The foundation - insulated Swedish slab (USP) refers to slab foundations.

A distinctive feature is that this foundation, among many, is a more progressive and original type of foundation, which, in principle, meets the most modern requirements for energy efficiency of the house, and, in principle, the construction of the foundation as a whole. USP foundation for post-Soviet times is a relatively young option.

For the first time, information about the foundation of an insulated Swedish slab appeared on construction forums 10 - 15 years ago. There it was very actively discussed. But a number of points that are definitely worth knowing when using such foundations were omitted. Mostly there were odes of praise addressed to this foundation.

Pros and cons of USP

Advantages of USHP, like all slab foundations	Disadvantages of USHP and all slab foundations
Loads are transmitted fairly evenly, since the slab, to a greater extent than just a tape, distributes the loads and transfers them evenly to the base in the form of soil under the foundation.	They are subject to the risks of heaving and uneven settlement since they are located in an unfavorable zone of soils with low bearing capacity, as well as in the freezing zone, because they are not deepened by the supporting base to the freezing depth.
Solidity. All monolithic work on pouring the foundation with concrete is carried out in one step. When pouring, a concrete pump and a deep vibrator must be used. The result is a monolithic layer of concrete, which is very important for the foundation.	There are nuances regarding the arrangement of communications and the topography of the site
Small amounts of work. Unlike monolithic strip foundations, there is much less work on USP, both earthworks and the tying of reinforcement, acceptance of concrete, and installation of formwork.

Differences from a conventional slab foundation:

When installing USHP, a large volume of insulation is used. It is used around the perimeter of the foundation and, as a rule, not to the depth of freezing, but to the depth of the foundation, this is usually 600 mm, which corresponds to the standard size of a sheet of extruded polystyrene foam.

Also, insulation is used directly under the slab and blind areas must be insulated.

This type of foundation, according to Dmitry Marchenko, is far from ideal. Marchenko believes that the choice of this type of foundation is more likely to refer to failed decisions than to rational decisions.

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After this type of foundation was promoted on construction forums, it was actively picked up by manufacturers of polystyrene foam insulation materials and made technological maps and instructions for arranging these types of foundations. As a result, the topic of USP received even greater status as professional solution for laying the foundation of a private house. It is not without reason that these manufacturers became interested in this particular foundation technology - it uses a very large amount of insulation and most of it is simply used irrationally; one could easily do without it.

Marchenko expresses the opinion that this technology is beneficial not for the owners of the future home, nor for builders, but rather for manufacturers of expanded polystyrene foam.

Dmitry Marchenko studied this foundation in detail and did not see anyone else interested in this foundation other than manufacturers of extruded polystyrene foam.

How rational is the foundation of USHP?
On many sites promoting this foundation you can see a large list of its advantages. According to Dmitry Marchenko, most of these advantages are simply far-fetched and in fact have no basis in evidence.

Reality and advertising using USP

ADVANTAGES INDICATED FOR USHP	VALIDITY OF THE USHP FOUNDATION
USHP is a fairly cheap type of foundation, because... A much smaller volume of reinforcement and concrete is used, and a much smaller volume of excavation and monolithic work is used.	For comparison, a strip monolithic foundation is usually taken. Indeed, USHP uses less concrete - the slab thickness is only 100 mm and less reinforcement - the reinforcement is knitted in just one layer. But many years of practice show that one layer of reinforcement is not enough. You need 2 layers of reinforcement and they must be tied with clamps with a certain step, additional “pawns” must be made from the reinforcement. But this is not included in the proposed USP technology. Therefore, the main disadvantage of this foundation is a weak slab. Also, this foundation uses a lot of high-quality insulation. And any insulation will not work here; you need high-quality and expensive extruded polystyrene foam. And for example, for a house with a slab measuring 10 x 10 meters, 18 cubic meters of insulation will be required. And the foundation with so much insulation becomes simply “golden” in cost. In terms of price, it covers even a monolithic strip foundation. Therefore, such an advantage as a low price is fundamentally wrong. Also, installing a sand cushion is not the cheapest pleasure. First you need to choose the native soil, then bring in sand. The sand must be moistened layer by layer and compacted; this all must be compulsorily observed. These are additional costs.
USHP is suitable for building houses on any soil, both heaving and non-heaving, subsidence and non-subsidence, etc.
This foundation distributes loads evenly.
Suitable for all types of houses - wooden, brick, lightweight concrete, etc.

The thickness of the sand cushion is 300-400 mm, so high-quality sand compaction is very rarely achieved. Very often builders neglect this.

For example, they do not do it layer by layer or do not spill it enough, or, on the contrary, fill it with sand and then it cannot be compacted properly. And even if all this is done efficiently, there will still be places of uneven compaction throughout the entire area of ​​the sand cushion. As a result, this will lead to the fact that the base of the sand cushion under the house, and it will not be local, but common to all the slabs, may turn out to be uneven and lead to uneven shrinkage of the foundation. uneven shrinkage of the foundation, in turn, will lead to possible cracking of the foundation, and then reinforcement in one layer will be extremely insufficient for the foundation to maintain its geometry and not crack, which will result in the appearance of a crack in the load-bearing structures of the house. Thus, the sand cushion affects the stability of the entire house.

Another disadvantage is the possible deformation of the EPS itself. Despite the fact that the manufacturer claims high technical and operational characteristics of its products, that the material has very high compression properties, practice shows that under heavy loads it works, at least, not as stated in its characteristics. This means that deformations of the material are possible, which will lead to uneven shrinkage of the foundation. Extruded polystyrene foam directly under the foundation slab receives enormous loads in the form of pressure from the house, which means its durability is questionable. Despite the fact that manufacturers claim ideal qualities, there are very few stories of using EPS in this way, there is no information on its caking over 10-15-20 years, and this calls into question the integrity of the entire house. There is no certainty that a person will want to risk his investment in a house in order to experiment on himself how conscientious the EC manufacturer was.

The disadvantage of this foundation, like other slab foundations, is the low base. Usually it is 10 cm already from the blind area mark and the wall structures of the house are in very close proximity to the ground, which means they will be in a zone of high humidity, which is a very vulnerable moment for our climate. A base height of 10 cm is not enough for our climate, in our climatic conditions the base should have a height of 50-60 cm. This will provide sufficient distance from the ground for wall structures and remove any moisture and snow from them. Like other types of slab foundations, this foundation will require a level area and the absence of any slopes on either side towards the house, because any rain or melt water will wet the side parts of the foundation base and these places will heave unevenly, it will undermine the blind area, it may even lead to the lifting of some part of the foundation, and if the foundation plays unevenly, deformations may occur on the foundation or on the wall structures.

Majority technological maps or instructions for arranging this foundation imply the installation of a drainage system. It must be installed in a warm zone of the earth, otherwise the drainage will most likely simply be torn apart by heaving in the first winter. It will fill with water and in winter, when the temperature is below zero, it will simply freeze and burst. But any drainage system has a tendency to silt, and in this case this system under the house will have a greater tendency, because Already at the stage of laying the foundation of the house, it will be exposed to possible risks of clogging from the workers; the vibrating plate will work. Of course, protection is provided in the form of geotextiles, but practice shows that there are joints and some shortcomings of the builders, as a result of which the drainage systems are flooded. There is a way out that partially solves the situation; inspection hatches are built through which drainage systems can be flushed under water pressure, but in most cases hidden drainage systems are not the best solution, especially if this is not done by drainage specialists, but by ordinary builders foundation construction. In such cases, very often missed important points, because if there is no practice, it cannot be replaced with information from the Internet. Moreover, simply laying drainage pipes is not enough. You need to make a branch with a slope, you need to make a receiving well, install a drainage pump. This will result in an even greater increase in construction costs.

On the site you will have to allocate space for a drainage well, regularly maintain and monitor it, clean out the drainage system, which is likely to completely silt up in 5-10 years. And the maintainability of drainage systems in these places is simply impossible. Any excavation work in this place will simply lead to settlement of the foundation. This is another disadvantage to questions about the price of this foundation. At this point, we can basically say that this type of foundation is not profitable.

But its shortcomings don't end there.
Private houses are usually built outside the city, where there are large numbers of rodents, ants, etc. And the insulation under the foundation is an ideal place for them to build burrows. The insulation will not be complete, and the pressure from the house will remain the same. Hence, deformations, subsidence of the insulation, and along with it subsidence of the foundation are possible. And within 10-5 years, the picture with the geometry of the foundation may deteriorate dramatically.
There is a solution that is partially used in the construction of any house, since it is always rational to insulate the blind area of ​​the house, insulate the foundation to prevent freezing of the slab, to prevent frost from getting under the foundation, even a monolithic one, therefore, when installing insulation from EP, the right solution is always to install a protective mesh . But if you protect the entire volume of insulation with a metal mesh, then it is very expensive, and it is not a fact that ants will not be able to get into it.

As for heated floors when installing this foundation: The installation of underfloor heating pipes can already be carried out at the stage of its construction. The underfloor heating pipes are attached with clamps to the fittings, which are located at the bottom of the slab. And as a result, after pouring, you get a ready-made foundation in which the heated floor pipes are located, which means you will not need to use a classic system to install heated floors using insulation, when insulation is installed on the monolithic slab of the house, heated floor pipes are laid, a screed is made, and as a result you also get heated floors, but you pay extra for this work.

The floor screed, which is installed through heated floor pipes, has a relatively low density and, accordingly, heat capacity, in comparison with a monolithic slab. This allows the underfloor heating pipes to relatively quickly warm up the screed layer and release heat into the room. If you look at the underfloor heating system in USHP, it is different from the classic screed. we get: the stove itself has a high density and a high heat capacity, which means that in order to heat this stove, the boiler must work much more. and you will have to pay more for it in order to warm up the entire volume of concrete and only then will it give off high-quality heat to the room. And if the thickness from the underfloor heating pipes to the final coating is 5-6 cm, then in the case of USP this distance increases by 2-2.5 times. And in order to warm up your house, you must warm up the stove itself for 1-2 days, and only then will some thermal effect begin from the heated floor pipes. This system is very slow to warm up and cool down. Therefore, if we compare the installation of heated floors, then the classic system is more advantageous, because it allows, at lower costs in heat energy, to quickly transfer this energy to the room.

Because this system directly connected to water, it may have problems with leaks. Construction workers may accidentally crush or damage a pipe, which may result in the need for repairs. In the case of the classical system, the screed is broken, the breakdown site is located and eliminated. Here the breakdown location is not difficult to find, because it will form a wet spot on the floor. and in the case of a monolithic slab, finding the location of the damage will be quite problematic; you will also have to make a lot of effort to get to the pipe, and the solidity of the supporting structure of the house will be damaged. And in the case of a screed, finding and eliminating the hole will not affect the integrity of the load-bearing structures.

Like all other slab foundations, this foundation requires a clear technological calculation, as well as a clear understanding and clear design engineering systems zero cycle already at the foundation stage. Those. If, when installing other types of foundations, you have the opportunity to think about moving the pipe outlets before installing the plumbing, then with this system you will not be able to move the already installed pipes anywhere. ,
If you are faced with the fact that you have pipes and sleeves coming out of your foundation slab, always protect them; covering them with something is an incomplete solution; the most proven solution is to make boxes out of wood. .
The technology is beneficial for manufacturers of extruded polystyrene foam.

Readers of our portal are well aware of the statement “the fate of a house depends on the reliability of its foundation.” That is why it is necessary to approach his choice thoughtfully, carefully weighing all the pros and cons. In this article, FORUMHOUSE experts talk about the strengths and weaknesses of foundations using USP technology, and help to understand what benefits and risks a developer receives when choosing this particular type of foundation.

• Pros and cons of USP;
• Preparation for installation;
• How to reduce the cost of construction.

USHP: pros and cons

When the word “foundation” is mentioned, most developers imagine a simple concrete foundation, made in the form of a slab or strip. But many have heard about this type of foundation, in which all the necessary communications are carried out in advance, and the foundation itself is a perfectly flat surface, already prepared for the installation of the finished floor.

This approach allows you to significantly reduce the construction time of a building, and if the foundation is well insulated, it acts as a heat accumulator, reducing heating costs and making your home comfortable and energy-saving.

This type of foundation for a house is called an “insulated Swedish slab.” Opinions about the place of origin of this technology vary, but experts are unanimous on one thing - compared to conventional ones, the foundation using USHP technology is a more energy-efficient and functional foundation for the construction modern house. Let's consider the pros and cons of the USHP foundation.

Advantages of USP

In 2008, FORUMHOUSE recorded the first mention in Russia of a foundation using USP technology as ideal for frame construction. In our latitudes this technology was not yet known, but after that a short time gained enormous popularity.
Here are its main advantages:

• Possibility of installation on almost any type of soil;
• Fast construction time and high quality designs;
• A layer of thermal insulation reduces heat loss in the room;
• Less concrete consumption compared to a conventional slab foundation;
• The base has already been prepared for laying the finished floor;
• The necessary engineering communications are pre-integrated into the insulated Swedish stove.

Disadvantages of USP

But no matter how good the USHP foundation is, it also has some minor disadvantages. And these disadvantages can become arguments against such a solution to the fundamental issue:

• Increased requirements for the materials used, equipment, qualifications of workers and the need for strict adherence to technology, which leads to an increase in the cost of work;
• Compared to a strip foundation, a foundation using USHP technology has a lower height (on average from 300 to 400 mm);
• Important condition: on uneven areas with a large difference in heights for such a house foundation, you need to first level the site, which also leads to an increase in the cost of work;
• When using an insulated Swedish stove, the construction of a basement is impossible or significantly complicated, and the costs of its construction lead to an unjustified increase in the cost of the house;
• Since all communications are carried out inside the insulated Swedish stove, access to them for carrying out repair work difficult in an emergency.

What is USP

This type of base for building a house is a low-level monolithic foundation. Its main difference from regular stove The point is that in USP all necessary communications are established in advance, namely:

• Water heated floor system;
• Water supply and sewerage system;
• Power supply system.

USP scheme

For what soils is USHP suitable?

Alexander ZemskovCEO of BAUBILD

For an insulated Swedish slab, there are practically no restrictions on the type and composition of the soil on which it can be located. USHP has proven itself well on difficult soils with high groundwater levels and low bearing capacity. This type of foundation is successfully used in cold regions, where seasonal freezing of the soil leads to the emergence of frost heaving forces.

By replacing the unstable soil under the USP with a cushion of sand and crushed stone and “reinforcing” the base with geotextiles, it can be placed on very difficult soils, and the drainage system will lower the groundwater level in the building area.

When deciding to use USP technology as a foundation, it should be taken into account that the technological complexity of its manufacture significantly exceeds other types of slab foundations.
Before starting installation it is strongly recommended:

• Draw up a detailed project of both your future home with all the necessary communications and the foundation;
• It is necessary to strictly adhere to the technology and construction sequence;
• ​The laying and maintenance of all communications must be carried out with an accuracy of centimeters.

Insulated Swedish stove: how to reduce the cost

Since an insulated Swedish slab cannot be compared with a conventional strip or slab foundation, it is necessary to find out what benefits the developer should receive if he chooses a similar type of foundation for his home. Comment from our expert:

Mikhail Leontyev Project Manager at Schwedenplate

The developer immediately receives all the elements he needs in the future: a foundation, a subfloor and a heating system with the necessary communications. We can say that thanks to the speed of construction, in one month you will receive a complex system that can be connected to a heat source. And due to its heat capacity, the use of a USHP foundation provides additional advantages when heating with heat pumps.

Alexander Zemskov

On average, a foundation of 100 m2 is made in 7 days. The concrete surface of the insulated Swedish slab does not require additional screed, and, thanks to grinding, it is completely ready for laying the final floor covering on top of it. And an integrated approach to construction allows us to reduce the final cost of installation.

A strip foundation with a set of communications such as drainage, heated floors, laying water supply pipes, laying electrical cables, installing sewerage and additional insulation can be implemented in at least 30 days, and its final cost will be 20-30% higher than USP.

USP for frame houses

An insulated Swedish stove is ideal for energy-efficient and passive houses, since heat loss through the floor will be minimized. This is just a godsend for frame houses that have low heat capacity. In this case, the USHP foundation will act as a heat accumulator in the house and will not allow the frame to cool quickly.

By using teaching materials FORUMHOUSE you can.

Installation of USHP - preliminary stage

An insulated Swedish slab can be called an advanced version of a conventional slab foundation, but, like any foundation, the USHP slab requires special preliminary preparation. The company’s chief engineer explains what points the customer needs to look at before pouring "Fundamentally.rf"» Vladimir Sidorov:

Vladimir Sidorov

Before starting construction, you need to obtain information about the soil on your site. Otherwise, it is impossible to correctly determine either the foundation design or the construction budget.

The design should be determined not by the customer, but by the design engineer, who calculates the loads and prepares a feasibility study. The intended purpose of slab foundations is soils with weak bearing capacity; a pile or strip foundation under load in such soils will simply “sink” into the ground; their use on these soils is unacceptable.

It is important to remember that the USP is a shallow foundation, and, accordingly, requires solving the issues of groundwater and perched water drainage. And the mandatory installation of a drainage system and blind area.

What to check during installation

When laying communications in this type of foundation for a house, you should pay close attention to the compliance of design solutions with how work is carried out on the construction site.

In contact with

Classmates

Construction of foundations using insulated Swedish plate (USP) technology - complex and responsible task, which requires knowledge and careful adherence to technology.

The cost of a mistake in this matter is deformation, distortions or destruction of the building, which can happen suddenly.

Therefore, the importance of having detailed and accurate information about the correct construction of the foundation cannot be overestimated, and any opportunity to obtain any information should be fully exploited.

The USHP foundation is a special case of the so-called floating slab.

Design

USP refers to shallow slab foundations, which means there is no deep pit. Usually a deepening of about 40-50 cm is required, that is, it is necessary to remove the top layer of fertile soil in order to prevent plant growth that causes destruction of the base.

A recess is dug about a meter on each side more than required according to the building drawings. The perimeter of the recess is equipped with an additional groove into which a drainage pipe is laid to drain water from the preparatory layers. For a material such as Swedish slab, the laying technology has its own characteristics.

Correct device USP involves such actions as preparation, which consists of layers of crushed stone and sand, laid alternately and compacted by pouring water. Then a layer of waterproofing is laid, covered with another layer of crushed stone and the construction of the formwork begins.

In parallel with this, the insulation for the USHP is laid out so that it tightly covers the entire area and walls of the formwork. At the same time, reinforcement of the USP and installation of communications and heated floors are carried out. Upon completion of these works, the formwork is poured with concrete, which must be kept until the state of primary crystallization for at least 2 weeks.

For your information: It should be noted that the slab has stiffening ribs for reinforcement under the load-bearing walls.

Calculation

Calculation of the USP thickness of the slab is carried out using methods that correspond to the general rules of calculation for slab foundations, taking into account correction factors.

For the correct result you will need large amount of data:

• soil bearing capacity;
• soil pressure (heaving loads);
• structural loads (weight of the building with its internal contents and roof);
• action atmospheric precipitation- weight of snow in winter period, rain and wind loads that USHP blocks must withstand.

Making a USP foundation: the technology of work implies the following - to obtain more accurate data on the properties of the soil, data on the depths of aquifers and seasonal changes in the level of soil waters is needed.

Important! It is necessary to take into account that working with this data is not easy, as is obtaining it; independent calculation of the USP may be an overwhelming task. In any case, experts strongly advise contacting professionals with such problems.

As a last resort, you can use an online calculator, of which there are quite a few on the Internet, but to get a more accurate result, you should check it with several similar calculators. They all work using different methods, and comparing the calculations will help you decide on the most correct solution.

USHP construction technology: step-by-step instructions

In order to build a USHP foundation with your own hands, you will need to perform the following operations:

1. Preparation. Calculations, design work, it is necessary to prepare materials for USP, etc.
2. Marking. Determining the location of the foundation and pit on the site.
3. Arrangement pit, site planning (if required). Drilling a trench to drain water.
4. Trenching for sewerage and water supply.
5. Laying a drainage pipe along the perimeter of the pit and outlet into the trench.
6. Backfilling a layer of crushed stone. Its thickness depends on the design weight of the building; in general, it is half the thickness of the preparatory layer.
7. Backfilling a layer of sand. The thickness is approximately equal to a layer of crushed stone. Sometimes this procedure is simplified by pouring a layer of sand and gravel mixture (SGM) over the entire thickness of the preparation.
8. Thoroughly compact the preparatory layer mechanically or by watering.
9. Layer Laying waterproofing. Various rolled film materials, geotextiles, etc. are used.
10. Filled on top cut-off from crushed stone (PGS) 5-10 cm thick
11. Surface carefully leveled and compacted.
12. Thermal insulation is being laid. Most often, extruded polystyrene foam is used for USP foundation grades, designed for high loads. Foam plastic for USP is placed under the ribs in one layer, under the remaining parts - two layers of 100 mm each. To obtain a warm blind area, the insulation area can be increased by 0.5 m on each side.
13. The sheathing is being built. To do this, it is best to use even edged boards and bars; unedged boards are strictly not recommended.
14. Inner part of the sheathing lined with one layer of insulation, to create a kind of “trough” of extruded polystyrene foam (EPS) for USP.
15. The fittings are being installed and in parallel, installation work on communications is underway - warm floor and water supply with sewerage. The quality of all connections should be carefully checked; any questionable area or element should be redone or replaced in order to correctly build a foundation from an insulated Swedish slab with your own hands.
16. After completing all installation work another one is being produced control check of all pipes, their ends are securely sealed to prevent the entry of earth, concrete, etc.
17. Inner part of the formwork poured with concrete to the thickness suggested by the USHP design.
18. The part of the insulation remaining outside the slab is poured with concrete - a insulated blind area. Some builders consider this position optional, but most advise not to neglect the additional opportunity to eliminate the impact of ground loads.
19. Poured slab aged for at least 2 weeks until brand strength is achieved, after which the surface polished and is prepared for further work - this is correct device USHP foundation.

This is how you install an insulated Swedish stove with your own hands.

Insulated Swedish stove with a high base

One of the significant disadvantages of USP is low location of the ground floor floor above the ground.

This drawback can be partially eliminated by constructing a high basement, that is, constructing a basement floor that raises the level of the first floor to more acceptable values.

This is achieved by increasing the thickness of the bedding during preparatory work and by building a wall around the perimeter of the section, insulated from the outside with EPS.

Thus, the result is an insulated Swedish slab, the installation technology of which is identical to the usual method.

You won’t be able to achieve any higher values, since you’ll just end up with an additional floor, the difference in heights only allows for increased comfort for residents.

For your information: Alternatively, a basement floor can be built, that is, an additional slab can be built above the main one to a height of about 2 m. In this case, the main slab can be buried deeper into the ground, and communications can be introduced in the usual way, without pouring them into the body of the slab.

Warm floor is also installed on the top plate of the base, which somewhat changes the physics of the USP operation, but not fundamentally. The result is a ground floor, insulated with USP with a cellar (basement), which can be used for household needs.

Useful video

Check out visually how to make a USHP foundation: do-it-yourself insulated Swedish slab in the video below.

conclusions

In conclusion, it should be noted some the complexity of the DIY USP design and the rather high cost of the foundation. Costs consist of many factors, some of which can be significantly reduced if certain opportunities and conditions are available. In this case, one should take into account the specifics of using USHP for heating and its contribution to home insulation - the house actually stands on warm stone, the efficiency of such a radiator is very high.

In addition, the complex geological conditions of the site sometimes simply leave no choice when everything alternative options do not work or are ineffective. Therefore, USP should not be considered as an expensive invention that can be completely dispensed with. This modern development, allowing constant savings on heating, ultimately saving money for its owner.

In contact with

My opinion on USP, its clear pros and cons:

1. geology and foundation design are actually not needed. Foundation projects are always difficult. And here, in principle, there are enough drawings distributed from manufacturers and people who know and build these slabs well; for lightweight houses, even calculations are not necessary because there is already strength, well, of course, if you don’t make a gag, like “ribs are enough 15 cm high and 20 cm wide ".
2. if you do it well right away, then in reality the floor of the first floor is almost ready - just lay some of the floor coverings
3. you can safely leave one foundation for the winter, cover it with a film from precipitation and nothing will happen to it (provided that an insulated blind area is made)
3. .. uh.... mmm..... that's it

1. In any case, experienced workers must build, such a foundation can be made independently, but again, at the stage of pouring concrete, specialists are needed, and the declared levelness of the floor of the 1st floor must be done! In most cases, you still end up with a subfloor that needs to be further leveled - sanded, topped up with a self-leveling machine, because who really does it smoothly.
2. I personally don’t like it when a residential building stands purely on thermal insulation, it seems that everything according to calculations and so on should stand for quite a long time, but still pure conservatism of a personal nature is against this method.
3. there is no basement, ground floor, etc.
4. It seems to me that rumors about cheapness are exaggerated; this foundation is not that cheap.
5. I don’t like thick layers of insulation under a power screed, where they are not very necessary, but then there will be a lot of concrete, this is the concept, the thickness can of course be reduced with a sand cushion, but this is additional labor costs
6. in case of problems, it is impossible to reach the communications that are located under the foundation. You will have to open the power screed with a concrete breaker in order to carry out something or repair or replace
7. We are poorly solving the issue with living creatures, which in theory can get into the layer of thermal insulation, this again requires costs - sprinkle with crushed stone or dig in a stainless mesh
8. low level of the floor relative to the ground level, within some limits it can be made higher than usual by raising the blind area, but do not make a classic when the basement part, which is real and not drawn on the walls, has a height of 60-70 cm to the level floor of the first floor.
9. The topic is more “fashionable” than necessary, and many simply promote it as “advanced technology” and even this works out well because there is a fairly confident demand for this type of foundation.

Tell me, what would you do for yourself?
The cottage has a classic monolithic strip foundation resting on the ground and having a full basement floor.

Click to expand...

Now USHP has become very common and, in principle, any summer resident with a farm can fill it and make it much more correctly than a shallowly buried tape. I see these foundations all the time. I didn't see any problems.

An insulated Swedish slab - otherwise known as a USHP foundation - is a monolithic reinforced structure of shallow foundation. Utilities are laid there and heating mechanisms for the first floor are created. The reliability and functionality of the solution is supported by specific preparatory manipulations; it is economical and maximally adapted to the realities of the domestic climate.

A distinctive property of the insulated Swedish stove is the presence of energy-saving materials throughout the entire area and perimeter of the sole. A ready-made rough surface for the first floor is formed; it already contains utilities and a warm floor.

The structure is formed by the following layers:

• concrete pouring,
• reinforcing rods,
• shock-absorbing layer
• insulating materials.

The concrete monolith has a thickness of 10 cm, it is formed in one day, in this case the layering of the pour is eliminated and the cost of work is reduced. Insulation helps to isolate the structure from the ground. Reinforcement is performed using metal rods and mesh; they protect the foundation from cracking and keep it intact during periods of natural soil movement.

The shock-absorbing layer consists of crushed stone and sand; Swedish technology also involves the use of clay. The latter protects the geotextile separating the mineral layers from moisture. Water supply and sewage systems are laid in the thickness of the sand covered with insulation.

The insulation is based on styrene derivatives; the material is laid vertically along the perimeter, from below, under the blind area. Drainage communications in tandem with hydro- and vapor barrier layers prevent the destruction of the foundation under the influence of moisture and groundwater.

Pros and cons of the Swedish scheme

Key advantages of the solution:

• low cost of construction due to the limited number of materials used and execution without the involvement large quantity workers;
• preventing freezing of the soil under the base, thanks to the additional layer of thermal insulation, the slab gets rid of shrinkage and heaving;
• built-in underfloor heating system helps optimize heating costs;
• speed of assembly;
• the foundation slab turns into a full-fledged subfloor; it can be covered with finishing without prior leveling;
• the insulation used has enhanced compressive strength, in this case the shrinkage of the building does not exceed 2%;
• insulating the foundation will protect the premises from dampness and mold;
• The design is durable and suitable for use in regions with harsh climates.

Among the disadvantages of USP are:

• the need for a stronger foundation, such a slab cannot be installed on silty, vegetative (chernozem without cutting off the top layer), peaty soils;
• impossibility of using insulated Swedish slabs for multi-storey buildings;
• restriction of access to a significant segment of utility connections, since the latter are embedded in the thickness of the slab.

The specificity of the monolith is such that it excludes the possibility of arranging a basement in the house.

Areas of application of the plate

This category of basis for buildings is actively used in the implementation of projects that do not have a basement or ground floor. The technology under consideration is appropriate for buildings whose maximum side size does not exceed 15 m. Optimal conditions:

• regions with a harsh climate (in this case, heat loss at home is significantly reduced);
• areas characterized by high groundwater levels;
• in private housing construction using water-based heated floor technology;
• in the process of erecting panel, frame, panel structures, in the case of using half-timbered technology;
• when constructing walls in the form of brick or block masonry.

For weak and heaving soils that do not have high bearing capacity, screw and bored foundations are more appropriate.

Slab calculation and survey work

Survey activities make it possible to determine the characteristics of the soil and calculate the bearing capacity. Potential fluctuations in the lower layers, soil composition, and groundwater levels are taken into account.

Special computer programs, used by professionals, make it possible to consistently determine the properties of all layers separately during construction with adjustments to actual loads.

Next, they begin to mark the territory and form natural axes. The contours of the pit are applied to the ground, cast-offs are mounted, serving as supports for pulling the cords (the latter serve as guides when assembling the formwork). Compared to traditional pegs, cast-offs have a practical U-shape; their position is leveled once in the horizontal plane.

The pit has larger dimensions than the future foundation: allowances are left within a meter. The indentations will serve as the basis for ring or wall drainages.

Review of materials and tools

When creating a Swedish stove with your own hands, you will need the following resources:

• medium grade sand,
• crushed stone,
• geotextiles,
• 10 cm extruded polystyrene foam;
• drainage pipes,
• formwork boards,
• reinforcing bars and tying wire for combining them;
• pipelines for water heated floors and utilities;
• nylon mounting clamps.

You also need to prepare working tools:

• shovels - bayonet and shovel,
• level,
• wheelbarrow,
• screwdriver,
• grinder,
• knife and hacksaw,
• vibrating plate,
• concrete mixer,
• deep vibrator,
• trowel.

Work is carried out in seasonal protective clothing.

Technology for pouring insulated Swedish slabs

The following is step-by-step instruction to create a USP foundation with your own hands: the work is divided into such stages as arranging drainage, creating a shock-absorbing cushion and laying communications, introducing thermal insulation, reinforcement, concreting.

Excavation and drainage works

Using bayonet shovels, the plant layer is completely removed, otherwise the slab will shrink as a result of rotting organic matter. The area is treated with chemicals that can stop plant growth.

The surface is covered with sand and thoroughly compacted, followed by a layer of dry crushed clay, which also needs to be compacted. The pit is covered with geotextile so that the edges of the fabric protrude 30 cm beyond the slab being constructed.

The technology for arranging a USP foundation involves the creation of a full-fledged drainage system, thanks to which the base of the structure is freed from storm water, groundwater, and melt water. The perimeter is surrounded by a trench; its depth should correspond to the diameter of the perforated pipes used. It is necessary to make a slope of several degrees from the building: this will ensure gravity flow. Vertical wells are located in the corners - they will provide convenient access to drainage elements.

Excavation procedure:

1. Geotextiles are covered with a layer of crushed stone.
2. The corners of the building are equipped with wells made of solid corrugated or smooth pipes with a diameter of 20-30 cm, they are mounted vertically.
3. Corrugated pipelines are laid along the perimeter of the foundation, the ends of which go into adjacent wells (appropriate holes should be left here).

The trenches are covered with crushed stone and reinforced with geotextiles on top.

Engineering wiring and shock-absorbing cushion

The next layer is a crushed stone-gravel shock-absorbing cushion 15 cm high. The base is covered with fine sand, it is compacted with a vibrator or manual tamper.

Utilities are assembled on a sand bed, the ends of the pipes are brought to the surface, and the working elements of the system are subsequently connected to them. The use of larger diameter cases in the process ensures the repairability of the bundles. A well for sewerage is provided outside; with its help it is easier to inspect and repair components.

Next, the surface is covered with a layer of gravel up to 15 cm, compacted and covered with a waterproof material as waterproofing, for example, budget roofing felt. Overlapping joints are sealed, the edges of the covering should protrude beyond the slab by 15 cm.

Formation of a thermal insulation layer

Extruded polystyrene foam is optimal here; it has high compressive strength. Metal mesh, broken glass, and ceramic foam will help protect the material from infestation by insects. Slabs 10 cm high are mounted in two layers: one of them covers the blind area and the foundation area, the second is laid out 45 cm from the edge, forming stiffening ribs. Grooves are left for future walls.

The material is fixed with plastic nails with wide heads, the joint areas are covered with adhesive. Expanded polystyrene boards are placed in a checkerboard pattern to prevent the formation of cold bridges.

The reinforcement is tied with rectangular clamps and laid in the form of a frame, focusing on the future protective layer of concrete - this is manipulation under the grillage. The slab is reinforced with two reinforcing meshes provided between the stiffeners.

A heated floor is installed in the thickness of the monolithic base: the circuit is mounted on the upper mesh and secured with nylon clamps. In areas where doorways and load-bearing walls are located, pipelines are protected with durable sleeves. A distance of 10 cm is maintained between the branches to avoid waste of material. Each room must have a separate circuit.

The distribution elements brought to the top are fixed on vertical rods, the collector is placed on separate reinforcing bars. The lifting areas of flexible pipes are reinforced with corrugated covers.

Concreting the base

The foundation is poured with concrete mortar at one time; for this purpose, a concrete mixer truck with a pump is used. Trowels and shovels help spread the mixture evenly over the entire surface. For compaction you will need a deep vibrator or vibrating plate.

A completely dry base must be sanded, since the concrete slab formed at this stage will subsequently serve as the floor for residential premises. Experts recommend constructing the USP at the end of summer: during this period the groundwater level is at its lowest.

Potential problems and ways to prevent them

Proper calculation of the thickness of a monolithic USHP foundation determines the durability and stability of the structure. A massive option will cause shrinkage; too thin will cause cracks and warping of the walls. In the case of difficult soils, it is better to entrust the design to professionals.

If there is a high groundwater level on the site, careful drainage of the foundation will be required during construction in the off-season. The perimeter of the future foundation is surrounded by a trench through which drainage is arranged. Complicated conditions involve laying drainage pipes directly under the slab.

When pouring concrete for a USP device, you need to make sure that the spreading solution does not put pressure on the formwork, otherwise it will be damaged or bent. A mandatory preventive measure is the installation of wooden supports made of spacer bars in the ground along the outer perimeter in increments of 50 cm.

It is better to fill the slab at a time, otherwise, due to non-compliance with the solidity of the structure, cracks may appear at the border of different portions of concrete. If the dimensions of the base imply dividing the process into several stages, each layer must be strictly horizontal.

When creating a reinforcing frame, you need to cover the metal rods with a layer of mortar of at least 3 cm, otherwise moisture can get into the reinforced concrete structure and cause its premature destruction. All stages of work require accuracy and scrupulousness - this is the key to success in the construction of a Scandinavian slab foundation.