Pipes

How to strengthen a foundation made of FBS blocks from the inside. Foundation made of FBS blocks: pros and cons

In order to save time and taking into account the delivery schedule of building materials, the time for arranging the strip foundation was limited to 3 days. Therefore, full-scale work on arranging the foundation from FBS was not carried out.
After the construction of the building frame (log frame), the installation of the roof truss system and the roofing work, the work schedule tied to the delivery of building materials and the hiring of labor and construction equipment ceased to be relevant.
Therefore, it was decided to return to finalizing the foundation, combining this work with landscaping the area around the house (arrangement of the blind area).

1. Reinforcement of a prefabricated strip foundation made of FBS

No matter how high-quality the base (cushion) on which the FBS blocks are laid is, they remain unconnected to each other. There are gaps between individual blocks. Over the course of a month, individual blocks showed slight shrinkage and gaps formed between the foundation and the framing beam.
In order to prevent further uneven shrinkage of the foundation and structure, it became necessary to strengthen the foundation of the erected structure.
For this purpose, the technology of external frame reinforcement was used using metal reinforcement and pouring a belt of cement-gravel mixture.

The following tools were used to carry out the work:

A hammer drill with a set of drills of various diameters;
Angle grinder (grinder);
Metal scissors;
Wire cutters;
Hammer;
Roulette;
Shovels.

Considering that the construction of the foundation was carried out less than a month ago and the trench for laying FBS blocks during this time was filled with construction waste and the collapsed soil was cleared with shovels from the entire perimeter of the foundation to the gravel base.
After this, holes 100 mm deep were drilled in the FBS blocks to secure the anchors to which the strapping (reinforcing) reinforcement should be attached.

2. Attaching reinforcement to anchors

Sections of reinforcing rod 200 mm long were used as anchors. bent at the end at a right angle for easy fastening of reinforcement bars.
The hole in the FBS was drilled 1 mm smaller than the diameter of the reinforcing bar (anchor). The anchor was driven into the hole with a heavy (2 kg) hammer.
The reinforcement was mounted on anchors and fastened with annealed steel wire d – 4 mm.

3. Fastening reinforcement in the spaces between FBS

Particular attention was paid to reinforcing the corners of the foundation. To do this, the rods were bent at right angles and tied together with several wire ties with reinforcement rods on the adjacent side. The length of the corner arm averaged 1000 – 1200 mm.

4. Fastening reinforcement at the corners of the foundation

5. Formwork installation

To pour a continuous concrete belt around the FBS foundation, formwork was installed. Material - waste left over from lumber after installing the roof - thick boards 40-50 mm– sawed to make pegs. The formwork lining was made from substandard boards of thickness 25 mm., remaining after installing the roof sheathing and thick plywood 10 mm. The thickness of the cement-gravel mixture belt was 100 mm.

6. Fastening the formwork sheathing with twisted wire

7. Construction of the drainage system

Parallel to the foundation to a depth of 500 mm. a trench was dug around the entire perimeter of the building. Crushed stone of fraction 20-40 is poured onto the bottom in a layer of 200 mm. A plastic plumbing pipe d 150 mm is laid on top of the crushed stone. with holes d 16 mm. drilled with a feather drill for wood.

8. Installation of the drainage system

The pipes were connected using corner connectors. In the corners of the building and in the middle, along the long side of the building, vertical bends were installed, rising 150 mm above the soil surface. The holes were closed with perforated plugs.
The laid pipe was covered with crushed stone to the level of the soil surface around the house.

9. Pouring the blind area around the house

10. Preparation of cement-gravel mixture

Cement was used to prepare the solution M400, alluvial river sand and construction crushed stone fractions 5-20 . In proportion 1: 1,6: 3,2 . The mixture was prepared in a concrete mixer V – 70 liters with electric drive.

All work was carried out by 2 workers. The total time to complete the work was 5 days.

To reduce the delivery time of a facility, the optimal technical solution is a prefabricated strip foundation. Industrially manufactured FBS blocks are used in its production.

Prefabricated tape is inferior in geometric stability and spatial rigidity to monolithic structures, so it is often reinforced with an armored belt. It is a monolithic grillage reinforced with meshes along the perimeter of the MZLF, poured into the formwork.

For ease of design, there are different sizes of concrete products. They need to be laid on cement-sand mortar with row bandaging, similar to half-block brickwork.

The abbreviation stands for wall foundation blocks, since in projects with a basement/ground floor or technical underground, the tape is the wall of the lower level. The dimensions of concrete products and the characteristics of FBS are regulated by domestic ones from 1978. There are block modifications:

hollow FBP - for lightweight bases;

cut-out FBV - a recess in the upper part for wiring communications and installing jumpers;

solid FBS – for reinforced bases.

The standard dimensions of the latest modifications are:

length - 2.4 m or 1.2 m (indicated in dm in the marking, in practice it is slightly less than this size);
width – 0.3 – 0.6 m in increments of 0.1 m (corresponds to the declared size);
height – 0.58 m or 0.28 m.

Laying the foundation is allowed only with a widening downward; reinforced concrete products with a height of 0.28 m are used as the top row to adjust the base to the design level. There are blocks (only FBV, FBS) with a length of 0.88 m, their other sizes do not differ from the standard ones.

When choosing the width, you need to focus on the design of the walls and the presence of a plinth in the project. For example, on a block 0.4 m wide, you can lay 38 cm of masonry, make 51 cm walls, letting it out, or 64 cm with an external/internal overhang at the same time. One row of brick or wall block allows a 5 cm cornice in any direction; in several rows a 10 cm cornice can be installed on both sides, maximum.

If the moisture content of the blocks is more than 12%, they are considered defective and cannot be sold until this characteristic decreases. Concrete of classes B 7.5 – B 15 is used in production; frost resistance is required to be indicated in the documentation.

They do not have FBS reinforcement; depending on the soil, it may be necessary to strengthen the base of the foundation using the following technology:

pouring a concrete base - height 20 - 40 cm, width twice as large as that of the block used, two rows of reinforcement with reinforcing mesh (bar of periodic section 12 - 16 mm);
installation of FL slabs - reinforced by default, have an upper platform of the same size as the block, installed adjacent to each other or apart;

Without FL or a concrete base, it is allowed to install FBS exclusively on the sandy soil of the bearing layer, which lies below the freezing mark of the region.

Instructions for laying blocks

The main document when assembling block strip bases is the TTK technical map, which indicates the composition of the team (minimum), special equipment, and the sequence of operations.

This takes into account the dimensions of concrete products, the presence of openings (input of communications into the dwelling below ground level + ventilation vents 30 - 40 cm from the ground surface, openings (basement doors + basement windows).

Before installing the FBS, it is necessary to order/mix masonry mortar (approximately 1.5 buckets for each block) so that the foundation has a strong bond.

What special equipment is used
When choosing lifting equipment, it is necessary to take into account the dimensions of concrete products (FBS + FL foundation slabs). Depending on the dimensions, their weight will change significantly. The most popular special equipment:

truck crane – maximum boom GP at maximum reach, minimum number of rearrangements;
manipulator - no need for trucks, blocks, pillows are unloaded from the side of the same equipment, however, the number of rearrangements will increase due to the small load capacity with a maximum boom reach, which is important in dense buildings, in the absence of entrances to the building under construction from all sides.

Therefore, the choice depends on the specific conditions of the site; other special equipment (for example, a pipe layer, an excavator) is used extremely rarely.

Preparatory work

Prefabricated strip foundations are buried by 0.4 - 2 m (MZLF, deep, respectively). At the initial stage the following work is performed:

planning - removing the fertile layer, leveling the landscape in the building area;
excavation - trenches around the perimeter for a project without a fall or a foundation pit for a cottage with a basement;
drainage - without exception, all concrete structures operating underground are subject to corrosion; to prevent wetting, drains (slotted, perforated corrugated pipe) are laid along the perimeter of the building with a general slope into the underground container;
cushion - backfilling of non-metallic materials (20-40 cm sand compacted with a vibrating plate) instead of heaving soil of the bearing layer;
screed - necessary for laying rolled waterproofing, high-quality sealing of joints of roofing felt or polyethylene film; it is impossible to perform this work when laying waterproofing on crushed stone;
waterproofing - strips of rolled material are laid overlapping, glued to the screed, the joints are treated with mastic;
thermal insulation - the technology is relevant only for shallow foundations of MZLF; expanded polystyrene is laid on top of the waterproofing, retains the geothermal heat of the subsoil, and compensates for heaving forces in clay layers.

Drainage cannot be laid under FL slabs or a concrete base; pipes must be located further than these structures and below their base. Drainage properties are enhanced by filling pipes with crushed stone.

Making the base

To increase the supporting plane of the FBS blocks, it is necessary to widen the bases of the concrete strips. For this purpose, FL slabs are used, which have unified dimensions with the blocks. They can be laid periodically (maximum step 0.7 m) or closely. Due to the complex configuration (beveled edges) at the junction points, it is necessary to fill the voids with concrete.

FL blocks for the base of a block foundation

When choosing monolithic concrete preparation, the technology looks like:

installation of formwork - board or plywood panels 20 - 40 cm high around the perimeter of the walls, the width of the box is twice the base of the block;
reinforcement – two reinforcing mesh (12 – 16 mm corrugated);
pouring - ready-mixed concrete with vibration compaction or manual bayonet.

The second option is preferable - despite the industrial production of FL slabs, monolithic structures are better able to withstand loads and have a stable geometry throughout their entire service life. However, to reduce the volume of concrete work and the waiting time for a reinforced concrete structure to gain strength, the technology of laying FL slabs is preferable.

Laying corners

For prefabricated concrete foundations, the tilting of individual elements within the structure is not allowed. Installation of FBS is, in fact, large-format masonry, where dimensional parallelepipeds are used instead of bricks. The technology looks like:

installation of corners - two blocks at each corner with a 1.5 - 2 cm layer of mortar around the entire perimeter, the horizontal of the upper edge (in two planes), the vertical of the outer corner (plumb or bubble level) is controlled, the vertical seam is filled with mortar immediately;
installation of interfaces - blocks are installed at the junctions of internal walls with external ones (T-shaped node), control of the upper edge using a cord stretched along the corner elements;
outlining openings - blocks are mounted near basement doors, windows on both sides;
filling the row - entire blocks between those previously mounted along the cord.

If the foundation is single-row (baths, outbuildings, MZLF frame, log cottages), the voids are filled with ceramic bricks, all concrete surfaces are waterproofed. To strengthen the structure, a grillage can be made.

For a multi-row tape, operations are repeated for each row of FBS. In this case, dressing is necessary:

in the corners FBS are mounted in the reverse order;
in the joints, the internal walls run outward, the blocks of the external walls adjoin them at their ends;
near the openings, short or cut in half products are used.

Bandaging in adjacent vertical corners is allowed ¼ – ¾ of the standard length of the blocks. Openings in the foundation walls are necessary for ventilation, operation of the underground level, and entry of communications. For laying lintels, FBV products are used or periodic laying of FBS with filling of the resulting voids with brickwork.

Cutting FBS blocks

The foundation has different sizes and configurations, so the existing dimensions often do not satisfy the project conditions. The blocks do not have reinforcement, so they are easily broken off by specialists by hitting a crowbar/corner placed on a solid base. There are several splitting technologies:

through a crowbar - the blocks are placed on top of each other on a crowbar, one edge is hooked by a splint along the very edge, when lifted, the splint breaks off, the product falls onto a metal rod, breaking off in this place;
with a hammer drill - holes are drilled around the perimeter, wooden plugs are hammered into them, and the wood is generously watered with water, which breaks the concrete when it swells;

The following video clearly shows how to split a block:

Is an armored belt necessary?

The spatial rigidity of a block foundation is lower than that of a monolithic structure. The products are not reinforced; often there are no FL bottom slabs or a concrete base. To strengthen the base, structural reinforcement is used along the top row. This is a standard operation of pouring a grillage into formwork with two reinforcing belts made of reinforcing mesh (cell 5 x 5 - 15 x 15 cm, or a reinforcement cage is knitted). The armored belt is a high-strength plinth that binds the masonry, increasing the service life of the building many times over.

A prefabricated strip foundation made using this technology will have a resource sufficient for several home owners only if all points are met. If the blocks are not waterproofed, there is no drainage, no reinforced belt, the structure will gradually collapse.

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When most people hear the word “foundation,” they think of either a solid reinforced concrete base or a base on pillars or piles. At the same time, they forget about the existence of another option - FBS construction, which is actively gaining popularity among professional builders and amateurs. It is worth taking a closer look at the foundation made of FBS blocks, the step-by-step instructions for performing which are so simple that even a beginner can figure it out.

Features of the material

Difference between FBS and other blocks

Foundation building blocks, abbreviated FBS, are monolithic rectangular concrete bricks of large size, reinforced with a frame of reinforcing bars.

The demand for the material is determined by the special stability provided by the reinforcement.

There are two methods for connecting FBS to each other:

Application of cement mixture. Laying building blocks is done using the same technology as laying bricks. In this case, proper bandaging of the joints is necessary, in addition, the location of each new block relative to the previously installed ones should be adjusted.
The use of a specially designed dry adhesive composition, when diluting which it is very important to maintain the correct proportions. This method does not require special physical and time resources, however, from a financial point of view it is unprofitable: the cost of the mixture is higher than the price of cement mortar.

Advantages and disadvantages

Before building a foundation from FBS blocks, the pros and cons of the planned structure must be taken into account and worked out, otherwise there is a risk of being disappointed in the finished foundation.

The block base has many advantages over other foundation options. It is worth highlighting the following:

Possibility of independent device. The laying technology is quite simple; even an amateur can handle the installation;
Small time investment. Due to the fact that the construction of the foundation involves the use of large building elements installed in a checkerboard pattern, the work can be completed in one day;
Durability and sustainability. The blocks have a high load-bearing force and are not afraid of mechanical influences;
Convenience. Manufacturers provide all the subtleties that may affect the work with FBS. To simplify the construction procedure, each particularly large product is equipped with hooks, with which you can easily move the blocks;
Strength. Additional strengthening of the base is provided by special grooves, which FBS almost always have;
Possibility of installation on unstable and frozen soils. If construction is carried out in regions where a cold climate predominates, or in areas with weak soils, then this option will be a real salvation.

In addition to impressive advantages, foundations made from FBS blocks, like all existing foundations, also have negative qualities:

Solid value. The raw materials themselves are not cheap, and besides, it may be necessary to hire construction equipment, which will also negatively affect the budget;
Possibility of uneven shrinkage. This is due to the fact that the base is not a monolith.

Naturally, basic designs of this type are not without drawbacks, but their positive characteristics fully compensate for all the disadvantages.

Design of a basis from FBS

In order to competently build a prefabricated block base that will serve for decades, it is necessary to design it responsibly. What should you consider when creating a project? Please note:

Type of soil in the building area;
Path of soil waters;
Soil freezing level;
All possible loads;
Number of floors of the future building;
Dimensional characteristics of the base and basement (if provided).

The first three points determine the depth of the structure and the level of its waterproofing.

If the design is completed, you can begin the foundation, the installation of which is carried out in several stages. All stages have their own nuances, and therefore should be considered in more detail.

Stage 1. Marking and working with soil

Before marking is carried out, the area is cleared of debris.

Following the design, pegs (wooden pins or scraps of reinforcement) are installed in places that correspond to the corners of the future building. A strong twine is pulled between the pins. Similarly, mark the locations of the load-bearing walls under which the foundation will lie.

After this, the upper fertile layer of soil is removed and a trench is dug for the FBS structure. The minimum width of the trench should be equal to the FBS block, plus 20 cm - this will simplify installation and waterproofing work.

Stage 2. Laying the pillow

If the project involves the construction of a basement, then it is impossible to do without installing a base made of concrete mixture (or slabs). If there is no basement to be built, a sand and crushed stone cushion is laid at the bottom of the trench. Sand is poured (layer thickness is up to 15 cm), watered and compacted. Next, crushed stone (10 cm) is poured, which is also compacted.

If the site has clay soil, it is worth filling up, moistening and compacting the sand again.

Stage 3. Arrangement of formwork and reinforcement cage

The formwork is installed along the walls of the trench. It is made of wood (the minimum thickness of the boards is 2.5 cm), connected with self-tapping screws. The height of the formwork should be similar to the height of the reinforcing belt and equal to 10-15 cm.

The metal belt is made of D12 or D14 rods, fixed with knitting wire. The mesh size of the “mesh” is 10 by 10 cm or 15 by 15 cm. The width of the belt should be equal to the width of the FBS.

The finished mesh is placed on the pillow.

Stage 4. Pouring concrete

The resulting structure is slowly filled with concrete mixture. To prevent air bubbles from forming in the thickness of the solution, the mixture is pierced with a steel rod or a vibrator is used. To make the structure more stable, the reinforced frame should be poured in one go.

After laying, the concrete is leveled and allowed to harden. The maturation of the material will end after 28 days, after which you can proceed to the next stage.

Stage 5. Laying FBS

Work with the FBS itself requires the presence of a truck crane or several assistants, since the blocks are quite massive.

First, a cement mixture is prepared, for which raw materials of at least M100 are used. One block requires from 10 liters to 15 liters of mixture.

The block laying scheme is quite simple:

Products are laid on the corners of the building;
Ropes are stretched between the blocks;
FBS are set by level;
The gaps between the elements are filled with cement mixture.

The finished row is coated with a 1.5 cm layer of cement mixture. Each new row is installed in the opposite direction to the previous row with a shift of 50%.

Stage 6. Hydro- and thermal insulation

Moisture has a very detrimental effect on concrete, which is why high-quality waterproofing is simply necessary for a FBS base. It is performed using roofing felt sheets and bitumen mastic, which is used to treat the base from the outside and inside.

For thermal insulation, polystyrene foam is used, the sheets of which are glued over the waterproofing with special glue.

At the end, the free space between the walls of the trench and the base is filled with soil and sand in several stages. Each new layer is conscientiously compacted.

The foundation hardens within a month. After this period, you can begin building the walls.

Video about laying FBS blocks:

Prefabricated foundations are quite a rarity in domestic individual housing construction. However, such a foundation system is not without its advantages. Today we will analyze the construction of FBS foundations, the benefits of using this technology and possible pitfalls that await an inexperienced developer.

Organization of work execution

Prefabricated concrete foundations are used where monolithic construction is impossible or undesirable for a number of reasons: from the significant distance of the concrete unit and unfavorable climatic conditions to the developer’s simple unwillingness to deal with the complexities of constructing formwork, reinforcement and pouring heavily buried structures.

At the same time, a foundation made of FBS has a much higher construction speed with a significant reduction in labor costs. However, the technological complexity of constructing a prefabricated foundation for a house can be even higher than with monolithic concreting. It requires the involvement of earth-moving and loading equipment, careful calculation of the order of laying blocks and adherence to the order of construction work.

The general procedure for constructing a foundation from FBS is as follows:

Marking out the site according to the construction project and alignment diagram.
Excavation work: removing soil to the freezing depth, forming inclined walls of an open pit according to the calculated collapse prism.
Pouring a monolithic base, or installing a cushion or footing.
Laying the blocks in order, bandaging them with cement mortar and reinforcing mesh at the corners and junctions.
Holding the foundation until shrinkage is completed.
Filling of the reinforced seismic belt and installation of the first floor.
Construction of the walls of the first floor.
Installation of waterproofing and insulation of the foundation.
Backfilling of soil.

The composition and order of work may differ slightly. In particular, when the groundwater level is high, artificial drainage of the construction site can be carried out, but, depending on the hydrogeology of the site, a drainage system can be laid both at the initial stage and immediately before backfilling. However, after studying the features of the construction of prefabricated block foundations, most questions about the technology and stages of their construction will disappear by themselves.

Load-bearing qualities and stability of the foundation

The lack of solidity of prefabricated foundations significantly reduces their structural strength. The main destructive effect comes from lateral deformations of the soil and frost heaving forces. Despite the fact that block foundations perfectly withstand compressive loads, their resistance to displacement is very low if the base does not experience a sufficiently high degree of compression from the building structures located above. In turn, the absence of a common reinforcement frame makes the prefabricated foundation very susceptible to bending and twisting influences.

Two main rules in the construction of prefabricated foundations:

Their location is entirely in the freezing layer of soil or below the freezing depth, which prevents the structure from being lifted by frost heaving forces.
Elimination of lateral impact from the ground until the moment when the compressive effect is high enough so that the friction forces between the blocks prevent their displacement.

In this case, it is also necessary to level out the difference in the density of the soil layer on which the foundation rests. This is done by installing blocks on a monolithic reinforced concrete grillage strip or slab, which acts as a load distribution from the resistance of the soil.

Preferred soil types

Prefabricated foundations are not suitable for subsidence and highly heaving soils due to the low degree of resistance to bending loads. At the same time, one should not confuse cases when a load-bearing base is assembled from FBS and options for using blocks for the construction of basement walls. In the latter case, the supporting function is performed not by the blocks themselves, but by the NZLF tape or the monolithic slab underneath them.

The construction of a foundation from blocks using basic technology is shown for dry and hard-plastic underlying soils, the bearing capacity of which, in terms of the bearing area and the weight of the building, provides a reliability coefficient of the order of 1.2-1.4. In general, we can recommend laying a prefabricated foundation without a grillage with a bearing capacity of the soil of at least 4.5 kg/cm2.

Construction of a monolithic armored belt for laying FBS blocks

If the density of the underlying soil provides a bearing capacity of the order of 3.8-4 kg/cm 2 (sandy loam, fatty clays) or conversion to mass and bearing area does not guarantee a positive reliability coefficient, the foundation should be laid on top of a sand and gravel preparation with a trapezoidal profile. If the safety factor is less than 1, FBS can only be laid on a grillage or, at a minimum, on an expanded concrete base.

Types of foundation blocks

The FBS range is not particularly wide. According to GOST 13579-78, with a block height of 30 or 60 cm, their width can be from 30 to 60 cm in increments of 10 cm. The length of the blocks ranges from 90 to 240 cm, while the standard binder seam is already included in the length and height dimensions, that is, in reality the blocks are 20 mm shorter and lower.

By default, foundation blocks do not have reinforcement with the exception of embedded mounting loops. Concrete of strength class from B7.5 to B15 is used as the main material. At the same time, when making blocks to order using standard forms, there are no restrictions on placing linear or mesh reinforcement in concrete, or using a mixture with special parameters, for example, with increased frost resistance.

For the construction of concrete foundations and load-bearing basement walls, foundation wall blocks (FBS) are used; in some cases they are made of heavy concrete. Varieties of blocks made of silicate or expanded clay concrete are unsuitable for load-bearing and critical structures. In turn, foundation blocks can be marked FBV (with a longitudinal groove) or FBP (with voids in the manner of a cinder block).

Combined device systems

So, in the classic version, the FBS foundation is designed incredibly simply and even primitively: a lower and upper reinforcing belt, between which there can be an arbitrary number of rows of blocks, but usually no more than 4-5. This type of foundation is optimal for buildings without a basement or technical subfloor, that is, the blocks are supported on all sides by soil, and their squeezing inward is excluded.

If there is a basement or ground floor, compressive loads along horizontal axes can be compensated in two ways:

Strengthening the seams with 8 mm reinforcing mesh, compensating for the internal tension zone.
Installation of internal lintel walls.

It is also possible to lay FBS on unstable soils, but, as already mentioned, only if there is a load distribution system - a pile-grillage or strip foundation. If desired, the cutouts of FBV slabs can be used for arranging prefabricated monolithic foundations. In this case, the cutouts of the blocks serve as trays for embedding lintels or filling belts, due to which high-quality perception of bending loads is ensured. The same goals can be achieved using conventional FBS blocks, between which, after 1-2 rows, reinforced belts are cast on attached formwork.

Problems of insulation and waterproofing

The main disadvantage of prefabricated foundations made of FBS is their low localizing ability. If it is necessary to equip a dry basement, the joints between the blocks pose a serious problem, and these are far from cold seams of monolithic concreting.

There are several ways to solve this. The main one is cutting the outer sides of the joints and laying a bentonite cord in them. However, even such efforts will not be enough if special concrete with low water absorption was not used in the production of the blocks.

In general, the insulation of prefabricated foundations is applied by surfacing using high-quality fabrics based on cross-linked polypropylene or fiberglass. In this case, the hydraulic barrier needs to be temporarily fastened in the upper zone of the foundation above the ground level, otherwise there is a high risk of its detachment due to atmospheric influences, because the foundation will remain open almost until construction is completed.

The problem of defrosting low-quality concrete can also be solved by insulating the outer surfaces of the foundation and blind area. For these purposes, ordinary inexpensive low-density PSB is used, which is temporarily attached to the blocks on top of the insulation using an adhesive method, and then supported by backfill soil.

Choosing a foundation for building a house with a basement is 30% of construction costs. To reduce costs, a foundation made of FBS blocks, which ensures a long wear resistance life, would be relevant. To build a structure yourself, you need to rent special equipment, draw up a house project and dig a pit. Foundation blocks are an industrial technology that, if the sequence of measures is followed, can be successfully used in suburban, private and country construction. How to waterproof a foundation from FBS blocks

Advantages and design characteristics of the base

The FBS foundation is made in the form of a reinforced concrete pad and block vertical walls. A foundation made independently from strong foundation blocks eliminates reinforcement, because concrete has the ability to compress.

Reinforced blocks - FBS concrete structures from which the foundation is made - have a number of advantages for owners of private or suburban plots. The advantages of construction activities include:

ease of installation work;
high strength and frost resistance characteristics that the base will ultimately receive;
low cost compared to the reliability of the base;
selection of product parameters according to the configuration of the house or the depth of the fundamental structure.

The economic benefit of building a foundation from FBS blocks is manifested in the absence of costs and time for the construction of formwork or a frame made of reinforcement. The foundation can be created in any weather, and, moreover, there is no need to wait for the concrete dough to gain strength. Scheme of a foundation made from FBS blocks

Design types of products

The foundation, made of concrete foundation blocks, is made as a strip or has a columnar structure. The strip building can withstand the weight of a high-rise building or a one-story house. The dimensions of the wall material are determined by the thickness of the ground wall, the type of soil, and the number of storeys of the building.
Columnar laying of foundation blocks is justified only on dense soils. If construction is carried out on marshy soils, support slabs or piles are used.

Standard sizes of FBS products

FBS foundation is one of the types of blocks, the technical regulations for the production of which are specified in GOST 13579-78. The regulatory document considers materials, design characteristics and rules for transporting products. Solid blocks of increased strength are made from a concrete-based mixture with a density of 1.8 t/m3.
To build a block foundation, elements of several standard sizes are used:

width from 30 to 60 cm in increments of 10 cm;
length 9, 12 and 24 dm;
30 or 60 cm high.

FBS type blocks from which the foundation is made are fixed with a mounting loop or bent. A good storage option is to be placed on a wooden platform 3 cm thick. Laying a foundation from FBS blocks with your own hands

Installation sequence

Step-by-step instructions for installing concrete block elements consist of performing the following technological steps:

Site analysis (detection of soil type, level of freezing, groundwater level).
Excavation work (marking the territory, digging a pit).
Organization of the pillow.
Consecutive laying of blocks under a certain type of foundation.
Performing waterproofing.
Arrangement of thermal insulation.
Backfilling of the base.

The correct foundation, made from FBS type blocks, implies not only the correct algorithm for how to lay concrete blocks. The measures require careful planning of the height of the walls, taking into account the existing basement floor and the depth of soil freezing.

Conducting terrain analysis

Taking into account the type of soil and groundwater level makes sense if a prefabricated strip concrete foundation running along the lines of the house needs to be organized on the site - the construction of FBS type blocks involves digging a trench.

To make a structure correctly, it is important to calculate its support. The elements are located 30 cm below the soil freezing level, which eliminates cracking of the material during frost heaving. If there is a basement, the depth of the structure is planned to be 20-30 cm below the floor surface.

Making a foundation from shallow FBS blocks is justified for light buildings made of wood, aerated concrete, polystyrene concrete, and SIP panels. The depth of the structure is determined by the type of soil. When working on dense soils, it is better to follow the standard placement of elements - 2.5 m. Monoliths without deepening are constructed only by construction specialists, since as a result of ignorance of the technology, the building can warp. Installation of FBS blocks using a crane to build the foundation

Carrying out excavation work

The foundation for a house made of concrete blocks provides for the correct marking of the territory. The site planning is carried out according to the design documentation and consists of two stages.

Marking the territory and digging a pit

Professional guidance from specialists presents a clear markup algorithm:

Driving in stakes. They are located at a distance of 50–100 cm from the corners of the structure to prevent soil shedding.
Stretching the cord. It is placed according to the external walls, provides for the presence of a plinth and the width of the block.
Additional activities. If the building has a bay window or an entrance, then a prefabricated or strip type foundation created from FBS type blocks is marked with chalk or primer.
After all tasks are completed, the final result is checked against the project and adjusted.

Excavation work is carried out taking into account existing communications, groundwater and soil. When the installation of the foundation is carried out in the basement, it involves laying slabs, and on the site there is weak soil, a foundation pit at a depth of 40 cm is justified. It is better to deepen the trench tape by 30 - 70 cm.

Digging a pit is done as follows:

The top layer of soil is removed to the selected depth.
For a deep pit, a barrier is installed.
Vertical surfaces are leveled and waterproofing is laid.
On loose soils, the walls are marked at an angle; when cutting through the aquifer, the trench expands and 3-5 ledges are made, depending on the type of soil.
The verticality of the walls is periodically monitored.
Foundation from FBS blocks for a private house. Further tasks include laying geotextiles, forming a cushion based on gravel and sand.
What are the additional requirements for digging a hole? Carrying out work in the dry season to prevent soil erosion.

Pillow installation

The foundation for a block house, depending on the soil, is laid on reinforced concrete slabs, sand, gravel mixture or crushed stone with medium fractions.

Reinforced concrete option

You can make a heavy strip foundation, working with elements made of concrete blocks, by laying reinforced concrete products as a cushion. Activities are subject to the following algorithm:

Leveling the base - soil.
Laying a sand base with a thickness of 0.3 - 0.5 (based on the type of soil).
Correct installation of FL slabs.
Making a reinforcing seam at the joints.
Medium or coarse sand is selected for the substrate, since it shrinks less and the foundation for a house made of blocks does not deform.

Features of sand-based pillows

A sand cushion is useful to create a prefabricated foundation made of blocks. The substrate is characterized by ease of implementation and low cost. A prefabricated strong foundation made of FBS concrete blocks will distribute the load of the building onto the ground.

Application of sand and gravel cushion

The structure, made from a mixture of gravel and medium-sized sand, is distinguished by good load-bearing capacity and ease of implementation. In comparison with a sand foundation, the laid frame - a strong strip foundation, massive of dense concrete blocks - will have a high cost. The advantage of using sand and gravel is the good density of the materials - they can withstand the weight of a high-rise building.

Pouring a concrete pad

Option suitable for buildings with increased load. Step-by-step instructions for reinforcing and pouring concrete dough:
The formwork is being installed. Use the materials you used to decorate your site - plywood, OSB, boards with waterproofing.
A reinforcing frame is made based on a mesh belt and profile rods with vertical jumpers.
The concrete mixture is poured in one go.
The composition is laid along the upper side of the formwork frame. Foundation made of FBS blocks - advantages and structural characteristics of the base

Block laying technology

The construction of a FBS foundation requires preliminary preparation of drawings. A simple diagram will allow you to understand how to lay the first row of blocks on the foundation, and the next one after it. Bandaging must be performed with a displacement of the elements by 25 cm.

Nuances that are important to consider:

the optimal length of products should be 2.4 m - this reduces the number of seams;
coupling with reinforced concrete pads by filling voids with concrete mixture is required;
installation of ventilation ducts with a total area of 0.004 units of the basement space.

In case of weak soil, the first row is reinforced with a monolithic reinforced concrete belt.

For the rigidity of the main structure, a foundation placed on prefabricated blocks laid by hand is relevant. The measures are carried out taking into account the location of the corners on the same line, the presence of elements near the communication holes and the tightness of all products.

Correctly making a foundation from FBS blocks means following a step-by-step methodology:

When placing a foundation made of durable FBS blocks on the ground, learn how to properly lay blocks on concrete dough. Work in a similar way to brickwork.
Performing a T-shaped dressing with an overlap in? height of the element (dense soils) and to the full height (soils subject to compression).
Filling the solution only with a shovel and then leveling it.
Filling vertical joints after a row of blocks has been made.
Verticality control with beacons (deviation angle of 2-3 degrees is allowed).
Formation of technological openings, slightly larger than those indicated in the project for quick fastening of anchors or bricks.
The last row of the structure is widened by installing 40 cm elements on 60 cm blocks - this increases the spatial rigidity of the house. The foundation from FBS blocks is the basis of construction

Final stage

Do not forget about waterproofing and backfilling measures. Manipulations are carried out on any soil and include the following:

Waterproofing. The made block layer is treated with roofing felt, bitumen, and liquid rubber.
Backfill. The constructed monolith dries for several days, after which it is covered with sand with fine fractions and compacted.
The final manipulations consist of organizing drainage and blind areas.

A foundation made of concrete blocks is a structure that, if you become familiar with the algorithm in detail, will not be costly in terms of time and money.