A shallow-depth strip foundation (hereinafter referred to as MZLF) is one of the types of strip foundations, which is characterized by a slight deepening, much less than the depth of soil freezing, and a relatively small consumption of concrete mix. This article discusses the main advantages and disadvantages of MZLF, the most common mistakes during their construction, a simplified calculation method suitable for private developers (non-professionals), recommendations for building a foundation with your own hands.

The main advantages of MZLF are:

- efficiency - the consumption of concrete is much lower than in 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 earthwork, less volume of prepared concrete (this is especially important when it is not possible to pour the finished mixture from the mixer);

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

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

The most common mistakes made with the MZLF device:

1) the choice 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 sprinkling with non-porous material (sand). According to fig. 1 (right) we can say that in winter time year, the soil will freeze to concrete and, rising, drag the tape up, 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) incorrect reinforcement of the foundation - the choice of the diameter of the reinforcement and the number of rods at your discretion;

4) Leaving the MZLF unloaded for the winter - it is recommended that the entire cycle of work (construction of the foundation, erection of walls, and arrangement of the blind area) be performed 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 ground must support the weight of the house, which is transferred to it through the foundation. Please note that it is the ground that holds the mass of the house on itself, and not the foundation, as some believe.

If, if desired, an ordinary private developer can still calculate the weight of the house (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 geological and geodetic surveys. Everyone knows that this procedure is not free. Basically, architects who make a project at home resort to it, and then they calculate the foundation based on the data received.

In this regard, it makes no sense to give formulas for calculating the size of the MZLF within the framework of this article. We will consider the case when the developer is building 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 from 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 can you determine the latter is described

I. MZLF on medium and strongly heaving soils.

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

Notes:

- the number in brackets indicates the material of the pillow: 1 - sand of medium size, 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 margin of safety will be even greater;

- options for foundation designs and reinforcement options, see below.

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

Notes:

- the numbers in brackets indicate the same as in table 1;

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

Table 3: Unburied foundations of unheated log and timber structures with wooden floors.

Notes:

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

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

1 - monolithic reinforced concrete foundation; 2 - sand filling of the sinuses; 3 - sand (sand-gravel) pillow; 4 - reinforcing cage; 5 - blind area; 6 7 - waterproofing; 8 - plinth; 9 - ground surface; 10 - sand bedding; 11 - turf.

Option a.- the upper plane of the foundation coincides with the surface of the earth, the plinth is made of bricks.

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

Option c.- the foundation rises above the ground by 50-70 cm, while it is also the base.

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

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

Option e.- a shallow-depth strip foundation on a sand bed is used quite rarely on weak (peaty, silty) soils at a high level ground water for wooden buildings. Depending on the size of the building, backfilling is done either under each tape, or under the entire foundation at once.

Reinforcement of a shallow strip foundation.

Reinforcement of MZLF 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, while it must be immersed in the concrete thickness by about 5 cm. It makes no sense to place working reinforcement in the middle of the tape (as you can sometimes see on the Internet).

Table 4: Foundation reinforcement options.

The MZFL reinforcement schemes are shown in the following figure:

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

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

II. MZLF on non-rocky and weakly rocky soils.

Shallow-buried strip foundations on non-rocky and slightly heaving soils do not have to be made only from monolithic concrete. You can use other local materials, such as rubble stone, red ceramic bricks. 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, you can not even reinforce them.

For 2 and 3-storey 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 meshes made of Vp-I reinforcement ∅ 4-5 ​​mm with a mesh size of 100x100 mm. Nets are laid every 15-20 cm.

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

1 - foundation; 2 - plinth; 3 - blind area; 4 - waterproofing; 5 - draft floor (shown conditionally); 6 - mesh of wire reinforcement, 7 - reinforcement according to the 1st option (see tab. 4)

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

Options in. 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: The values ​​of the width of the sole of the MZLF on non-rocky and low-rocky soils.

Stages of construction of a shallow strip foundation and recommendations.

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

2) The foundation is marked and trenches come off. It is recommended to start earthworks only after the delivery of all necessary materials. The process of extracting the trench, pouring the tape, backfilling the sinuses and constructing the blind area is desirable to organize continuous. The less time it takes, the better.

3) Dug trenches are covered with geotextiles. This is done so that the sand cushion and the sandy backfill of the sinuses do not eventually become silted up with the soil surrounding them. At the same time, geotextiles freely pass water and do not allow plant roots to germinate.

4) In layers (layers of 10-15 cm), a sand (sand-gravel) pillow is poured with careful tamping. Use either manual rammers or platform vibrators. Do not take ramming lightly. Shallow foundations are not as strong as foundations filled to the full depth of freezing, and therefore a freebie here is fraught with the appearance of cracks.

5) The formwork is exposed and the reinforcing cage is knitted. Do not forget to immediately provide for the supply of water and sewer to the house. If the foundation is also a plinth, remember about the ventilation (does not apply to buildings with floors on the ground).

6) Concrete is being poured. The filling of the entire tape must be carried out continuously, as they say, in one go.

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

8) The sinuses are backfilled with coarse sand with layer-by-layer tamping.

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

As mentioned at the beginning of the article, it is not allowed to leave the MZLF unloaded or underloaded (the building was not fully built) for the winter. If nevertheless this happened, 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. It is also not necessary to clean the snow on the building spot.

It is highly discouraged to build a shallow strip foundation in the winter season in frozen ground.

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

The most cost-effective and easy-to-arrange version of the foundation for houses made of brick, wood or aerated concrete, erected on normal soils that are not prone to heaving.

The page provides detailed information on the calculation methodology and technology for the construction of a shallow strip foundation. You will also get acquainted with the video, which explains the most important points of creating a strip foundation with your own hands.

Shallow strip foundation - calculations

There are two types of calculations that must be performed when designing a shallow strip foundation: the first is the calculation of its bearing capacity and dimensions, the second is the calculation of the materials needed to create the foundation.

The calculation of the bearing capacity is a complex process, it is necessary to take into account a very large number of factors: the depth of freezing and soil resistance, the deformation loads that the soil will exert on the future foundation, the weight of the structure, and many others.

Rice. 1.1: Shallow strip foundation

The calculation of the required materials from start to finish can be done independently. To do this, you need to know the dimensions of the foundation, on the basis of which further calculations will be performed on such materials as:

• Concrete;
• Fittings and wire for knitting;
• Crushed stone and sand;

As an example, we give the calculation of the materials necessary to create a shallow strip foundation 40 cm wide and 60 cm deep, under a house with a wall perimeter of 54 m (length - 9 m, width - 6 m).

To calculate the materials, we need to determine the volume of the foundation: the perimeter of the tape must be multiplied by its width and length

54*0.4*0.6 = 12.96 m3;

Calculation of materials for compacting bedding

Fine crushed stone and sand are used to create a compacting bedding. Soil compaction is necessary in order to reduce the deformation and buoyancy loads that the soil exerts on the foundation.

Rice. 1.2: Sealing pad diagram

• We calculate the volume of the backfill layers (they will be the same, since the thickness of the layers is identical): 56 (length similar to the perimeter of the base) * 0.4 (w) * 0.1 (t) = 2.24 m3.

The weight of 1 m3 of crushed stone and sand is data that can be found in any building guide: 1 m3 of sand weighs 1440 kg, crushed stone - 1600 kg. Now we calculate the mass of materials we need:

• Mass of sand: 2.24 * 1440 = 3225.6 kg;
• Mass of crushed stone: 2.24 * 1600 \u003d 3584 kg.

Calculation of the mass of concrete

Concrete- the main part of the cost estimate for the construction of a shallow strip base. If you have a concrete mixer, you can do it directly on the job site, or you can order a ready-made concrete machine.

To fill a shallow strip base, according to the current SNiP, it is necessary to use concrete of the M300 standard, since concrete of a lower density will not provide the required bearing capacity of the foundation strength.

Rice. 1.3: The structure of M300 concrete used for pouring foundations

The nominal mass of 1 m3 of M300 concrete is 2389 kilograms. To determine the total weight of the required concrete, we need to multiply the volume of the foundation tape (12.96 m3) by the weight of 1 m3 of concrete:

12.96 * 2389 \u003d 30,961.44 kg.

Since concrete tends to shrink during curing, the mixture must be taken with a margin of 3-4% of the required weight:

30961.44 * 0.03 = 928.9 kg;

Total we need 31.9 tons of M300 concrete.

Calculation of materials for base reinforcement

Any strip base requires mandatory reinforcement with an armored frame of two horizontal belts, which are connected by vertical bridges.
To create a horizontal frame contour, hot-rolled A3 rebar (12 mm in diameter) and A1 rebar (8 mm) are required. for jumpers. The frame is connected with a knitting wire.

Based on the total length of the foundation strip, the length of the required reinforcement A3 can be calculated:

• 54 * 4 (number of frame contours) = 216 m;

In addition, we will need an additional 10 m of reinforcement to strengthen the corners of the frame. The total length of the A3 rods is 226 meters.

Rice. 1.4: Reinforcement of a shallow strip foundation

Now we determine the number of reinforcement A1 for jumpers. Considering that the frame must be recessed ten centimeters deep into the foundation, and the height of our base is 60 cm, the height of the vertical jumper will be 40 cm.

• We calculate the total number of vertical rods: (54 / 0.2) * 2 = 540 pieces;
• That allows you to determine the required length of the reinforcement: 540 * 0.4 = 216 m.

It takes about 20 cm of wire per frame connection. Based on the total number of jumpers (540 pcs), we calculate the number of connections and the length of the binding wire:

• 540*2 = 1080 connections;
• 1080 * 0.2 \u003d 216 m of knitting wire.

Shallow strip foundation - construction technology

Construction shallow strip foundation begins with the marking of the territory. For this, pegs from rebar scraps and scourging are used, through which the contour of the future base is marked on the ground according to the project.

earthworks

If the walls of the pit crumble during digging, it is necessary to make temporary supports from the boards. It is also extremely important to keep the bottom of the trench vertical, as any slopes will increase the amount of material used to create the compacting pad.

Upon completion of digging and leveling the walls of the pit, we proceed to the arrangement of the backfill. The first ball is sand. It is necessary to pour it out in layers, 3-5 centimeters each, and each layer must be shed with water and tamped so that the sand gets the maximum density.

Rice. 1.4.1: Sand bed formation

A layer of crushed stone is poured over the sand, which also needs to be compacted by hand tamping.

Formwork installation

To create the formwork, boards with a thickness of 20 mm are used, which are fastened together with the help of bars and self-tapping screws or a metal corner.

Rice. 1.5: Formwork for a shallow strip foundation

Spacers made of wooden beams are installed along the outer contour of the formwork, the spacing of the spacers is 50 centimeters, they are necessary so that the formwork does not deform from the weight of concrete.

Inside the formwork, the boards must be covered with oilcloth, since the cement milk of liquid concrete can flow into the gap between them. Upon completion of the installation on the formwork, we mark the level at which the filling will be performed.

Reinforcement

The technology of reinforcing a shallow foundation according to the requirements of SNiP does not require mandatory strengthening of the middle part of the foundation, since it does not experience critical loads. It is enough to equip the frame along the upper and lower contour of the tape.

Such a frame consists of two vertical belts of reinforcement A3 with a diameter of 13 mm, which are connected by vertical bridges of smooth 8 mm reinforcement. The frame is fixed with knitting wire.

Hand knitting wire is most conveniently done with a crochet hook. The fixation of one knot requires 20-25 cm of double-folded wire.

Rice. 1.6: The layout of the reinforcement in the frame to strengthen the strip foundation

The reinforcement frame is knitted in a place convenient for you, and only then the finished part of the structure is placed inside the formwork. It is extremely important to perform the correct connection of the reinforcement at the corners of the foundation, since it is in this place that the bearing and deformation loads on the foundation are maximum.

In places corner connections it is necessary to install additional L-shaped reinforcements from reinforcement with a diameter of 13 mm. U-shaped connections are no less reliable, which you can see in the image below.

Rice. 1.7: Scheme of connecting the corners of the reinforcement cage

Pouring concrete

To pour the foundation with concrete, it is recommended to order the finished mixture in the required volume, since one-time pouring provides the best final strength of the base.
If you are deprived of this opportunity and are forced to prepare concrete yourself, be guided by the proportions of cement, sand and gravel shown in the image.

Rice. 1.8: Pouring concrete into a shallow strip foundation

After pouring concrete into the formwork, it must be processed with a vibrocompactor or a perforator with an appropriate nozzle. Compaction allows air bubbles to be removed from the concrete, which adversely affect the final strength of the foundation.

Upon completion of the compaction, the concrete is leveled using a rule and covered with oilcloth or tarpaulin. If the foundation is being built during the hot season, the concrete must be regularly moistened during the maturation process to avoid cracking. The concrete foundation receives its design strength in 3-4 weeks.

Do-it-yourself shallow strip foundation (video)

A video that examines in detail the technology for creating formwork for a shallow strip foundation.

We make the reinforcement cage for the strip foundation correctly.

We figure out how to properly knit reinforcement into a frame to strengthen the strip foundation.

Features of pouring concrete into the strip foundation formwork.

The shallow strip foundation has become popular for the construction of private houses due to its versatility and the possibility of building without the use of heavy equipment and for relatively little money. How to build a shallow strip foundation with your own hands?

When is MZLF applied?

A shallow strip foundation (MZLF) is a type of strip foundation with a laying depth of no more than 70 cm. This type of foundation has become widespread in individual construction due to several significant advantages:

• relatively low cost
• a small amount of earthworks,
• no need to use heavy equipment,
• applicability to different types soil,
• low cost of building materials.

It is possible to build on it houses up to 3 floors from timber, logs, frame, brick with lightweight masonry, from foam concrete.

The shallow foundation is suitable for both non-rocky and heaving soil. You can not do it on biogenic soils: peat, sapropel, and also on clay.

Types of MZLF

A shallow strip foundation can be either monolithic or prefabricated. The monolithic foundation is a concrete reinforced tape, which is located along the perimeter of the building and under the bearing walls. In the case of a prefabricated foundation, this tape is made from foundation blocks held together with cement mortar. It will take much less time to create a prefabricated foundation, but its service life is shorter than that of a monolithic one.

Combination of pile and strip foundation - pile-tape shallow foundation. The tape in this case rests on screw or bored piles, a sand or gravel cushion is made under it. The pile foundation is made on difficult soils or with elevation changes on the site.

Construction order

Before making a shallow strip foundation, it is necessary to conduct a geodetic examination to find out

• soil composition and quality,
• the depth of its freezing,
• ground water level.

These parameters affect the choice of the type of foundation and the depth of its laying. However, if you want to save on expensive expertise, it is enough to drill pits in several places on the site to assess the quality of the soil.

• Clay soil can be rolled into a ball with your hands.
• Loam can also be rolled into a ball, but it will be cracked.
• Sandy loamy soil will partially crumble.
• Sandy soil cannot be rolled into a ball.

The construction site must be cleared of debris and plants, trees uprooted, and the fertile soil layer removed.

Next, markup is carried out - the dimensions of the house are transferred to the site. To do this, you need a rope and pegs. First of all, mark the front wall of the house, which looks out onto the street. Next, two other walls are built perpendicular to it. To check whether a rectangle is even, compare its diagonals. There are beacons in the corners. At a distance of about a meter from this contour, a blind area is installed from boards, on which ropes are pulled, showing the dimensions of the strip foundation. It is possible to apply dimensions directly to the ground with lime mortar.

After that, they dig a trench. Its depth is equal to the thickness of the tape plus the thickness of the sand cushion. The thickness of the pillow is usually 20 cm. Usually, a trench for a shallow strip foundation is made 0.5 m deep and 0.6-0.8 m wide.

Under heavy structures, such as a stove, a porch, a ladder, they dig pits.

The pillow is made of sand, crushed stone or a mixture of them, 30-50 cm thick. A common option is also a two-layer pillow: 20 cm of crushed stone and 20 cm of sand. If the soil in the area is dusty, then geotextiles should be laid in the trench before backfilling the pillow.

The pillow is poured in layers, compacting each layer. If it is two-layer, first pour 10-15 cm of sand, ram it. To facilitate this task, the sand is wetted. Next, gravel is poured and also tamped. The surface of the pillow must be strictly horizontal, this can be checked using a level. A waterproofing material is laid on top - roofing material.

Monolithic MZLF

Next, collect the formwork. For it, boards or panel materials are used, such as plywood, OSB and others. The board must be at least 5 cm thick. The boards are knocked down into shields. The formwork should be a few centimeters above the expected concrete level. The height of the tape above the ground must be less than or equal to the depth and equal to 4 tape widths.

The shields are fixed with pegs, interconnected with screws or nails. Fasteners must not protrude into the formwork. If they are in concrete, cracks may appear or even a piece of concrete may break off. Also, the formwork for a shallow strip foundation is additionally strengthened with inclined supports (struts) made of timber with a cross section of at least 5 cm. Supports are located on the outside at a distance of about 0.5 m. Holes for communications must be drilled in the formwork. Pipes are inserted into them.

From the inside, the formwork is lined with polyethylene for waterproofing and reducing adhesion to concrete. You can also use fixed formwork made of extruded polystyrene foam.

Reinforcement

The device of a shallow strip foundation necessarily includes reinforcement. The armature is knitted with knitting wire. The use of welding to join the bars is not recommended as these are the areas where corrosion is most likely to occur. Reinforcement schemes are shown in the figure.

The minimum number of bars for the frame of a shallow strip foundation is 4 pieces. Longitudinal reinforcement must be class AII or AIII, have a ribbed section. The longer it is, the better - each connection reduces the strength of the frame. For the transverse parts, thinner smooth reinforcement (6-8 mm) is used. For a shallow foundation, two reinforcing belts are sufficient, only 4 longitudinal bars. The reinforcement should be 5 cm from the edges of the foundation. Between the vertical jumpers there should be 30-40 cm.

It is especially important to properly reinforce the corners. To do this, the bars are bent in such a way that the entrance to another wall is at least 40 bar diameters. At the same time, near the corners, the distance between the vertical jumpers should be half that in the wall.

fill

It is better to take factory-made concrete, brands not less than M200 (for wooden houses) and M250 (for brick ones). At self-manufacturing it is better to mix concrete not by hand, but in a concrete mixer.

It is advisable to fill the entire foundation in one go. Concrete is poured in layers, each layer is leveled and compacted. For this purpose, it is better to use a vibrotamper. The last layer is leveled according to the mark applied to the formwork. Professional builders who have already made more than a dozen foundations recommend sprinkling concrete on top with dry cement. This is necessary so that the top layer grabs faster. The foundation freezes for about a month.

Anti heave

Before you make a tape shallow foundation on loam, you need to know that anti-heaving measures are needed for such soil:

• drainage,
• waterproofing,
• warming.

For more information about the insulation of the foundation, see the video:

Important! It is highly desirable to complete the entire cycle of work (build a house completely) in one season so that the foundation does not remain unloaded for the winter. Otherwise, the forces of frost heaving can squeeze the foundation out of the ground, deform or break. If it is not possible to complete the house before the cold weather, then the ground around the foundation must be covered with any heat-insulating material (straw, sawdust). Snow on the site does not need to be removed.

MZLF on piles

The foundation on piles is made on difficult soils. For this, screw or bored piles are usually used. A sand cushion is poured under the tape. It will resist heaving of the soil.

Bored piles are made right on the site. To do this, wells are drilled, pipes, a reinforcing frame are placed in them and poured with concrete. The depth of the wells should be below the freezing level of the soil.

The pile reinforcement must be connected to the tape frame. To do this, it must rise above the sole of the tape by at least 40 cm. If screw piles are used, holes are drilled in them, reinforcement is threaded through them and connected to the tape frame.

A shallow strip foundation, both monolithic and prefabricated, can be made independently. On it you can build houses from different materials and different heights (up to 3 floors), it is used on different types of soil.

A shallow strip foundation (MZLF) is a type of strip foundation, which is located 0.3-0.7 m below the zero level. The construction of this type of foundation requires a minimum of financial and labor costs. MZLF is great for light buildings erected on various soils. The foundation has its advantages and disadvantages, as well as a special construction technology.

Shallow strip foundation: scope, pros and cons

The bearing capacity of MZLF, in comparison with bases of another type, is estimated as average and largely depends on the type of soil on the site. A shallow foundation is suitable for the construction of country houses, timber buildings, frame houses, as well as for outbuildings, a bathhouse, a barn, etc. A shallow foundation is not suitable for brick houses, large foam concrete cottages and gas blocks. For such buildings, an excellent option would be a combined foundation on piles, for example, a pile-tape shallow type on bored supports.

It is desirable to build a foundation of this type on slightly heaving and non-heaving soils. Ideal - sandy and sandy soils with a low moisture content. The groundwater level should be at least 0.5 m below the depth of laying. Most clay soils are classified as medium and high heaving soils. Features of the construction of the base with a small depth of laying on heaving soils will be considered below.

The advantages of this type of bases include

• profitability, concrete consumption is 30% lower than in the construction of a conventional buried strip foundation or a base with a monolithic floor slab;
• ease of construction, you can build it yourself without the involvement of workers and special equipment;
• a small amount of earthworks - a narrow trench is dug with a depth of no more than 0.7 m;
• small area of ​​contact between the structure and the ground.

Among the shortcomings of the MZLF note

• pouring is carried out at stable temperatures above +10 C;
• limited use due to low bearing capacity
• erection is possible only on a flat surface with a slope of not more than 5 degrees;
• lack of a basement in the house.

Expert opinion

Sergei Fedorov

Professional builder. Experience 18 years

Ask an expert

If you are planning to build an MZLF base and “freeze” the construction site, then keep in mind that you cannot leave the base unloaded for the winter! When freezing, the soil will push out the monolithic tape, which will lead to a violation of its integrity.

Design features of a shallow foundation

A shallow-depth monolithic-strip foundation is being erected on a flat surface. When building a house on a slope, you will have to combine the MZLF with a pile foundation, using supports to equalize the height difference. In terms of strength and resistance to deformation, the structure must comply with SNiP 2.03.01-84.

In the context of a shallow foundation, it looks like this:

Features of the MZLF, which must be taken into account in the calculation and construction:

1. The depth of the foundation sole depends on the depth of soil freezing.
2. Be sure to install a pillow of dry bulk materials: a mixture of coarse sand and gravel.
3. With a high level of groundwater, drainage is performed under the foundation and around it.
4. The base on which the monolithic tape is installed is compacted as much as possible.
5. Be sure to equip the blind area to drain rainwater and snow.

Considering these features, we can conclude that the bedding pad and the blind area are an integral part of the shallow foundation. The requirements for the blind area are specified in SNiP 2.02.01–83.

Calculation of a shallow strip foundation

The calculation of the MZLF, which is being built on low and non-rocky soils, is not difficult. During the calculation, three main parameters are determined:

Depth

It is determined on the basis of SN "Foundations and Foundations". The document specifies the following minimum values ​​for the depth of the foundation footing:

• when soil freezing is less than 2 m - 50 cm;
• when the soil freezes to a depth of 3 m - 75 cm;
• when the soil freezes over 3 m - 100 cm.

For most regions middle lane the laying depth of the MZLF will be 50 cm. For light buildings, such as a frame shed or a small country house this parameter can be reduced to 30 cm.

Monolithic belt width

In order not to make complex calculations, we recommend taking the width of the sole based on the table:

Wall and floor materials	Number of floors	MZLF sole width, m
Lightweight masonry or aerated concrete walls with reinforced concrete floors	1	0,6
	2	0,8
	3	1,2
Wooden frame walls with wooden floors	1	0,4
	2	0,4
	3	0,6
Log walls with wooden floors	1	0,3
	2	0,4
	3	0,6
Timber-framed walls	1	0,2
	2	0,3
	3	0,4

Height above ground level

The higher the monolithic tape rises above ground level, the better the floors of the house will be protected from dampness and cold. However, the height of the foundation to maintain stability and bearing capacity must be correlated with its width. The best option: the height of the tape above the zero mark is equal to its width.

Example: The laying depth is 50 cm. The width of the monolithic tape according to the table is 30 cm. This means that the height above ground level will be 30 cm, and the height of the entire monolithic tape will be 80 cm. The height of the ground part of the MZLF should not be lower than the snow level. The value of snow height depends on the region (it can be found on the Web). For the regions of the middle zone, this value does not exceed 8-10 cm.

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Calculation of MZLF on heaving soils

When building a house on heaving soils, more complex calculations are made, the purpose of which is to determine the heaving deformation. It is quite difficult to make such a calculation on your own, so you need to entrust it to professional designers or use a ready-made table:

Name and degree of heaving of soils	Number of floors of the building	Foundation footing width b, m	Pillow thickness t, m	Foundation design option	Reinforcement option
clays, loams and sandy loams, sands are fine and silty wet - medium sandy	1	0,3 / 0,2	0,6/0,7	G.	3
	2	0,3 / 0,2	0,5 / 0,6	G.	3
	3	0,3 / 0,2	0,4 / 0,5	G.	3
clays, loams and sandy loams, sands are fine and silty wet - strongly heaving	1	0,3 / 0,2	0,7 / 0,8	G.	4
	2	0,3 / 0,2	0,6 / 0,7	G.	4
	3	0,3 / 0,2	0,5 / 0,6	G.	4

In column 2 "Width of the sole" and column 3 "Cushion thickness" through the / sign, the values ​​\u200b\u200bare indicated for heated and unheated rooms. The column "Reinforcement option" indicates the minimum number of reinforcing bars that must be used to reinforce the monolithic tape.

Shallow foundation device: construction technology

The technology for erecting MZLF is not complicated, pouring can be carried out according to SNiPs 3.03.01-87, 2.02.01-83 or according to our instructions. The base for a frame house 10 x 10 m can be poured in 1-2 days. Before you start pouring, you need to decide where you will take the concrete solution. There are two options:

1. 1order concrete class B22.5 ... B17.5 at the nearest RBU. In this case, the mixture will be delivered to you at the specified time by a concrete mixer truck. If the ABS cannot drive up to the place of pouring, then a special sleeve is used, through which the concrete solution will be supplied to the formwork. Ordering a sleeve will slightly increase the cost of ABS services. In addition, you will have to pay for every hour of downtime of the special vehicle.
2. 2 prepare the concrete yourself. At the same time, you will not depend on RBU and spend much less money, however, the quality of the concrete mix will be slightly lower. When mixing concrete, the recipe must be strictly observed. To prevent the concrete from setting ahead of time, special additives can be used. Concrete can be prepared immediately after formwork has been installed.

Installation of MZLF: step by step instructions from A to Z

Preparatory work and markup

The device of a shallow foundation begins with the preparation of the site, which consists in removing debris and uprooting stumps. The top layer of soil with vegetation is cut off. If necessary, leveling and backfilling of the soil is carried out, followed by tamping.

The markup is carried out as follows: the perimeter of the future foundation is established, beacon pegs are hammered in the corners. Ropes are pulled along the future monolithic tape.

The diagonal between the corners should be strictly 45 degrees. You can check the evenness of the markup using a tape measure and a building level.

Trench and cushion device

The depth of the trench depends on the depth of the foundation and the thickness of the pillow. In width, the trench is made 10 cm wider than the calculated thickness of the monolithic tape. This is necessary for the installation of formwork. During the construction of the MZLF on loose soils, it is possible to strengthen the slopes of the trench with boards. Pillow filling is necessary to reduce the impact of frost heaving forces on the foundation. The thickness of the cushion, as a rule, is 20-30 cm for weakly heaving and non-heaving soils. For heaving - is determined by the table, which is given above.

For the corners where the walls of the future house intersect, it is necessary to strengthen the reinforcing cage by installing additional vertical rods that are welded to the longitudinal rods. Such reinforcement allows the strip foundation to withstand the critical loads acting at the intersections of the walls.

It is possible to lay the armoframe on a prepared pillow, but it is better to do this on the starting layer of concrete. The thickness of the starting fill should not exceed 20% of the entire height of the tape. Concrete pouring helps to create a more even surface on which the reinforcement cage is laid. If you decide not to fill in the starting layer, then to raise the reinforcement cage above the pillow surface by 5-7 cm, you should use supporting fungi.

Armoframe should be located in space, nowhere in contact with the backfill and formwork.

Pouring concrete

Filling should be carried out at a temperature of +10 C and above. Before pouring, the formwork must be moistened, then the concrete will lie more evenly. It is necessary to pour the mixture in layers, the layer thickness should not exceed 40 cm, optimally - 20-30 cm. Each layer is subjected to 5-10 minutes of vibration compaction. This technology does not allow the formation of voids inside the concrete. To supply the concrete mixture to the formwork, it is necessary to use an elastic sleeve or chute.

Layered pouring of the foundation

After pouring, the formwork is covered with a vapor-tight film. The hardening of concrete lasts 25-30 days, after which the formwork is disassembled, and the sinuses between the foundation and the trenches are covered with soil.

Insulation of a shallow foundation

Professional builders recommend that you definitely insulate the MZLF. It is recommended to do this immediately at the time of construction of the structure. An insulated foundation will protect the floors of the house from dampness and cold, which is especially important when arranging the floor “on the ground”. In this case, in the absence of thermal insulation, all the heat from the floor will go into the ground.

There are external and internal thermal insulation MZLF. External - when the insulation is attached to the outside of the monolithic tape, internal - from the inside. External insulation is considered mandatory, and internal insulation is usually done if the house is with a cellar basement. What heater to use? There are a lot of options. The most popular are:

1. Penoplex. A dense thermal insulator that perfectly saves heat. Its service life is much longer than that of conventional foam. Penoplex is resistant to rodents, mold and practically does not absorb moisture. In terms of price / quality ratio, this is the best material for thermal insulation of a shallow base.
2. Styrofoam. The extruded material is slightly inferior to foam plastic in terms of physical and mechanical properties. However, the price of expanded polystyrene boards is 20-30% cheaper. It can be used in dry and dusty soils with minimal moisture.
3. Polyurethane foam. Liquid sprayed thermal insulation is an expensive option, but at the same time it has many advantages: no joints between the plates, a service life of at least 50 years, minimal water absorption and resistance to aggressive environments.

Use insulation based mineral wool for thermal insulation of the foundation is strictly prohibited! Mineral wool absorbs moisture well, so the insulation will quickly become damp and lose its heat-insulating properties.

The technology of insulation depends on the chosen material. Heat insulator plates are attached to a monolithic tape with glue, and then reinforced with a special mesh. A layer of plaster is applied on top. The plinth is finished along with the installation of the blind area.

Features of the construction of MZLF on heaving soils

Heaving soils do not allow moisture to pass through, preventing it from going deep, so precipitation accumulates near the surface of the earth. When building a building from blocks or wood on heaving soils, drainage must be done, and the backfill must be at least 30 cm. When building houses, a set of protective measures for the foundation is carried out:

1. The backfill is made from non-porous soil. Waterproofing must be laid under the sand and gravel cushion. It is better to use geotextiles, which prevent silting well.
2. Drainage is arranged at the level of the sole of the monolithic tape. Drainage pipes are laid at a distance of at least 1 m around the foundation. The slope of the pipes depends on their diameter: the smaller the pipes, the greater the slope should be.
3. Installation of insulated blind area. The blind area contributes to the diversion of water from the MZLF. A layer of insulation under the pavement prevents freezing of heaving soils around the house.
4. Storm sewer device. The main purpose of stormwater drainage is the effective removal of precipitation from the site. For a shallow foundation, a well-executed storm drain will avoid flooding and subsequent freezing of heaving soils.

For buildings with walls made of small-format materials (block, brick), a shallow strip foundation is the best solution. In terms of the cost-effectiveness of the construction budget, it is in third place after pile and columnar foundations. Provides a multiple margin of safety, allows you to make an exploitable basement level.

Step-by-step instructions for arranging a shallow strip foundation (MZLF)

On heaving soils, it is recommended to insulate the sole of the MZLF tape, on sands, sandy loams, you can do with the insulation of the blind area. Therefore, the technology for the worst geological conditions will be considered below. In order to build a shallow strip foundation on their own, the developer needs to perform the following steps:

• calculate the width of the tape, the cross section of the reinforcement, draw up a reinforcement scheme;
• make trenches (cottage without basement) or foundation pit (ground floor);
• lay drains for drainage, insulate the sole;
• make a sub-base, mount the formwork, lay reinforcement;
• concrete the tape, not forgetting about the communication input nodes, ventilation ducts;
• provide care for concrete, waterproof all edges of the tape in a convenient way after stripping;
• for an operated basement, it is necessary to insulate the outer walls of the tape.

Then it remains to insulate the blind area, line it with waterproof material, integrating a storm drain into the outer perimeter. At each stage, there are nuances, without knowing which you can drastically reduce the resource of an underground structure.

Geology, geodesy and calculation

To build a shallow strip foundation with your own hands with a high operational resource, it is not necessary to order geological surveys. It is enough to dig holes in several places, to determine the composition of the soil at different depths visually:

• if it rolls into a tight ball that can withstand being squeezed by fingers without breaking, it is clay;
• loam in a similar situation will be covered with a network of cracks;
• the sandy loam will partially crumble;
• it is impossible to roll sand into a ball in your hands.

Each specified rock corresponds to its own design resistance (kg / cm2), which is necessary to calculate the bearing capacity of the foundation. It is taken from tables:

• loam - 1.8 - 2.8;
• pebbles with dusty clay - 4 - 4.4;
• sandy loam - 2 - 3;
• crushed stone with sand - 6;
• clay - 1 - 2 (watered), 2 - 3 (plastic), 3 - 5 (medium dense), 4 - 6 (dense);
• gravel with sand - 5;
• sand of different fractions - 3 - 5;
• dusty, wet sand - 2 - 3.

The minimum value of the design soil resistance is observed for silty sand (1 kg / cm2, uncompacted slag dumps, sand, ash, industrial waste. If the developer is not sure about the composition of the soil, he can play it safe by assuming the design resistance to unity on a normal site.

Or 0.8 units if it is suspected that the soil in the building spot is bulk, there is no self-consolidation due to the period of the embankment being less than 24 months. This is guaranteed to provide a solid safety margin for a high operational resource of the foundation.

Calculating the width of the tape is not difficult:

W = combined load / design resistance / length of the perimeter of the tape

The prefabricated load is calculated by adding the weight of all structures (foundation, ceilings, roofing, walls, partitions, cladding, insulation), furniture, residents, snow, wind load. The last values ​​are also taken from the SP tables for a particular region of operation. Practice shows that, taking into account the thickness of the walls, a width of 40 - 50 cm is enough for an MZLF tape with a double margin of safety on the most problematic soils.

The depth of the MZLF is selected as follows:

• 0.4 m - if protection against heaving forces is provided;
• 0.45 m - on sandy soils with a low level of GWL;
• 0.5 m - when clay freezes by 1 m;
• 0.75 m - at a freezing mark of 1.5 m;
• 1 m - in regions with a freezing mark of 2.5 m.

To provide protection against winter swelling, the following technologies are used:

• replacement of the soil under the sole of the tape with non-metallic material (0.4 m minimum);
• drainage system around the perimeter, blind area and storm water on the surface;
• insulation of the MZLF sole and blind area.

Drainage removes moisture, soils are not saturated with water, which reduces heaving forces. A layer of insulation allows you to save the geothermal heat of the bowels, stop freezing from the outside from the contact of the soil with cold air. Therefore, if you include in the estimate insulation, non-metallic material for the foundation cushion, drainage sewer pipes, the budget of the MZLF, buried by 40 cm, will still be less than tapes at the level of 1 m without a heat insulator and drainage systems.

Scheme of insulation MZLF. Instead of foam, it is better to use extruded polystyrene foam.

The height of the tape above ground level is selected depending on the project:

• for an operated basement floor, it is better to deepen it by 1 m, raise it above the surface by 1.7 m, ensuring the ceiling height in the underground is 2.2 - 2.5 m;
• a height of 0.4 m above the zero mark is convenient for the manufacture of a small technical underground, in which communications can be placed, the manufacture of ventilation products (25 cm from the blind area), five steps of the porch;
• concreting flush with the ground (or at a level of +0.2 m) allows you to reduce the construction budget for the manufacture of floors on the ground (no need for a slab, floor beams).

Any of the indicated dimensions allows you to normally lay two layers of reinforcing mesh inside the tape with a protective layer of 1.5 - 4 cm in accordance with the standards.

Marking and earthworks

The fertile soil layer is removed completely, trenches are dug under the pillow.

They begin the device of a shallow strip foundation with markings in accordance with the recommendations. Unlike columnar, pile foundations, not axes are brought into the building spot, but cords are pulled along the outer and inner perimeter of the tape:

• mark of the first corner of the main facade - 3 m from the border of the site, 5 m from the center line of the street (3 m from the axis of the passage);
• the wall of the main facade - the tension of two cords along the cast-offs (bar 60 - 80 cm between two pegs), indicating the outer, inner face of the MZLF;
• side walls - after finding right angle for each wall, according to the triangle method (5 m hypotenuse, 4 m, 3 m legs), cords are pulled along the cast-offs for them similarly to the previous method;
• rear facade - two cords in exactly the same way;
• internal walls - similar to the indicated options.

Then it is necessary to mark the foundation pits for separate foundations of the power structures of the cottage, equipment weighing more than 400 kg. These are a porch, an internal staircase, a fireplace, a stove, pumping equipment, a backup generator, etc.

The horizontals of all cast-offs are aligned in a common plane with a level or a laser plane builder. Cords should be located 5 - 7 cm below the upper side of the formwork.

In the considered version of the MZLF with a warmed sole, additional earthworks will be required. The trenches for the tape will have to be expanded by 0.5 - 0.8 m inside the perimeter of the building, 0.8 - 1.2 m outside. This is necessary for laying a heat insulator, making a drainage system, providing access to the outer walls of the waterproofing tape, pasting with polystyrene foam.

For earthworks, it is not necessary to pull the cords, it is enough to draw the contours of the trenches on the soil with lime mortar. If there is a basement, a pit is made, corner cast-offs should not interfere with excavation by special equipment.

Sand or gravel substrate

In different regulatory documents, the thickness of the underlying layer under a monolithic foundation of non-metallic materials has a different value. For example, in the norms it is three times the width of the MZLF, the construction allowance (Sazhin's edition) is regulated by 30 - 80 cm, depending on the soil. In practice, the most commonly used method is:

• 20 cm of sand - spilled with water or compacted with a vibrating plate;
• 20 cm of crushed stone - ramming with a vibrating plate or manual bayonet in layers.

A sand cushion of 20 cm is laid, it must be rammed with a vibrating plate.

There are projects that use only sand (40 cm) or only crushed stone of a similar layer thickness. In other MZLF with solid operating experience, a mixture of PGS was used. In any case, an individual developer needs to know the features of inert materials:

• when wet, sand almost completely loses its bearing capacity;
• crushed stone retains strength, has draining properties (lack of capillary moisture);
• it is easy to lay a layer of rolled material on the sand for waterproofing the MZLF sole (relevant for high groundwater levels);
• the sharp edges of the rubble will definitely damage this waterproofing, so you have to fill in the screed-footing to protect the hydroglass from damage.

On top of the sand, crushed stone (thickness 20 cm) is laid and compacted.

At the same stage, drains are laid along the perimeter of the tape at the level of its sole. They are looped into a common circuit with a single slope to an underground reservoir, where effluents will be collected by gravity.

With a 40 cm deepening of the MZLF, it is possible to completely get rid of the heaving forces by lining the outer plane of the tape with a 5 cm layer of expanded polystyrene, continuing the heat insulator layer horizontally at the level of the sole of the tape. The layer width is 60 cm, the thickness of the insulation is 5 cm. If the foundation lies at a depth of 0.7 - 1 m, the insulation of the blind area at a depth of 30 - 40 cm becomes a more economical solution. In the latter case, heaving forces do not disappear completely, but decrease to an acceptable level.

formwork

This stage of construction of the MZLF is regulated, which provides terminology, instructions for the manufacture of formwork. Most often, shields are made of materials:

• edged board - a minimum thickness of 5 cm, the pros are the reuse of lumber (for example, partitions, roofing), cons - a long assembly of panels;
• multilayer plywood - bakelite, moisture-resistant modifications are too expensive, private developers use multilayer birch sheets;
• OSB - can also be used after demoulding, has moisture resistance, retains geometry.

The only serious requirement for formwork panels is the absence of gaps in the joints of more than 2 mm. The footing is often poured without formwork, using the walls of the trench as it. Formwork installation technology for low-depth tape has several options:

• removable - the upper side of the shields is 5 - 7 cm higher than the design mark, to the inner wall of the decks it can
• attached extruded polystyrene foam;
• non-removable - assembled from polystyrene blocks, jumpers give structural rigidity.

The first option is preferable to the others, since after pouring the surface must be waterproofed. It is better to mount a layer of insulation on top of the waterproofing carpet.

We expose and strengthen the formwork.

Shields are fixed vertically with couplers (step 0.5 - 1 m), jibs. Inside them, at different heights, it is necessary to make holes for the through passage of the sleeves. In the underground part, engineering systems will be introduced through these pipes. Above the ground, these holes will become ventilation vents through which moisture will be removed from the underground.

Reinforcement and pouring

Foundations on heaving soils experience both compressive and tensile loads. Therefore, the tape is reinforced in two planes - at the upper edge and near the sole. However, the rods must be protected with concrete to prevent corrosion. The minimum protective layer is 1.5 - 4 cm. The monolithic foundation should be reinforced with bars of 8 - 16 mm with a periodic section in the longitudinal direction. To impart spatial rigidity to the reinforcing cage, rectangular clamps made of smooth 6–8 mm reinforcement are used.

One of the possible schemes for reinforcing corners and mates.

Contrary to the misconception that thicker rods are needed when prefabricated foundation loads increase, this is not true. The calculation is made according to the cross section of the tape - it should contain 0.1% of the reinforcement of the total area. The calculation of reinforcement can be done on your own in the following way:

• determination of the total section - you need to multiply the height of the tape by the width (in millimeters), divide by 100;
• search for a section of a longitudinal bar - is performed according to a table with reinforcement schemes (for example, when choosing a scheme 2 + 2, a thick bar is required, 3 + 3 is thin, but in larger quantities);
• adjustment - is made taking into account the protective layer (4 cm), the requirements (40 cm maximum between the rods in one row);
• clamps should be a maximum of ¼ thinner than the main rods.

We reinforce the corners according to the scheme presented above.

Armoframe is connected by wire manually or mechanically. Welded meshes are used by professional developers who operate with large volumes of work. Each weld is a potential source of corrosion.

We reinforce the conjugations.

The main requirements for reinforcing MZLF are:

• overlap spacing in adjacent rows of one belt at least 60 cm;
• overlap length 50 rod diameters.

It is forbidden to join the bars at the corners and in the junctions of the walls with a crosshair. In these areas, one of the rods should bend, go to the adjacent side by 40 - 60 cm, and then overlap with the next piece of reinforcement. To provide a protective layer at the bottom of the tape, the lower bars are laid on concrete pads or polymer racks.

• 3.7 / 1.9 / 1 - for grade B 22.5 (corresponds to M 300);
• 3.9 / 2.1 / 1 - for grade B 20 (corresponds to M 250);
• 4.8 / 2.8 / 1 - for grade B 15 (corresponds to M 200);
• 5.7 / 3.5 / 1 - for grade B 12.5 (corresponds to M 150);
• 7/4.6/1 - for grade B 7.5 (corresponds to M 100).

Manual mixing is not recommended, grade M 7.5 is used exclusively for footings. The mixing time of the components inside the concrete mixer is 1.5 minutes. The most demanded modifiers for concrete mixtures that improve their properties.

Do not forget to lay sleeves in the formwork for communications and air, if necessary.

Before pouring, only exfoliating rust, fresh corrosive deposits are removed from the reinforcement, on the contrary, it improves the adhesion of reinforced concrete components. Therefore, professionals often soak the rods in water for 2 - 3 to finish knitting frames.

When concreting, the following requirements must be observed:

• laying the mixture in one direction in layers of 40 - 60 cm for compaction with the nozzle of a deep vibrator;
• filling the formwork in one go or installing vertical partitions, continuing concreting after 75% concrete strength, removing the film from its surface at the junction;
• technological breaks of more than 2 hours between individual concreting operations are not allowed, since after this period hydration begins;
• it is forbidden to dump the mixture from heights greater than 2 m (the level of 0.5 m is considered optimal).

A monolithic foundation should not have technological seams in the corners. If pouring in one step is unrealistic for these volumes, the partition is mounted in the middle third of the span.

The nozzle of the deep vibrator is lowered into the mixture for a few seconds until the appearance of milk, the cessation of air bubbles. When rearranging the working body, the vibration zone should overlap the previous one by a third. The disadvantages of manual baying with a reinforcing bar are the increase in work time.

Concrete care and stripping

The technology of laying the mixture without fail includes the care of concrete in the formwork up to a curing of 50 - 70%. These measures ensure the protection of the mixture:

• from waterlogging - shelter with a film in the rain;
• from freezing - a heating cable, a layer of straw, warm formwork in winter;
• from intensive evaporation - a film or a layer of sawdust on the surface with irrigation with a scattered jet (watering can) in the first three days.

This avoids shrinkage caverns, cracking, internal stresses. Instead of sawdust, tarpaulin, burlap or sand is used. Humidification in the heat begins after 8 hours, maintaining the compress in this state regularly. For example, at a constant temperature of + 30 degrees, stripping is possible on the 4th day, at + 20 degrees on the 8th day, at + 10 degrees in two weeks. In the off-season (average temperature + 5 degrees), stripping is carried out on the 29th day.

The waterproofing technology makes it possible to increase the resource of a partially buried reinforced concrete structure up to 70-150 years. A monolithic foundation is protected from moisture in several ways:

• coating with bituminous mastics in 2 - 3 layers, resource 15 - 30 years;
• pasting with rolled materials on a polymeric, fiberglass basis (2 - 3 layers), a resource of 20 - 40 years;
• impregnation with penetrating mixtures or adding them to concrete during manufacture, resource 50 - 100 years.

After stripping, we apply waterproofing to the side faces of the foundation.

In the first two versions, the surface of the MZLF tape is pre-primed with primers in one layer. Comprehensive protection includes priming, coating with mastics, pasting with hydrostekloizol. This allows you to increase the service life up to 70 - 100 years. Penetron products change the molecular structure of concrete to almost the entire depth. Protection is not afraid of mechanical damage and has the same resource as concrete.

We insulate the outer walls of the foundation to the full height. The insulation is glued to bituminous mastic, the use of mechanical fasteners is prohibited, because this will lead to the destruction of waterproofing and concrete. Further, it is desirable to insulate the blind area around the foundation according to the scheme given above.

If necessary (high groundwater level) do.

The considered technology is suitable for individual construction. Following the above recommendations, even a non-professional can calculate the cross section of the tape, reinforcement. Step-by-step instructions will allow you to make MZLF without errors, providing a high foundation resource.

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