is calculated, the orientation should be on the parameters of the width of the tape. The next step is to remove the soil layer to a depth of 200-220 mm. Then the formwork is placed and the soil lying in the trench is compacted. Clay with a thickness of at least 50 mm is laid on the entire bottom, which compacts well. A 100 mm layer of sand is placed on the clay layer, compacted, then a 50 mm layer of crushed stone is added.
The next stage is a reinforcing mesh with the installation of a special expansion joint at the junction of the base and the concrete strip, all this is compacted and leveled. The distance between expansion joints should be 2-3 m, and they must be made at the corners of the building. To do this, you can use slats, placing them at a level identical to the surface, taking into account its inclined force.
To give additional strength to a concrete structure, ironing can be done, which is done using the wet method.
A concrete blind area, which is made from high-quality materials in compliance with the required proportions and technology, will serve for at least 20 years. For even longer service life, you can cover the structure with paving slabs. It is of high quality, tolerates temperature changes and cold seasons well, and can withstand heavy traffic.
Price
The cost of reinforcing mesh differs depending on the type and size of the cells:
| Kinds | Cell sizes | ||
| 50*50*5 mm | 100*100*4 mm | 150*150*8 mm | |
| Classical | 270 rub. | 110 rub. | 140 rub. |
| Standard | 260 rub. | 100 rub. | 150 rub. |
| Fiberglass | 140 rub. | 80 rub. | 130 rub. |
| Geogrid | 130 rub. | 110 rub. | 110 rub. |
| Metal | 270 rub. | 100 rub. | 150 rub. |
The most important and useful information on the construction of blind areas is collected in this section.
