The topic of this article is the calculation of the construction of a house of aerated concrete. We have to estimate the required thickness of the walls and calculate their total volume, which will allow us to estimate the estimated costs. In addition, we will try to find a way to calculate the estimated load on the foundation for calculating its area.
Базовые требования к утеплению стен из газобетона изложены в СНиП 23-02-2003 «Тепловая защита зданий». Нам, однако, более интересно одно из приложений к строительным нормам, где перечисляются конкретные значения сопротивления теплопередаче для разных регионов страны.
|City||Requirements for heat transfer resistance, m2 * C / W|
Note: for cities not included in the list, approximate values are determined by extrapolation of the nearest settlements from the list.
What to do with this data? Use when calculating the minimum required wall thickness. For calculations, we lack another group of reference data - thermal conductivity of aerated concrete of various grades in density.
|Brand by density||Thermal conductivity in a dry state, W / (m * s)|
Methodology and calculation example
With an increase in the wall thickness with a fixed thermal conductivity of the material, its thermal resistance increases proportionally. The minimum thickness value is calculated by simply multiplying the required resistance to heat transfer by the thermal conductivity of the material; the result we get in meters: (m2 * C / W) * (W / (m * C)) = m.
Давайте своими руками выполним расчет газобетона на дом в Krasnodarе. Наш выбор остановится на конструкционно-теплоизоляционном газобетоне D500: умеренная цена и прекрасные теплоизоляционные качества соседствуют в нем с достаточной прочностью, позволяющей обойтись без армокаркаса для двухэтажного строения.
2.44 m2 * C / W * 0.12 W / (m * C) = 0.29 m. Obviously, 30 cm thick blocks are quite enough.
It should be clarified: our calculation is greatly simplified. In reality, the heat conductivity of the walls is influenced by their humidity, the thickness of the plaster (if any) and the type of interior decoration of the gas concrete.
The calculation of materials for the construction of a house of aerated concrete includes the calculation of the volume of the walls. One of the leading manufacturers of building materials, Aeroc, suggests adhering to the following formula: (L * H - S) * 1.05 * B = V.
- L is the total length of the walls in meters;
- H - their height (for buildings of complex architecture - the average height);
- S - the total area of all openings.
- 1.05 - trimming amendment.
- B - thickness of the block.
- V - result in cubic meters.
So, for a single-storey building with a size of 10x10 meters and a height of 3 meters with a flat roof and a wall thickness of 0.3 m with one door (2 * 0.9 m) and eight windows (1.2 * 1.4 m), our calculations will look like this :
V = (10 * 4 * 3- (2 * 0.9 + 8 * 1.2 * 1.4)) * 1.05 * 0.3 = 32.9994 m3.
To clarify: we calculated only the volume of material for external walls. Partitions calculated separately by the same formula.
How to calculate the cost of a house of aerated concrete?
More or less, an exact result can be obtained only in one way - by making an estimate for all the works and materials. However, you can resort to approximation. Let's take as a model a typical calculation of the cost of building a house of aerated concrete, made by one of the Russian dealers of YTong.
According to his estimate, the cost of aerated concrete blocks for walls is 116,270 rubles; the total cost of all building materials is 590,000 r.
The cost of wall blocks, therefore, is 116270/590000 = 0.197 total cost of materials.
Now we recalculate the estimated costs based on our calculations.
- With the current cost of aerated concrete D500 at 3,600 rubles per cubic meter, the cost of exterior walls will be 3,600 * 33 = 1,18800 rubles.
- Estimated costs for the purchase of all building materials can be estimated at 118800 / 0.197 = 603045 p.
Recall: the above method gives a very significant error. The real construction budget may differ by tens of percent calculated in this way.
Mass and foundation
How to estimate the specific pressure on the foundation?
Calculate the mass per meter of the wall itself is not difficult. In our case, it is equal to the product of the height, thickness and density of the wall: 3 * 0.3 * 500 = 450 kg.
Practice shows that the mass of the structure, subject to the use of materials of approximately the same density, is approximately equal to twice the mass of the supporting walls. For reinforced concrete floors on aerated concrete walls, you can safely take the ratio of 1: 3; in this case, the pressure per meter of the foundation will be 450 * 3 = 1350 kg.
Instructions for calculating the minimum width of the foundation based on the bearing capacity of the soil. Suppose that it is 1 kgf / cm2. In this case, the minimum square meter of the foundation should be 1350/1 = 1350 cm2, which will give us a width of 13.5 centimeters.
Taking into account the fact that strip foundations are extremely rarely constructed with a width of less than 400 mm - the condition is more than feasible.
Finally - some useful information on the construction of aerated concrete.
- Reinforcement of masonry is highly desirable.. Usually in every fourth row, two lines of reinforcement are laid in the grooves.
- Technological openings and holes better to do with a diamond tool. Diamond drilling of holes in concrete leaves the edges perfectly flat, without chipping.
In addition: for reinforced ceilings, cutting of reinforced concrete with diamond circles is also convenient in that it allows you to pass reinforcement without a tool change.
- Mauerlat and truss system are mounted only on the armopoyas.
- In earthquake-prone areas, armo carcass is required.
We hope that the above (albeit very rough) calculation methods will help the reader to prepare for construction. As usual, additional information can be found in the video in this article. Successes!