Insulated Swedish foundation technology. Construction technology of insulated Swedish plate. Installation of UWB - preliminary stage

In low-rise construction, you can do without pouring a monolithic concrete foundation and make a reliable, warm foundation for the future building. This opportunity is provided by foundations made using technology. UWB.

The abbreviation stands for insulated Swedish stove, which is effectively used in European countries. In Russia, the technology became known since 2009, but is not currently widely used - developers are just starting to master it.

The lack of interest is caused by the lack of complete and reliable information about this type of foundation. At first glance, the technology seems complex and expensive. In fact, the cost of work is lower than pouring a conventional monolithic concrete slab.

The structure of the insulated Swedish plate

The data in the article is purely informative and is not an instruction for arranging a UWB foundation: it requires precise engineering calculations that are tied to a specific building site.

There are several arrangement options, however, the differences are personal in nature and do not affect the overall installation technology. In fact, the Swedish foundation resembles a multi-layered pie, consisting of the following elements:

ground base with a pre-prepared drainage system;

geotextile substrates;

sand and gravel pads with areas for sewer pipes and utilities;

insulating layer;

waterproofing;

second layer of insulation;

strapping from fittings and underfloor heating systems;

concrete slab (medium thickness 100 mm);

floor finishing.

At first glance, the design seems cumbersome and complex, but this is an illusion. All work can be done on your own without the involvement of heavy construction equipment.

Provided that the work is carried out correctly at all stages, a solid foundation is obtained, with stiffeners and a standard heating system. This design completely prevents possible heat loss, while it has a high bearing capacity.

Advantages and disadvantages

Some of the shortcomings can be eliminated if the work is entrusted to qualified designers and workers. However, the involvement of specialists makes the financial benefit less attractive.

UWB or monolithic foundation?

At first glance, the economic benefits of arranging the UWB are imperceptible - a large amount of building materials are required, which cost a certain amount of money. The estimate includes the purchase of:

insulation;

fittings;

floor insulation systems;

other materials.

When pouring a monolithic foundation, such expenses are not required: the foundation is prepared, reinforcement is purchased, piping is made and concrete is poured. However, the financial benefits of pouring a monolith are understandable only to non-professionals.

Such a foundation can be compared to a bank loan: if there are not enough funds, fill the site, and then gradually build further. The process turns out to be extended in time, which implies a rise in the price of building materials. In addition, the monolithic foundation needs to be insulated and waterproofed, utilities will also be connected to the building.

UWB is suitable for people who understand the benefits of such a design and build a house that will be warm and cozy, regardless of the vagaries of the weather. If you make calculations for energy savings for 10 years forward, the attractiveness of the insulated foundation will increase. Against this background, a monolithic foundation looks like an ordinary slab, which requires additional investment.

Step-by-step technology for arranging UWB

The workflow begins with the involvement of technical experts who are able to calculate the bearing capacity of the soil, the likelihood of seam movement and the drainage system. After that, the arrangement of the foundation is carried out in a certain sequence.

The Swedish foundation is never laid on a fertile soil layer: this is guaranteed to lead to a shift in the structure during the construction of the building. Therefore, such a layer of soil is completely removed from the construction site.

The pit is made shallow: usually 2-3 shovel bayonets, however, its external dimensions should go one meter beyond the boundaries of the walls of the future building. The bottom of the pit is lined with geotextiles with the substrate running on the side walls.

Storm sewerage and groundwater drainage are necessary in order to ensure the dryness of the foundation. For these purposes, geotextiles are covered with a layer of rubble, an underground reservoir is made with pipes connected to it. To lay the drainage system along the perimeter of the pit, trenches are formed with a slope towards the main well.

Engineering communications

The next step is the distribution of pipes for water supply and sewerage. Communications are necessarily deepened below the level of soil freezing in winter.

In addition, it is necessary to plan in advance the location of the risers in the house, bring the pipes outside to connect to centralized or autonomous water supply systems.

Given the shortcomings of UWB, it makes sense to immediately duplicate the communication system in order to use the reserves in case of a malfunction. At this stage, a sand cushion is added, which is necessarily compacted by a rammer.

The first layer - closes the perimeter of the pit completely.

Second - recedes at 40-45 cm inside.

This is necessary in order to install along the edges L-shaped modules from expanded polystyrene for an external bypass.

At this stage, the distribution of the "warm floor" system is carried out with the installation of collectors and temporary pressure testing of pipes. Next, a two-layer reinforcing belt is made from reinforcement with a diameter 12-16 mm. Recommended grid pitch 15*15 cm.

Formwork manufacturing

For this, they can be used L-shaped modules expanded polystyrene, reinforced on the outside with boards and spacers to prevent their extrusion under the action of the concrete mass. The classic version can also be used: an internal frame made of thick plywood panels. The formwork height is calculated based on the following values: insulation thickness (20-30cm) and the plate itself (no more than 10 cm).

This stage does not differ from the arrangement of a monolithic foundation. The concrete mixture is fed continuously to prevent the formation of joints and is necessarily compacted with internal vibrators to evenly fill the internal space.

Keep in mind that the contact of the vibrator with pipes of "warm floor" or reinforcing mesh is highly undesirable.

Formwork can be removed after 72 hours after filling. If work is carried out in hot weather, the plate is covered with burlap or plastic wrap, periodically moistened with water. In winter, a heating system is laid before pouring.

Do you want to build a house on an energy efficient and solid foundation? Choose insulated Swedish stoves. When laying this material, engineering communications are simultaneously created.

UWB is a shallow foundation slab in the ground. Insulation is laid around the perimeter of the structure and under the base. It is equipped with engineering communications and a floor heating system.

The insulated Swedish slab (USHP) is both a ready-made solid foundation and a draft floor of the lower floor with an integrated heating system. Perfectly flat base surface reduces the cost of interior finishing work.

Advantages of UWB

The main advantage of UWB is that it is a complex solution. It is possible to equip a foundation of a similar type separately, using various technologies and materials. However, this approach increases the cost of construction. Insulated Swedish slab is a more economical and faster way to build a monolithic base.

1. The foundation based on UWB can be laid on any soil. This results in an insulated base with a plinth finish.
2. The ceiling of the first floor is completely ready for finishing. The ideally flat surface is suitable for laying flooring without a screed device.
3. Engineering communications are built into the UWB - pipes for water supply, electrics, sewerage.
4. The foundation has an efficient water disposal and drainage system, which allows you to keep house structures dry.
5. A low-temperature water heating system is integrated, for the operation of which it is only necessary to connect boiler equipment.
6. The insulation around the UWB completely protects the structure from frost heaving.
7. Foundation energy efficiency. Insulated Swedish stove allows you to save on heating.
8. Efficient heat accumulator.
9. Fast installation - up to 2 weeks.

When laying UWB, several factors are taken into account: potential pressure on the entire structure, freezing depth and soil properties.

Stages of arrangement of UWB.

Solid slab foundations, even before the advent of high-strength insulation, were considered an effective means of compensating for seasonal (frost heaving) and non-seasonal soil movements. Being "floating", they retained the relative position of all elements of building structures relative to each other even when houses hit the zones of small landslides. The original engineering innovation that combined the solution of energy efficiency problems was the so-called USP foundation, the technology of which came to us from Sweden and Germany. This article describes the design and operational features of the insulated Swedish plate (this is how the abbreviation "UShP" stands for).

About 10 years ago, the first domestic enthusiasts - developers used standard projects of this particular company. According to Dorocell, the optimal energy-efficient foundation for low-rise housing construction is a high-quality monolithic concrete slab with stiffeners, external thermal insulation and built-in heating.

Scheme of the technology for the installation of an insulated Swedish UWB board using TechnoNIKOL materials

Thermal insulation, representing a kind of "trough" for pouring concrete, serves as a natural fixed formwork.

Here is a detailed overview of the foundation of the insulated Swedish plate:

1. Formwork made of PSB-S polystyrene is assembled on compacted sand and gravel bedding. At the bottom of the backfill bed, slopes are made and a drainage pipe is installed.
2. Formwork 400 mm high consists of slabs 100 mm thick and forms rectangular grooves along the perimeter with a section of 400 × 200 to form stiffeners and a bed for pouring the main slab 100 mm thick.
3. Reinforcement of the ribs is carried out in two belts with a profile of variable section with a diameter of 8 - 12 mm. Reinforcement of the floor slab is carried out using a welded mesh 150 × 150 mm.
4. Pipelines of the heating system are immured into the floor slab. Reinforcement of the floor slab is carried out using a welded mesh 150 × 150 mm, laid over the pipes of the warm floor.
5. In addition to the heated floor, other communications are also poured with concrete - plumbing, sewerage, electrical wiring in the rooms.
6. The blind area is insulated along the perimeter of the foundation with 70-mm PSB-S slabs adjacent to the outside of the polystyrene formwork at the depth of its contact with the backfill.

Thermal insulation skirt around the foundation slab prevents freezing

The described scheme corresponds to the load formed by a two-story house with load-bearing walls made of cellular concrete, as well as climatic conditions with a frost index of 4000 - 8000. An increase in the load requires an increase in the section of the stiffeners, and a more severe temperature regime requires the addition of one or two additional layers of insulation.

There is an alternative technology for installing an insulated foundation: UFF - insulated Finnish slab. An overview and features of this type of foundation are described in

The best video about UWB technology

Pros and cons of the Swedish stove

Most importantly, as a result of the installation of the foundation according to the warm Swedish plate scheme, the developer receives a solution to a whole range of issues:

• efficient drainage,
• frost protection,
• energy saving,
• heating,
• comfortable microclimate,
• communications laying,
• as well as obtaining the floor surface for finishing coatings.

Other benefits of the scheme include:

• For frame houses, UWB compensates for their main drawback - the low heat capacity of the walls. A massive insulated foundation takes on the function of a backup heat accumulator.
• Price. Despite the fact that the Swedish scheme is not a cheap pleasure, it includes not only a zero cycle, but a whole range of stages. Performing these works separately costs much more in total.
• Timing. When performing work by a team of qualified specialists, everything will take, on average, about a week.
• Versatility. The technology is suitable for most soils and climatic zones of the Russian Federation.
• Indispensable in the construction of buildings of the "passive house" class.

Disadvantages of a foundation based on a warm Swedish plate:

• Conditional (psychological) disadvantage: low base. In houses with a conventional foundation, a high plinth is necessary to ensure normal indoor humidity. Until now, many of our compatriots tend to consider the height of the base as one of the guarantees of the quality of housing.
• Maintainability of communications. Since the floor slab is a stressed structure, it is highly undesirable to violate its integrity to repair immured pipelines. On the other hand, there are other laying methods and technical solutions that compensate for the lack of a circuit. But all these measures lead to an increase in the budget.
• Requires highly qualified performers. Not every team will take on the turnkey delivery of the UWB.
• It requires one-time significant capital expenditures, therefore it is not suitable for developers who rely on construction in small (in terms of money) stages.
• Not suitable for peaty soils and other soils with low bearing capacity, as well as sites with large slopes.

Technology development: methods, materials, components

To date, more than 1.5 million houses have been built under the UWB scheme in Germany and the Scandinavian countries. In Northern Europe, technology insulated monolithic slab foundation received the status of generally accepted and is reflected in the EU building standards. In the United States, complete external insulation of slab foundations is not very common, since 90% of the country's territory has a frost index of no more than 3000. However, UWB has found application there too: first of all, in the construction of "passive houses".

Over the past 10 years, project developers have given greater preference to extruded polystyrene foam (EPS) as a material that provides more uniform shrinkage of foundations and retains thermal insulation properties regardless of time and operating conditions. Stresses in concrete arising from the operation of shallow slab foundations were studied in detail. According to their results, the builders abandoned the idea of ​​using heaters with different ultimate strengths (previously it was assumed that in order to equalize shrinkage under the floor slab, it is necessary to use less durable boards than under the stiffening ribs). It has been proven that the most dangerous stress concentrators in a slab can occur at the junction of different types of heat insulator.

Manufacturers of extruded polystyrene foams began to produce materials and components specialized for the installation of UWB.

For example, Dorocell currently manufactures a complete set of XPS fixed formwork "constructor" parts in-house. The hallmark of the company are blocks with built-in guides for fittings. Some brands pay more attention to the aesthetic properties of the components: the sides of the formwork are molded in the form of plinths of a traditional variable section.

If we talk about the domestic market, then 2 brands can be distinguished on the market: TechnoNIKOL and Penoplex. Both companies produce XPS of the European quality level for slab foundations built using UWB technology. I would like to dwell in more detail on the specialized TECHNONICOL CARBON ECO SP series. In addition to the basic plate formats, it includes L-shaped profiles for quick mounting of the boards. In addition to the section, these elements are interesting in that CSPs (cement particle boards) are fixed on their base parts from the outside. DSP allows you to apply decorative plaster without additional preparatory stages. Thus, installation of UWB with the help of TechnoNIKOL components is currently the most convenient.

Algorithm for mounting an insulated slab foundation

For a full cycle of work on the arrangement of the USP, you will need the following basic materials:

• Geotextile;
• 100 mm EPPS boards for formwork formation and 70 mm boards for blind area insulation;
• fittings Ø12; welded mesh 150×150;
• Concrete grade not lower than M350 with the necessary additives, taking into account the pouring time and air temperature, anti-capillary crushed stone, coarse sand;
• Pipes of the PEX or P-PE type for a pressure of at least 6 bar at a coolant temperature up to +95 ° C, as well as a protective corrugation;
• Collectors for 1 "" (for a house with an area of ​​\u200b\u200bnot more than 250 sq. M. In most cases, 2 pieces are needed);
• Shut-off and valve fittings as part of Eurocone compression fittings, 1" ball valves and a pressure testing unit of the system;
• Special fasteners consisting of dish-shaped dowels, studded plates, FS-30/40 clamps, double-sided adhesive tape.

After performing geological surveys, strength calculation and purchase of materials, the marking of the future foundation is carried out. Based on the addition of 0.3 - 0.5 m to the edge of the insulated blind area, the perimeter is determined. The axes of the internal load-bearing walls are marked, as well as the points and directions for laying communications. Further work is carried out as follows:

1. Removal of fertile soil;

   

2. Laying geotextile along the bottom with an overlap of joints of at least 15 cm;
3. Layer-by-layer backfilling with crushed stone and sand is carried out. Each layer of 10 - 15 cm is rammed with a vibrating plate with water added for greater compaction;

   

4. Laying of communications - water supply, sewerage, power cables, ground loop, drainage system. When laying sewers, provide slopes. When arranging drainage, in addition to observing slopes, provide drainage wells. Check the operation of slopes with water.

   

5. Backfill drainage and sewer trenches and check the overall flatness of the backfill pad.

   

6. Proceed to the assembly of heat-insulating formwork. If L-profiles are not used, then you will need to perform a significant amount of work. First, the boards are glued end-to-end at a 90° angle with a special adhesive. For additional fastening, plate-shaped dowels and plastic fastening corner elements are used. Secondly, the resulting boards need to be fixed on the outside with plywood or boards, supporting them with battens.

   

7. Starting from the second or third layer of polystyrene, niches of stiffeners are formed during installation. Plates in a horizontal plane are laid "in a run", with a displacement of the joint line.
8. On top of the last layer of XPS, if necessary, a layer of vapor barrier is laid.

   

9. We proceed to the reinforcement of the stiffeners. Reinforcement is provided by four longitudinal reinforcement bars Ø 10 - 12 mm, forming the upper and lower chords. Power frames are connected with special clamps outside the formwork. Ready-made power units are installed in the grooves and fastened with the help of FS clamps.
10. With the help of the same clamps, a 150 × 150 grid is mounted for the floor slab (rod diameter 6 - 10 mm).
11. On the laid grid, underfloor heating pipes are mounted with fixation with nylon clamps. When crossing stiffeners and doorways, pipes must be protected with corrugations.

    

12. After installation of all contours of the warm floor, a connection is made to the collector. The places where pipes rise to the collector are protected by corrugation.
13. Each circuit is filled with coolant separately. Filling is carried out through the manifold until all air is expelled from the system. Then leak tests are carried out. After testing, it is necessary to crimp all connectors of the system.

    

14. Before concreting it is necessary to check the structure. The check consists in control measurements of the formwork, inspection of the reinforcement, cleaning the site of debris, protecting the outlets of communications from concrete, as well as checking the fixation of these outlets on the formwork. At the end of the preparation, the entire initial environment with the location of communications should be captured on detailed photos and an internal act of examination of the formwork and engineering systems should be signed.
15. We select a concrete supplier and order a mixture with the properties required for the project.
16. On the day of concreting, large-sized equipment (mixer, concrete pump) is placed, the mixture is accepted in terms of quality, the mixture is laid and taken care of. Laying works are carried out in accordance with the standard for this type of work, observing working methods and time intervals. During laying, it is necessary to carefully control the flow of mortar under the reinforcement elements. Surface leveling is carried out with the help of vibrating screeds. In the stiffening ribs, vibration treatment of the incoming mixture is provided. In order to ensure the required dehydration mode, the concrete is covered with a polyethylene film.

    

17. In the future, it is required to control the course of dehydration and check the surface for a set of strength of 15 kgf/cm2. This indicator makes it possible to carry out other construction work at the facility.

    

18. While the concrete is gaining strength, it is possible to organize the cleaning of the territory and the lining of the outer surface of the basement with a finishing material.
19. After facing the basement, it is necessary to organize a blind area. It is recommended to lay a drainage membrane over the blind area slabs. At the end of the work, the blind area is backfilled.

What stages of installation of the insulated Swedish plate is permissible and advisable to do it yourself? If you do not have experience in carrying out the described types of work, then only paragraphs can be recommended for independent implementation. 2; 6; 7; 8; 10; 14; 15; 17; 18; 19.

Persons with the necessary skills, but working alone at their facility, are allowed to carry out all types of work, except for concreting. An exception may be objects with a small area (up to 30 - 40 square meters).

At the initial stage of the construction of the building, the foundation is laid. Not only requirements are imposed on the foundation to ensure the stability and durability of the building. It is important to reduce the cost of maintaining a comfortable temperature in the room due to the energy efficiency of the foundation structure. The insulated Swedish stove meets these criteria. It is a solid reinforced concrete base, combining a warm floor and engineering communications. Let us dwell on the design features and manufacturing technology.

Foundation "Swedish plate" - purpose and scope

Thinking about the design of the foundation, most developers choose between tape, slab and pile structures. However, modern construction methods and innovative technologies make it possible to build a fundamentally new foundation. The Swedish slab is a shallow-depth slab-type base made of concrete and reinforced with a reinforcing cage.

The Swedish foundation slab is a multi-layer structure. The construction in the form of a kind of sandwich allows you to speed up the construction cycle and solve a set of important tasks:

Insulated Swedish slab (UShP) - a modern and complex foundation design

• effectively insulate a monolithic foundation slab;
• arrange electrical cables, water pipes and sewer networks;
• prevent possible deformation of the base;
• maintain a comfortable temperature in the room by heating the floor;
• create a reliable base designed for laying a decorative coating.

A foundation slab with an integrated heating system is used for the construction of buildings on soils containing an increased concentration of sand particles, peat, and clay inclusions.

The design features and the margin of safety of a monolithic slab allow the construction of buildings of various types:

• log buildings;
• timber houses;
• frame buildings;
• panel houses;
• buildings made of bricks and porous concrete blocks.

The use of light building materials makes it possible to erect buildings on a warm slab, the maximum number of storeys of which is 3 floors. The Swedish slab is constructed after performing thermal engineering calculations, as well as design measures that take into account the load from the mass of the structure and the characteristics of the soil. It is important to choose the right building materials from which the walls, ceiling and floor are built. Electrical appliances, together with internal communications, are placed in accordance with the project documentation.

A warm foundation in the form of a slab is a complex structure, the construction of which is associated with an increased amount of costs. When deciding to build an insulated Swedish UWB slab using modern insulation, all factors should be carefully evaluated.

Multilayer construction is preferred in certain cases:

• when the construction object is located on problematic soils;
• in the construction of buildings with a box height of up to 10 m;
• when located near the zero mark of groundwater.

The decision to use the insulated Swedish slab as the foundation of the building is made individually after analyzing all the factors.

Insulated Swedish stove - main advantages and disadvantages

The operating experience of the slab foundation in Sweden confirms that the Swedish warm slab combines innovative technical solutions aimed at energy saving. UWB plate is widely used abroad and is being gradually introduced by our builders.

The number of supporters of the new foundation is constantly increasing due to its advantages:

• reduced duration of construction activities. The necessary engineering communications are laid simultaneously with the construction of the foundation;
• no unevenness on the concrete surface. Grinding the subfloor at the final stage of construction allows the flooring to be laid on the concrete;
• preventing deformation of the soil under the foundation during freezing. Thermally insulated foundation minimizes the likelihood of soil deformation at negative temperatures;
• the possibility of building an insulated base without the use of special equipment. The absence of the need to use lifting devices reduces the amount of costs;
• innovative multi-layer foundation design. The mains of the heating circuit are placed in a concrete base, which makes it possible to avoid additional measures for their laying;
• the possibility of using UWB slabs for building houses on various soils. A solid foundation, in the construction of which reinforcement is used, allows the construction of facilities on problematic soils;
• uniform increase in the temperature of the concrete base when heated. It is ensured by compliance with the technology of laying heating mains;
• maintaining a comfortable temperature. Due to the increased efficiency of the heating system and the processes of convective heat transfer, it is easy to maintain the required microclimate;
• decrease in air humidity. Regardless of the moisture concentration in the soil, the formation of dampness, mold and fungus indoors is excluded.

The Swedish warm plate under the influence of efforts from the weight of the building does not crack and reliably insulates the room. Along with the advantages, the UWB plate has the following disadvantages:

• the complexity of the implementation of repair activities associated with the complexity of access to concreted communications;
• insufficiently high durability of the Swedish plate, due to the limited duration of operation of the heat insulator;
• the impossibility of arranging the basement;
• the need for qualified performance of heat engineering calculations, since the thickness of the Swedish plate depends on the characteristics and size of the insulation;
• increased estimated cost of work associated with the implementation of special thermal and strength calculations;
• the impossibility of arranging a heat-insulated foundation slab in sloping terrain.

Despite these disadvantages, such a slab is superior to traditional types of foundations in many ways.

Swedish stove - device diagram and technology specifics

Insulated slab is a type of slab foundation made in the form of a sandwich.

The multi-layer construction includes the following levels:

• communication. It includes electrical cables, water pipes and a sewer main;
• warming. Includes sheet expanded polystyrene in extruded form, heat-insulating foundation base;
• amplifying. Made of reinforcing steel with a cross section of 12-14 mm, preventing cracking of the heated floor;
• heating. Consists of a system of water mains designed for the circulation of the coolant;
• carrier. It is a concrete base that protects the heating lines and serves as the base for the construction of the building.

The creation of a foundation according to Swedish technology provides for a sequence of work, according to the requirements of the technological process. The entire foundation base is submerged into the soil to a shallow depth relative to the zero mark. Due to this feature, the possibility of frost heaving of the soil at high humidity is excluded.

In what sequence is the installation of the Swedish plate?

Compliance with the Swedish plate construction algorithm affects the strength properties of the base and energy-saving characteristics. The overall scope of work includes:

1. Construction of a pit.
2. Installation of drainage pipes.
3. Laying communications.
4. Insulation installation.
5. Assembly of a warm floor.
6. Concreting.

Consider the main features of the stages.

We mark the site

The indicated stage of work provides for the transfer of the foundation project to the local conditions. Prior to marking, it is important to carry out geodetic surveys aimed at determining the nature of the soil and the depth of the aquifers.

During the markup process, the following are determined:

• contours of the foundation;
• ways of connecting engineering communications.

After marking, it is important to protect the site from precipitation by arranging storm sewers.

We carry out earthworks

Earthworks include the following works:

1. Cleaning the construction site from construction debris and vegetation.
2. Extraction of the fertile soil layer to a depth of 0.4-0.5 m.
3. Formation of a compacted sand layer 30 cm thick.
4. Extraction of soil along the perimeter of the pit for drainage lines.
5. Backfilling of clay at the bottom of the pits, moistening and compaction of the clay layer.

After completing the excavation, proceed to the next step.

We equip the drainage system

Sequencing:

1. Lay geotextile.
2. Pour in gravel.
3. Compact the rubble.
4. Lay drainage pipes.
5. Fill in a layer of gravel.

After laying all layers, cover the backfill with geotextile fabric.

Laying engineering communications

When performing work, observe the following sequence:

1. Perform the installation of communications.
2. Pour in a layer of sand.
3. Compact the sand bed.

After installation, it is important to check the correct connection of engineering networks.

We select a heater and make its installation

When choosing a heat insulator, give preference to heaters with reduced thermal conductivity.

It is advisable to use extruded polystyrene foam, which has the following advantages:

• resistance to the development of microorganisms;
• environmental cleanliness;
• resistance to moisture.

Lay expanded polystyrene in two layers with an overlap of sheets of 40-50 cm. Use special fasteners for fixing.

We lay the reinforcing mesh and mount the heated floor

When performing reinforcement, pay attention to the following points:

• use a tie wire to connect the reinforcement;
• lay the reinforcing mesh in two tiers;
• ensure a distance to the heat insulator of 30-40 mm.

Install heating lines in accordance with the layout. Use plastic pipe supports.

When laying heating lines, pay attention to the following points:

• ensuring a distance of 100 mm between the heating lines;
• indent from external walls 150-200 mm;
• correct pipe laying according to the developed scheme.

After laying the lines, check the tightness of the system with compressed air.

We mount the formwork

The installation of the Swedish slab requires the construction of formwork along the perimeter of the foundation. For formwork, plywood or plank panels are used, reinforced with props. The inner surface of the formwork structure is lined with polystyrene sheets. They provide thermal insulation of the foundation base from the end part.

Performing concrete pouring

When concreting, observe the following requirements:

• pour concrete with a 10-centimeter layer;
• fill with an interval of no more than an hour;
• use a vibrator or plate to tamp the concrete.

Moisten the surface of the concrete during the hardening process, cover the base with polyethylene to protect it from moisture evaporation.

The "Swedish plate" foundation ensures the stability of buildings and has enhanced energy-saving properties. will provide reliable protection of the base from moisture. According to the Swedish method, monolithic can also be poured. For building a house on an insulated base, aerated concrete blocks and slabs are suitable. When building a house to reduce heat loss, you should pay attention to the plan of floor slabs. An important point is the sealing of the seams on the ceiling between the plates.

If you are pursuing the goal of building a house with a zero energy balance, then one of the most attractive types of foundations will be UWB. The technology of its device has already been brought to technical perfection and tested for decades of operation, today we will describe it in detail.

Insulated plate construction

Unlike a conventional monolithic slab, the UWB foundation has a number of design features that provide it with outstanding stability and heat saving performance. Another characteristic feature of the Swedish stove is the use of premium quality materials. This implies significant financial investments, but the result is definitely worth it: with a service life of over 50-70 years, the developer receives a finished floor with almost deaf insulation and the ability to establish a multi-storey building even on very weak and heaving soils with high GWL.

Warming of the Swedish plate is carried out by a special assortment of products from extruded polystyrene foam. Since even with a relatively small thickness, the slab can have a significant dead weight and withstand the mass of a building up to 2-3 floors, the insulation material must be highly resistant to compressive deformations - from 200 kPa. Cheaper PSB cannot boast of sufficiently high strength indicators.

The elimination of manifestations of frost heaving under the foundation is achieved by a continuous belt of insulation along the perimeter of the foundation and a blind area that drains water. Insulation under the blind area is usually 50-70 mm, with thermal conductivity of insulating materials not higher than 0.035 W / m * K. With the same indicators, the thickness of the insulation layer of the plate itself can reach 200-250 mm. The maximum value of deformation of high-quality insulation under full load with such a thickness is about 10-15 mm.

Another feature of the UWB is increased strength and spatial rigidity, which is achieved due to the special configuration of the lower part of the foundation. Along the perimeter and under the bearing walls, the slab has protruding ribs that evenly distribute the load over the entire support area and give it very high rigidity. Even during the construction of a two-story stone house, the pressure force on the ground rarely exceeds 0.6-0.8 kgf / cm 2, respectively, the building will stand stably even on moisture-saturated sandy loam, peat soil and plastic clay.

In view of the features described above, the main task in the construction of UWB is to ensure that the slab does not experience deformations under the weight of building structures. In general practice, the height of the stiffeners is between 2 and 5 plate thicknesses. At the same time, if the span between the ribs exceeds 50-70 values ​​of their thickness, the slab is reinforced either with a denser reinforcement scheme or with additional intermediate ribs.

Excavation and preparation

In reality, there are quite a few configurations of the Swedish plate, which differ in thickness and reinforcement scheme. However, this does not change the essence of the technology for a very extraordinary reason, which is quite difficult for the layman to accept. The fact is that the durability and stability of the UWB are ensured not by the design of the slab itself, but due to the correct preparation of the base under it.

It all starts with the removal of a fertile layer of soil or digging a deeper pit, if a basement is planned under the house. In this case, the bulk of the soil is removed in an area larger than the slab itself. In each direction, 40-50 cm should be retreated from the planned marking of the foundation, plus the depth of the slab, multiplied by approximately 1.35-1.5. This need is due to the fact that both under the slab and under the blind area a dense incompressible backfill is being prepared, which easily “releases” water. In this case, the width of the blind area is always determined by the depth of the foundation, because the spread of liquid during seepage through the backfill occurs like a fan. Thus, the greater the depth, the wider the wetting spot. The radius of this spot for the bedding material under the slab is about one and a half times the depth.

After removing the soil, the pit is cleaned manually and covered with needle-punched geotextile, then it is backfilled. The first is sand - high-quality river sand, without clay inclusions and with the smallest possible compaction coefficient, that is, fractions from 1.3 to 2 mm. Sand is poured in layers of 50-70 mm and rammed in a vibrational way with a slab mass of about 100-120 kg. The thickness of the sand bedding is at least 20 cm, but in general it can reach 2-2.5 values ​​of the nominal thickness of the slab. To arrange a thicker layer of sand usually does not make sense.

If groundwater may appear at the obtained mark, a system of drainage pipes wrapped with geotextiles is laid in the pit around the perimeter to prevent silting. To provide the necessary slope, small gutters are undermined in the sand, while the common plane remains strictly horizontal. After the installation of the drainage system, the pit is covered with a geofabric with a density of 250 kg / m 2, then gravel is poured with a fraction of 15 to 30 mm. In the best case, crushed granite is used, which is poured in layers with a gradual decrease in the fraction up to 10-15 mm.

The functions of the gravel pad are to drain the lower plane of the slab and distribute the load. Backfilling is carried out to the mark at which it is planned to support the ribs of the slab. The depth of support is determined by the thickness of the plate with stiffeners, with the assumption that the plane of the finished floor will be 20-25 cm above the adjacent soil.

Insulated formwork device

The Swedish plate has a continuous belt of insulation of the lower plane without cold bridges. It is quite simple to arrange such a thermal protection scheme for a flat slab foundation, however, the presence of ribs makes its own adjustments. Especially for this purpose, special products are produced for the formation of fixed formwork.

The formation of external stiffening ribs is carried out by means of L-shaped trays, which are set along the perimeter of the slab and are aligned along the marking cords and the level. The outer edge of the trays determines the total thickness of the slab and the rib, the inner one is formed manually using plates cut in place. The necessary strength of the formwork to withstand the loads during pouring is provided by external decks made of sheet materials, supported by stakes driven into the ground along the upper and lower chords.

When the formwork of the ribs is assembled, the space between them is backfilled with thorough compaction by flushing or vibration. Backfilling can be carried out with sand or fine road gravel, there is not much difference in that. In order not to disturb the geometry of the formwork, temporary plastic jumpers are inserted into the trays.

When filling the cavities between the ribs, it is not brought out flush with the inner walls. Instead, the inner walls protrude by the thickness of the insulation boards used. After the outer belt of thermal insulation is assembled, the formwork is covered with a profiled type waterproofing membrane. In the corners, the hydrobarrier is carefully cut and laid on top of each other with an overlap of 150-200 mm, snapping the pimply locks.

On top of the waterproofing, an internal insulation belt is mounted, represented by 2-3 layers of XPS 50-70 mm each. In this case, the size of the trays is reduced by the thickness of the insulation, which must be foreseen in advance. Fixation of EPS is usually not carried out, since the formwork is built on the day before pouring or a day earlier. In strong winds, the slabs can be tied together with small portions of universal glue or pressed down with oppression until the reinforcing cage is assembled.

UWB reinforcement

The insulated Swedish slab contains a small amount of reinforcement, but it is correctly distributed in the thickness of the concrete for the highest quality load perception. The assembly of the reinforcing cage begins with the ribs: U-shaped clamps are laid in them from smooth structural reinforcement with a diameter of about 8 mm, the size of which is selected taking into account the protective layers of concrete 50 mm on each side. The tails of the clamps are released 20-25 cm above the upper reinforcement line of the common plane.

The slab itself is reinforced with two layers of a grid of rods from 8 to 14 mm in two rows, while the thickness of the rods in each layer is different. Due to the fact that the main load on the slab plane comes from the resistance of the soil, the main working reinforcement, which perceives tensile loads, is located in the upper zone and the thickness of the rods is higher here. The bottom row is made of thinner reinforcement, but with a smaller cell size, it is necessary to give monolithic strength, it is also used as a mounting system for fastening communications.

When laying the mesh, it is knitted in place, placing longitudinal rods on remote chairs, providing a protective layer from below about 40 mm. Cross bars are laid on top, all intersections are tied with wire. For reliable fixation of the upper row, U-shaped anchors are tied to the lower grid, to the upper tails of which longitudinal rods of the main reinforcement are attached with wire. After the upper mesh is fully connected, the reinforcing cages of the ribs are slightly lifted, the outlets of the tails are bent and tied to the rods of the upper row of reinforcement.

Laying communications

The construction of the UWB is carried out in such a way that all the necessary communications or channels for their laying remain in the slab. In order not to lose sight of anything, here is the maximum list of what can be hidden in the thickness of concrete:

1. Underfloor heating pipes or cable;
2. Entering water into the house;
3. Waste channels with access to bathrooms and riser locations;
4. Water outlets for household needs;
5. Introductory electrical cable in a protective sheath or only a sheath with a cord for pulling;
6. Electricity outlets for street lighting and household needs;
7. 2-3 spare channels for pulling communication lines or additional cables.

It should be borne in mind that the hidden laying of communications when placing metering stations inside the building may require the execution of an act of hidden work. So that communications cannot be damaged during pouring, they are laid exclusively inside rigid shells, the most budgetary example of which is technical HDPE pipes from recycled materials. So that the pipes are not squeezed by the mass of concrete, they are jammed and spool valves are cut in to pump air under a pressure of 3-3.5 atm.

Concrete pouring and processing

The advantage of the Swedish slab is that concrete work takes place in one stage, respectively, the speed of construction is one of the highest. A real Swedish slab requires factory-prepared concrete. This requirement is connected not so much with the need to ensure the exact value of the grade, but with the need to pour the entire slab at one time without the formation of cold joints.

Since the Swedish slab is installed on a drained site, concrete of strength class B20 and above is suitable for its manufacture, but without any special claims for frost resistance. The discharge of the concrete mix starts from the center of the formwork so that the walls of the trays experience the dynamic effect of water hammer only at the final stage of pouring. As the mold is filled, the concrete is carefully compacted with a deep vibrator, while due to the relatively small thickness of the slab, one can not be afraid of delamination.

Alignment of the concrete slab can be carried out as a manual rule with subsequent grinding, or immediately brought to zero using a vibrating screed. The finished floor surface in both cases is ready for laying most light coatings, from linoleum to parquet.