Slab foundation for an aerated concrete house

Various types of building materials are used for the construction of residential buildings. Particularly popular is gas-filled concrete, a block of which has good thermal conductivity and low weight. Despite the low density of aerated concrete blocks, a reliable foundation for a house made of aerated concrete is necessary. A monolithic slab for a house made of aerated concrete is a proven solution. It compensates for the reaction of the soil and ensures the stability of the building. It is important to correctly perform foundation calculations, on the basis of which the height of the foundation slab for a house made of aerated concrete and its size are determined.

Preparation process

Sketch of stage-by-stage work on the foundation slab
When constructing a frame house, the slab should not be too powerful, 30 centimeters is enough. If a house is built from brick, the dimensions of the floor thickness can reach 50-80 cm. A standard cushion of 200 mm thickness is poured under a small house made of aerated concrete and lightweight foam blocks.

Let us consider step by step the work for a heavy structure for a brick house.

The site is leveled and is wider in size than the future building by 1.2-1.5 meters. We cook more widely because of ease of use, as well as to ensure the full floating effect. We remove the top layer of soil to a depth of 40-50 cm, and in this process you can use either small equipment or dig a pit manually. This foundation pad does not require deep excavation.

The sand is compacted to a very dense cushion. The vibratory rammer can be used electric or gasoline (in the absence of an electrical network). For the frame version, tamping passages can be reduced up to 8 times over the entire plane of the intended ceiling.

Stage two is the arrangement of wooden removable formwork for the floor slab. It is made from flat boards 120 mm wide, and is mounted around the entire pre-marked area; its height must correspond to the height of the entire future floor slab. We must not forget about communications; it is better to arrange their laying and insulation in advance.

Stage three - preparation of the reinforced frame. Here the thickness of the overlap is taken into account. In this case, it is recommended to manufacture a spatial frame. Reinforcement with a diameter of 12 mm is suitable. With this installation, the cell is made 300x300mm, tied together with wire. During installation, distances are used so that the ceiling reinforcement does not lie on the sand, but has a gap. A gap of 40 mm will be sufficient.

Stage five - pouring floor slabs under a brick house. In fact, it is no different from pouring a house made of aerated concrete, a frame structure or a house made of foam blocks, except for the obligatory compaction with a vibrating lath or deep concrete vibrator. A house made of foam blocks does not weigh as much as a brick one; compaction is not necessary there.

It is strictly prohibited to lay a structure without a well-compacted sand cushion; it compensates for soil movements during heaving. The use of road slabs is justified in the construction of country houses and dachas, where it is not possible to carry out the construction process all year round. And also during the construction of small frame-type country houses, or from light foam blocks or aerated concrete.

The soil under a slab foundation may freeze if the load-bearing soil is highly mobile or measures have not been taken to insulate concrete abutments and blind areas. The foundation must have good support.

Despite the ease of construction, installation work using road slabs requires skills and preparation; these are still heavy concrete structures. The construction of any facility in which reinforced concrete slabs will be used requires the use of heavy equipment. It is advisable to cast the foundation (slab) yourself, saving the budget allocated for construction.

Pillow is a guarantor of reliability

Compacted sand cushion for a slab foundation
The strength of a slab base is also closely related to a well-equipped cushion. The two layers of which it consists, that is, gravel and sand, work differently.

The top layer is gravel. Due to its characteristics, the material allows moisture to pass through, preventing it from collecting directly under the slab. Thus, water enters the lower layer - sand. Its tasks are to divert water to the underlying layers and evenly distribute pressure, compensating for heaving forces.

After determining the basic requirements for the arrangement of foundations, you can move on to more specific examples of laying foundations for various types of structures.

USP at a price of 3,000 rubles per m2 - reality or magic

I don’t know how, but here is a real person, Alexander Dobrynin, who could do this. I quote:

In 2022, I built a USHP for myself. Followed all the rules described in the Dorocell cards. Area with terrace 146 m2 All materials and delivery cost 430 thousand, that is, 3 thousand rubles/m2 for materials.

Here's the full calculation:

The tractor dug a pit, buried water pipes, then leveled the sand and pulled away the selected soil for 11,000
Then three workers leveled the pit and dug a trench for drainage for 8,000
Purchased 200 m2 of geotextile 150 for drainage and 200 m2 of geotextile 300 for the slab for 13,800
70 meters of drainage pipe 7000
5m3 of crushed stone for filling a drainage pipe - 7500
Drainage wells, covers, various gaskets and transitions for 12725
Drainage pump and hose - 2000
The first layer of ASG - 45 tons - 19500
Filling the rest of the cushion with sand 90 tons - 42000
Buying a tamper - 25,000, after filling I sold it for 20,000. Total I write 5,000
Sewer pipes and fittings – 6780
Eps TechnoNIKOL CARBON ECO SP 12 packs - 32820
PSBs-25 GOST 21 cubic meters or 105 sheets for 44940
Adhesive foam Tytan 5 cans and gun for 2172
Flat slate 8mm - 10 sheets for 4400
Reinforcement 12 - 400 kg, 6 - 600kg, 8 - 100kg for 42560
Knitting wire 20kg – 2037
Hooks 2 pcs – 326
MP water supply pipes - 7880
Mushrooms for fastening L-blocks 10-180 - 500pcs - 2340
Chairs with supports – 750pcs for 3930
Heated floor pipes 4 coils of 200m each - 17824
Various ties 2000pcs approximately 1500
Insulation for pipes - 1000
Manifold for 8 outlets with flow meters, with Eurocones and delivery of TC from MSK - 15100
Rack profile Knauf 50-50 - 19 pieces - 4250
Concrete pump - 13200
Concrete B25 M350 P4 - 19m3 - 89300

The total is 420,884. I’ll add all sorts of little things, screws, lace, delivery, maybe I forgot something. Let it be 430,000 rubles. The total area of the house with a terrace is 146.6 m2, the price is 2,933 RUR/m2. If you don’t count the terrace, then the area is 124 m2, the price is 3,468 RUR/m2

Pile

Recently, the use of . It is similar in design to a columnar structure, but instead of pillars, piles or supports are used. Unlike pillars, piles are narrower, longer and are divided into the following types:

screw;
bored;
driving.

— iron pipes with blades at the bottom for easy entry into the ground. The shallow installation method allows you to screw them in with your own hands; for greater depth you will need to use a special device. The inside of the piles is filled with concrete.

Wells are prepared for bored piles. A reinforcement cage is inserted inside the pipes and concreted. In practice, screw and bored piles are more often used. The tops of the installed piles are combined with a supporting structure, which allows masonry to be carried out. It is unstable to ground movement, so this type can only be used on dense soils.

Features of aerated concrete

Aerated concrete is one of the types of cellular concrete. The material has a porous structure, which gives structures a lot of positive properties:

low weight, allowing to reduce the power of the base;
low thermal conductivity, allowing you to save thermal energy and save on heating.

The acquisition of such useful qualities was accompanied by the appearance of disadvantages:

lack of load-bearing capacity inherent in dense grades of concrete;
inability to withstand pressure and multidirectional loads (tension or bending);
high hygroscopicity.

It is necessary to understand that the shortcomings of the material were a consequence of its advantages and were not unexpected - all acquired qualities were calculated in advance, both positive and negative. However, for a long time, builders could not develop their attitude towards the new material, out of habit expecting from it the properties of dense concrete. It took almost 100 years for the technology of building houses from aerated concrete to receive the recognition it deserves and capture its niche among other building materials.

At the same time, aerated concrete has many advantages:

the precise geometric shape and smooth surface of the blocks allows you to significantly reduce the thickness of the seams. Unlike the usual 10-15 mm, 2-4 mm is made here, which allows you to reduce the number of cold bridges and eliminate the so-called. “wasteland”, i.e. presence of voids in the seam line;
the blocks are much larger than bricks, which significantly speeds up the process of laying walls. In terms of volume, one gas block replaces about 30 bricks. At the same time, the masonry turns out to be very neat and even, especially if tongue-and-groove protrusions are made on the gas blocks;
cutting and processing the surfaces of blocks is not difficult, since the material can be cut with a regular hacksaw. The work is no more difficult than the process of sawing wood. You can adjust the masonry with high precision without creating too thick vertical seams;
untrained people with minimal experience in performing such work can build walls from aerated concrete.

However, the properties of aerated concrete impose certain requirements for installation - for example, an external moisture-proof finish is required. In addition, there are restrictions on the height of buildings (the most popular structural and thermal insulation grade of aerated concrete can be used for the construction of houses up to 3 floors). These limitations and the need to use atypical installation and operation techniques for a long time prevented the material from receiving the correct assessment and earning recognition from builders.

Another feature of houses made of aerated concrete is that they are demanding on the quality of the foundation. Here it is necessary to place the emphasis correctly: the buildings are light and do not require powerful supporting structures. At the same time, the foundations must be reliable and ensure complete immobility, otherwise the walls will crack or completely collapse. As a rule, small houses are built on shallow strip foundations, which are much cheaper and do not require as much excavation work. But, if the soil conditions of the site do not allow it, it is necessary to build more complex support structures that are quite economical and durable.

Factors influencing foundation depth

Regardless of what type of base you use, the bottom mark of the base of the structure is determined by a set of rules, taking into account the following factors

Regardless of what type of base you use (shallow or shallow, strip or slab, FBS or monolithic), the lower mark of the base of the structure is determined by SP, taking into account the following factors:

Type of soils, their features and characteristics. Complete information about the composition of the soil at the construction site can be obtained after geological surveys. You won’t be able to do these things yourself; you’ll have to turn to specialists. Also, the calculation of the depth of the foundation is influenced by the level at which groundwater flows. You will also receive this data after conducting hydrogeological studies of the area. According to the joint venture, average temperatures in the region should also be taken into account

This is especially important if a shallow or shallow foundation will be used, because the structures may be affected by heaving forces in winter. Availability of a heated basement. Average depth of rock freezing in the region.

Soil type, ground level and heaving forces

If you are making a shallow or buried foundation for a house with your own hands, then you should follow some recommendations

If you are making a shallow or recessed foundation for a house with your own hands from aerated concrete, brick, wall blocks and other materials, then you should adhere to the following recommendations from the joint venture:

When building on rock and coarse rocks, as well as on gravelly, coarse and medium-fraction sand, the distance from the top of the earth to groundwater does not matter in the winter season. In this case, any type of foundation can be used, regardless of what depth of soil freezing the calculation shows. According to the joint venture, shallow foundations and non-buried foundations can be used on such soils.
When constructing foundations from FBS and reinforced concrete on rock made of fine and silty sand, as well as hard sandy loam, the choice of foundation type:

does not depend on the calculated freezing depth if the groundwater is at least 2 m below the calculated freezing mark;
the foundation should be no higher than the freezing point according to calculations, if the groundwater level is no more than 2 m above the freezing mark. Under these conditions, sandy loam can have any consistency.

On sandy loams of plastic and fluid consistency at any groundwater level, a shallow foundation and a non-buried foundation should not be higher than the freezing point of the rock according to calculations.
On hard loams and clays, a shallow slab or strip foundation can be used, provided that the groundwater level is at least 2 m below the freezing point.
On soft-plastic loams and clays, provided that the groundwater level approaches the freezing mark no closer than 2 m, you can use any type of shallow foundation (the classification of shallow foundations is given above) for houses made of aerated concrete, logs and timber. However, in this case, according to the joint venture, for houses made of aerated concrete and other lightweight materials and blocks, measures must be taken to protect the foundation from saturation with surface water.
If a slab or strip foundation made of FBS or monolith is erected with your own hands on fluid and fluid-plastic loams and clays at any groundwater level, according to the calculation, the laying depth should not be higher than the freezing point.
In conditions where a slab or strip foundation made of reinforced concrete or FBS is built on loams and clays with a groundwater level no more than 2 m above the freezing point, the mark for laying the base of the foundation structures is calculated to be no higher than the freezing mark.

How to make the right choice

For the construction of houses from aerated concrete blocks, pile, strip and slab foundations are suitable. Structures made from pipes are the most inexpensive, tape is more expensive, and the slab is very expensive. However, each type of foundation is suitable for certain purposes:

for heaving foundations, a slab and screw piles are suitable,
For a house with a basement, a strip foundation is suitable.

For an accurate calculation, it is advisable to contact a designer who can determine the best type of structure and calculate its cost.

Height of floating slab above surface

According to the standards SP 21.13330 slab foundation

can be buried to any distance, focusing on the groundwater level and soil composition. However, the higher the slab is located above the surface, the longer the lifespan of the wall materials. For example, the maintainability of the lower crowns of a log house is much higher if they are located above the ground.

Therefore, for timber and log buildings, slabs with stiffeners are usually used:

cup-shaped - a slab is cast, after the concrete has gained strength, formwork is installed, reinforced concrete beams are made under the load-bearing walls
inverted bowl - the outer formwork panels are higher, the inner ones remain under the concrete structure for the entire period of operation, the inner perimeter is filled with sand or polystyrene foam is laid to insulate the structure

On heaving soils, calculation

reinforcement sections, mesh cells of the lower and upper chords. It is forbidden to rigidly connect foundations to a sidewalk or blind area with a floating slab. Various loads and uneven freezing of soils under these structures can lead to the opening of cracks in reinforced concrete.

In this case, the calculation

is carried out to stretch the sole from prefabricated loads, the upper surface of the slab when heaving forces occur.

Attention: The lower mesh can be made from rods 10 – 16 mm, since prefabricated loads are always present. The lower mesh is knitted from rods 8 - 14 mm, since swelling is partially balanced by the weight of the house. Thus, the slab foundation for outbuildings has a thickness of 10 cm

To support the cottage, you will need to calculate the load-bearing capacity. The choice of thickness is influenced by the size of the protective layer of concrete and the minimum allowable distance between the reinforcing mesh

Thus, the slab foundation

for outbuildings it has a thickness of 10 cm. To support the cottage,

load-bearing capacity calculation The choice of thickness is influenced by the size of the protective layer of concrete and the minimum permissible distance between the reinforcing mesh.

The foundation is by far the most important part of the future home. It depends on it how strong and durable the building will be. In addition, before construction it is necessary to carry out preparatory work, which includes: soil analysis, calculation of bearing load, selection of the optimal location on the site. Based on the results obtained, it is determined what thickness should be selected.

Even if a two-story building is built from timber, its total weight represents a fairly significant load for the foundation of the house, and therefore it is advisable to choose a monolithic type of foundation. Naturally, in order to do everything correctly, you need to know what thickness of the monolithic foundation for a two-story house should be maintained.

First, it’s worth considering the types of foundation:

For the base, reinforced concrete blocks can be used, reinforced directly at the construction site using reinforcing bars.
But more often, owners of individual houses prefer to pour a solid monolithic slab at the construction site. Thanks to this, a durable and solid monolithic slab is obtained.

A monolithic foundation can be laid in two ways: shallowly buried and, conversely, deeply buried. For wooden houses, a shallow type of monolithic foundation can also be used. It goes into the ground no more than 60 cm, but it’s worth making a small adjustment.

Such foundations can be laid on soils that are ideal in their composition and have sufficient density. In other cases, regardless of the ease of construction and the materials used for it, it is necessary to analyze the properties of the soil. There are places where even a light bathhouse has to be placed on a strong and deeply buried strip foundation.

A deeply buried monolithic foundation ensures not only proper distribution of the load-bearing load, but also excellent stability on soils that do not have good stability.

Strip foundation for a house made of aerated concrete

It is constructed by digging a pit around the perimeter of the house and under the internal load-bearing walls. A monolithic structure made of reinforced concrete, which forms a closed loop, allows for the stability of a house made of aerated concrete blocks. In this case, the costs of materials and labor are reduced (compared to a monolithic one), but the requirements for the foundation are increased.

And the main requirement is either to eliminate the heaving of the soil by arranging a foundation cushion on non-heaving layers of soil (in itself, this already requires significant digging into the soil). Or you can bet that the foundation, poured onto a prepared base of crushed stone and sand, will move synchronously with the heaving of the soil, and thus neutralize its effect on the walls of the aerated concrete house.

In terms of depth, there are two subtypes of strip foundations:

Buried below the soil freezing depth (SFD)

A deep strip foundation is arranged so that the base of the foundation is below the freezing level of the soil and is protected by insulation from the influence of frost heaving of the soil.

A recessed strip foundation is good because it allows you to build a basement or ground floor, as well as add elements of the house’s infrastructure, for example, make concrete entrance steps.

Shallow foundation for a house made of aerated concrete (MZLF)

A shallow strip foundation is ideal for building an aerated concrete house on normal soils that are not mobile and not prone to heaving. Since the two main factors influencing the foundation's ability to provide dimensional stability have been eliminated, there is no need to go below the freezing depth. For MZLF, a depth of 500 mm is considered sufficient. Under such conditions, it is possible to build a two-story house from aerated concrete blocks or a house from aerated concrete with an attic.

On heaving soils, it is possible to construct a shallow foundation on a thick, densely compacted bed of sand and crushed stone. Such a layer will serve as a replacement for heaving soil with non-heaving soil. But in this case, it is also necessary to take into account the depth of groundwater. If the level is high, a shallow foundation should also not be poured. At the same time, it is undesirable to build a house from gas blocks with a height of more than one floor on the MZLF, which is located on heaving soil.

Note. Experts strongly recommend allowing strip foundations of both types to gain strength for at least a year after pouring. During this time, he will reveal possible shortcomings, which are easier to correct along the way than after the construction of the house.

Conclusion. A strip foundation is justified on simple soils or on heaving ones, but with the maintenance of the arrangement technology.

Pouring a monolithic slab.

Properties of the monolith.

Thickness of the foundation slab for a one-story aerated concrete house.
The advantages of cast foundation slabs include the following:

high mechanical strength, protecting aerated concrete from cracking. Even if soil movements occur under the building, this will not affect the geometry of the foundation;
suitability for installation on any type of soil: clay, peat, sand, stone or mixed;
complete independence from the depth of groundwater;
affordable manufacturing technology that allows work to be carried out without the involvement of expensive specialists;
durability.

However, some disadvantages must be taken into account:

a large volume of excavation work when digging a pit;
impossibility of arranging a deep basement;
significant costs for materials.

Preparing for work.

Preparatory activities include:

clearing the area of debris and, if possible, of old trees that could interfere with the approach of equipment;
markings at the corners of the future foundation. Dimensions are selected based on the design documentation for the house. In this case, the length of each side of the foundation must exceed the length of the corresponding wall of the house by at least 1 m. This will simplify the work when installing the formwork.

Digging a pit.

Since the base area of the house is quite large, the amount of work will be noticeable even if it is only slightly buried. Therefore, it will be wise to use the services of construction equipment. However, it is recommended to remove the last 15 cm of soil by hand. This will allow you to continuously monitor the depth of the pit and the horizontalness of its bottom.

For the surface option, the pit depth should be 30 cm, for the buried option – 50 cm.

Thickness of the foundation slab for an aerated concrete house.

IMPORTANT. If, when digging a pit at some point, the depth exceeds the calculated one, you should not simply fill the resulting hole with soil. It would be much safer to slightly increase the depth over the entire area, and then pour a higher pillow.

Filling the pillow.

Thickness of the foundation slab for an aerated concrete house.
For a surface foundation, it will be enough to fill in a layer of sand 30 cm thick. In the case of a buried foundation, first fill up 20 cm of gravel, then 30 cm of sand. The finished pillow is carefully compacted with a vibrating platform.

Installation of formwork.

For formwork, it is recommended to use durable boards that do not have mechanical damage. The quality of the material is very important here, since the mass of concrete being poured will be very significant and the formwork must be guaranteed to withstand this load. The boards are fastened together with nails.

Thickness of the foundation slab for an aerated concrete house.

Supports must be placed outside the formwork wall. The reliability of the resulting structure is checked by strong kicks on it. When struck, nothing should move.

The inner side of the formwork walls is wetted with water. This will give a smoother surface to the side edge of the slab.

Filling the screed.

A monolithic foundation will require pouring two layers of screed. The thickness of each layer is 4-5 cm.

Thickness of the foundation slab for a two-story aerated concrete house.

You can start pouring the second layer only after the first has dried. Polyethylene waterproofing is laid on the dry screed so that the overlap of adjacent sheets is about 10 cm. The film reserve at the edges of the pit should be at least 1 m. After this, the second layer of screed is poured.

Reinforcement.

Thickness of the foundation slab for a two-story aerated concrete cottage.
The frame is made of class A-III reinforcement. The diameter of the rod is 10-16 mm, which depends on the number of floors of the house. The result should be two mesh fields formed by wire squares with sides of 15-20 cm. The reinforcement is tied together with steel wire with a diameter of 5 mm.

Thickness of the foundation slab for a single-story aerated concrete private cottage.

Pouring concrete.

The quality and uniformity of the concrete poured is of paramount importance. To make the foundation for a house made of aerated concrete as strong as possible, it is advisable to use a mixer with a feed pump. The standard volume of an automixer is 6-8 cubic meters of solution. The delivery boom of a concrete pump can be up to 30 m long. It is better to clarify this parameter in advance, which will allow you to more accurately plan the pouring process and options for approaching the machine to the site.

If for some reason it is impossible to use a mixer, then to ensure a continuous supply of concrete, you can use manual mixing in a concrete mixer. However, this will require the involvement of additional workers and constant quality control.

Electric concrete mixers allow you to get from 50 to 200 liters of solution in one mixing cycle. Mixing time is from 3 to 5 minutes. However, it should be taken into account that additional time will be required for feeding cement, sand, water and crushed stone into the mixer, as well as time for unloading and delivery to the pouring site. Accordingly, you need to plan the pouring process based on 10-15 minutes per batch cycle. When using a 50-liter concrete mixer, pouring 1 cubic meter of solution may take about 5 hours.

The supplied mixture is distributed over the entire area of the formwork. This procedure can be simplified by using a guide chute. This will require additional manual raking of concrete over the entire area of the foundation to be poured. Although the solution is quite liquid, when you try to pour it into one point, the heaviest fractions will settle at the point of supply, and only the watery component will be able to spread freely over the reinforcement field. This is fraught with the appearance of unevenness in the strength characteristics of the slab and cracking when drying.

Thickness of the foundation slab for a two-story aerated concrete private house.

Immediately after pouring, the concrete mixture should be thoroughly compacted using a submersible vibrator. This will remove air bubbles and increase the strength of the concrete pad. It would not be superfluous to additionally tap the entire perimeter of the formwork with a sledgehammer, where strength is especially important.

The poured slab is smoothed to a complete horizontal level. This process is controlled by a thin layer of water protruding from the solution and showing all the depressions and elevations.

It is not always possible to completely fill the entire formwork in one working day. The order of work suspension will depend on the duration of the pause:

if work stops for less than 12 hours, then the finished surface is simply covered with plastic film. Before continuing work, the film is removed, and the exposed “concrete milk” is washed off from the concrete. Then pouring continues as usual;

in the case when the pause exceeds 12 hours, the concrete will begin to gain strength and it will be necessary to use the “cold seam” technology. To do this, work begins only after the already poured volume of concrete has completely hardened.

IMPORTANT. It is strictly not recommended to continue pouring onto slightly dried concrete. The hardened layer in this case will have a very small thickness and will burst under the weight of fresh concrete being poured.

The monolithic foundation will be ready to continue construction after one month. During the first week, it is recommended to moisten it with water as it dries. This will prevent the appearance of cracks. The remaining free ends of the waterproofing film are wrapped on the plate and soldered to it with a torch.

By using the technology of pouring a monolithic foundation slab under a house made of aerated concrete blocks, you no longer have to worry about subsidence of individual sections of the foundation. The walls will remain intact, because even if the foundation tilts slightly, this will happen immediately over the entire area, without leading to the appearance of cracks.

Calculation procedure

So, the calculation of a monolithic foundation slab begins with a detailed calculation of the size of the sand cushion. This is an important step, since it allows you to create a reliable foundation for pouring concrete. As for sand, fine-grained mountain sand is usually used here, since it is inexpensive and acceptable for backfilling. As for the thickness of the sand cushion for a monolithic house foundation slab, it varies from 20 to 60 cm.

An important point when laying a sand substrate is that it must be compacted. To do this, use a specialized tool, such as a vibrating plate. Experts recommend watering the sand, which will eventually allow it to compact even better. This will increase the bearing capacity of the base. But the latter can take up to 1 cm of thickness, which is absolutely normal.

An important step is that it is recommended to pour crushed stone on top of the pillow. The size of the crushed stone cushion is from 5 to 10 cm. The crushed stone fraction can be small, where a fraction of 5-20 is ideal. The base after backfilling should be perfectly flat relative to the horizontal plane. It is also recommended to compact the crushed stone cushion.

The next step can be considered the calculation of reinforcement. Here, not only the total amount of metal is determined, but also the diameter of the rod, the pitch between the rods, and the possibility of using a mesh is decided. It is recommended to tie the reinforcement in at least two layers, where the first passes at a distance of 5 cm from the sand cushion, and the second does not reach the top point of the base of the future monolithic slab, also by 5 centimeters. As a result of pouring, we will get the fact that the reinforcement will be inside the monolithic slab. The reinforcement frame is knitted from a rod using a welding machine or knitting wire, with a pitch of no more than 50 mm.

Next, proceed to the calculation of the slab itself

Here it is extremely important to maintain the height of its rise, which should not be less than 150 mm. This slab is suitable for light, unloaded houses made of frame material or logs

As for two-story houses with slab floors, the size of the slab must be at least 25 cm. Rarely, the foundation is buried to the extent of freezing, since this is fraught with excessive investment of money in the project. We suggest considering a calculator for calculating the thickness of a monolithic foundation slab under a separate heading.

Slab base

Based on the experience and observations of many specialists, it is worth asserting that the concrete foundation is reliable.

Thanks to the large area, the load exerted by the house is distributed evenly over the surface, eliminating the slightest distortion.
The slab frame makes destruction from soil heaving impossible. When there is frost pressure on the base, it rises synchronously with the soil, maintaining the overall integrity of the structure.

Another name for a slab base is floating. The slab-type base has a large reinforced area, which, under loads, begins to move synchronously on all sides. The risk of cracks and destruction is eliminated.

Slab

When starting preparation, you need to go through the most labor-intensive stage - digging a pit. Work in the pit consists of several stages:

Excavation.
Leveling the surface.
Backfilling of crushed stone cushion.
Pouring a small layer of pre-screed.
Installation of a waterproofing layer.
Laying concrete slabs.

The foundation must stand for sufficient setting. The problem is laying the slabs. They weigh a lot and require the use of construction equipment.

Foundation for a house made of aerated concrete

When choosing a foundation for a house made of aerated concrete, four main types are considered:

Monolithic

This is a durable and reliable type of base. To construct it, several layers of reinforcing mesh are formed and filled with concrete mortar. This option is most resistant to various weather conditions and soil movement. This eliminates the possibility of deformation of the building and the appearance of cracks. A monolithic foundation for a house made of aerated concrete is suitable for heavy structures and complex structures. It can be built on almost all types of soil and can withstand even the harshest climates. The disadvantage is the relatively high price; this is the most expensive but also the most reliable type of foundation.

Tape

One of the most popular and economical options for the construction of various structures. Depending on the type of soil, groundwater level and expected load from the building, one of several subtypes of this foundation is selected. They are divided according to the degree of immersion into the soil into: shallow and buried. Both options have high levels of stability and reliability. The installation price and construction speed are lower than that of a monolithic one due to the smaller amount of necessary materials.

Columnar

It is possible to install a columnar foundation for an aerated concrete house in Moscow and the Moscow region, provided there is stable soil and no slope. If the criteria for the construction site are met and basements are not planned, then this option will be very profitable and economical. When installing it, the poles are installed vertically at the corners of the building, at the intersections of walls and in areas of maximum load. The entire structure is interconnected to evenly distribute the load.

Pile

This foundation for a private house made of aerated concrete is best suited if there is unstable soil, difficult terrain or a high groundwater level. Depending on the specific case, bored or driven piles are used. To strengthen the base structure and distribute the entire load, a monolithic grillage is used.

Regardless of the chosen foundation option, when building a house from aerated blocks, it is mandatory to install waterproofing and additional insulation of the basement. This will reduce the influence of moisture and prolong the durability of the structure.

We pour foundations in Moscow and the Moscow region and guarantee the quality and reliability of the erected structures. To achieve this, our staff employs highly qualified designers and builders with extensive experience in construction work. We use only high-quality materials and special products. technique. In our work, we use modern methods and technologies for constructing foundations and apply an individual approach to each order.

On our website you can use the foundation calculator for an aerated concrete house to roughly calculate the cost of our services. Our specialists will answer any questions you may have by phone free of charge.

We provide a free service for a specialist to visit the construction site. There he will be able to make a more accurate calculation, taking into account all the features of the site and construction requirements.

All details and features of the order are specified in the contract. After signing it, we strictly comply with all points. The price also remains fixed and cannot be changed.

Our professionalism and well-coordinated work at all stages of construction guarantees timely delivery of the project on a turnkey basis.

Step-by-step instructions - do-it-yourself foundation

The thickness and height of the tape of the base under consideration, as well as the depth of its placement, are selected based on soil analysis, climatic conditions of the area and the number of storeys of the building being built. Without knowledge in this area, it is better to entrust this design stage to a professional. There are many nuances and requirements of GOSTs that must be observed.

But it is quite possible to create a support for your house using a ready-made project yourself. But in order to avoid mistakes, it is best to make the strip foundation yourself with the step-by-step instructions given below. It describes all the intricacies of building such a structure for a typical one-story cottage.

Stages of work

The first stage is marking and excavation work. Regardless of the depth of the foundation, the sole must rest on solid layers of soil. It can be clay, sandy loam, rocky layers or loam. They are usually hidden under turf and layers of ordinary soil. All this will have to be torn down and removed before starting to build the foundation of the house.

To mark the area you will need pegs, tape measure and twine. If the soil is dense, then the walls of the dug trench will make excellent formwork. It will only be necessary to build it up from above. If the soil is loose and constantly crumbling, then the trench will have to be dug somewhat wider so that formwork boards can be placed inside the hole.

The second stage is preparing the pillow. The bottom of the dug trench is leveled with sand and fine gravel. This sand and gravel layer should be thoroughly compacted, pouring water as it is poured. It should be between 10–30 cm in height. This cushion serves to redistribute and reduce point loads on the strip foundation from below during seasonal heaving of the soil.

The third stage is placing the formwork. Here you will need bars with a cross section of 30 to 40 mm and boards with a thickness of 15–20 mm or laminated chipboard. The formwork created for the concrete foundation of a house will subsequently be required to withstand a considerable mass of concrete poured into it. It should be made strong and reliable. If, after filling with the concrete mixture, it collapses, then everything will have to start again.

If the groundwater at a construction site is high, then reinforced concrete will require waterproofing. From above, at the level of the base of the house, it is usually done as a coating. And to protect that part of the base that remains in the ground, roofing material should be laid in the trench on the sides and on the bottom. It will reliably protect concrete from excess moisture in the soil at the stage of its hardening and after.

The fourth stage is laying the reinforcement. For reinforcement, steel rods with a cross-section of 14–16 mm and thin dressing wire are usually used. The reinforcement can also be fastened using electric welding. But in this case, you need experience working with a welding machine and yourself. Plus, when performing welding, you must be prepared for the occurrence of metal corrosion in the future.

Inside the trench, a frame of reinforcement with cells of 25–30 cm should eventually be formed. Moreover, it is laid so that the steel is covered on all sides by the poured concrete. Otherwise, the metal will inevitably begin to rust, and the house will definitely not last long.

The fifth stage is pouring concrete or laying out FBS. If it is decided to equip the foundation for a house being built using block technology, then this greatly speeds up the process of its construction. Here you don’t have to make formwork and wait almost a month for the concrete to set. However, support on foundation blocks will cost more than a monolithic counterpart. Plus, they will have to dig a larger trench in width. To distribute the loads for the bottom row, FBS masonry is made with an expanding base. If a monolithic option is chosen for the support structure, concrete should be poured immediately over the entire surface. No breaks in length and no layers in height. A monolith is just a monolith. The house must stand on a reliable foundation.

When preparing the concrete mixture yourself, you need to mix cement, sand and crushed stone in proportions 1: 3: 3

But it is better to initially order a ready-made solution with a grade of M300 or higher.

When pouring concrete, it is extremely important to ensure that no voids form inside it. There are special vibrating machines to perform compaction.

However, you can also use a piece of reinforcement to pierce the poured mass and release air from it.

The sixth stage is waterproofing and blind area. It is allowed to begin waterproofing work 3-4 days after pouring concrete. It takes about three weeks for it to fully set. But you can already begin treating the strip foundation for the house with mastic, even if it has not yet completely hardened.

Also, along the entire perimeter of the building, you will need to make a blind area to drain rainwater away from its walls.

"Pillow" under the base

Do not forget that in addition to such a parameter as the thickness of the strip foundation, it is necessary to calculate the thickness and cushion under it. In this case, everything also depends on the type of soil. If sandy soil, as is known, is not subject to change, then you can be sure of the reliability of the foundation, but on heaving soil everything is much more complicated.

Clay soils, or areas in which groundwater is located close to the surface, are subject to severe heaving in frosts, which also affects the foundation of the building. Also, such soils undergo changes not only in winter, but also in autumn and even in summer. For example, during heavy rains they swell, but during drought they settle, because of this the difference in soil marks can be 10-15 cm.

Of course, with an incorrectly constructed foundation, such significant changes in the soil will not go unnoticed and will most likely lead to the foundation not being able to withstand the load and bursting.

To prevent troubles, the strip foundation is not only laid at a depth below freezing of the soil, but also a sand cushion is placed under it.

Calculation of sand-crushed stone cushion

Schematic representation of a slab foundation indicating the thickness of the sand and crushed stone cushion.
The thickness of the cushion often varies depending on the condition of the soil and the type of building, as well as what the house is made of. The thickness depends on many indicators, because for wooden buildings a cushion 15 cm thick is enough, but for massive houses made of aerated concrete - no less than half a meter. But, as a rule, the thickness of the pillow is calculated individually for each home, taking into account the following factors:

soil condition and structure;
degree of soil freezing;
soil heaving and seasonal movements;
soil moisture and the height of soil horizons;
material of the house and total mass of the building;
slab dimensions.

Crushed stone in the cushion is needed to compensate for the heaving of the soil, so crushed stone compensates for the low density of the soil with rockiness. It is also an excellent drainage material, especially on clay soils with high moisture content. Sand ensures uniform distribution of the mass of the building over the entire area of the sole.

Choosing the type of foundation for the garage

Arrangement of a garage slab base

Garages are classified as lightweight non-residential premises, but it should be borne in mind that additional load will be placed on the floor from the weight of the machine. Therefore, it is necessary to decide on the choice of the most suitable base option. From the experience of constructing such buildings, the following must be taken into account:

Building design. Design features include the number of floors, dimensions, height of the walls and materials that will be used in their construction. This determines what the load on the base surface will be. This also includes the functionality of the future garage. Will it be used to repair the car, that is, will it have special performance characteristics?
Condition of the soil under the garage. Different types of soils also require different design solutions when building the garage itself and, in particular, when laying the foundation.
The level of water occurrence and the level of freezing, and therefore the impact of frost heaving forces.

In addition to the above, the possibility of using the garage for storing food and belongings is also taken into account. Accordingly, it must be equipped with electrical wiring and ventilation. Most of these structures have a basement and an inspection pit. Other features are possible in the form of additional insulation and sewage systems.

Summarizing all the above requirements for a garage foundation, a universal solution arises - a floating monolithic slab. This can be a buried monolithic reinforced concrete slab, or a monolith, on a layer of crushed stone and sand.

The disadvantage of the design is still the same - a significant volume of concrete pouring and significant costs for reinforcing the slab. However, regardless of the rise in cost of the structure, many give their preference to this type of foundation due to its undeniable advantages:

The construction of the slab is possible regardless of the complexity of the soil.
The floating structure prevents the movement of garage elements and prevents damage.
After carrying out the necessary measures for waterproofing and drainage, the structure will always be dry, regardless of the water level.
The slab will serve as a floor that can support the weight of the car. Accordingly, no base is required for arranging the floors. Immediately after laying the slab, you can screed and begin additional finishing.

There is an opportunity to install a heated floor, abandoning traditional radiators. This solution will save on heating the garage. Thanks to its integral design, the slab prevents rodents and insects from entering the room.

Recommendations

“What kind of reinforcement is needed for a strip foundation?” Most often, reinforcement with a diameter of 12-14 mm with a ribbed profile is used. Clamps are bent from reinforcement in the form of squares or L-shaped elements, which are fastened manually with special wire.
Plastic reinforcement: pros and cons of its use:

a light weight;
high tensile strength;
does not corrode;
does not bend;
high price;
the material is flammable.

“What is sand concrete?” Sand concrete is a new building material. It consists of Portland cement, coarse and fine sand and various plasticizers. Used in the construction of foundations and masonry. This sand-cement mixture is often used for floor screeds.

An example of calculating the main parameters of a foundation slab

Sketch of the optimal thickness of the foundation slab

To correctly understand the calculation of the parameters of a slab foundation, as well as clearly calculate the required amount of concrete, it is worth using the following example:

A typical building made of aerated concrete with an area of 100 m² (10x10) is accepted and a slab foundation on rocks 0.25 m thick of a shallow type is selected for it.
The volume of the slab in such cases is 25 m³. This is the total amount of concrete required to fill such a structure. Here the volume of the reinforcement mesh is taken as zero, so as not to complicate the calculations. In practice, such calculations are also carried out, but for large structures.
Installation of stiffeners, which are used to increase the reliability of the structure. The spacing of the stiffeners is 3 m, which creates squares.
The length of the stiffeners will correspond to the length of the foundation, and the height will be the thickness of the slab.

So, to pour a slab foundation with an area of 100 m², you need to use 25 m³ of concrete. A certain amount of reinforcement, waterproofing and sand and crushed stone for the cushion will also go here. In general, I would like to note that any developer can calculate the thickness of the slab independently; it is enough to have minimal mathematical knowledge.

But if you immediately calculate the foundation slab, you can generally control the costs of building materials, keep an eye on unscrupulous builders, and also clearly determine the size of a house made of aerated concrete or brick. You can also calculate the required amount of materials using our online calculator.

How is the process of pouring concrete mortar carried out?

For concreting, use a self-prepared mixture or a ready-made solution supplied using a concrete pump. Procedure:

Fill the formwork with mortar.
Distribute the concrete mixture inside the formwork.
Compact the concrete surface thoroughly.
Plan the surface of the slab.
Place plastic wrap on the stove.
Moisten the concrete periodically.

Regardless of the thickness of the slab for aerated concrete, the hardening process lasts 4 weeks.

Benefits of a foundation slab

The technology for constructing a foundation slab is simpler than that of a strip structure.
When constructing low-rise buildings, the slab option has advantages over strip and pile structures. When implementing the work, you will have to spend money on concrete and reinforcement, but you can save on a number of other expense items. For example, since the slab surface serves as the subfloor of the lower floor, there is no need to install a ceiling. The preparation of panels for formwork here requires significantly fewer boards than when arranging a strip foundation.

Such a foundation is well suited for arranging a water-heated floor - in this case, the system is laid inside the slab (instead of preparing a special screed for it).

Among the technical units for installation work, you will need a concrete mixer. There will be no need to spend money on excavators and lifting machines during construction.

Excavation

It is undesirable to leave dug trenches open for a long time, so immediately after the installation of the temporary drainage system is completed, it is necessary to begin excavation work.

It is recommended to start work by marking the territory. In places marking the boundaries of the foundation, pegs are driven in. The fertile layer of black soil should be removed.

Digging a trench is done either manually or using special equipment. When arranging a shallow strip base, it is not advisable to use large equipment; you can do it with a shovel.

Using earthmoving machines, work is carried out in two stages:

Rough excavation.
Finishing the trench.

It is recommended to prepare in advance a place to place the layer of soil to be removed.

Design advantages

When pouring a monolithic slab, you can immediately install a heated floor system

In addition to being economical, a big plus of this type of base is the large surface area of the slab. Due to this, the pressure on each square centimeter of soil is reduced, which prevents deformation processes and uneven settlement. Other advantages include:

Possibility of installation on different types of soils, including those characterized by increased mobility or high water rise. If you have to build a house on “inconvenient” soils, slabs are an excellent option. However, on a slope it is difficult to make a reliable foundation of this type; here it is better to choose piles.
Excellent insulation ability. If the foundation is made in accordance with the technology, good protection against heat loss is achieved. It also does not allow moisture to pass through.
Durability: A solid slab can last more than a century without signs of deterioration.
Rigid design thanks to a reinforced frame, large dimensions and a structure that does not include suture elements. This makes it suitable for buildings made of brick, aerated concrete and other materials that react negatively even to minimal movements.

Brick and monolith

Calculating the foundation for a brick house will be a little more complicated, since you will have to operate with larger loads. The weight will be approximately 200-300 kg per square meter.

Brick was first used in ancient Rome, but until the 19th century it was used only for the construction of houses of rich people. The material is durable, has good thermal insulation, is durable, fireproof and environmentally friendly. However, construction requires large financial costs, and the foundation in this case must be very strong.

Calculating a monolithic foundation will be a little more complicated than in previous options, since the mass of the building will be approximately 350 kg per square meter.

Only the frame is made from reinforced concrete. The construction speed is very high, there are no seams, good thermal insulation and durability. However, the downside is that the calculations are more complex.

Solid foundation

If construction is not your main specialty, it is very difficult to make correct calculations and take into account all the nuances, so calculations should be performed long before the start of construction work.

Very often you can find the consequences of improperly laying the foundation for a house, which appear after the first winter and the most common reason is the owner of the house saving money on the construction of the foundation.

For example, a strip foundation erected to a depth of 60 cm with a soil freezing depth of 110 cm, with a two-story building made of timber, will lead to the fact that the foundation simply will not withstand the load and will crack.

Next, the owner will have to take measures to strengthen the foundation and additional reinforcing rings along the entire belt. Therefore, the most important stage in construction is geological surveys, which allow one to study the properties of the soil and determine the depth of freezing. A shallow foundation will also mean that the basement will constantly freeze, so that subsequently you will have to do additional insulation of the lower floor.

Having determined the properties of the soils located on your site, you can easily calculate what the thickness of the foundation should be in this area. And do not forget that when installing a strip-type foundation, it is necessary that the foundation is at least 30 cm above ground level.

And in no case do not save on money, even if you are very unlucky with the soil and preliminary calculations have shown that you will have to build a monolithic foundation. A solid foundation is, first of all, a high indicator of the safety of the entire house, and therefore it must meet all requirements. In addition, repairing the foundation, on the construction of which you tried to save money, may cost you the cost of the constructed foundation.

Choosing a monolithic building support

The choice of a monolithic foundation is relevant for a 2-story and 1-story house. The monolith must be poured in the place where the house is planned to be built. As in previous cases, all work begins with digging a pit of the required diameter.

You will have to calculate it yourself. This house foundation must be poured according to the area of the building. Additionally, it wouldn’t hurt to make formwork.

When arranging a monolithic foundation, you cannot do without reinforcement. The concreting itself must be completed in one step. Reinforcement can be neglected if you plan to build a small building.

But then the concrete will have to be poured in several stages. The thickness of the monolithic foundation slab layer should be approximately 15 centimeters. The solution can be poured a second time only after the first layer has hardened.

Country residents often ask professional builders how to make a strong monolithic foundation for a one-story house. They give them useful recommendations that they can later use during the construction of a residential building. Often, masters share with beginners the secret that they should not forget about bayoneting the structure. This work should be carried out with a regular shovel. Bayoneting helps remove air bubbles from the concrete mixture, which can harm the foundation of the house.

A monolithic foundation is one of the most expensive types of foundations for aerated concrete houses. Moreover, not everyone will be able to cope with its filling. But this option is the most reliable.

Basic design calculations to ensure structural reliability

The calculation of a slab foundation for a house made of aerated concrete is carried out in various ways at the design stage:

manually using a regular calculator;
using ready-made software.

Correctly performed calculations allow you to determine:

need for building materials;
thickness of the monolithic foundation base;
strength characteristics of the foundation;
load-bearing capacity of a reinforced concrete slab.

At the calculation stage, the following characteristics are also determined:

the total weight of the future structure, taking into account constant and variable loads;
surface area of the foundation to determine the amount of heat insulation;
the amount of pressure that the foundation slab with the building exerts on the soil surface.

Let us dwell in more detail on the features of performing certain types of calculations.

How to calculate the thickness of a monolithic slab for a house made of aerated concrete

The thickness of the foundation slab for an aerated concrete house is calculated on the basis of statistical information, taking into account the pre-calculated mass of the structure.

Calculation of foundation strength

The vertical size of the foundation slab is determined by summing the following dimensions:

the height of the compacted sand and gravel layer, which acts as a damping cushion. Depending on the characteristics of the soil, the thickness of the crushed stone-sand backfill ranges from 10 to 30 cm;
the thickness of the concrete layer poured inside the panel formwork of a certain height. The average thickness of a reinforced concrete base ranges from 15 to 25 cm.

Having summed up the indicated values, we obtain the total thickness of the monolithic base, taking into account the damping layer of 25-55 cm.

How to calculate the thickness of slab monolithic foundations.

Thickness of the foundation slab for an aerated concrete private house. Sketch indicating the thickness of the slab foundation.

Monolithic slab foundations can be found not only in private, but also in commercial construction. Monolithic slabs are able to withstand heavy loads; the mass of the constructed building is evenly distributed between the slab and the ground, so there is no subsidence factor in such foundations.

They can be of different designs, installation depths and types, but in general they consist of concrete and a reinforcing belt. Additionally, a sand-gravel cushion and waterproofing are used, but these are related materials and do not actually affect the thickness of the slab. Often used as a base for aerated concrete and brick buildings.