The foundation is the foundation of any structure. When planning construction, special attention should be paid to this part of the house. Destruction of an incorrectly made foundation entails a violation of all structures, therefore, savings in this matter are inappropriate. The cost of the foundation for the house takes from 30% to 50% of the cost of the construction of the building box. For reliability, architects usually lay some margin of safety in the planned foundation. You can calculate the cost of the foundation for a house only after you have a construction plan, because the price of work directly depends on the type of foundation and its technical characteristics. Also, a specialist can make recommendations on the appropriateness of using one or another technology of erecting the foundation of a structure in each specific case.
What determines the cost of the foundation for a house
The foundation takes on the weight of the building and evenly distributes it to the surface of the earth. Therefore, the worse the soil in its bearing capacity and the heavier the building, the more thoroughly the foundation should be. Accordingly, its value will increase. For light houses, it is advisable to erect pile or column foundations, and for heavy buildings it will be necessary to arrange strip or monolithic foundations.
The price of any
type of foundation is directly related to its depth, which depends on the depth of freezing of the soil. A high base (above 20 cm) increases the consumption of materials on the foundation. In central Russia, the basement is equiped with a height of 40-50 cm. This is due to the amount of snow falling in winter. Also, in case of problem soil, additional measures may be required: drainage for groundwater abstraction, soil compaction. Before starting work, it is advisable to conduct geological exploration of the site. It costs about 2500 rubles, and will save you from many unpleasant surprises.
Types of foundations
By depth, they distinguish:
- shallow (0.4-0.7 m);
- buried (1.2-1.5 m).
By design, the foundation can be:
- Tape. Shallow strip foundation is widely used in individual housing developments, since the cost of foundation for a house in this case is much lower than other types of foundations, and the bearing capacity is sufficient for most soils. It is not necessary to lay it below the level of freezing of the soil, since it is “floating”.
- Monolithic. It is equipped for heavy buildings, as well as if a basement is planned under the house. Suitable for complex heaving soils with deep freezing. The cost of the foundation for a house with a basement is significantly increased due to the cost of excavation and concrete.
- Columnar: concrete columns are poured into the ground at a distance of about 1.5 meters, a grillage is mounted on them.
- Pile. Variety - the foundation on screw piles. A great advantage in the speed of construction, as well as in the ability to perform a quick winter construction of the foundation for the house. Its cost for buildings with a small area is comparable to the cost of a strip foundation.
- Butovy - from stones fastened with concrete mortar.
- Block - from reinforced concrete blocks fastened with reinforcement and poured with concrete.
How to determine what foundation is needed to build a house
The type and depth of the foundation is determined by the specialist at the project development stage. At the same time, geological exploration data and building weight are taken into account. It is clear that the cost of the foundation for a wooden house is much lower than for a two-story brick mansion. The least cost will bring the foundation on stony and dry sandy soils, with sufficient depth of groundwater, with a low level of soil freezing in winter. You will have to spend money on the foundation if the soils are heavy, with low bearing capacity (clay, loam), with a high level of groundwater, with deep freezing of the soil in the winter (margin of safety for frosty soil heaving).
The bearing force of soils in decreasing order:
We will illustrate with examples how to calculate the cost of the foundation for a house. Let's take the characteristics for central Russia: the depth of soil freezing is 80 cm, the base is 50 cm high, groundwater is 1.5 meters below the freezing depth. The house is one-story, with one internal load-bearing wall, size - 10 x 10 meters.
Strip foundation
Lay the foundation around the perimeter of the house and under load-bearing walls. Shallow tape bases are suitable for almost all soil types. The cost of the strip foundation for the house in this case is minimal. They are erected under frame buildings and wooden buildings. A recessed type of base is equipped with brick, aerated concrete and concrete houses. The “floating” reinforced concrete strip compensates well for all soil movements and has a large footprint.
Calculation of the cost of the strip foundation
The cost of the strip foundation for the house consists of the following items:
- Earthworks: digging a trench. Length: 4 * 10 m + 10 m = 50 m. Width: 50 cm + 10 cm = 60 cm. Depth - 120 cm. Volume is 36 m3. Cost manually: 36 * 500 rubles = 18,000 rubles. Here, as agreed. Cheaper digging (calculation from running meter): 50 m * 200 rubles = 10,000 rubles.
- The device of the sand cushion (20 cm). Sand volume: 0.2 * 0.6 * 50 m = 6 m3 At a price of 600 rubles you get 3600 rubles.
- The device of crushed stone pillows (15 cm). 0.15 * 0.6 * 50 m = 4.5 m3 We multiply by 1500 rubles, we get 6750 rubles.
- Formwork: board 15 cm wide, 20 mm thick, length 6 m. Approximately 2.5 cubic meters. subject to crop. Total 2.5 * 3500 rubles = 8750 rubles.
- Reinforcement. Armature 12 mm, 450 meters * 25 rubles = 11250 rubles.
- Pouring concrete. Volume: length 50 m * height 130 cm (80 cm + 50 cm) * width 50 cm = 32.5 m3 At the price of concrete with delivery of 2000 rubles per cubic meter. it will turn out 65,000 rubles.
Total cost of the strip foundation in our case will be 105350 rubles.
Monolithic foundation
This type of foundation is set up for heavy houses, as it has a high bearing capacity. It is the most durable and durable, its only minus compared to non-continuous ones - there is no place for technical wiring under the house. If necessary, hide communications in addition equipped with a tape grillage.
Calculation of the cost of a monolithic foundation
When assessing the cost of a monolithic base with a plate thickness of 30 cm, take into account:
- Earthwork - digging a foundation pit. Volume: 10 m * 10 m * 0.65 m = 65 m3 Cost: 65 * 300 rubles = 19500 rubles.
- The device of the sand cushion (20 cm). 20 m3 * 600 rubles = 12000 rubles.
- The device of crushed stone pillows (15 cm). Crushed stone needs 15 cubic meters. It will cost 22500 rubles.
- Formwork device. Board 20 mm, volume: 40 m * 40 cm * 20 mm = 3.52 m3 The cost is 12320 rubles.
- Reinforcement. Reinforcing mesh with a cell of 20 cm, you need 1020 m. Cost 25500 rubles.
- The cost of filling the foundation under the house: 10 m * 10 m * 0.3 = 30 m3. Price - 2000 rubles per 1 cubic meter. The total cost is 60,000 rubles.
The total cost of the monolithic foundation is 151,820 rubles.
Pile screw foundation
The foundation is laid below the freezing depth. Well established on heterogeneous, marshy and "floating" soils. Metal piles with a helical strip welded to the rod are screwed into the ground at a distance of about 2.5 meters from each other. The blades of the pile should rest on a dense layer of soil. A concrete or metal grillage is installed on top, connecting the supports to each other. To equip this type of foundation, you do not need to level the site, all communications are freely located inside. Unsuitable for rocky soils, construction of houses with a basement, for it you need to additionally build a basement.
Calculation of the cost of pile-screw foundation
The calculation of the cost of the foundation for a house on screw piles is as follows.
- The cost of piles. Piles 2.5 m long, 14 pcs. * 1850 rubles = 25900 rubles.
- Screwing piles, in principle, can be done independently. When contacting construction companies, the installation of one pile will cost about 1,500 rubles. In this case, the pile-screw foundation will cost about 50 thousand rubles.
- Welding: cutting piles, welding the tip.
- Arrangement of grillage. There are two options: weld a metal channel, or fill in reinforced tape. Consider a variant with a concrete reinforced tape grillage 50 cm high, 0.5 cm wide: concrete 12.5 m3. will cost 25,000 rubles, formwork - about 3,000 rubles.
In total, a pile-screw foundation will have to pay 53,900 rubles. Add transportation costs and how much welding costs to you.
The costs of building any foundation also add the cost of hydro and thermal insulation. Currently, the market offers a variety of materials that meet various customer needs.