What foundation is needed for a house made of aerated concrete? There is no single correct answer. Almost any of the possible will be an excellent start for the presented type of construction. It is worth noting that the design of the base for a wooden or brick building is selected quickly, however, new materials have their own standards and requirements.

Attention! The project of the foundation for a house made of aerated concrete requires deep understanding and knowledge of some tricks that will help speed up the pouring process and create a structure that will withstand almost any load.

When designing a foundation for a house, many make a fatal mistake - counting that for a light material, a massive foundation is not required. The strip foundation for a house made of aerated concrete must have a calculated strength and depth, otherwise, soon, the structure of the house will crack. The main task of a concrete substrate during construction is to create conditions under which all the pressure force will diverge evenly without peak areas.

Strip foundation for aerated concrete house

The main problem in the construction of aerated concrete supports for a house is the buoyancy force. It is this force that is balanced by buildings that are built of heavier materials. To solve the problem, you need to understand what the ideal width will be. The concrete substrate for a one-story aerated concrete house can be shallow, but it is worth paying great attention to exactly how it will be designed.

Important! For shallow foundations, use a sand cushion. It is this cushion that contributes to the better stability of the foundation, even with deep freezing of the soil.

It is worth noting that the most suitable option is a pile support structure for a house made of aerated concrete, as in the video:

The presented form of the foundation of the house, due to additional piles, is able to keep the base of the building from deformation on almost any soil or ground. Thanks to the piles, the deepening of which, as a rule, reaches 1 meter, they give the load to the soil and resist the pushing forces.

The foundation for a two-story house made of aerated concrete

In order to construct a foundation with your own hands for a two-storey aerated concrete house, it is necessary to take into account all important aspects of the construction. Among all, the main ones are:

• the mass of the wall and the force of pressure per one linear meter of the base of aerated concrete;
• the mass of floors, which will exert additional pressure on the base of the building;
• roof weight as additional weight.

When building a two-story house, an important question remains - what size of foundation is needed for a house made of lightweight material. Professional builders who are engaged in the construction of such buildings recommend using a structure that will be at least 10 centimeters wider than the building block at the top and 15-20 wider at its bottom. It is this wedge-shaped design that will maximally prevent the house from sliding down on the ground. Also, when using such a base, you should pay attention to the substrate, which, as a rule, made exclusively from sand.

In general, the calculation of the base for a house made of aerated concrete can be carried out using an ordinary calculator for calculating a strip base for a building.

Foundation slab for aerated concrete house

This type of foundation is characterized by the fact that concrete is poured directly under the entire surface of the structure. There are some positive and negative aspects of using such a building foundation. Among the positive ones are:

• ease of pouring concrete mixture immediately on the construction site;
• using less reinforcement to strengthen the base;
• the foundation itself, if desired, can serve as an excellent floor inside the built house;
• the distribution of the mass of the entire house on the stove, reduces the buoyancy acting on the house.

Among the negative aspects of the use of this type of foundation, it can be noted:

• high costs for concrete for the preparation of concrete mixture;
• the need to level a larger surface horizontally, which is possible only with the help of special equipment;
• to fill such a foundation, you need to choose a flat area or carry out a large amount of earthwork to level the area for pouring;
• this type of foundation requires lengthy miscalculations of water, gas and disposal fittings;
• the need for careful selection of soil to accommodate such a base structure;
• long-term drying of the surface with a monolithic form of pouring will not allow construction to be carried out immediately after organizational work.

Attention: like a strip structure, the presented view can "rest" on piles, which will increase the permissible load directly on the foundation.

Much attention should be paid directly to the characteristics of the soil under the future building. The disadvantages of choosing such a foundation include shallow bedding: while high-rise buildings without additional fortifications can "float" after a while due to soil erosion. Also, the presented type of foundation pouring is not suitable for those regions where the freezing depth is higher than the 1 m mark.

To directly calculate the volume of concrete required, a geometric formula should be applied. As an example:

The height of our future foundation will be 30 cm, the width for the building, taking into account the fact that the foundation is 10 cm larger than the walls themselves, is 620 cm, the length of the structure, with the same taking into account, is 1020 cm. We translate all values ​​into meters:

• 10,2.

Now we multiply all the obtained indicators among ourselves and get the volume of concrete that we need to fill the base. 0.3 * 6.2 * 10.2 = 18.97.

Taking into account the fact that when concrete dries, it loses part of the water, we need about 19.2 cubic meters of the mixture.

• Date: 29-04-2015
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• Rating: 90

Houses made of aerated concrete blocks today enjoy a certain popularity due to their many advantages. In order for the structure to be reliable and durable, it is necessary to correctly complete the foundation for the house made of aerated concrete. There are several options here: you can build a strip foundation, some types of columnar. Which one is better is determined by the external conditions, the type of soil.

Aerated concrete is one of the most reliable and cost-effective materials for building a house. It is environmentally friendly, has good heat and sound insulation.

Foundation options for aerated concrete houses

Monolithic tape option for aerated concrete house is the best option. It can be installed on almost any type of soil, it perfectly dampens all seasonal deformations, distributes loads. If you do not know which base is better to put, then stop at the tape, which is very simple to build.

The manufacturing process includes:

• digging a trench and filling a sand and gravel mixture;
• installation of formwork, after which a reinforcing frame is needed;
• pouring concrete mixture.

When a house is being built with fairly limited funding, a solid and inexpensive pile-grillage foundation can be made.

The piles for it are laid to a depth of two and a half meters with a step of 1.5-2.5 m. From above, the pillars are connected using a monolithic beam, that is, a grillage, which should have a cross section of 300 by 400 mm. A correctly placed foundation of this type perfectly withstands the loads even from a massive two-story house.

If aerated concrete blocks are used in the construction of a house, then the pile-slab option can also be used. In this case, it is best to use asbestos-cement pipes as supports, which are mounted to a depth of 2.5 m. They are connected using fittings. Further, the pipes are poured with concrete to form a single structure. You can use this type of foundation for a house on almost any soil, especially for complex soil types.

Back to the table of contents

Calculation of the strip foundation for aerated concrete house

An example should be considered of the correct type for a house, which is composed of gas silicate blocks.

Suppose that it is planned to build a house made of aerated concrete, the overall dimensions of which are 9.1 × 8.8 × 6.3 meters with a roof area of ​​123.5 sq. M. will be tape.

The construction will be carried out on clay-type soil, the freezing point is at a depth of up to 90 cm. The groundwater lies at a depth of about two meters. The foundation of the house will have the following parameters:

• tape width - 30 cm;
• height - 75 cm;
• length - 44.9 m;
• base foot area - 13.47 m2 (44.9 × 0.3 = 13.47).

The specific pressure for clay soil (according to the reference data) is 10 t / m2, that is, this value is higher than the obtained one. This means that all calculations were made correctly, it was designed with a high level of reliability.

When deciding which foundation is best to choose for a house made of aerated concrete, several factors must be taken into account. First of all, the properties of the wall material affect the design features. Foundations for houses built from aerated concrete must take into account some of the distinctive characteristics of this material.

Features of aerated concrete blocks

Here we will consider those characteristics that have a direct impact on the foundation for a house made of aerated concrete. Before choosing a type, consider the following features.

Gas blocks are piece material. Even with the correct choice of the masonry mortar and the observance of the technology for performing the work, they are weakly connected with each other. This factor translates into the fact that the walls of the building are extremely sensitive to various deformations of the base.

If the foundation for a house made of aerated concrete sags or, conversely, rises from the ground, cracks may appear on the walls of the building. The cracks will in most cases be oblique. The opening width and length depend on the scale of the displacement of the building support. To prevent the occurrence of damage, it is required to provide reliable supports that will resist various kinds of displacement. The structure should connect the wall from separate blocks into a single system.

The task of the foundation is to prevent such phenomena

The foundation for aerated concrete is needed less powerful than for a brick house. This is due to the lower density of the material, and, accordingly, the mass. For comparison, the density of gas blocks is from 350 to 700 kg / m3, while a brick wall will have a density of 1800 kg / m3. Blocks with a minimum density cannot be used as structural elements; the material of load-bearing walls has a mass of 500 to 700 kg per cubic meter.

Despite the advantages of blocks in comparison with bricks, it is worth remembering that the material is inferior to wood. Also, the building will be heavier than the frame house. When choosing foundations for houses made of lightweight aerated concrete, this feature must be taken into account.

What types of foundations are used

All foundations, depending on the working conditions, can be divided into four large groups:

1. columnar;
2. pile;
3. tape;
4. slab.

The first and second in private construction (taking into account the most popular sections) have a relatively low bearing capacity. Such elements work only for compressive loads. It is especially advantageous to make them from concrete, since this material has good compressive strength. Also recently they have become widespread.

The strip foundation takes up mainly compressive loads. When installing on soft ground, slight bending effects may also occur. If the monolithic foundation is made in compliance with the technology, they do not cause problems.

The use of a slab foundation differs in that this design works in bending and punching. Concrete does not resist such influences very well. To prevent damage, a mixture of sufficiently high grades is chosen for pouring, and reinforcement is prescribed with special care. Before installing the slab, it is recommended to calculate its strength and rigidity. Only a professional designer or constructor can perform such work.

How to choose the type of foundation

Before choosing which type of support is best to use for a house made of aerated concrete, you must consider the following points:

• geological conditions of the construction site, foundation strength, soil water saturation, groundwater level;
• the mass of the building (when comparing buildings made of the same material, this characteristic is strongly influenced by the number of storeys);
• economic opportunities.

Influence of soil characteristics

Soil moisture and soil type affect the elevation of the support. Soils on the site can be one of the following types:

• coarse;
• coarse sand;
• medium sand;
• clay;
• loam;
• sandy loam;
• fine or dusty sand;
• bulk soil.

The last two positions have very low strength indicators. It is not recommended to build on such bases (only pile foundations can be an exception). The best option would be to replace the material with medium to coarse sand.

The best soils for construction will be coarse and sandy (medium and large)... Such bases are highly durable and are not prone to frost heaving (one of the main enemies of foundations for aerated concrete houses).

Refractory clays and loams also have good strength characteristics. But all clay soils (clay, loam, sandy loam) can lead to uneven elevation of the building in winter. This phenomenon occurs due to frost heaving. In this case, the outer walls of the building rise more than the inner ones. Cracks appear on the walls of the gas blocks. When building on such bases, it is required to take timely measures to prevent frost heaving.

When building on heaving soils, it is necessary to choose those types of foundations that are buried below the freezing of the soil. The value is determined according to regulatory documents. On average, this value is within 1-2 m.

The foundation for a house made of aerated concrete (its sole) must be at least 50 cm above the groundwater level. Depending on the location of the moisture, you can use a buried structure (it goes into the ground by 1.5 m or more) or (in this case, the laying is taken to be about 70-100 cm). Also, when choosing the depth of the foundations, it is necessary to take into account the need.

Structural features of the building and load on the foundation

To choose which foundation is best for a block house, it is recommended that you familiarize yourself with the table below. The dimensions and thickness of the support part are assigned by calculation.

The answer to the question of which foundation is best to apply depends on many factors. None of them can be missed.

Instructions

Aerated concrete, unlike other building materials, has one, but a significant drawback: it is very susceptible to any kind of deformation. The bending resistance of the blocks is so low that even small movements in the foundation can cause cracks along the entire wall. Therefore, when starting the construction of such a house, the main attention should be paid to its foundation.

Requirements for the foundation for a house from

Given the peculiarities of this material, the choice of types of bases here is significantly limited. For buildings made of gas silicate, the most stable and well-reinforced foundations are required. These include: monolithic slab, strip and columnar bases. It is extremely important to make the correct calculation of the bearing capacity and strength of the foundation for gas-block houses with a basement or a high basement.

It is not easy to build a high-quality foundation for such buildings, but the matter can be significantly complicated if there is a high level of groundwater at the construction site. For the developer, in this case, there are two ways out: either to build a house from another material, or to mount drainage communications. In the latter case, housing construction costs will increase significantly.

A high level of groundwater is dangerous due to waterlogging of the soil and the risk of frequent flooding in the spring and autumn periods. All this is fraught with premature destruction of the foundation and, accordingly, deformation of the base and the house. Wet soils are classified as highly heaving, those in which various forces are powerfully acting on the foundation: pushing, compression, expansion, and others. Therefore, for the construction of a house from gas blocks on heaving soils, it is required to qualitatively waterproof the base and make an annular or wall drainage.

Optimal foundation for a gas block house

For small buildings, a monolithic strip base will be enough. It is not recommended to build gas silicate buildings on prefabricated foundations. The depth of the belt is calculated based on the type of soil and other factors of the construction site. A pile foundation is also suitable for such structures. But it must be wrapped in a solid frame of a reinforced concrete grillage. This precaution will prevent cracking of the aerated concrete walls.

A monolithic reinforced concrete slab is a more expensive base, but it is much more reliable. On such a foundation, a building made of gas silicate blocks can stand for many decades without any damage. It is this solution that is optimal for an individual developer.

Advice 2: Which foundation is best for aerated concrete house

In order to choose the right base for a house from gas-based blocks, you need to know what is the peculiarity of such buildings and what requirements are imposed on the foundation on which they will be located.

Instructions

Aerated concrete houses have their own characteristics: they have a low mass due to a relatively light building material and require a solid foundation that can compensate for all ground movements and prevent cracking of porous aerated concrete. Therefore, for such buildings it is necessary to erect a buried reliable foundation.

What is the best foundation for aerated concrete houses on unstable soils?

For these conditions, screw piles are best suited. What is their advantage? First of all, this is the depth of laying the supports. The piles are screwed into the ground until they are securely fixed in it. As a rule, the base of the support is 30-50 cm below the freezing point of the soil. This provides a guarantee that the house does not warp from the effects of heaving forces. Such a foundation is suitable for absolutely all types of soil, regardless of the depth of its freezing and the level of groundwater. Installation of screw piles is an optimal solution even if the relief on the site is complex with significant differences in height.

The screw foundation is characterized by a high installation speed: it can be installed in just one working day. For a long time it was believed that for a house made of gas silicate blocks, a recessed monolithic slab is the optimal solution. But practice has shown that screw piles are a more reliable and acceptable solution, especially for unstable soils with high humidity. Among other things, such a base is much cheaper and more durable.

Individual construction involves some flight of imagination in the design and construction of a house, but the opinion that an aerated concrete house can be built without a foundation is deeply mistaken. And it is based on the fact that such a building is light enough, and a foundation is not required for it. This is far from the case - aerated concrete still has weight, and for a standard typical project of a house measuring 6 x 10 meters, this value will be approximately 60-80 tons. Add furniture, finishing materials, communications, the weight of residents and strangers, add the necessary margin of safety - and you will get such figures that you won't want to build a house without a solid concrete foundation.

The main selection criteria are functionality and profile purpose of structures, assemblies and materials. The requirements listed below apply to any type of foundation:

1. Any foundation is designed to ensure the stability of the geometric shapes of the building, that is, the rigidity of the structure;
2. The even distribution of the load from the weight of the completed house on the ground is another purpose of this structure. Any increase in the load on a random site can cause a distortion of the building, the appearance of cracks, the destruction of the material;
3. Compensation of heaving forces in order to prevent deformation of the housing;
4. Minimization of lateral forces from the ground on the plinth, base and load-bearing walls of the building.

For any foundation, the depth of soil freezing in the region and the level of groundwater passage are of decisive importance - these parameters affect the actual depth of the foundation. In the absence of groundwater and underground sources on the site, then when calculating the depth of the pit for the foundation for a house made of gas blocks, the depth of soil freezing is not taken into account, and for all soils, except for clayey, concrete can be poured above this level.

Clay soil is heaving soil, and therefore, in such areas, the foundation for a house from a gas block is necessarily laid below the geological point of soil freezing. In such soils, atmospheric moisture seeps into the clay layer and condenses into large volumes. At negative temperatures in the soil, water turns into ice and expands, and only upward, creating pressure on the foundation. Clay prevents lateral and bottom expansion, so the soil swells up.

If the house is built of gas blocks, then such swelling will lead to deformations, cracks, destruction of the concrete structure and walls of the house. Research shows that up to 8000 kg of soil pressure per square meter of foundation. Therefore, for objects erected from aerated concrete, it is necessary to equip the reinforcement of the foundation and walls. At critical points (windows, doors, arched openings), the armored belt should be strengthened.

Depth and types of foundations

Compliance with two rules will make the calculation more accurate:

1. Distance (H) from the bottom of the base to the ground surface should be ≥1.5 (H) before the beginning of the level of soil freezing;
2. The base foot should start above the groundwater level ≥2 m, but ≤ 0.3-0.4 m from the depth of soil freezing.

The SNiP for low-rise construction does not indicate the laying of MLM (shallow strip monolithic) foundations. But, since the average freezing depth in the Russian Federation lies in the range of 0.8-2.5 meters, in the south of Russia the MLM foundation is laid at a depth of 0.3-0.4 meters, in the north - 0.7-0.8 m ...

Slab foundation

It is considered the most reliable design, it provides an ideal distribution of all loads from the house and from the soil.

1. When equipping a slab base, the manifestation of pressure from soil heaving is leveled.
2. The probability of deformation and destruction of the concrete slab from the weight of the building is minimal.
3. It is necessary to equip a drainage system, which prolongs the life of the foundation and the house.

The slab foundation, which is mistakenly called floating and monolithic, is erected from reinforced concrete slabs with pouring joints and floors with a concrete solution.

The advantage of using slabs is the speed of construction, despite the laboriousness of earthworks. The arrangement of the pit includes several stages: the creation of a sand-crushed stone cushion, tamping and the creation of a concrete cushion between the sand-crushed stone layer with a layer of waterproofing.

The disadvantage is the need to use special equipment for digging a pit and laying reinforced concrete slabs.

Monolithic base

When arranging a monolithic base, it is advisable to prepare concrete immediately on the site or order the required volume at the factory so that the monolith can be poured in one go. With such an organization of the work process, you can immediately form steps, formwork and other designed structures of the house.

Reinforcement is not necessary for buildings 6 x 10 or smaller. It is recommended to pour the mortar in layers ≤ 15 cm thick - the upper layer is poured after the lower one has set. With layer-by-layer pouring, vibratory ramming or bayonetting of the solution is carried out in order to squeeze out all the air from the concrete.

Tape base

The concrete tape is poured after digging a trench, which runs along the perimeter of the object and under the internal walls that act as load-bearing ones. Reinforced concrete monolith provides the immobility and stability of the building at a much lower estimated cost of building materials and labor.

The main requirement for LF is to level the effect of heaving soils, which is achieved by creating a sand-crushed stone cushion. There are two types of strip foundations, depending on the depth of the laying:

1. Deeply buried - below the starting point of soil freezing without insulation;
2. The same design and the same construction methods, but with insulation from the manifestations of heaving of the soil at negative temperatures.

Deeply recessed tape (GZLF) is an excellent opportunity to make a warm basement or basement.

MZLF base

The shallow tape foundation is optimized for non-rocky and stationary soils. The absence of the main destabilizing factors (heaving and movement of the soil) makes it possible to deepen the base to a depth of ≤ 0.3-0.5 m. On the MZLF base, you can build a two-three-story house from aerated concrete blocks, even with an attic.

Sand-crushed stone pillow is required, as it plays the role of the impact of heaving soil. The depth of passage of groundwater is also taken into account - if they are too close, it is recommended to lay a pile or columnar foundation. If the house is placed on a heaving site, then it is necessary to limit ourselves to a one-story project. Also, when laying the MZLF, it should gain strength for 6-8 months with constant moisture on the surface for the first 2-5 days.

Brick foundation

The foundation with the main building material in the form of bricks is laid on the same soil as for MZLF. The requirements for the house are the same - a one- or two-story building, no more. The advantage of such a brick base is that it can be given a complex geometric shape without the use of formwork or additional concreting. The disadvantage is the need for waterproofing. To erect such a foundation, you need to use solid brick M-200 and higher with a frost resistance coefficient F 35-F 10.

Columnar structure

The foundation for the house made of pillars is designed to be fastened at the main load points and along the perimeter of the building. This is the most economical solution, but such a foundation can not be used for all projects and soils, but only for areas with a steep slope, when observing seasonal soil creep or loose soil. It is also impossible to build a basement or underground garage for a house with a columnar foundation.

In practice, two options are implemented - prefabricated columnar and monolithic foundation on pillars. When pouring pillars, it is necessary to immediately provide for a drainage system for the base itself, basement and formwork to protect against soil moisture.

Pile foundation

Piles are driven in when groundwater flows close to the surface of the site. Piles are similar to pillars in functionality, but they are made of smaller diameter, longer, and are made not only from concrete with a cavity inside - there are metal, wooden, reinforced concrete piles. Also, piles are divided into products of the screw and bored type.

The screw pile is used for construction on weak, subsidence and heaving soils, as well as if the site has a large slope.

1. The most common material for making a screw structure is steel. The lower end of the pile has blades in the form of spirals, facilitating deepening, and making it possible to attach the pile to the bearing soil layer. Screw-in depth - ≥300 mm. The pile blades act as an anchor to minimize the displacement of the foundation;
2. Bored piles are used on sandy and sandy loam soil, on clay and loam, as well as on peat soils, as they can withstand up to 10 tons per pile.

Screwed in screw or bored piles are fastened to each other with a monolithic concrete grillage. With a low cost of such a foundation, it is in demand only on complex types of soils.

Requirements for any type of foundations

Dimensions, foundation depth, basement height and other parameters are calculated for each house separately. The project includes the planning of all construction processes, including the construction of any type of foundation, on which the service life and reliability of the aerated concrete structure depend. The type of foundation is selected taking into account the sum of all loads from the house and its contents, including furniture. The less the house weighs, the cheaper it will cost to build a foundation for it.

1. When designing the base, it is allowed to reduce it in width by 25%, but the depth of the base and the quality of the reinforcing frames must ensure the leveling of the influence of ground movements on the house;
2. The maximum static load on a concrete base consists of the weight of walls, roofs and ceilings, the maximum load in a local period of time is furniture, household appliances, etc .;
3. Terrain relief. With a large slope or frequent height differences, difficulties may arise with the construction of a GZLF or a monolithic slab. For such areas, it is recommended to use piles or poles;
4. Geological and geodetic characteristics of the area - the level of occurrence of underground sources and groundwater, bearing parameters and properties of soil heaving;
5. Arrangement of waterproofing layers in the vertical and horizontal plane, insulation of the foundation. If you use hard material for insulation, then you can expand the area of ​​distribution of the load from the house to the base.
6. Economical design that does not compromise quality and durability. Saving on the quality of concrete, reinforcement or insulation is fraught with the fact that both the foundation and the house will often have to be repaired, and maybe some structural elements, especially load-bearing ones, will have to be replaced. For the construction of the foundation, M200 concrete is recommended in the classic ratio with sand and gravel - 1: 3: 3. Instead of reinforcing rods to strengthen the foundation, a chain-link and other flexible materials cannot be used, and the rods themselves can be fastened together only with soft knitting wire. It is not recommended to exclude from the structure of the house any elements or layers of insulation, hydro or noise insulation that are unnecessary, as you think, or layers.

An erroneous calculation when choosing the type of foundation or incorrect use of calculated data can cause the appearance of cracks on the walls and in the base.

Any foundation - MZLF or GZLF, slab or monolithic - should be reinforced with reinforcement. Reinforcement cage is necessary, as concrete has a low resistance to tensile loads.

Concreted internal reinforcement absorbs most of the breaking moments, which increases the strength of the entire foundation. The foundation for a house made of aerated concrete blocks is reinforced with special rods Ø 12-16 mm in the longitudinal direction, and reinforcement rods Ø 6-10 mm in cross-sections.

In the frame, the reinforcing bars are recruited by connecting with a knitting wire; welding can be used in the corners. Wire is preferred in that it creates play between the rods, allowing the framework to remain flexible and resilient for optimal resistance to dynamic loads.

The reinforced frame is immersed in concrete by 5-7 cm from all sides of the foundation. This distance is set by a lining or by attaching special plastic or wooden supports for the reinforcement. You can also use broken brick, metal corner, trim boards or timber.

The foundation for a house made of gas blocks updated: January 5, 2017 by the author: Artyom