The simplest and accessible way fulfillment rough coating for premises of any purpose is the arrangement of a concrete floor on the ground. Although the procedure does not require special skills, the quality of the final floor directly depends on the observance of certain technical points related to its arrangement. How to make a concrete floor on the ground and how to pour a concrete floor on the ground, we will consider further.
Characteristics and components of the concrete floor on the ground
When arranging any floor on the ground, the main thing is to ensure its high-quality thermal insulation. It is because of its installation that in the end it is possible to obtain a multi-layered floor, called a pie.
The production of floors on the ground directly depends on the type of soil and its features. The first and most important requirement for the soil is the level at which groundwater is laid, which should be at least 500-600 cm from the surface. Thus, it will be possible to avoid movements and heaving of the soil, which will be reflected on the floor. In addition, the soil should not be loose.
For more quality performance of all works, the requirements for the installation of thermal insulation should be determined, which are as follows:
- prevention of heat loss;
- penetration protection ground water;
- providing sound insulation;
- prevention of vaporization;
- ensuring a comfortable and healthy indoor climate.
A warm concrete floor on the ground contains the following components and stages of work:
1. Cleansing the soil from the top layer. In addition, the surface is carefully leveled.
3. Then a pillow of gravel or crushed stone is installed on the sand. It is this area that prevents the rise of groundwater, in addition, it additionally levels the surface. The thickness of the filler layer is about eight centimeters.
4. The next layer is the use of reinforced steel mesh. It is an excellent fixer for the concrete base. In addition, it is a place to fix metal pipes. Reinforced mesh not used in all cases, but only when additional reinforcement is needed.
5. The next layer is more than 5 cm thick and is a subfloor. For its arrangement, a concrete solution is used. After it gains strength within 2-3 weeks, the next layer of the “pie” is installed on the surface.
6. This layer consists of a special membrane or waterproofing film that prevents the risk of absorbing excess liquid. concrete base. The film is laid with an overlap, in order to avoid the appearance of cracks, construction tape is used, with which all butt sections are glued.
7. Next stage- installation of insulation, which is recommended to use foamed polystyrene foam or high-density polystyrene with a foil coating. If there is too much load on the floor, it is better to use insulation in the form of plates.
8. Next, waterproofing or roofing material is installed. After which the construction of the final screed is carried out. It is on it that the final finish coating will be installed. The thickness of this layer is from 8 to 11 cm. This screed needs to be reinforced.
Concrete floor in a house on the ground: advantages and disadvantages of arrangement
Among the advantages of manufacturing a concrete floor on the ground, it is worth highlighting:
- security reliable protection foundations from the effects of low temperature, the soil on which the floor is settled always differs only in temperature above zero;
- a variety of heat-insulating materials for floor insulation allows you to build a structure with good performance prevention of heat loss;
- the floor that will turn out as a result is finished with any of the existing floor coverings;
- no special calculations are required for the floor, since the entire load is taken by the ground cover;
- the arrangement of a warm floor perfectly heats the room, in addition, they heat up quickly enough, and the heat is distributed evenly throughout the room;
- underfloor heating on the ground has good soundproofing characteristics;
- in addition, mold and dampness are practically not formed on such a floor.
Among the disadvantages of a rough concrete floor on the ground are:
- when using a multilayer floor, the height of the rooms is significantly reduced;
- in the event of a malfunction for dismantling, a lot of material resources will be required;
- the arrangement of the floor on the ground requires a large investment of material, physical and time resources;
- if the groundwater is too high or if the soil is highly loose, it is not possible to equip such a floor.
Construction of a concrete floor on the ground: the choice of materials
As mentioned earlier, to equip a concrete floor on the ground, you will need to build multilayer construction. It is recommended to use as the first layer river sand, further rubble or expanded clay.
After their installation, a rough screed is installed, waterproofing film and thermal insulation. Next, a finishing screed is installed, which is the basis for laying finishing materials.
The main function of sand and crushed stone is to protect the premises from the penetration of moisture into it. When using crushed stone, it is necessary to carefully compact it, and crushed stone must be treated with bitumen.
If the soil is too wet, the use of expanded clay is unacceptable. Since it absorbs excess moisture, and then changes its shape. After covering the layer with a film based on polyethylene, a rough screed is poured, with a layer of about eight centimeters. Further, a waterproofing of two overlapped polyethylene layers is installed on it. Please note that polyethylene must be very tightly interconnected to prevent moisture from entering the room.
- extruded polystyrene foam;
- mineral wool;
- foam glass;
- polystyrene, etc.
After that, the finishing screed is arranged, which is necessarily reinforced. To ensure the evenness of the screed, the use of beacons is recommended.
Concrete floor on the ground manufacturing technology
The floor should be started only after the walls and roof have already been erected. Manufacturing procedure concrete pavement on the ground includes the following steps:
- carrying out work to determine the height of the floor and its marking;
- cleaning the top layer of soil and compacting the base;
- installation of gravel or gravel;
- hydro- and thermal insulation works;
- strengthening concrete screed;
- installation of formwork for pouring mortar;
- direct filling.
The floor on the ground is built in such a way that it is flush with the doorway. Markings should be applied around the perimeter of the building. To do this, marks are installed on the walls, at a distance of 100 cm from the bottom of the opening. When the markup is done, it should be lowered back one meter. This line will become a guide for pouring concrete. For easier marking, it is necessary to install pegs on which the ropes are pulled along the corner parts of the room.
The next stage of work involves cleaning the base from the top layer of soil. First you need to get rid of any debris that is on the floor. Gradually remove the entire top of the soil. The concrete floor on the ground has the appearance of a structure, up to 35 cm thick. Therefore, the soil that is removed from the surface must be of exactly this thickness.
With the help of special equipment, such as a vibrating plate, the surface is compacted. In its absence, it is enough to use wooden log, with handles previously nailed to it. The resulting base should be even and dense. While walking, no marks should be left on it.
With a lower location of the soil in relation to the doorway, only its upper part is removed, the surface is well compacted, and then covered with sand.
Further work is carried out on the installation of gravel and gravel. After compaction of the base layer, backfilling with gravel is carried out, the thickness of this layer is about 10 cm. Tip: After backfilling, the surface is watered with water and compacted again. To simplify control over the evenness of the surface, it is necessary to drive pegs into the ground, set in relation to the level.
After the gravel layer is leveled with sand. The layer should have the same thickness, about 10 cm. In order to control the evenness of the surface, use the same pegs. For the arrangement of this layer, it is recommended to use ravine sand, which has various impurities.
On the sand, crushed stone is laid, with a fraction of 4x5 cm. Then it is compacted, and the surface is sprinkled with sand, leveled and compacted. Lay the gravel in such a way as to avoid the appearance of its protruding edges on the surface.
Please note that each of the layers laid on the floor must be previously checked for horizontality. Therefore, in the process of work, use the building level.
Thermal and waterproofing of the concrete floor on the ground
To create a waterproofing layer, it is enough to apply polyethylene film or membranes. The waterproofing material should be rolled out around the entire perimeter of the floor, try to bring its extreme sections a few centimeters beyond the zero designations. The sheets are overlapped and fixed to the surface with adhesive tape.
In order to improve the thermal insulation of the floor and prevent freezing of the soil, it is recommended to treat the floor with mineral wool.
Features of the reinforcement of the concrete floor on the ground
In order for concrete to acquire the desired strength, it must be reinforced. To perform this process, it is recommended to use a metal or plastic mesh, reinforcement bars or reinforcing wire.
To install the reinforcing frame, special stands should be equipped, the height of which is about 2.5 cm. Thus, they will be located directly on the concrete floor.
Please note that the use of a plastic mesh involves stretching it on previously clogged pegs. When using wire, welding and the skill of working with it will be required to make a reinforcing frame.
In order for the pouring procedure to be quick and the result to be of high quality, it is necessary to install the guides and mount the formwork. Divide the room into several equal segments, the width of which is no more than 200 cm. Install guides in the form of wooden bars, the height of which is equal to the distance from the floor to the zero mark.
To fix the guides, use thick cement, clay or sand mortar. A formwork is installed between the guides, which is the former of cards poured with concrete mortar. As a formwork, it is recommended to use plywood with moisture-resistant characteristics or wooden boards.
Please note that the guides and formwork are brought out to zero and aligned in relation to the horizontal surface. Thus, it will be possible to obtain a base that is distinguished by evenness. Before installing the guides and formwork, they should be treated with a special oil, which will facilitate the process of pulling them out of the concrete mixture.
Technology of pouring concrete floor on the ground
Filling is carried out once or maximum twice. Thus, it will turn out to build a homogeneous and powerful structure. In order for the concrete floor on the ground to serve its owners with their own hands for a long time, it is best to order a special concrete mortar from the factory. Its strength and quality is much higher than that of a home-cooked composition.
For self-production of the solution, you will need a concrete mixer, cement of a grade of at least 400, river sand and aggregate in the form of crushed stone.
In order to prepare a concrete mortar, one part of cement, two parts of sand and four parts of filler should be mixed, while, based on the total amount of ingredients, half of the water will be required.
All ingredients are mixed in a concrete mixer, make sure that all ingredients are well mixed with each other. Start pouring the floor from the area opposite to the entrance to the room. Pour three, four cards at a time, and then use a shovel to level the composition over the entire surface.
To ensure good adhesion of concrete to the surface, the use of a manual concrete vibrator is recommended.
After most of the cards are filled, it is necessary to carry out a rough leveling of the surface. For these purposes, you will need a rule, two meters wide, which is stretched across the floor with smooth movements. It is the rule that will help get rid of excess concrete that falls into empty cards. After leveling, the formwork should be removed and the remaining sections filled with mortar.
After leveling the entire floor area, cover the floor with polyethylene film and leave for a month. Please note that after a few days, the surface is constantly wetted with water, in order to avoid drying out of the concrete, the formation of cracks and looseness of the base.
The final stage involves the treatment of the floor with self-leveling mixtures, which equip the screed. It is the mixture that will help to make the base perfectly even and eliminate minor surface irregularities.
Work also begins from the corner opposite the door, it is recommended to use a shovel to apply the mortar, and a rule to level the base.
The floor is defended for 72 hours. Next, the floor is ready for laying floor finishing materials. It is this type of concrete floors on the ground in a private house that will allow you to get a solid and durable foundation.
Concrete floors on the ground video:
Despite their high strength, concrete screeds may need additional reinforcement. This is relevant in conditions of high mechanical loads, when pouring unrelated structures, in case of shrinkage and deformation of concrete.
Reinforcing concrete floors are not always implemented. But, reinforced structures win in terms of operational and technical specifications. Steel protects the screed from cracking that occurs during the maturation of concrete due to natural shrinkage.
The device of a reinforced concrete floor is reasonable in order to protect the structure from mechanical pressure, vibration loads. In general, we can talk about long-term operation.
When a reinforced concrete floor is laid:
- if the project will lay a floating screed. This issue is especially relevant in the presence of loose substrates, in the presence of a large number layers (steam, hydro, thermal insulation);
- if the floor is laid on the ground, which is due characteristic features soils (heaving, etc.), especially in the presence of heat-insulating layers based on expanded clay;
- topical building codes and the rules dictate mandatory reinforcement in underfloor heating systems. Without reinforcement, such structures are more susceptible to deformation, due to constant temperature changes;
- concrete flooring is always reinforced in industry, especially in areas with high traffic and under heavy equipment.
Reinforcement is a mandatory stage of work with a concrete layer height of more than 50 mm
Materials used
When pouring concrete screeds, only those reinforcing materials are used that are approved for use by the current rules and regulations.
This group includes:
- steel meshes (reinforcing, wire);
- fiberglass - for bulk reinforcement;
- fiberglass meshes;
- grids based on modern polymeric materials.
Certainly the most durable structures created on the basis metal fittings. They are successfully used in industrial premises, garages, warehouses, open street areas. The solution is suitable for the installation of screeds on the ground.
Fiberglass and polymers are optimally matched to the requirements of underfloor heating screeds. They are not suitable for the construction of structures on the ground. Such materials are light, do not give an additional load on the overlap, but do not work well for breaking. It can be said that this perfect solution for places with small loads.
Volumetric strengthening with fiberglass provides protection against shrinkage deformations, blocks the formation of microcracks. The material is introduced into the concrete formulation, but is not suitable for working on soils (or is used in combination with traditional reinforcement).
In addition, fibrous varieties do not provide protection against bending and tensile stresses.
The nuances of reinforcing concrete floors
For concrete floor structures, which will have high and ultra-high loads, it is better to choose metal reinforcement. The diameter of the bar is determined depending on the operating conditions and loads. In practice, this is 6-12 mm. The most common cell size is 10*10, 20*20 mm.
The reinforcing mesh can be connected into a single system with a knitting wire or by welding. Both options work successfully in screeds on the ground. The current standards allow the installation of the grid in two layers. The cost of reinforcement depends on the mesh size, material consumption, and bar diameter.
Finished wire mesh is available in sheets and rolls. The basis is a wire of class VR-1 and d 2-6 mm. The material is suitable for the device of rough screeds in conditions of moderate loads. Cell dimensions can vary within 50*50 - 200*200 mm.
Principles of working with metal reinforcing mesh:
- regardless of the technology used, the mesh must be placed in the thickness of the concrete. This will protect the steel from corrosion;
- the base is cleaned of delamination, dirt, dust;
- the detected cracks need to be expanded, dedusted, treated with soil and repaired with a repair mortar;
- the base is primed in 2-3 working approaches;
- hydro and sound insulation flooring is carried out with gluing of overlaps and access to the walls;
- marking is carried out using the level;
- the reinforcing mesh is laid on stands so that the material is in the concrete body, observing an overlap of one cell;
- joints are tied with knitting wire;
- beacons are mounted on top of the reinforcement layer using metal U-shaped profiles;
- a solution is laid out between the beacons, alignment is carried out using the rule;
- when the concrete has set, the guides are dismantled, the resulting voids are filled with mortar.
The screed is protected by a covering material and is protected for 5-7 days
Features of reinforcement with plastic meshes
If the concrete structure is arranged on the floor slabs and too high loads are not expected, it makes sense to turn to plastic reinforcing meshes. This is the optimal solution for strengthening screeds up to 80 mm thick, including when implementing self-leveling systems and underfloor heating.
The advantages of such materials are much lower mass compared to steel, high elasticity. Plastic is able to stretch, which works to preserve the integrity of the structure under the action of shrinkage processes.
The material is sold in rolls, at an affordable cost (from 120 r / sq.m.). You can count on convenient transportation, installation, cutting. Plastic is not subject to corrosion, resistant to aggressive environments. The reinforcement technology is identical to the previous one.
Features of the use of fiberglass materials
Only fiberglass that has been treated with special impregnation works with concrete. This prevents the destruction of the material in an alkaline environment, which is typical for cement mortars. The most common reinforcing meshes are woven on the basis of aluminoborosilicate glass.
If we talk about the benefits, they are identical to their polypropylene counterparts. The scope of application is the same as plastic nets. Fiberglass is an easy to transport, lightweight, elastic material, but it does not withstand high temperatures (200 degrees limit) and is unsuitable for areas with an increased risk of fire.
Features of bulk reinforcement
The basis of such amplification is a mixture fibrous materials. It can be polypropylene, metal, basalt, fiberglass. The material is introduced into the concrete formulation during the preparation of the solution. After the screed has gained strength, a monolithic coating is formed, which is minimally prone to cracking.
The choice of material type is based on the purpose of the screed. So, for lightweight structures, polypropylene and fiberglass are required. For higher loads, it makes sense to pay attention to metal varieties. If the structure will be operated in difficult conditions or on outdoors, apply basalt fiber.
When mixing the solution, the fiber is filled up at the stage of mixing the dry components, after which mixing with water is carried out. The composition is laid out on the base and aligned along the guides. Volumetric reinforcement is easily combined with traditional.
Concrete floor works
The device of the concrete floor is implemented using the following technological operations:
- pouring a reinforced concrete slab of the appropriate thickness, or compacting the soil, installing a sand and gravel cushion;
- reinforcement in one layer;
- pouring concrete along guides, class not lower than B22.5. Guides are arranged using an optical level. Alignment is realized by an aluminum rule (5-7 m). Without guides, they work on liquid beacons using a vibrating screed. The sealing of the screed is realized by deep vibrators;
- grouting is carried out by concrete trowels when the base gains strength and can withstand the weight of a person and equipment. During the operation, the film formed as a result of the hardening of the solution is removed. Work is carried out 3-6 hours after laying the solution at t not lower than +20 degrees;
- the second grouting and smoothing with the blades of the trowel to a mirror finish;
- distribution of roller care products;
- filling the seams with sealing profile materials.
It is necessary to cut expansion, temperature-shrinkage seams with a cutter to a depth of 1/3 of the thickness of the structure
Detailed list of works
The compacted soil base is filled with sand. The average layer thickness is 200 mm. Layer-by-layer compaction with vibrating plates is carried out. The sand must be compacted in accordance with the design marks, which is controlled by a level. Another technology involves the construction of reinforced concrete slabs.
Installation of formwork, guides
Concrete floor is being laid separate sections- cards. These are rectangular zones of the required size. The actual fill map options depend on total area surfaces and the possibility of laying mortar in one work shift.
Along the perimeter of the cards, formwork is installed under the mark of the finishing floor. Material - wooden board 50 * 100 mm. In the boards, holes should be pre-drilled for the reinforcement pins in increments of 50 cm. The formwork lines should overlap the pattern of expansion joints.
If the installation will be carried out along the guides, they are arranged on the basis of metal profiles, or a steel corner 50 * 50 * 3 mm, or a profile pipe 40 * 20 * 2 mm.
Guide rails are welded to rebar posts with a diameter of 12 mm. Evenness is controlled by an optical level. All places where the surface adjoins load-bearing structures pasted over with a damper tape based on polyethylene foam, for example, Izolon 4 mm thick.
Profiles should be treated with engine oil before filling. The rough base is moistened with water.
Reinforcement
AT concrete floors reinforcement is carried out in accordance with the project, based on the expected loads. You can use a welded road mesh with a diameter of 4 mm, a cell size of 20 * 20 cm. The material is laid in one layer, overlaps are provided. Reinforcement clamps are mounted - chairs to ensure protective layer in 20 mm.
All overlaps are fixed with a knitting wire with a diameter of 1.2 mm. Overlaps and protective layer are checked. Before laying the reinforcing mesh frame on the base, it is recommended to put a polyethylene film. This will reduce moisture loss from the concrete mix and provide waterproofing.
If the project requires laying a reinforcing mesh in two layers, you can use a road mesh with a diameter of 5 mm and a cell size of 15 * 15 cm. The bottom layer is mounted on plastic clamps (support 35-50), which will give a protective layer of 35 mm.
Upper - mounted on special strip clamps, taking into account gaps in the areas of shrinkage and technological seams. For work, strip fixators FP 60-4.0 are taken. They are connected to the mesh with a tie wire and provide a protective layer of 25 mm.
Concrete laying
When laying concrete according to the maps, there should not be long technological breaks, that is, more than 60 minutes
After the installation of reinforcement and formwork, it is the turn of pouring the concrete mixture. The choice of material is based on the type of construction, method of installation and transportation. When working on floors, a class not lower than B22.5 is applied.
If the area and working conditions do not allow the mixer to drive close to the object, concrete pumps are used. With a small amount of work, concrete mixers are used. The filling must be continuous, otherwise the risk of cracking is high.
In order to increase the plasticity and workability of the solution, it is permissible to introduce C-3 plasticizers into the formulation (in the factory).
Leveling and compaction
Compaction of the solution is carried out by deep vibrators. For leveling along the guides, a rule is taken. Work with the surface is carried out in 3 technological approaches. If the concrete shrinks, the mortar is added with a shovel in the required quantities.
Control over the correctness of laying is implemented using a level, which corresponds to SNiP 3.04.01-87.
If the guides were planted on liquid beacons, they act as deep vibrators and vibrating screeds. The work is carried out in 2 working approaches. With this technology, plasticity and workability of the solution are required, for which it is recommended to introduce plasticizing additives C-3. Concrete is laid and leveled so that the top is slightly above the level of the screed. Next, the tool is pulled along liquid beacons.
Under the action of vibration, the solution settles to the required level and is leveled. But, it is required to ensure that the tool constantly slides over the surface. If the material settles below the level, it is added with a shovel.
Grout
Before grouting, a technological break is arranged. The structure must gain the required plastic strength. Final time depends on humidity and temperature environment. As a rule, 2-7 hours are enough.
During this time, the material will gain strength so that it will be possible to safely step on its surface without leaving marks deeper than 3 mm. They start processing with a trowel with disks in several technological approaches. Where concrete adjoins building envelopes, walls, doorways, columns, grouting is carried out first. This is due to the fact that in these areas the solution gains strength faster than in the main area.
Primary application of dry hardeners
After grouting, a dosing trolley is taken and dry topping is applied. Quantity - 50-60% of the total consumption. On average, it is 1-1.5 kg/sq.m. The total consumption is in the range of 2.5 kg/sq.m., but may increase equivalent to an increase in floor loads.
When the composition absorbs moisture from concrete slab, which can be traced by darkening, the first grouting is carried out by concrete finishing machines with a disc. Work begins near walls, columns, doorways . Work is continued until a uniformly mixed mixture is formed on the surface.
Topping should be completely saturated with cement milk and connect to the surface
Second application of hardener
When the first grouting is completed, the remainder of the mixture is spread immediately. This will allow the topping to absorb the moisture from the laitance before the water evaporates. The application is carried out in such a way as to compensate for the possible uneven application of the first layer.
When moisture has been impregnated, which is traditionally traced by darkening, proceed to the second grout. They work until the topping is completely saturated. If additional compaction is required, the treatment can be duplicated.
smoothing
Finishing grout is realized by blades. Based on the state of the surface, the interval between approaches is determined. The concrete should become opaque without getting your hands dirty when touched. Work is completed when a smooth, even surface is formed.
Now you can cover the concrete with polymer compounds. The material is applied with rollers. This will prevent too rapid loss of water.
Cutting of thermal shrinkage seams
For 2-3 days after completion of work, shrinkage and technological seams should be cut. To determine the readiness of concrete for work, a trial cutting is required. The edges of the seam should not crumble and be painted.
Seams are required to compensate for shrinkage and temperature processes occurring in the structure during concrete hardening. Plus, they prevent linear thermal deformations that occur during operation.
Joint cutting map: from 2.5*2.5 m to 3*3 m. The pattern must match the axes of the columns. In the area of the columns, the cutting is made in the form of a rhombus. They act in such a way that the glass of the column is located inside the rhombus. Cutting depth - 1/3 of the thickness of the screed. Width - no more than 3-5 mm. Next, the recesses are filled with sealing cords. It is better to use a special profile seal.
What determines the price of reinforced concrete floor
The overall level of costs is based on a number of factors, the main of which are the presence of upper protective layers, area, number of layers, type of reinforcement, quality of concrete.
Area is practically the only factor that cannot be influenced in any way. The larger the room, the more expensive the work will cost. However, large companies offer discounts on large volumes of work.
The quality of the mortar, the presence and type of reinforcement affect not only the costs, but also the overall characteristics of the finished structure. Trying to save on price will result in the floor having to be repaired or replaced. Conversely, an excessive number of layers and unnecessarily reinforced reinforcement will increase the load, and with the slightest error, this will lead to a loss in the durability of the coating.
The presence of upper reinforcing layers has a very significant effect on the cost of the floor.. But against the background of such costs, the durability of the system increases.
The layers provide floor protection against excess moisture, mechanical damage
conclusions
The quality of the concrete floor is directly dependent on the quality of the concrete. Choosing the optimal solution, they are guided by the strength, durability, moisture resistance of the material, therefore, work on the construction of the structure begins with the choice of concrete class, as applied to each specific object. It is important to organize proper training, backfilling and tamping of the lower layers of the structure.
If we talk about reinforcement, the rule applies here - a lot does not mean good. The reinforcement system must be designed taking into account the operational loads and working conditions. Otherwise, you can count on excessively high costs and excessive loads on the base.
Otherwise, the production of concrete floors requires the participation of conventional building materials and equipment: concrete mixers (if not ordered finished material), brushes, rollers, shovels, polyethylene films, reinforcing additives, etc.
The process of reinforcing the floor under a concrete screed is shown in the video:
In this article, we will analyze in detail the design and construction of a monolithic concrete floor on the ground. Under the "floor on the ground", further in the article, we will understand the concrete floor, made inside the contour of the foundation, right on the ground. Consider FAQ associated with this floor, and the structure itself from the ground to the finish coating.
With what types of foundations can you make a floor on the ground
A concrete floor along the edge can be used with a strip foundation, and with a columnar foundation (or a foundation using TISE technology). The slab foundation itself (by its design) is immediately a floor on the ground. With a strip foundation, the floor structure, as a rule, adjoins the foundation wall.
Rice. 1. Adjoining the floor on the ground to the strip foundation
Rice. 2. Adjoining the floor on the ground to column foundation with a low grillage
With a columnar foundation or a foundation using TISE technology, the floor structure on the ground can be adjacent to the grillage (if the grillage is low), or located below the grillage (if the grillage is high).
In the case of a high grillage, the gap between the floor structure and the grillage is closed when the floor is filled, for example, with boards (can be unedged). These boards remain in the structure, they are not removed, Figure 3.
Rice. 3. Adjoining the floor on the ground to the columnar foundation in the case of a high grillage
The height of the floor device on the ground relative to the strip foundation
Rice. 4. Floor on the ground on the tape extension
Rice. 5. The floor on the ground is adjacent to the wall of the strip foundation
Rice. 6. The floor on the ground is located above the foundation tape
Rice. 7. Floor on the ground adjacent to the top of the tape
There are no constructive mandatory recommendations regarding the mark (height) of the floor device on the ground. It can be arranged at any height shown in Figures 4-7 above. The only thing you need to pay attention to when choosing this option is where the front door will be in height. It is advisable to attach to the mark of the bottom of the door so that there is no difference between the bottom of the door and the floor, as in Figure 8, or so that you do not need to then cut an opening in the tape under the door.
Rice. 8. Height difference between the floor on the ground and the doorway
Rice. 9. Floor on the ground flush with the doorway
Note: opening under front door it is better (more correct) to foresee at the stage of pouring the tape. Just do not flood this place, insert boards or polystyrene there, so that an opening remains in the tape. If you forgot to leave the opening, then you will either have to make the entire floor higher (and this will increase the cost of backfilling), or cut an opening in the finished tape, cut the reinforcement in it, loosen it, etc.
Thus, if the opening under the front door is made correctly (at the stage of pouring the tape), then we arrange the floor on the ground so that the top of the floor is flush with the opening under the door (taking into account the finishing coating). In order to correctly calculate the thickness of the floor structure, and determine from what mark you need to start its construction, you need to understand what all its layers will be in thickness, what it depends on. More on this later.
There are no such cases. Even when the groundwater level is high, it is more correct to arrange a monolithic floor on the ground than a floor on logs, for example. The type of soil, seismic, freezing level - all this also does not affect the possibility of constructing such a floor.
Note: We do not consider situations when the house is raised above the ground on piles, it is clear that then such a floor is not suitable.
Floor construction options on the ground
Rice. 10. Floor construction on the ground at ground water level higher than 2 m (with waterproofing)
Rice. 11. Floor construction on the ground at low groundwater level, below 2m, with backfill
Rice. 12. Floor construction on the ground at low groundwater level, below 2m, without filling, with pouring instead of a rough screed
Rice. 13. Floor construction on the ground at low groundwater level, below 2m, without filling, with a rough screed
Rice. 14. Floor construction on the ground in combination with a warm floor
Note: Figure 14 shows underfloor heating pipes and a reinforcing mesh above them. Between the floor pipes and the reinforcing mesh, - no gap, just drawn for clarity.
Description of the main layers of the floor on the ground
Let's analyze the main layers (pie) of the floor on the ground. We consider the design from the bottom - up. We will describe all the layers that may be, without reference to a specific pattern.
- compacted soil- the basis for the device of a floor, has to be qualitatively condensed;
- Backfill layers(sand 7-10 cm and gravel 7-10 cm). Backfill layers can be made to protect against capillary rise of water and can be made as a leveling layer. Crushed stone in the bedding layer should be of a fraction of 30-50 mm (large). The sand in the bedding layer can be any, both river and quarry (ravine). It depends on the purpose for which the backfilling is done, whether it is possible to replace crushed stone with expanded clay, you can read about this in the paragraph Is it possible to replace crushed stone with expanded clay, in the same article, below. It is important that the layers of backfill are well compacted. There are conditions when a bedding device is mandatory, and when it is not. You can read about this in the paragraph What determines the design of the floor on the ground, in the same article, below;
- Rough floor screed on the ground. This is a layer on top of the bedding or compacted soil. Executed by polyethylene film(it spreads on the ground or bedding), the thickness of the rough screed is 5-7 cm. It can not be reinforced. Sometimes rough screed replace with a spill. About spilling - in the next paragraph, about when it is possible to replace a rough screed with a spill - in the paragraph Is it possible to replace a rough screed with a spill, in the same article, below. Crushed stone in the design of the rough screed should be a fraction of 5-10 mm (fine). The sand in the design of the rough screed must be river, not quarry (ravine);
- Spilling (filling) the floor on the ground. It is arranged by spilling a layer of bedding with a solution. The thickness of the pouring is equal to the thickness of the bedding layer. It is arranged without a plastic film;
- Waterproofing. It is arranged from roofing material, 1-2 layers. Roofing material can be taken the most common, without sprinkling. There are conditions when waterproofing is required. You can read about this in the paragraph What determines the design of the floor on the ground, below;
- . We recommend using EPS with a density of 28-35 kg / m 3, or polystyrene with a density of 30 kg / m 3 and higher as a heater for the floor on the ground. The thickness of the insulation is determined by calculation (depending on the climatic zone);
- Finishing screed. The thickness of the final screed is 7-10 cm. The crushed stone in the construction of the final screed should be a fraction of 5-10 mm (fine). The sand in the construction of the finishing screed must be river, not quarry (ravine). A finishing screed (unlike a rough screed) is necessarily reinforced. Reinforcement is carried out with a mesh with a wire diameter of 3-4 mm. How to choose, 3 mm or 4 mm, is written in the paragraph What determines the design of the floor on the ground, below;
- Finish coating . Finishing floor covering on the ground can be any. Accordingly, the details of the device are different for each type of coverage.
The presence and sequence of floor layers on the ground
What determines the design of the floor on the ground:
- From the level of occurrence of groundwater;
- From whether these floors will be with heat carriers (warm) or not;
- From operational loads on the floors.
How exactly the construction of the floor on the ground depends on these factors, we will analyze below.
1. By the presence of waterproofing. Our recommendations: to arrange waterproofing from roofing material (1-2 layers), if the groundwater level lies closer than 2 m from the bottom of the floor along the ground. In addition, when the groundwater is located closer than 2 m, we recommend that you make sure to add sand and gravel, Figure 10. If the level is lower than 2 m, then you can make the floor without waterproofing. At a level lower than 2 m, sand and gravel filling is not required, Figure 11, 12, 13.
Note: You need to focus on the highest groundwater level that can be on a particular construction site. That is, to watch how high the water rises in spring, during floods, etc., and this is the level to take into account.
2. If there are heat carriers in the floor structure on the ground, it is necessary to make a gap between the walls and the floor, 2 cm. This requirement is the same for both water and electric underfloor heating. The gap is made at the level of the finishing screed (with coolant). All layers below the finishing screed are placed to the walls without a gap, Figure 14. You can read more about installing a water-heated floor in the article.
3. If it is planned that something heavy (heavier than 200 kg / m 2) will be placed on the floor on the ground, then we reinforce the finishing screed with a mesh with a wire diameter of 4 mm. If the load is up to 200 kg / m 2, then it can be reinforced with a wire mesh with a diameter of 3 mm.
Important points when installing a floor on the ground
I would like to analyze these important points on the basis of questions that, as a rule, readers of our portal have when installing a floor on the ground.
Can interior walls be placed on this floor?
Yes, it can be placed on a 4 mm wire-reinforced screed internal walls from brick (to brick), from a partition block (100 mm), and a wall half a block thick. By "block" is meant any block (expanded concrete, shell rock, aerated concrete, foam concrete, etc.)
Can crushed stone in the bedding layer be replaced with expanded clay?
Backfilling is performed, as a rule, in order to break the capillary rise of water. Expanded clay swells from water, and, as a bedding material, is not suitable. That is, if the bedding was planned as additional protection from water - such a replacement cannot be done. If the backfill was planned not as a protection, but simply as a leveling layer, and the water is far away (deeper than 2 m from the base), and the soil is constantly dry, then crushed stone can be replaced with expanded clay for flooring on the ground.
Can crushed stone in the bedding layer be replaced with broken bricks, building materials waste?
It is forbidden. If the bedding was planned as additional protection against water, then broken brick and other waste will not fulfill their task in the bedding. If the bedding was planned not as a protection, but simply as a leveling layer, then we also do not recommend such a replacement, since these materials are of different fractions, it will be difficult to compact them with high quality, and this is important for normal operation floor structures.
Is it possible to replace crushed stone in the bedding layer with expanded clay, pour more of it, and then not put insulation?
To replace 50-100 mm of EPPS (that's how much on average is needed to insulate the floor on the ground), you will need 700-1000 mm of expanded clay. Such a layer cannot be compacted with high quality, so we do not recommend doing this.
Is it possible not to reinforce the screed?
You can not reinforce the rough screed. It is imperative to reinforce the finishing screed.
Is it possible to reinforce the screed with a non-mesh? Is it possible to put just metal bars in the screed instead of a reinforcing mesh, without tying them together, or other metal parts?
No, in order for reinforcement to work, it must be performed by a mesh.
Can waterproofing be laid directly on the layers of backfill?
No, waterproofing must be laid on a flat and solid base (in our case, it is a rough screed), otherwise it will quickly become unusable due to uneven loads.
Is it possible not to make a rough screed and put waterproofing or insulation (if there is no waterproofing) directly on the layers of backfill?
For waterproofing dismantled in the paragraph above. Insulation must also be laid on a flat and solid base. This base is the rough screed. Otherwise, the insulation may move, and subsequent layers too, and this may lead to cracks in the floor.
Is it possible to do a spill instead of a rough screed?
Let's analyze what we mean by "rough screed" and "pouring". A rough screed is a layer on top of the bedding or compacted soil. It is carried out on a polyethylene film (it spreads on the ground or bedding), the thickness of the rough screed is 5-7 cm. The thickness of the pouring is equal to the thickness of the bedding layer. It is arranged without a plastic film. Now about whether it is possible to replace the rough screed with a spill. If the water is closer than 2 m, and the bedding (sand and gravel) was carried out as a layer that prevents capillary rise, then watering cannot be done. Because the spilled rubble will not cut off the capillary rise of water. If the backfill was carried out for leveling purposes, and the water is deeper than 2 m, then you can do the spill instead of the rough screed. If there is no backfill at all, and the screed is carried out directly on the compacted soil, then both a rough screed and a spill can be done. It only turns out that it makes no sense to do the spill, since for it you still have to pour sand about 3 cm and crushed stone about 10 cm, and the sand in this case is river, and the crushed stone is about 10 mm fraction. In general, it is easier to perform a regular rough screed.
Does polyethylene under the rough screed replace waterproofing?
The function of this layer is to prevent concrete milk from going into the layers of backfill or into the ground. This layer is purely technological, it does NOT replace the main waterproofing (roofing material over the rough screed). If the water is deeper than 2 m, then waterproofing (roofing material) is not needed, but this does not mean that we “replaced” it with polyethylene. It's just that these layers have a different function, and do not replace one another. When installing a rough screed and water deeper than 2 m, a layer of polyethylene is still needed.
Where is it correct to place the reinforcing mesh in the finishing screed?
Does it matter where exactly the reinforcing mesh is located in the finishing screed layer (bottom, top or center)? If the screed is without heat carriers, then the mesh should be located 3 cm from the top of the screed (that is, approximately in the middle). If the screed is with heat carriers, then the mesh must be on top of the pipes, plus 2-3 cm of the protective layer.
Rice. 15. Finishing screed without coolants, reinforcement
Rice. 16. Reinforcement of the finishing screed with coolants
Some may say that the concrete screed is not very reliable and always remains cold. And its advantages include, perhaps, efficiency, environmental friendliness and fire resistance. It used to be like this, but the application modern materials and progressive technologies makes the service life and reliability of the screed much higher, and heat insulators provide a comfortable surface temperature.
The arrangement of a concrete screed on the ground is not always rational decision. There are certain restrictions that must be taken into account:
- no basement or basement;
- groundwater flow at a depth of at least 4-5 meters;
- the presence of heating in the house, since freezing of the soil can lead to deformation of the screed due to a higher load on the foundation.
Having decided to create a concrete floor on a soil base, you need to make sure that flooding does not threaten the house. It is possible to start arranging the screed only after the construction of the walls and roof of the structure.
A concrete pavement on an earthen base consists of several layers, each of which performs an important function. Layers are created from various materials, as a rule, the "pie" includes the following components:
- sand layer;
- crushed stone or gravel layer;
- waterproofing material;
- draft concrete floor;
- steam and heat-insulating layer;
- clean concrete floor.
As a finisher floor covering any commercially available material that conforms to stylistic direction interior and most harmoniously fit into the design of housing.
In no case should you start pouring concrete directly onto the ground, because the first two layers of the “pie” prevent the penetration of moisture from the soil into the floor covering, which can occur by capillary action. Creating a concrete screed is not the easiest and fastest process. The main difficulty lies in the fact that the work takes place in several stages. It’s not worth messing around, because as a result, a high-quality coating should be formed that is not prone to dust formation, airtight and resistant to loads.
The layered structure is the key to a long service life of the screed and its wear resistance. Modern technology for creating a concrete screed can be divided into two big stage: preparatory work and directly arrangement of the concrete pavement. Each of these stages consists of several parts.
Video - Floor screed on the ground
Preparation for the arrangement of concrete screed on the ground
Preparatory work is a mandatory step in creating a concrete floor, it is they who take the lion's share of the time in the process of arranging the screed. But it is not possible to do without them, unless, of course, you want to get a low-quality result.
filter layer
First of all, it is necessary to deal with the compaction of the earth at the base, which will help prevent its subsidence and, accordingly, possible cracking of the screed. Concrete floors on the ground are often equipped in combination with strip foundation at least 1-1.5 meters deep, filled with sand inside.
But this approach is not acceptable if the house is on a clay plot. After all, clay retains moisture, therefore, if there is sand inside the foundation, water stagnation forms and a real “pond” appears under the building. That is why in clay areas it is necessary to arrange drainage.
The best course of action in this case is:
- clay extracted during the creation of the pit is filled with its lower part;
- performed internal thermal insulation at home and external insulation foundation. These actions are aimed at leveling the heaving of the soil even in the absence of heating in the building;
- gravel is poured onto the prepared earth, and then carefully compacted. The quality of the rammer in this case is very great importance, since it is a question of preventing the formation of voids. It is carried out with the help of special ramming mechanisms;
- sand is poured onto the gravel, which is also carefully rammed and smoothed.
The thickness of the filter layer depends on the characteristics of the soil, as a rule, sand and gravel pads are not thicker than 15-20 cm each.
Waterproofing layer and rough screed
After backfilling the foundation, you can begin to arrange the waterproofing of the future screed. The most popular materials for this purpose are polyvinyl chloride and bitumen-polymer membranes. If the moisture level for the house is within the normal range, then you can get by with a conventional polyethylene film 250 microns thick, which is laid in two layers.
The edges waterproofing material should be slightly higher than the expected level of the final concrete screed. Special attention it is worth paying attention to laying waterproofing in the corners, since it is through them that moisture most often penetrates. If the material does not completely cover the perimeter of the room, then its elements are overlapped and fixed with adhesive tape.
The optimal material for a rough screed is "lean" concrete, in which crushed stone is added. The resulting surface does not have to be perfectly flat, and high requirements are not presented to her. It is quite enough if it does not have differences in height of no more than 4 mm. At the same time, its thickness should be about 4 cm.
Thermal insulation layer
Insulation of concrete screed - milestone Therefore, much attention is paid to the choice of thermal insulation material. It must have the following qualities:
- high strength;
- low thermal conductivity;
- fire resistance;
- ease of use.
Most often, preference is given to foam, polystyrene foam or a layer of mineral wool. Required thickness material is determined by the location of the house. For example, in central Russia, slabs 10 cm thick can be used for insulation, in less warm regions - up to 20 cm.
The laid heat-insulating material must be covered on top with a film of polyethylene, which performs two purposes at once: it prevents penetration concrete mortar into the space between the insulation elements and provides a vapor barrier.
Stages of arranging a concrete screed on the ground
Preparatory work ends after the creation of a heat-insulating layer. However, it is impossible to immediately proceed to pouring concrete - you need to take care of the strength and reliability of the future structure.
Screed reinforcement
The next step is the laying of reinforcement, which will give the concrete surface additional strength and durability. Traditionally, a road mesh is used for this purpose, the diameter of the bark bars varies between 5-6 mm. The dimensions of the cells in this case are 100 * 100 mm or 150 * 150 mm. Such reinforcement will prevent the appearance of cracks on the screed during shrinkage.
It is best to place the reinforcing layer a few centimeters above heat-insulating material, because this way it will be inside the concrete pavement. If the operational load of the floors is very high, then a reinforcing cage is used to strengthen them.
The photo clearly shows the mesh laid on the waterproofing
Formwork creation
Before starting the arrangement of a finishing concrete screed, guides and formwork are mounted. This technology allows you to more accurately maintain a given level. The available area is divided into equal segments, the width of which does not exceed 2 m. After that, guides are installed, their height should correspond to the desired level of the screed. Guides are fastened with a cement mortar, in which clay and sand are introduced.
Then, formwork is laid in the space between the guides, thereby dividing the base into rectangular parts, which are subsequently filled with cement mortar. Guides and formwork are brought to the desired level and aligned horizontally, serving as a guarantee of evenness of the future coating. After pouring, they will be removed from the concrete, which is quite difficult to do, therefore, to simplify this process, they are covered with special oil.
In order to obtain a monolithic surface, the screed is poured in several passes:
- work begins from the corner located on the opposite side of the door. After filling several rectangles, the solution is distributed with a spatula over the entire area;
- then comes the time rough leveling, which is carried out by movements of the rule towards itself, while excess concrete is removed;
- on the treated areas, the formwork and guides are removed, and the voids that appear are filled with a cement mixture.
This procedure is maintained until the entire floor area is filled. For sealing concrete surface you can use a special vibrator that will speed up the process and remove all voids. When the screed is completely ready and leveled, it is kept under the film for 3-4 weeks and moistened periodically. On the finished monolithic surface, it is possible to pour a leveling screed made of concrete M-100 and higher.
Creating a floor screed on the ground is a task subject even to home craftsmen. Modern technology the process is maximally facilitated, the main thing is to follow the stages of work, do everything efficiently and listen to the advice of specialists:
- the screed level is set taking into account existing or planned doorways. The marking of the level must be carried out around the entire perimeter of the base. Stretched cords will help simplify orientation;
- if in preparatory work the clay layer is involved, then it should be moistened and then compacted - such an obstacle will become almost insurmountable for groundwater;
- a concrete screed on an earthen base - a multilayer "pie", each of the layers in which must be carefully aligned horizontally;
- the thermal insulation characteristics of the concrete floor can be improved with expanded clay, cork or plywood layer;
- the thickness of the rough screed should be about 8 cm, and the heat-insulating layer should be at least 10 cm;
- while creating reinforcing cage for a concrete floor that has to withstand severe operational loads, it is best to use rods with a diameter of 8 mm;
- the concrete surface is prone to cracking; in order to avoid this trouble, expansion joints. After cutting, they must be sealed;
- to prevent the appearance of dust on the screed, special impregnations are used, which are applied no later than 7 hours after the concrete layer has been compacted.
It is very important to use high-quality materials when arranging a concrete screed, especially for the “stuffing”, that is, insulation and waterproofing. If they fail, then the whole structure will lose its strength and will not last long. You should not save on screed materials, otherwise you will later have to spend much more money on repairs.
The result of the implementation of competent work with quality materials will be the appearance of a reliable and durable concrete floor. It will not only withstand high operating loads, but will also serve as an ideal base for applying any of the topcoats on the market today.
Floors with a properly equipped concrete screed will last more than one year, or even decades. Observing technological sequence and paying due attention to all its stages, an amateur who has very modest knowledge about the repair process and possesses minimal skills will also cope with the creation of a screed.
tables
| Concrete brand | Mass composition, C:P:Sh, kg | Volumetric composition per 10 l of cement P/Sch, l | |
|---|---|---|---|
| 100 | 1: 4,6: 7,0 | 41/61 | 78 |
| 150 | 1: 3,5: 5,7 | 32/50 | 64 |
| 200 | 1: 2,8: 4,8 | 25/42 | 54 |
| 250 | 1: 2,1: 3,9 | 19/34 | 43 |
| 300 | 1: 1,9: 3,7 | 17/32 | 41 |
| 400 | 1: 1,2: 2,7 | 11/24 | 31 |
| 450 | 1: 1,1: 2,5 | 10/22 | 29 |
| Concrete brand | Mass composition C:P:Sh, kg | Volumetric composition per 10 liters of cement P/Sh, l | The amount of concrete from 10 l of cement, l |
|---|---|---|---|
| 100 | 1: 5,8: 8,1 | 53/71 | 90 |
| 150 | 1: 4,5: 6,6 | 40/58 | 73 |
| 200 | 1: 3,5: 5,6 | 32/49 | 62 |
| 250 | 1: 2,6: 4,5 | 24/39 | 50 |
| 300 | 1: 2,4: 4,3 | 22/37 | 47 |
| 400 | 1: 1,6: 3,2 | 14/28 | 36 |
| 450 | 1: 1,4: 2,9 | 12/25 | 32 |
| Styrofoam | polyurethane foam | Min. plate |
|---|---|---|
| open cell structure | There is both open and closed cell structure | Fibers randomly arranged in vertical and horizontal directions |
| Poor moisture permeability | Almost impervious to moisture | Almost does not absorb moisture |
| Lightweight material | Lightweight material | Medium-light material |
| Medium strength | Low strength | Low/medium strength |
| Average compressive strength | Low compressive strength | Low to medium compressive strength |
| Non toxic | Non-toxic, emits carbon monoxide and carbon dioxide at a temperature of 500 degrees | Non toxic |
| Not suitable for high load use | Not all slabs are suitable for high load applications |
Concreting performed with high speed on large areas, is the most economical way to level the old and equip the new floor. After curing smooth surface becomes the ideal basis for any finish coat. To increase the service life of the screed, reinforcement of the concrete floor is used. This process is carried out using various materials and designs from them.
According to their functions and location, the screed is divided into the following types:
- draft - rests on the ground;
- multilayer - includes heat and sound insulating gaskets;
- leveling - is laid on the draft layer, serves as the basis for flooring or tubular insulation;
- construction - lies on the floor slab.
It is advisable to reinforce the self-leveling concrete floor when arranging rough and multi-layer screeds (in the absence of a monolithic support, the effect of tensile and bending loads increases), as well as to reduce the calculated concrete layer.
Types of reinforcing structures and materials
1. Bar frame. Most often, it is laid in two layers, made from rods with a diameter of 6 to 40 mm. Apply with a coating thickness of more than 8 cm.
2. Steel wire mesh. It is used for multi-layer screed on the ground or for hardening the coating in the garage, hallway, kitchen.
3. Polymer mesh. It does not strengthen the screed, but only prevents cracking during the hardening of concrete. It is used for self-leveling floors, reducing the consumption of cement. The grid is installed directly on the base or on the heat-insulating layer.
4. Reinforcing fiber for concrete. There are two types: metal and polypropylene. Polymer fiber gives concrete resistance to cracking during shrinkage, to temperature fluctuations, enhances water-repellent properties.
Metal fiber increases the resistance of concrete to vibrations. Replacing reinforcing mesh steel fiber, save time (the elements are introduced directly into the mixer), reduce the thickness of the screed. Microcracks lose their ability to expand.
5. Combined reinforcement. In addition to the frame mounted in the lower section of the cover, its upper layer filled with fiber - this is how the concrete floor screed is protected from cracks. The method is applied to the entire surface or in places of increased loads (where the floor is adjacent to walls or columns). Fiber should be dosed according to the instructions.
The main stages of concrete pavement reinforcement
The most time-consuming is the construction of a concrete floor with a soil base. First, according to the technology, a gravel-sand mixture is laid, then a foundation slab, a para-barrier film, thermal and waterproofing. Next, a reinforced concrete layer is mounted.
1. Depending on the thickness of the screed, in private construction it is reinforced with a frame of bars or wire mesh. The diameter of the reinforcement for reinforcement is taken from the range from 8 to 20, and the wire - from 4 to 6 mm. The cell size is maintained from 10 to 20 cm.
2. The frame of solid rods is knitted with a wire with a diameter of 2 - 3 mm, the layers of the frame are attached to the ribs. If scraps of material are used, they are overlapped with a half-meter approach.
The wire mesh is purchased ready-made (cells 5 - 20 cm) or knitted by hand. Purchased products are connected with a wire with an overlap of 1 - 2 cells.
3. Finished construction it is laid on clamps ("high chairs") at a level of about 3.5 cm from the base. When pouring, the steel elements should be in the middle of the concrete layer - in this case, the loads are evenly distributed over the surface of the coating, its mechanical resistance is ensured, and there is no metal corrosion.
Consumption of reinforcement for floor reinforcement
Table 1 shows the data for the mesh version of the reinforcement, and in table 2 - for single reinforcement with steel bars from 10 to 16 mm.
Material, per 1 m2 of floor |