Technologies for constructing a reliable foundation do not stand still. If quite recently in low-rise construction mainly strip and columnar foundations were used, today they have been joined by USP or insulated Swedish plate.

This is one of the types of shallow slab foundations. Why Swedish? Everything is simple here. This basis was invented and actively used in Scandinavian countries, where the climate is quite harsh. However, the USP has shown itself to be extremely positive and its high performance characteristics have been tested over the years.

Swedish foundation is an innovative product. The multilayer structure of the slab integrates: drainage, sewerage, water supply systems, insulation, and “warm floors.” As a result, it is not just a foundation. USHP is an ideal ground floor floor, insulated, with communications, ready for finishing decoration, for example with tiles.

Structurally, the foundation looks like this (section)

Advantages:

• Suitable for various soils, including difficult ones, such as watery and heaving.
• Foundation for the construction of houses from any materials, from light frame to brick.
• Integrated communications (all that remains is to connect the plumbing or make internal wiring) and a water-heated floor system.
• Excellent heat-saving properties.
• No installation seams, protection from mold and dampness.

The construction of the USHP foundation will not take more than two weeks, given the start of work from the zero cycle. This does not require heavy special equipment (except for a concrete pump), and there is no need for extensive excavation work.

Insulated foundation: we do the USHP ourselves

Is it possible to prepare USP yourself? Anyone can do this, it is enough to follow the technology and the procedure for performing the work.

The first thing you need to start with is drawing up a project. In this case, this is the most important stage. You should know in advance where and what communications will be laid, the heating intensity for each room, the installation location of plumbing, household equipment, and the heating collector.

Step-by-step USHP device

If we analyze the manufacturing technology of a slab insulated foundation, then it is necessary to highlight the following main points.

The top layer of soil is removed. If you want to save money, you can do this work with shovels. Otherwise, an excavator is hired. The bottom of the pit is leveled in the horizon.

it does an excellent job as a separating layer. During operation it does not rot or collapse. We talked in detail about geotextiles.

water supply, sewerage, depending on the project there may be electricity.

It is advisable to press wet sand in layers to achieve maximum cushion density. The thickness of the sand layer is about 15 cm.

Similar to the sand cushion, its thickness is also about 15 cm. The crushed stone is carefully leveled over the entire area of ​​the future foundation.

Formwork is assembled along the perimeter of the foundation. There are two options for its construction: from special polystyrene foam blocks or traditional wooden panels. It should be noted that the blocks are much more reliable, plus they perform thermal insulation functions.

Extruded polystyrene foam boards are actively used as insulation. They are laid in two layers, so that its total thickness is 20 cm. Between the layers there is a vapor barrier film.

Reinforcement USP

The reinforcement frame is attached to special stands. Corrugated rods with a diameter of 12 mm are used.

REHAU “warm floor” is laid on the reinforcement mesh

The material is special polyethylene pipes, maximally resistant to loads, not subject to chemical reactions upon contact with mortar mixtures. The layout is carried out in separate contours throughout the premises of the future building. In this case, you can easily regulate the temperature in each room by opening/closing the corresponding manifold valve. Lay out the “warm floor” like a snake or snail. The ends of the pipes are connected to the manifold and filled with air or antifreeze liquid. Under pressure, the tubes will easily bear the loads from the concrete layer and will not be damaged.

It should be noted that it is better to use a factory mixture delivered by machine. Using a concrete pump, the solution is evenly distributed over the entire base. Air bubbles are removed using deep vibrators and the concrete is leveled horizontally. The construction of the slab “in one pour” allows you to avoid seams, making the foundation monolithic. The thickness of the concrete layer is 10 cm. Next, the surface of the slab is polished to an ideal state.

When the concrete slab dries, the air is released from the “warm floor” system, and the collector outlet is preserved. The formwork is disassembled; if polystyrene foam blocks were used, then the supporting supports are removed. The insulated Swedish foundation is ready! Now you can proceed to the construction of walls, roofs, etc. But you no longer have to think about the gasket engineering communications, heating the first floor and leveling the subfloor for finishing with decorative materials.

The USHP will become a reliable and, most importantly, warm foundation for your home!

Do you also have a USP foundation? Tell us how you made it in the comments.

What is a warm foundation? Why do you need to insulate the foundation? Types and characteristics of insulated foundation.

A significant part of the heat (up to 20%) leaves the house through the concrete foundation. Mold, condensation and dampness appear on the internal walls of recessed structures mainly due to poor ventilation and poor thermal insulation. In addition, the waterproofing coating ages and quickly collapses as a result of freezing of the building walls and the waterproofing material itself. You can cope with such problems using technology warm foundation.

Most often there are two types of base:

• USP foundation technology;
• shallow structure;

USHP system

USHP (insulated Swedish plate)– This is a shallow cast slab base. The structure is insulated around the perimeter and over the entire area of ​​the sole. The Swedish stove forms the finished subfloor of the building, which is immediately equipped with a heated floor system.

USP

Reference: Extruded polystyrene foam is used as a thermal insulation material. This insulation is designed specifically for insulating the base from below.

Thanks to the addition of graphite elements to polystyrene foam, its compressive strength and resistance to sunlight are increased. Plus, the material is practically not subject to shrinkage, and the thermal insulation of the sole allows you to cope with the problem of soil heaving.

USP foundation technology is ideal for frame and other types of buildings. Its use is very appropriate in the construction of one and two storey buildings. The design allows you to cope with several problems at once. The Swedish foundation is a kind of “pie” consisting of layers laid according to a certain pattern. The order of laying layers is agreed upon when developing the project:

• soil;
• geotextiles;
• drainage outlets;
• layer of sand;
• layer of crushed stone;
• thermal insulation;
• frame made of reinforcement;
• heated floor system;
• concrete base.

Reference: When building a foundation on sandy soil, it is not necessary to include drainage in the design. The danger of flooding appears most often during snow melting, but during this period the sand also thaws. As a result, water seeps into the ground through the loose structure.

For high-quality operation of the structure, it is necessary to calculate the Swedish plate. Thanks to this, it will be possible to ensure uniform heating of all areas of the floor covering, determine the maximum and minimum power of the heating system, calculate the level of operating temperature that will need to be set during operation, as well as the level of heating of the concrete surface at it. Engineering calculations are made based on load indicators, load-bearing characteristics of the structures being constructed, and the type and condition of the soil.

Shallow design

Note: The technology for insulating the finished structure will be discussed below.

A warm, shallow-type foundation is built above the freezing depth of the soil. This is the reason for insulating it both horizontally and vertically. This design will serve as a barrier to the outflow of heat from the room, and will also protect the soil from freezing under the base itself.

Expanded polystyrene is also used as insulation, which, even with a minimum thickness (5 cm), provides high-quality protection of the foundation from freezing.

Important: the highest heat losses occur in the corners of the building, therefore the thickness and width of the thermal insulation layer in these places should be greater than in other parts of the structure.

Insulation of a shallow foundation

1. The first step is to dig a trench around the perimeter of the base, going deep to the foundation cushion. The width of the trench should be 5 cm greater than the freezing level of the soil.
2. The outer part of the base is treated with a bitumen waterproofing compound, applying it in a continuous layer over the entire surface of the foundation wall, including the base. You can also use bitumen-based roll material as waterproofing. It is glued to the wall using bitumen mastic.
3. The thermal insulation material is covered with a dense membrane or geotextile. This will give the insulation a flat and smooth surface, which will protect the material from damage as a result of soil heaving.
4. Upon completion of these procedures, drainage pipes are laid if necessary. The trench for them is filled with a sand and gravel mixture.

Expanded polystyrene boards are secured using gas burner. The waterproofing roll covering is heated in several places, after which the insulation is pressed tightly against the wall.

Owners of private houses, in an effort to make their home warm, sometimes pay attention only to the walls and ceilings. At the same time, they forget that insulating the foundation is an equally important point.

As a result, problems arise with cold floors and excessive heating costs. Once you invest effort and money in insulating the load-bearing base, you can save an impressive amount on heating costs.

What causes the need for thermal insulation?

A significant portion of the cool air enters the room through the foundation. Therefore, many building designs are designed to raise the floors above ground level. Warm, heated air rushes upward. When the roof is not insulated, heat leaks out. And the room is filled with cold air, which penetrates through the floors of the building. Therefore, the need for thermal insulation of the load-bearing base is obvious. If the walls are in frozen ground, the room will have to be constantly heated.

When it comes to preserving heat in an old house, you should remember that all components of the system must retain heat: the foundation, walls, ceilings and roof. If just one thing releases heat, the entire building will not be able to keep it at a high level.

High-quality foundation insulation can reduce the impact of groundwater and cold on the foundation of both wooden and stone buildings.

Insulation methods

All insulation methods are usually divided into two types. The first is before the foundation is poured, the second is the insulation of the finished structure. The first option is preferable and is the one that is used most often. In severe winter conditions, the concrete foundation is insulated on both sides.

Concrete is known for its almost complete lack of thermal insulation; it cools easily and heats up just as easily. During construction, they use both insulation, which is mounted directly into the formwork, and special permanent formwork. Such panels cost several times more than simple ones, but the amount of costs is lower than the price of dismantling simple formwork and subsequent insulation.

Insulating the foundation of an already used house is a complex and responsible undertaking. In cases where the building is built with insufficient foundation depth, freezing of the soil underneath will be very strong. In such situations, for thermal insulation, the foundation is dug both inside and outside, and later insulation is laid. At the same time, to prevent freezing of the floor in the basement of an old building, it is sprinkled with expanded clay.

For many years, the most commonly used methods of foundation insulation have remained unchanged: using earth, expanded clay or expanded polystyrene.

Earth insulation

This option is the most economical, despite the impressive volumes of sand that will have to be unloaded and leveled. The method consists in filling the earth up to the level of the future floor, as a result the entire basement and foundation are underground.

Soil insulation is carried out before the construction of the house begins. It is imperative to provide a ventilation shaft for the basement.

Advantages of the method:

• when insulating with soil, you don’t have to buy insulation;
• the house will not freeze through the basement.

Flaws:

• large volumes of earth and sand will have to be leveled;
• soil is a weak heat insulator;
• the foundation walls will let cold into the room, albeit in smaller quantities.

Thermal insulation with expanded clay

One of the cheapest and most effective methods. Sometimes builders combine insulation with soil and expanded clay.

During the process of pouring the foundation, expanded clay is placed into the interior of the pre-fabricated formwork. This method is used both for insulating walls and floors, in both cases it is quite effective. Unique properties expanded clay are enclosed in its porous structure, thanks to which it does not allow moisture and cold to pass through, and retains heat well. The only losses occur due to the fact that the cavities between the granules are filled with cement, which is a conductor for cold.

Expanded clay insulation is often used for strip foundations. With a low-depth foundation, the material is used to insulate the floor in order to completely get rid of freezing of the ground in the basement.
If insulation occurs after pouring, then the lightest formwork is usually used, since expanded clay is practically weightless. Sometimes slate sheets are used as formwork.

Expanded clay is a fragile insulation material. When used for floor insulation, lay on expanded clay mineral wool and film to protect against moisture.

What about foam?

When deciding how to properly insulate a foundation, the choice often falls on the foam insulation method. This is a universal and affordable material.

Polystyrene foam is sold in sheets that are easy to install. Therefore, its use allows you to do all the work yourself.

Waterproofing

Before fixing the insulation sheets, it is important to waterproof the surface. There are many methods of waterproofing:

• applying several layers of bitumen mastic;
• waterproofing with roofing felt;
• plastering the surface;
• application of special penetrating compounds.

Laying slabs

After ensuring waterproofing, sheets of expanded polystyrene are mounted on the insulated surface. The sheets are laid from the bottom of the foundation to the level of the future floor. The insulation is secured using special adhesives that are applied pointwise to its surface. Expanded polystyrene sheets must be laid close to each other to create a monolithic surface. The seams between the insulation boards are sealed with polyurethane foam.

Expanded polystyrene is destroyed over time when exposed to sunlight, so it should be securely covered with cladding panels on top.

Thermal insulation around the perimeter

Before insulating the foundation around the perimeter, you need to remove the soil along the entire base of the building to a depth of about half a meter and a width of about one and a half meters. After creating the trench, approximately 20 cm of sand is poured in and it is thoroughly compacted.

Expanded polystyrene slabs are installed on the “sand cushion”. For additional reliability, insulation materials are attached using special adhesives, for example, bitumen mastic. The joints formed between the plates are blown out with foam. You can also fill the gaps using cold applied bitumen mastic.

After fixing the insulation and completing the remaining related work, sand is again filled with a layer of at least 3 m.

Corner areas of buildings lose more heat than flat surfaces. Therefore, in these places you should use a larger (one and a half times) layer of polystyrene foam.

The advantages of perimeter insulation with expanded polystyrene foam are as follows:

• the design of the insulated foundation is protected from deformations and cracks;
• the basement is also thermally insulated;
• polystyrene foam has good performance properties, which makes it a fairly durable material.

Expanded polystyrene can also be used for internal insulation of an old house if external insulation is not possible. To do this, the inside walls are covered with foam boards. A room insulated in this way can become a full-fledged room.

Using penoplex

Penoplex material is more advanced than polystyrene foam. prevents its deformation, the building will last longer.

Penoplex has a closed-cell structure, so it is not susceptible to the destructive effects of water. Other important advantages of the material are its strength and low thermal conductivity.

How is installation carried out?

Penoplex can be installed only a week after waterproofing, the methods of which were described above.

Penoplex is produced in the form of slabs with grooves of a certain configuration. These grooves ensure a very tight fit of the plates to each other without gaps.

Fastening is carried out with special adhesives. You need to choose only those compounds that are not capable of destroying the insulation. The glue is applied pointwise, gradually treating small surface areas. The slab is applied to the foundation and pressed for 40 seconds. After gluing the slabs, proceed to the next section. The process continues until the entire surface of the base of the building is insulated.

The slabs must be glued so that they protrude 35–50 cm upward. After installation is completed, the resulting voids are filled with non-heaving materials. At the end, thermal insulation of the soil is carried out around the perimeter.

High strength sealed board using PU foam

Polyurethane foam or PPU - modern building material with many advantages. It is characterized by low thermal conductivity, strength, durability and environmental friendliness. Working with polyurethane foam is easy - no additional fasteners are required for installation, and it is applied to the surface quickly. PPU has high waterproofing properties that prevent moisture from entering, thereby protecting the building.

The main advantage of using polyurethane foam as insulation is the inability to spoil the result - the final coating is always obtained without cracks, irregularities and joints.

How to work with polyurethane foam?

It occurs by spraying insulation onto the surface using special installations. The resulting foam is firmly connected to the base of the structure, filling all cavities. The result is a high-strength slab, very hard and airtight. Since the material has a closed structure and there is no air gap, condensation cannot appear in such a product.

Thermal insulation of the foundation with polyurethane foam is the most effective method. It is suitable for both new buildings and for thermal protection of an old house. But the cost of such insulation is high and it is impossible to carry out the work yourself, since special equipment is required.

There are many options for waterproofing and insulating the foundation; all you have to do is choose which one is most suitable.

Construction of your own home can be done either independently or with the help of hired professional builders. The first option is much more reliable, especially if you have at least basic construction skills. Plus, it will allow you to save money on hiring workers. The second option, as is already clear, will cost you much more. And this applies not only to the financial side.

Expanded polystyrene is used for insulation

Besides the fact that you will need to find and hire workers, you will not be completely sure that the construction and all related work will be completed correctly. The same applies to purchased materials, on which “unscrupulous” foremen and workers quite often save. Therefore, when starting to build a house, you should carefully weigh all the pros and cons regarding a specific option for implementing your plans. In addition to the fact that you will need to correctly assess your capabilities, you will also need to decide how you will construct this or that element of the structure.

The very first and most important stage in the construction of each structure is construction. Much depends on this stage, including the level of strength of the entire building and the atmosphere in the entire room. As for how strong and long your home will serve you, the foundation should be built as reliably as possible. Insulation of the house can be done at later stages. Many residents of countries or regions of a particular state located in the northern part of the globe very diligently insulate the walls and ceilings of their home to insulate the room, but they forget about the foundation as one of the most basic sources of heat in the house.

Feature of the base

Foundation structure: soil, strip foundation, floor.

So, if you are installing any structure, then a foundation must be laid for it. This is required for this. so that the house stands for as long as possible and at the same time acts as a barrier to the entry of cold air into the room. In order to understand exactly how the above principle works, you should remember the elementary physics course from your high school course. Warm air currents are much lighter than cold ones, respectively, cold air is formed at the bottom and, gradually heating up, it rises to the top. This is why rooms with high ceilings are almost always cool. But it will never happen that all the cold air heats up and rises immediately. This happens gradually, without any action on the part of the person. The only thing that can change this state of affairs is insulating the foundation. Thanks to this event, you will not have to wait for the cold air to warm up, since there will only be warm air in the house.

Another mistake that occurs quite often during the construction of a house is that the foundation is not dug deep enough into the ground, and the distance between the floor and the ground is very small. This is not always due to an ordinary miscalculation; quite often it happens due to the fault of the builders. Those who do this or that work not for themselves have a peculiarity associated with the fact that they try to complete everything necessary very quickly, without really worrying that the work will not be done accurately and reliably.

Therefore, if you do not carry out the pouring yourself, then try to at least monitor how the work is carried out by hired builders.

Drainage: foundation, drainage pipe, wall.

They are not very often aware of the composition of a particular soil, as well as the fact that the foundation in regions with harsh conditions must be insulated. Many people believe that it is enough to just deepen the foundation in order for the house to stand level and secure. However, it should also be taken into account that a foundation that is not deep enough into the ground can freeze, which will lead to increased formation of cold air both in the underground and indoors.

Soil analysis is necessary in order to determine as accurately as possible the depth of groundwater at the site where the house is built. This will determine how deep you can pour the foundation. If the groundwater runs high enough, this will indicate that the foundation cannot be deepened too much. Moist soil conducts cold air even better than dry soil. Thus, it is advisable to take care of the insulation of the foundation even at the stage of building a house.

Installation

The depth of the trench depends on the distance to groundwater and the type of soil.

In connection with all of the above, it is necessary to conclude that a warm foundation can be built at the very beginning, and if a geological analysis of the soil does not allow this, then insulation will need to be done after the house is completely erected. In the case of the first situation, you must first dig a trench around the entire perimeter of the future house.

Depending on climatic conditions and the composition of the soil, its depth should be from 50 to 100 cm. After this, you can begin mixing the solution itself. Most often used, consisting of:

• cement;
• sand;
• crushed stone;
• water.

First you need to take one part each of water and cement, mix everything and add to them 3 parts sand and the same amount of crushed stone. The mixed solution must be poured into the dug trenches. You can resort to reinforcement in advance. This will allow you to strengthen the structure, and, accordingly, the entire house. For these purposes, materials such as old frames from any vehicle, old wire, pipes and any other scrap metal that is most likely lying around somewhere in the country or in the garage are perfect. Thus, if the depth meets all the above requirements, then this tab will allow you to insulate the foundation of the house to the maximum.

Thermal insulation methods

Concrete block foundation: sand cushion, blocks.

In addition to the option that involves constructing a foundation pit using liquid concrete mortar, there is another way to insulate a home. It is due to the fact that instead of mortar, individual concrete blocks are placed in the pit. They are ready-made material for the foundation, which is already reinforced and pressed into rectangular slabs. They can be columnar (have a regular rectangle in cross-section) and ribbon. They are concrete blocks in the form of trapezoids. The wide base of such slabs allows them to withstand enormous loads on the foundation and soil.

Insulation of an existing structure

Method of insulation using foam.

There are several options that you can resort to in order to insulate the foundation of a private house after it is completely built. The first option is due to the fact that insulation is necessary due to the fact that the foundation was not deep enough due to the negligence of the builders.

The second is due to the fact that it was not possible to dig a deeper foundation due to increased soil moisture. In the first case, in order to insulate the foundation, you will first need to dig around the foundation of the house outside and inside the house. After this, you will need to mix the concrete solution, the recipe for which has already been mentioned, and fill it with all the new trenches that were dug next to the main foundation of the structure.

This option is the most common and popular of all, which can allow you to insulate an incorrectly constructed foundation. In addition, the creation of this solution will not require large quantity money spent, which will have a significant positive impact on the family budget. You can mix the solution either with your own hands or using an electric concrete mixer. Another option involves using a drill and an attachment – ​​a construction mixer.

The second option involves the use of a much larger number of tools and materials for insulation. In order to make a warm foundation, the following can be used:

• expanded clay;
• Earth;
• expanded polystyrene.

Expanded clay is a porous material that retains heat.

Expanded clay is practically the cheapest material for insulating both a foundation that has already been built and one that is still in the process. In order to insulate the foundation with expanded clay, it is necessary to build lightweight formwork in the internal part, since expanded clay is also the lightest material to achieve this goal. Slate is most often used for this. Expanded clay is poured into the formwork, compacted and covered with waterproofing on top. This is necessary so that the expanded clay is not destroyed due to unfavorable climatic conditions.

The insulating properties of expanded clay are possible due to the fact that it is a material with a special porous structure. As already mentioned, expanded clay can also be used to insulate the foundation during its construction. To do this, expanded clay is poured into a dug pit, which is later poured with cement mortar. It consists of one part cement, the same amount of water and three parts sand. Expanded clay can also be used to fill the gaps between strip concrete slabs.

Penoplex insulation: foundation, penoplex, drainage, sand.

Earth is one of the most affordable materials that will allow you to insulate the foundation. To do this, you will have to dig up a certain amount of earth, which will subsequently be poured inside the house (in the underground). With its help, it will be necessary to fill the foundation completely. In this case, the size of the subfloor will be significantly reduced, but the cold will not penetrate into the room. This option can be successfully used in conjunction with plastering the external ground part. To do this, you will need to mix a cement mortar, the composition of which has already been mentioned. Then you apply the solution to the foundation. This can be done smoothly, or you can do it with sloppy strokes, imitating the unevenness of natural stone. You can then paint the stucco foundation or overlay it straight away decorative stone or tiles.

A shallow strip foundation (hereinafter referred to as MZLF) is one of the types of strip foundations, which is characterized by a shallow depth, significantly less than the depth of soil freezing, and a relatively small consumption of concrete mixture. This article discusses the main advantages and disadvantages of MZLF, the most common mistakes in their construction, a simplified calculation method suitable for private developers (not professionals), and recommendations for constructing a foundation with your own hands.

The main advantages of MZLF are:

- economical - concrete consumption is significantly lower than during the construction of a conventional strip foundation. It is this factor that most often determines the choice of this technology in low-rise construction;

- reduced labor costs - less excavation work, less volume of prepared concrete (this is especially important when it is not possible to pour the finished mixture from a mixer);

- smaller tangential forces of frost heaving due to the reduced area of ​​the lateral surface of the foundation.

However, during the construction of the MZLF, it is necessary to strictly adhere to the technology; a frivolous attitude to the process can lead to the appearance of cracks, and then all of the above advantages, as they say, will go down the drain.

The most common mistakes made when installing MZLF:

1) selection of the main working dimensions of the foundation without any (even the most simplified) calculation at all;

2) pouring the foundation directly into the ground without covering it with non-heaving material (sand). According to Fig. 1 (on the right), we can say that in the winter season the soil will freeze to the concrete and, rising, drag the tape upward, i.e. the tangential forces of frost heaving will act on the foundation. This is especially dangerous if the MZLF is not insulated and a high-quality blind area is not equipped;

3) improper reinforcement of the foundation - choosing the diameter of the reinforcement and the number of rods at your discretion;

4) Leaving the MZLF unloaded for the winter - it is recommended to carry out the entire cycle of work (construction of the foundation, erection of walls, and arrangement of the blind area) one construction season before the onset of severe frosts.

Calculation of a shallow strip foundation.

The calculation of the MZLF, like any other foundation, is based, firstly, on the value of the load from the weight of the house itself and, secondly, on the calculated soil resistance. Those. the soil must withstand the weight of the house transmitted to it through the foundation. Please note that it is the soil that supports the weight of the house, and not the foundation, as some believe.

If an ordinary private developer can calculate the weight of a house if desired (for example, using our online calculator located), then it is not possible to determine the calculated soil resistance on your site on your own. This characteristic is calculated by specialized organizations in specialized laboratories after conducting geological and geodetic surveys. Everyone knows that this procedure is not free. Mostly, architects who design a house resort to it, and then, based on the data received, they calculate the foundation.

In this regard, it makes no sense to provide formulas for calculating the size of the MZLF within the framework of this article. We will consider the case when a developer carries out construction on his own, when he does not conduct geological and geodetic surveys and cannot accurately know the calculated soil resistance on his site. In such a situation, the dimensions and design of the MZLF can be selected according to the tables below.

The characteristics of the foundation are determined depending on the material of the walls and ceilings of the house and its number of storeys, as well as on the degree of heaving of the soil. How you can determine the latter is described

I. MZLF on medium and highly heaving soils.

Table 1: Heated buildings with walls made of lightweight brickwork or from aerated concrete (foam concrete) and with reinforced concrete floors.

Notes:

— the number in brackets indicates the pillow material: 1 — medium-sized sand, 2 — coarse sand, 3 — a mixture of sand (40%) with crushed stone (60%);

- this table can also be used for houses with wooden floors, the safety margin will be even greater;

— see below for foundation design options and reinforcement options.

Table 2: Heated buildings with walls made of insulated wooden panels ( frame houses), logs and beams with wooden floors.

Notes:

— the numbers in brackets mean the same as in Table 1;

- above the line value for walls made of insulated wooden panels, below the line - for log and timber walls.

Table 3: Non-buried foundations of unheated log and timber buildings with wooden floors.

Notes:

- above the line values ​​for log walls, below the line - for walls made of timber.

Design options for MZLF on medium- and highly heaving soils, indicated by letters in the tables, are shown in the figures below:

1 - monolithic reinforced concrete foundation; 2 - sand filling of sinuses; 3 — sand (sand-crushed stone) pillow; 4 — reinforcement frame; 5 - blind area; 6 7 — waterproofing; 8 - base; 9 — ground surface; 10 - sand bedding; 11 - turf.

Option a.— the upper plane of the foundation coincides with the surface of the earth, the base is made of brick.

Option b.- the foundation protrudes above the surface by 20-30 cm, forming a low base or being part of the base.

Option c.- the foundation rises 50-70 cm above the ground, while it also serves as a base.

Option d.- non-buried foundation-basement; Table 3 shows that such foundations are used for unheated wooden buildings.

Option d.- used instead of options b. or V. when the width of the base of the foundation significantly exceeds the thickness of the wall (more than 15-20 cm).

Option e.— a shallow strip foundation on a sand backfill is used quite rarely on weak (peaty, silted) soils with a high groundwater level for wooden buildings. Depending on the size of the building, bedding is done either under each strip or under the entire foundation at once.

Reinforcement of a shallow strip foundation.

MZLF reinforcement is made with meshes of working reinforcement and auxiliary reinforcing wire. The working reinforcement is located in the lower and upper parts of the foundation, and it must be immersed in the thickness of the concrete by about 5 cm. The lower mesh works to deflect the foundation tape downward, and the upper mesh works to deflect the tape upward. There is no point in placing the working reinforcement in the middle of the tape (as can sometimes be seen on the Internet).

Table 4: Options for foundation reinforcement.

MZFL reinforcement schemes are shown in the following figure:

A.— a mesh with two working reinforcement rods; b.— a mesh with three working reinforcement rods; V.— T-shaped joint; G.— L-shaped corner joint; d.— additional MZLF reinforcement with a large sole width, when the sole is more than 60 cm wider than the base (the additional mesh is located only in the lower part.

1 — working fittings (A-III); 2 — auxiliary reinforcing wire ∅ 4-5 ​​mm (Вр-I); 3 — vertical reinforcement rods ∅ 10 mm (A-III), connecting the upper and lower mesh; 4 — reinforcement for strengthening the corner ∅ 10 mm (A-III); 5 — connection with wire strands (twisting length is at least 30 diameters of the working reinforcement); 6 — additional working fittings ∅ 10 mm (A-III).

II. MZLF on non-heaving and slightly heaving soils.

Shallow strip foundations on non-heaving and slightly heaving soils do not have to be made only from monolithic concrete. You can also use other local materials, for example, rubble stone, red ceramic brick. MZLF is laid at 0.3-0.4 meters without a sand cushion. Moreover, for wooden buildings and one-story brick (or aerated concrete) foundations, they don’t even need to be reinforced.

For 2- and 3-story houses with walls made of stone materials, MZLF is reinforced. Concrete foundations are reinforced according to the 1st reinforcement option (see Table 4 above). Foundations made of rubble or brick are reinforced with masonry mesh made from BP-I reinforcement ∅ 4-5 ​​mm with a cell size of 100x100 mm. The nets are placed every 15-20 cm.

MZLF structures on non-heaving and slightly heaving soils are shown in the figure below:

1 - foundation; 2 - base; 3 - blind area; 4 — waterproofing; 5 — subfloor (shown conditionally); 6 - mesh made of wire reinforcement, 7 — reinforcement according to option 1 (see table 4)

Options a. and b.- for wooden and one-story brick (aerated concrete) buildings.

Options c. and Mr.— for two- and three-story brick (aerated concrete) buildings.

The width of the sole b is determined depending on the number of storeys of the building and the material of the walls and ceilings.

Table 5: Values ​​of the width of the sole of the MZLF on non-heaving and slightly heaving soils.

Stages of construction of a shallow strip foundation and recommendations.

1) Before starting construction of the foundation, if necessary, it is necessary to ensure high-quality drainage of surface rainwater from neighboring areas from the building site. This is done by cutting out drainage ditches.

2) The foundation is marked and trenches are torn out. It is recommended to begin excavation work only after all materials have been delivered to the construction site. necessary materials. It is advisable to organize the process of cutting out the trench, filling the tape, backfilling the sinuses and constructing the blind area as a continuous process. The less it is extended in time, the better.

3) The dug trenches are covered with geotextiles. This is done so that the sand cushion and sand filling of the sinuses do not become silted over time by the surrounding soil. At the same time, geotextiles allow water to pass through freely and do not allow plant roots to grow.

4) A sand (sand-crushed stone) cushion is poured layer by layer (in layers of 10-15 cm) with careful compaction. They use either manual rammers or area vibrators. Tamping should not be taken lightly. Shallow foundations are not as powerful as foundations poured to the full depth of freezing, and therefore freezing here is fraught with the appearance of cracks.

5) The formwork is laid out and the reinforcement frame is knitted. Do not forget to immediately provide water and sewerage to the house. If the foundation is also a plinth, remember about the vents (does not apply to buildings with floors on the ground).

6) Concrete is poured. Filling of the entire tape must be done continuously, as they say, in one go.

7) After the concrete has set (3-5 days in summer), the formwork is removed and made vertical.

8) Produced backfill sinuses with coarse sand with layer-by-layer compaction.

9) A blind area is being constructed. It is advisable (especially with a small height of the foundation tape) to make the blind area insulated. This measure will further reduce the forces of frost heaving affecting the MZLF in winter. Insulation is made with extruded polystyrene foam.

As already mentioned at the beginning of the article, it is not allowed to leave the MZLF unloaded or underloaded (the building is not fully built) for the winter. If this happens, the foundation itself and the soil around it must be covered with any heat-saving material. You can use sawdust, slag, expanded clay, straw, etc. There is also no need to clear the snow on the construction site.

It is highly not recommended to build a shallow strip foundation in frozen soil in the winter.

In the comments to this article, you can discuss with readers your experience in the construction and operation of MZLF or ask questions that interest you.