As you know, there are such large categories of foundations: strip, slab, columnar and pile. But which foundation is better for aerated concrete? Let's find out.
Criteria for choosing a foundation for a building made of aerated blocks
The choice of foundation is determined by the following factors:
- Geological position of the construction site: soil saturation with water, groundwater level, foundation strength.
- The mass of the planned building.
- Your financial potential.
Most suitable soils: medium coarse. They have excellent strength and are resistant to heaving during frosts.
Good strength in loams and hard clays. But they are less resistant to heaving. Here, during construction, it is necessary to take timely measures to prevent frost heaving.
Construction activities should take place on those foundations that are buried below the soil freezing mark. The average value here: 1-2 m.
What kind of foundation is needed for an aerated concrete house? If according to the norm, then he should exceed the groundwater level by at least half a meter. And depending on the position of moisture, you can use a structure that is at least 1.5 m deep. Another option is a shallow structure (70-100 cm). Also, when deciding on the depth of the foundation, it is important to take into account the need for a basement.
Structural specifics of the building and pressure on the foundation
The following table is provided here. It reflects the types of soils and suitable foundations for them.
| Types of soils | House made of gas blocks. One-story. | House made of gas blocks. Double decker. |
| Soils with large debris. Sands of medium and large parameters. | Columnar or shallowly buried ribbon. | Columnar or ribbon with a T-shaped section. |
| Clays, loams and sandy loams (most often they are water-saturated) |
Pile with screw supports. | Tape or slab. The tape is located below ground freezing or is powerfully insulated. Monolithic tape is allowed. |
| Areas with a high groundwater position (swampy area) | Monolithic tape or FBS tape. The distance between the sole of the base and the water position is 50 cm. If the moisture rises very high, a slab base or screw piles are used. |
Slab |
So, what kind of foundation is suitable for building from aerated blocks? This is a tape and slab option.
Strip foundation. Shallow depth (MLF)
Its advantages:
- Reducing the volume of earthworks.
- High dynamics of construction.
- Additional measures are not necessary if the groundwater position is at least 1 meter from the ground surface.
- Laying on conditionally non-heaving and non-heaving soils.
According to the manufacturing method, it can be monolithic or prefabricated. For a house made of aerated concrete, the first one is better suited. It is stronger and more reliable.
By type of cross-section, MLFs are rectangular and T-shaped. The former have weak load-bearing qualities. Therefore, preference is often given to the latter. And the MLF in this situation is formed by a tape, a pillow with a horizontal arrangement and a vertical component.
Layer level
Before installing an MLF, it is important to study how deep the soil freezes in your area. It is also useful to rely on the data in the table below:
It is equally important to base your work on the position of groundwater. If they are closer than two meters to the intended base, it is better to make a buried foundation and arrange drainage technology.
Methods of protection
They are essential to extend the life of the MLF. They are:
- The tape is insulated along the entire laying height. Material – extruded polystyrene foam.
- A warm blind area is made. Material: concrete. The same insulation is laid under it. Thickness: 10-15 cm.
- Vertical waterproofing is done. She lies under the insulation. Material – bitumen roll or mastic.
- Water is drained from the foundation. Stormwater and drainage are installed.
- A sand layer of 30-50 cm is made. The type of sand is coarse or medium.
Stages of creating MLF
They are in many ways similar to the stages of creating a buried tape. They are:
- The zone is marked. A trench of the required parameters is made.
- A sand layer is installed (see point 4 above). It is carefully compacted.
- Foam formwork is installed.
- The structure is reinforced.
- The concrete composition is poured. The work takes place in one session. Required concrete: B15-B25.
- The concrete is compacted with a vibrator.
- The concrete hardens. It is followed by care.
- if necessary, the formwork is removed.
- The foundation is being waterproofed.
- The foundation is insulated.
- Backfilling follows.
- A blind area is created.
Disadvantages of tape base
- Impressive spending.
- A lot of building materials are needed.
- The need for waterproofing of each block.
Slab foundation (PF)
For aerated concrete construction, PF is a more reliable and durable option, especially if it is monolithic. It is suitable for erecting one- and two-story buildings. True, its cost is extremely high - almost a third of the price of the entire building. This is the case when specialists are involved. If you create the slab yourself, you can save money and create a high-quality foundation (if you follow the right rules).
Advantages of PF:
- Suitable for buildings of different heights (1-2 floors).
- Suitable for houses with a basement.
- There is no need to lay joists on the floor.
- The result is a powerful base that is resistant to seismic factors.
- Minimal risk of washing away with water.
- Device for areas with difficult soil.
Usually the slabs are created flat or ribbed. The second option is the most difficult for independent work. But its functionality is better, and it copes better with the loads from the building. This is the best option for a two-story house made of aerated concrete.
For it, you first need to create special ribs, and then the slab itself. Sand is used to fill the voids between the ribs.
And when your working area has very difficult soil, and you want to build a medium or small house, then it is better for you to arrange a flat PF.
Stages of creating a PF:
- The soil is being prepared. The work area is leveled. Adds soil. It is thoroughly compacted with a vibrating tool.
- Suitable base parameters (thickness, length and width) are calculated. The soil is removed to a depth of about 30 cm. This creates a “container” for future filling.
- The bottom of the “tank” is covered with geotextile. Drainage is done.
- The “container” is filled with a mixture of sand and crushed stone. The surface is watered and thoroughly compacted. Thick polyethylene is placed on it. And then - extruded polystyrene foam.
- The formwork is being assembled. Material – polystyrene foam. Wall thickness – up to 25 cm.
- . The fewer reinforcement connections there are, the stronger the binding will be.
- The end ends of the monolithic slab are reinforced.
- The slab itself is reinforced. Additional reinforcement is placed on columns, walls and supporting elements.
- The slab should be filled. Required concrete: M350 - M450. Water resistance rating – minimum W6. The concrete is supplied from the mixer. The far side of the PF is concreted first, then the near edges. Helpers are needed for the work. Someone pours the mixture, someone compacts it with a vibrator.
- The concrete is setting. After a day it is thoroughly watered. If work is carried out in the heat, the concrete is covered with thick polyethylene.
- Concrete needs 10 days to completely harden (if the air outside is +20 C) or 20 days (condition of street temperature +10 C)
About the monolithic foundation on video
Material from ProfiBlock:
Pile foundation (SF)
If the area for a building made of aerated concrete is a swampy area, an area near the coast, a slope, or a peat bog, then the best option (and the only one) is a pile foundation (PF).
Advantages of SF:
- Excavation work is required only for the hanging grillage.
- Powerful performance – maximum 14 days.
- No special equipment needed.
- A pick-up is needed only for high grillages.
- Full geological analyzes are not required. Test penetration of the pile will determine the depth. Next, select piles of suitable length.
Pile grillages are the optimal solution for a one-story attic building.
Disadvantages of the SF: it is necessary to thoroughly connect all the working elements; the slightest miscalculation can lead to the collapse of the SF.
Columnar foundation (StF)
It should be used when the groundwater position is 2 m from the columnar base. Suitable areas: those where there is rocky, sandy or gravelly soil. For an aerated concrete structure, such a foundation is of little use due to its serious disadvantages.
Cons of StF:
- Weak spatial rigidity.
- Tendency to fall due to lateral movements of the soil.
- The need for a large volume of operations to reduce heaving impulses.
- Completely unsuitable for a two-story house.
Material calculations
They follow the example of creating a monolithic LF. Basic calculations: parameters of blocks and the house itself.
Sample Project
- The planned living area of the house is 65 sq.m.
- Roof parameters – 124 sq.m.
- House parameters: 9 x 8 x 6.3 m.
- There is a load-bearing partition, it divides the house into two parts
- There are internal partitions. These parts are divided into rooms.
- Clay soil. Freezing – 90 cm.
- The water depth is 2 m.
Based on these data, the foundation is set with the following parameters:
- approximately 45 m in length,
- 75 cm high,
- 30 cm is the minimum width according to calculations.
Calculation of materials for the sole comes down to determining the area of the foundation: 0.3 m x 45 m = 13.5 sq.m.
Laying depth: 3/4 from the ground freezing mark, but at least 70 cm.
Concrete consumption
The required concrete is M150. The parameter used here is 13.5 cubic meters. This is the result of multiplying 0.3 * (0.25 + 0.75) x 45 = 13.5 m 3.
Specific gravity of reinforced concrete – 2500 kg/cub.m. Total mass of LF and base:
2500 kg/m 3 x 13.5 m 3 = 33,750 kg.
Blocks for external walls have parameters 60 x 30 x 20 cm, 500 kg/cub.m (density). Each block weighs 20 kg.
To create walls 30 cm wide you need 660 blocks. Calculation: 36 m (perimeter of the building) and 6.3 m (its height). Block length – 60 cm, height – 20 cm. To fill the entire perimeter, 1890 blocks are needed. Calculation: (36 m: 0.6 m) x (6.3 m: 0.2 m) = 60 * 31.5 = 1890.
Taking into account different openings, this value is reduced by almost three times.
Weight of all blocks: 20 x 660 = 13200 kg.
Blocks for internal walls have parameters 60 x 20 x 12 cm. Density 300 kg/cub.m. Each block weighs 4.35 kg. 560 of them are needed. Weight of all partitions: 4.35 x 560 = 2436 kg. For convenience, this value is rounded to 2400 kg.
Metal for creating external doors, provided that the standard door dimensions are 2 x 0.8 x 1.6. Weight – 250 kg.
Lumber for work is selected from coniferous wood. Their total volume is 23 cubic meters. After all, the specific gravity of such a rock is 500 kg/cub.m. Calculation: 500 x 23= 11500 kg.
Concrete slabs for the basement floor. Type - with voids. Their thickness is 0.22 m. Specific gravity is 1.36 t/cub.m. Area calculation: 9 x 8 = 72 sq.m.
Volume: 72 x 0.22 = 15.84 cubic meters.
Total mass: 15.84 x 1.36 = 21542 kg.
Facing brick. Calculation of finishing area: (9+9+8+8) x 0.25 = 8.5 m2.
There are 51 bricks per 1 m. Each brick weighs 2 kg. The formula works: 8.5 m 2 x 51 pcs/m 2 x 2 kg = 867 kg.
Calculation of composition (if 1 sq.m. of masonry requires 0.02 cubic meters of composition): 8.5 x 0.02 m 3 = 0.17 m 3.
Composition mass: 0.17 m 3 * 1.1 t/m 3 = 187 kg.
Total finishing weight: 187 + 867 = 1054 kg.
The entire mass of the building with loads
All calculations are summarized here. And without aerated concrete flooring it turns out:
33.75 + 13.2 + 2.4 + 0.25 + 11.5 + 21.542 + 1.054 + 0.61 + + 0.25 + 0.504 + 0.096 + 0.65 + 0.25 = 86.056 tons.
Taking into account overlap:
86,056 + 12,116 = 98,172 tons.
Snow load taking into account a flat roof: 124 m2 * 160 kg/m3 = 19,840 kg.
Here 160 is the average snow load.
Calculation of the payload resulting from furniture and residents: 6439×180=11682 kg, rounded - 11700 kg.
Cumulative load value from the entire structure: 88.4 + 18.6 + 11.7 = 118.7 tons.
Calculation of specific pressure (SP) under the foundation sole: P = 118.7/13.47 = 8.81 t/sq.m (the entire mass of the house is divided by the area for this sole).
You need to look at the reference materials. According to them, UD for clay soil = 10 t/sq.m. The parameter is greater than the obtained value (8.81). This means that all calculations are correct. And the LF for an aerated concrete house is designed correctly.
Calculations on a slab foundation
Under the same conditions as when working on a monolithic LF, it is necessary to calculate the area of the slab and its thickness. The calculation method is similar to the operations for calculating the LF. In this case, the height of the house is 6.3 m, then stiffening ribs are needed.
The parameters of the reinforcing elements are also important.
So a reinforcement rod is suitable with a cross-section of at least 2 cm. Its level is second. The interval between the rods is 9 cm. The reinforcement extends 5 cm from the cut of the slab. Calculation: 2 x 2 + 9 +5 x 2 = 23 cm. This is the thickness of the slab for the house in this case.
Calculation of foundation strength
Concrete grade – M350. Calculation:
118.7 tons: 36 (perimeter) x 0.3 (wall thickness) = 10.9. Rounded 11 mPa
The parameter of this brand of concrete is 25 mPa
Calculation of bearing capacity: the mass of the slab is divided by its entire area. The result obtained is compared with tabular data for a specific soil on your site. If the figure is lower, then the calculations are correct.
Which foundation is cheaper anyway? The most profitable design is the one with the least concrete consumption. And if, according to calculations (which is unlikely), there will be a slab, then there is no question - we are preparing the base for a slab structure.
Review of all types of foundations on video
Webinar from Gleb Green.
When deciding which foundation is best for a house made of aerated concrete, several factors must be taken into account. First of all, the design features are influenced by the properties of the wall material. 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, you need to consider the following features.
Aerated blocks are piece material. Even with the right choice of masonry mortar and compliance with the technology for performing the work, they are poorly connected with each other. This factor results in 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 subsides or, conversely, rises from the ground, cracks may appear on the walls of the building. In most cases the cracks will be inclined. The opening width and length depend on the scale of displacement of the supporting part of the building. To prevent damage, it is necessary to provide reliable supports that will resist various types of displacement. The design must connect the wall from individual blocks into a single system.
The task of the foundation is to prevent such phenomena
The foundation for aerated concrete needs a less powerful foundation than for a brick house. This is caused by the lower density of the material, and, accordingly, the mass. For comparison, the density of aerated blocks ranges 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 weighs from 500 to 700 kg per cubic meter.
Despite the advantages of blocks compared to brick, it is worth remembering that the material is inferior to wood. The building will also be heavier than a frame house. When selecting foundations for houses made of lightweight aerated concrete, it is necessary to take this feature into account.
What types of foundations are used?
All foundations, depending on operating conditions, can be divided into four large groups:
- columnar;
- pile;
- tape;
- slab.
Variants of bases used The first and second in private construction (taking into account the most popular sections) have a relatively low load-bearing capacity. Such elements only work under 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 absorbs mainly compressive loads. When installed on soft soils, slight bending effects may also occur. If a monolithic foundation is made in accordance with the technology, they do not cause problems.
The use of a slab foundation is different in that this structure works on bending and pushing. Concrete does not resist such influences well. To prevent damage, a mixture of sufficiently high grades is chosen for filling, 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 a foundation type
Before choosing which type of support is best for a house made of aerated concrete, you need to 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 floors);
- economic opportunities.
Influence of soil characteristics
Moisture in the soil and soil type affect the elevation of the supporting part. Soils on the site can be one of the following types:
- coarse clastic;
- 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 foundations (the only exception may be pile foundations). The best option would be to replace the material with sand of medium or coarse fraction.
The best soils for construction will be coarse and sandy (medium and coarse). Such foundations have high strength and are not prone to frost heaving (one of the main enemies of foundations for houses made of aerated concrete).
Refractory clays and loams also have good strength characteristics. But all clayey 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 made of aerated blocks. When building on such foundations, it is necessary 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 point 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 base) 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 1.5 m or more) or (the depth in this case is taken to be approximately 70-100 cm). Also, when choosing the depth of 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 supporting part are determined by calculation.
| Soils at the construction site | For a one-story block house | For a two-story block house |
| Coarse soils, medium and coarse sands | To save money in this case, columnar bases or strip bases with a shallow depth are used | Pillars are used for such buildings. In this case, the strip foundation for a house made of aerated concrete should have a T-shaped section (increased thickness at the bottom). It is better not to use a rectangular type of section due to low load-bearing capacity |
| Clays, loams and sandy loams (most often they are water-saturated) | You can use a pile foundation made of screw supports. They are perfect even in moisture-saturated soil. A reliable monolithic grillage is made along the pile heads, which will connect the individual supports into one system. A slab foundation would also be an excellent option (due to the low load, the thickness of the foundation used is relatively small, approximately 200mm) | The foundation for a house made of aerated concrete in this case is assigned to the strip or slab type. In this case, the tape must be laid below freezing or have reliable insulation. To protect the building from moisture, a drainage system, waterproofing and perimeter blind area are designed. The tape can be made of monolith or FBS blocks. The monolithic option is preferable, since the FBS are weakly connected to each other. You will still have to make a reinforced concrete belt along their edges. The thickness of the foundation is determined depending on the thickness of the walls. If a basement is not planned, a shallow slab is used. This approach will reduce construction costs |
| Areas with high groundwater levels (swampy areas) | As a supporting part, you can use a tape made of monolith or FBS. In this case, it is necessary to maintain a distance of -50 cm between the base of the foundation and the water level. If the moisture rises very high, a slab or screw piles are used as a foundation | Screw piles have a fairly low load-bearing capacity. When building a two-story house in a swamp, it is recommended to use a slab foundation as a foundation. |
The answer to the question of which foundation is best to use depends on many factors. None of them should be missed.
A house made of aerated concrete is a relatively light structure, since its density, on average, is only 500 kg/m3. This lightness provides advantages when constructing foundations. The load transferred to the ground from the weight of the building will be less, which means that the support area of some types of foundations can also be reduced, resulting in significant savings.
Aerated concrete houses can be built on any type of foundation, it all depends on the geology and architectural design.
Types of foundations
- Shallow tape.
- Recessed tape.
- Pile foundation.
- Slab foundation.
- Insulated Swedish stove.
Depending on the soil conditions and architectural design of the house, different types of foundations will be appropriate. A foundation suitable for one soil may be completely unsuitable for another. In this review we will try to explain how to choose a foundation for an aerated concrete house.
The choice of foundation is influenced by the following:
- House weight.
- Soil type.
- Soil homogeneity.
- Freezing depth.
- Ground water level.
Soils have several basic parameters that influence the choice of foundation type, namely: bearing capacity, heaving, freezing depth, uniformity and water saturation.
Soil bearing capacity– a value that shows how much load can be transferred to the ground. For example, loam can withstand 3.5 kg/cm2, and coarse sand 6 kg/cm2. That is, coarse sand can transfer twice the load, which reduces the requirement for the foundation support area.
Coarse sand and crushed stone are non-heaving materials and have a high load-bearing capacity. Therefore, they are used as a cushion for the foundation, replacing other soils with them.
Soil heaving– ability to expand when wet and at low temperatures. The wetter the soil, the more it expands, and the worse it is for the foundation, since frost heaving forces can lift and deform the foundation.
For example, in frost, silty loam can expand up to 10%, while sand expands by only 1%. Thus, if the freezing depth is a meter, then the loam will swell up to 10 cm, and the sand will swell by only 1 cm.
It is also necessary to take into account the location of groundwater and the depth of freezing.
Since aerated concrete has low bending strength, any deformations from the foundation can form cracks in the walls. Therefore, the base should be as motionless and rigid as possible.
To ensure the immobility of the foundation, it is necessary to make one or more conditions, depending on the type of foundation, namely:
- Laying foundations below the freezing depth.
- Creating a non-heaving cushion from sand and crushed stone.
- Arrangement of a drainage system around the perimeter of the building.
- Reducing freezing due to insulation of the foundation and blind area.
The difference in foundation settlement should be no more than 2 mm per meter. Such deformation will not create cracks in unreinforced aerated concrete masonry.
This type of foundation is the most common and inexpensive for a house made of aerated concrete. MZLF is used on normal, slightly heaving soils. The point of such a foundation is that it is laid above the freezing depth of the soil, which significantly saves money on concrete. An insulated blind area and an insulated base protect from the forces of frost heaving, which do not allow frost to pass under the foundation and reduce the depth of frost heaving.
Advantages and disadvantages of MZLF:
- Simplicity and low cost.
- Sufficient strength for a two-story house.
- Good foundation support area.
- One person can cope with its construction.
- Cannot be used on heaving and frozen soils.
Under a shallow belt, a sand cushion 20-50 cm thick and a layer of crushed stone 10-20 cm are placed.
The underground part of the foundation can be from 30 to 50 cm, and the base - from 30 to 60 cm. The height of the base can be, in principle, any, but not less than 30 cm. The greater the height of the tape, the stiffer the foundation.
- For long walls, you need to use a higher foundation strip.
- For MZLF, floors are made on the ground with preliminary filling of the base with sand and tamping.
- The blind area is made about a meter wide, always insulated with polystyrene foam 5-10 cm thick.
- You also need to observe the slope of the blind area to drain water from the foundation.
- The foundation base also needs to be insulated so that frost cannot pass along the foundation strip. See the diagram.
A buried strip is a foundation installed below the soil freezing depth, which can range from 100 to 250 cm.
This type of foundation is very expensive in terms of concrete consumption. This choice is justified only if a basement floor is required.
Let's calculate how much concrete is required for the foundation strip of a 10x10 meter house with a thickness of 40 cm and a strip height of 200 cm.
The length of the entire tape, taking into account the perimeter and the central beam, will be 50 meters.
The area of the foundation support is 50x0.4 = 20 m2.
The volume of concrete is 50x2x0.4 = 40 cubic meters of concrete.
The weight of such a buried foundation will be 100 tons + the floor of the basement will also need to be poured with concrete.
Foundation ground pressure – 100/20 = 5 tons per m2 or 0.5 kg per cm2.
In case of weak soils, to increase the support area, a heel is made on strip and pile foundations. The heel is a widening that distributes the load from the foundation over a larger area.
This type of foundation is an infrequent solution for aerated concrete houses, but there are cases when it is simply irreplaceable.
Advantages and disadvantages:
- Possibility of construction on steep slopes;
- On loose heaving soils with a high groundwater level;
- On soil with a large freezing depth above 1.5 m;
- Low load-bearing capacity due to the small support area.
- The tangential forces of frost heave can lift the piles.
It is worth noting the “Tise” piles, which have a widening at the bottom, which creates additional anchoring in the ground and greater support, compared to other types of piles.
The following types of piles exist:
- Screw-type (screwed in like screws).
- Pressed (pipes are filled with concrete).
- Driven (ready-made pillars are inserted into dug holes).
- Drilling (concrete pillars are driven in with special equipment).
Slab (monolithic) foundation for aerated concrete
This type of foundation is often used on soft soils and in places with high groundwater levels.
Slab foundations come with or without stiffeners. The ribs increase the rigidity of the slab, which reduces possible deformations during soil movements.
The slab has a large support area, which evenly distributes the load on the ground.
Depending on the soil and weight of the house, the thickness of the monolithic slab can be from 25 to 50 cm.
Under the slab there must be a compacted sand cushion 30 cm thick. In some cases, a layer of crushed stone is also laid on the sand, which prevents capillary suction of moisture from the sand into the foundation.
Advantages and disadvantages:
- High load-bearing capacity.
- High resistance to deformation.
- Finished subfloor.
- Inability to build a basement.
- High costs for excavation and drainage work.
- Low floor level relative to the ground.
- Difficulty in construction on uneven areas (slopes).
USHP is a monolithic foundation well insulated on all sides, in which water supply, sewerage, electrical and warm water floors are laid before concrete is poured.
USHP has good load-bearing capacity and can be used on weak, water-saturated and heaving soils.
USP solves several problems at once:
- Foundation.
- Basement insulation.
- Foundation waterproofing.
- Rough floor.
- Heating system.
Advantages and disadvantages:
- Good load-bearing capacity.
- Applicability on any soil.
- The slab is initially insulated with expanded polystyrene.
- There is no need to make a screed for heated floors.
- No cold bridges.
- The stove is a good heat accumulator.
- It is being built quickly.
- Big savings on heating.
- Excellent foundation waterproofing.
- Quite a profitable solution in the future.
When choosing a foundation for a building made of aerated concrete blocks, it is necessary to take into account all the technical characteristics of this material. Aerated concrete is a popular budget material, often used in the construction of residential buildings, cottages and outbuildings. It has a number of advantages, which is why it is in great demand. But houses made of aerated concrete are heavier than buildings made of logs or timber, so here it is worth thinking about a solid foundation.
Peculiarities
Aerated concrete is autoclaved cellular concrete. Over the history of its existence, it has found application in almost all areas of construction of structural elements of buildings and structures of any type. The characteristic features of this material make it very competitive in the building materials market.
The main advantages of constructing foundations from this material:
- independence from temperature changes;
- a light weight;
- quick installation and ease of installation work;
- environmental friendliness;
- moderate cost;
- excellent heat and sound insulation;
- high resistance to frost, and due to porosity, water will not quickly penetrate the material;
- versatility: aerated concrete can be sawed and drilled, thanks to which aerated concrete blocks can be given different shapes;
- at the factories where aerated blocks are made, there is a laboratory that controls the quality of the material;
- aerated concrete is a stone material, but is considered a fairly light material. Almost any type of foundation that meets the requirements for rigidity and deformation is suitable for it.
Projects
In terms of strength and design solutions, aerated concrete blocks are in no way inferior to conventional brick. They rarely become moldy or damp, and they breathe well.
Before building a foundation, you need to decide on the type of foundation, and also carefully design the future foundation of your house.
Slab
The slab type is one of the options for a shallow or shallow foundation. This is a reinforced concrete slab, under which a layer of sand and crushed stone is compacted. The slab option for a house made of aerated concrete has the highest possible load-bearing capacity, which is achieved thanks to the large supporting area of the slab, which occupies the entire area of the building.
In most cases, the thickness of the slab is from 20 to 40 cm. Monolithic slab-type foundations have greater spatial rigidity than a foundation assembled from individual slabs.
The main advantages of a slab foundation:
- ease of installation;
- low cost;
- high load-bearing capacity;
- the general platform is not subject to local deformation;
- the possibility of using the foundation as a floor for the basement;
- the height of the house can be higher than 2 floors with a load of 20-25 t/m2;
- ease of construction in difficult soils.
Cons: slab foundations are built only in houses where there is no provision for a basement.
Pile-grillage
Pile foundations have recently become increasingly widespread due to their reliability, versatility and ease of DIY installation. Very often, aerated concrete buildings are erected on screw piles connected to each other by a grillage in areas with close groundwater. Installation with a monolithic grillage will protect the block masonry from cracking that occurs during shrinkage.
Most often, when choosing piles for aerated concrete structures, preference is given to cast-in-place or screw supports. Such piles are easy to install even when erected independently.
Tape
The strip version is a reinforced concrete strip running along the entire perimeter of the building, as well as under the load-bearing walls. It is developed by digging a pit. This type of foundation is optimal for building an aerated concrete house.
The shallow option is ideal for constructing a building from aerated concrete blocks on ideal soil that is not prone to heaving and shifting. Sufficient depth is 500 mm. Otherwise, a deep strip foundation is built. The base of the base will thus be below the freezing level.
The recessed option is also good because it allows you to arrange a basement or ground floor or add decorative elements, for example, beautiful concrete steps.
Brick
A brick foundation would also be a good option for an aerated concrete house, but only if the soil is not prone to heaving, and also when building a one-story building.
For the device, only solid brick of grades not lower than M200 with frost resistance index F35-10 is used.
Columnar
Such a foundation can only be built on stable soils with smooth terrain. The structure consists of a reinforced concrete grillage, with brick, stone or concrete pillars installed at each corner and under the load-bearing walls. They can be round or square.
This option differs from competitors in its low cost, ease of installation work and calculations.
One of the types of columnar foundations for the construction of houses from aerated concrete blocks is the foundation using TISE technology - this is an individual construction technology and ecology. TISE differs from standard columnar foundations by the presence of a heel, which increases the area of support of the column, while reducing the amount of pressure per square centimeter of soil, thereby almost doubling the load-bearing capacity of the pile.
TISE is a type of foundation that does not require special equipment during construction; for installation you only need a TISE drill and portable formwork. One of the main requirements of TISE technology when constructing a structure is the lightness of the material. Therefore, the option of using aerated concrete is ideal here. Only if the rules are followed, a house built according to TISE will serve its owners for many years. Firstly, when developing a project, keep in mind that aerated concrete blocks do not like movement; it is also advisable to strengthen the concrete grillage, which will connect the piles with a single monolithic slab. Secondly, before building walls, make sure that the foundation is stable and ready for further construction. It is recommended to make the foundation before the fall, and in the spring, after checking the geometry, begin building the house.
Remember that TISE is only suitable for light buildings, and despite the fact that aerated concrete is lightweight, a large 10x10 house will already weigh about 2000 tons, so carefully weigh the pros and cons before future construction of the foundation. This foundation option is perfect for a 1-story house.
How to choose?
When choosing which foundation to lay for an aerated concrete house, consider not only the economic benefits, since the final durability of the foundation, as well as the entire building, depends on many factors.
You should choose a foundation for a house made of aerated concrete blocks based primarily on the type of soil, the depth of freezing of groundwater, natural conditions, and the surface topography of the site.
For example, a reinforced concrete slab is the best option, since it minimizes shrinkage deformations. When the soil moves, the slab moves with it, ensuring the safety of the house. Slab foundations can withstand even the most aggressive climatic conditions.
The shallow-depth strip version is suitable for houses standing on slightly or medium-heaving soils. And the foundation, buried to the depth of freezing, can be installed on heaving soils.
The columnar type of foundation is built only on stable soils with a flat surface.
In turn, the pile foundation is suitable for any type of soil, even clay.
Experts also advise taking into account the number of floors of a building, since depending on the number of floors, the total mass of the structure and, accordingly, the load on the foundation increases. If you have chosen a one-story house, then feel free to choose any foundation option from the above. But it is recommended to build a two-story building only on a monolithic slab or strip base. In this case, the depth and width of the tape in the latter version should be greater than when constructing a one-story building.
Before calculating the characteristics of the foundation for an aerated concrete house, you need to remember that this is a complex process that requires special care and attention. If you don’t want to turn to professionals, then each construction site owner can make all the calculations independently.
Before calculations you need to know:
- density and thickness of gas blocks;
- approximate weight of building materials and roof;
- number of storeys of the building;
- soil type;
- approximate snow load.
The design process includes not only drawing up drawings, but also developing basic communication details, designing a basement or garage in the basement, drawing up a wiring diagram, etc. After all, all these factors directly influence the choice of the type of foundation for a future building.
Before designing the foundation, decide on your budget. Of course, you cannot save on construction, but it is important to consider the feasibility of building an expensive foundation. The decision should be made only after examining the soil.
Construction
Building a foundation with your own hands is possible, but requires strict adherence to construction technology. Each type of foundation has its own step-by-step installation system.
Slab
As mentioned above, a slab foundation is perfect for aerated concrete houses. A foundation slab can last up to 100 years with the right approach to construction. The basis of reliability is proper reinforcement with reinforcing bars with a diameter of at least 12 mm. You should not skimp on materials, since it is the metal frame that works in tension and will not allow the slab to crack in the future.
A reinforced concrete slab is installed under the entire surface of the house. The parameters of the slab should be based on the design of the future aerated concrete building. For example, for garages or bathhouses the minimum thickness is 100 mm, and for a residential building - at least 200-250 mm. During construction, be sure to pay attention to the waterproofing of the slab: in the lower part, the base is waterproofed with rolled materials, and in the upper part - with coating or spraying.
To reduce heat loss, it is necessary to insulate the foundation.
Tape
The main material of a strip foundation is concrete, made from sand, cement and water. For better strength, it is necessary to strengthen the structure of the concrete base with iron reinforcement. Before construction, you need to clear the area of the proposed construction site and make the necessary markings of all load-bearing walls. Next, the differences in the surface are studied and the lowest point is selected, thus eliminating the difference in the height of the foundation. You can dig a trench, the bottom of which must be perfectly flat, with your own hands or using special machines. Next, a special cushion of sand and crushed stone is placed on the bottom.
Before pouring, the formwork should be installed, after which the reinforcement cage is laid along the entire perimeter of the foundation by driving in reinforcing bars.
For pouring, it is recommended to use factory-made concrete, which is poured into the bottom of the trench in layers of 20 cm. Each layer must be compacted to avoid the formation of voids. The surface must be leveled after completion of work.
The strip foundation must dry thoroughly before the construction of walls begins. This may take about one month.
Piles and pillars
The pile and column options are considered the most economical due to the low consumption of materials, as well as the high speed of construction.
From above, both types are connected by an iron horizontal grillage, on which the building is then built.
Gas block is a lightweight material that does not require squeezing out the adhesive solution. Compared to brick walls, aerated concrete blocks can be laid without pause. According to building codes, blocks with a thickness of 350-450 mm are used for laying external walls, and about 200 mm for internal walls.
Before laying the first row of blocks, it is necessary to carry out waterproofing work for the foundation. As a material for waterproofing, you can choose roofing felt or polymer - cement mortar based on dry mixtures. It is necessary to carefully level the base with a cement-sand mixture.
For country and cottage houses, as well as light buildings such as bathhouses, sheds or garages in summer cottages, block foundations are often used. Their advantage over monolithic ones is the ease of construction speed, as well as rationality in some architectural conditions. The block base allows you to equip basements, inspection pits and technical undergrounds in these buildings. How to make a block foundation correctly? And is it possible to use cellular aerated concrete in such work? Let's find out together.
The present time can be confidently called the century of artificial materials. It seems there has never been such a rich variety of component combinations in construction. In the field of concrete technologies, new artificial stone materials are still being developed, with properties superior to natural ones. One of them is aerated concrete, which was widely introduced into construction back in the 30s of the last century.
Aerated concrete is a fairly porous material, which includes: quartz sand, cement, gypsum and gas-forming agents. As a result of the chemical reaction, hydrogen is released, which forms small pores with a diameter of 1-3 mm. In construction, aerated concrete is used in the form of wall and partition blocks in a wide range of sizes. 
In the production of aerated concrete, it is customary to distinguish between two types of this technology:
- Autoclaved aerated concrete– this method is the treatment of the finished frozen mass of aerated concrete with water vapor under pressure above atmospheric. This is achieved by placing the material in a closed, sealed chamber - an autoclave. Next, the aerated concrete mass is dried in drying chambers with electric heating;
- Non-autoclaved aerated concrete– the manufacturing technology is similar to the previous one, with the difference that the composite mass of aerated concrete is kept in natural conditions or in autoclave chambers with steaming at normal atmospheric pressure until completely dry. The density of such aerated concrete is less than that of autoclaved concrete, but the price is also more affordable.
The following characteristics of aerated concrete are noteworthy:
- Density– the ratio of the mass of a material to its volume, expressed in kg/cm3. With an average density of aerated concrete of 600-700 kg/cm3. for structural and thermal insulation blocks, this indicator less almost three times that of ceramic bricks;
- Frost resistance– the ability of the material to withstand seasonal freeze-thaw cycles. With sufficiently high moisture absorption, this material can last quite a long time with good waterproofing;
- Thermal conductivity– for aerated concrete this indicator is extremely low, which allows it to be used as a heat-insulating material, for example, for the construction of basement walls.
Below is a table of comparative characteristics of building materials similar to aerated concrete.
In aerated concrete blocks, correctness of shape and clarity of dimensions prevail, making architectural elements and structures convenient and not difficult to calculate. It is very convenient to install using any fastening hardware - nails, screws, anchors or dowels. It is easy to cut to size with a regular hacksaw, and only a small amount of solution is needed for setting. There are three main types of aerated concrete blocks: structural, structural-thermal insulating and thermal insulating. The first two types are suitable for constructing foundations. 
Making a foundation from aerated concrete blocks step by step
In this section we will consider the option of a columnar foundation using aerated concrete blocks. The foundation structure consists of a number of pillars, shallow or not buried in the ground, and connected to each other by a beam floor.
It is noteworthy that for this type of foundation there is no need to dig a pit or level the terrain of the site, which means the volume of excavation work is relatively small. You can place a bathhouse, a workshop, a barn or even a small country house on them.
The foundation work cycle consists of the following stages:
- Arrangement of pillars– this technology uses several methods for constructing pillars. If only aerated concrete blocks are used in the work, then a cushion is placed for them at the bottom of the well. The blocks themselves are placed on a solution of special glue or finely dispersed cement-sand mixture with minimal seams (3-6mm). The part of the pillars buried in the ground is waterproofed with coating or bituminous materials such as roofing felt. The second method is to place aerated concrete blocks like formwork so that the middle of the column remains hollow for reinforcement and pouring mortar. The use of reinforced concrete will significantly increase the stability and durability of the pillars, and aerated concrete will protect against freezing and moisture penetration. From the outside, the pillars can extend in height to an arbitrary distance. If no additional premises are expected, it is usually 30-70 cm;
When arranging a grid of pillars, you need to pay attention to aligning them to the same height. This can be done using a hydraulic level or a laser level.
This video tells in detail about the construction of the prefabricated lower frame of the floor joist, knocked down from 50x150mm boards, their treatment with a fire-bioprotective solution, and the assembly of the entire structure and its fastening to the pillars.
A foundation made of aerated concrete blocks is a good solution for small frame or wooden houses. The technology for their use is simple and usually does not require the use of special equipment or skilled labor. And taking into account the properties of this material, and compliance with all requirements for its use, your foundation will serve as a reliable and durable basis for your country house or bathhouse.
