How to calculate the cost of the foundation under the house?
The foundation is the basis of any structure. Planning the construction, you should pay special attention to this part of the house. The destruction of an incorrectly made foundation entails a violation of all constructions, so the economy in this matter is inappropriate. The cost of the foundation under 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 base. Calculate the cost of the foundation under the house can only be after you have a plan for construction, because the price of work directly depends on the type of foundation and its technical characteristics. Also, a specialist can give recommendations on the advisability of using one or another technology for erecting the foundation of a building in each specific case.
What determines the cost of the foundation for the house
The foundation takes on the weight of the structure andevenly distributes it to the surface of the earth. Therefore, the worse the soil for its load-bearing capacity and the heavier the construction, the more thoroughly the foundation should be. Accordingly, its cost will increase. For light houses it is advisable to erect pile or columnar foundations, and for heavy buildings it will be necessary to arrange tape or monolithic bases.The price of any kind of foundation is directly related to itsdepth, 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 the central strip of Russia, the base is set at a height of 40-50 cm. This is due to the amount of snow falling in winter. Also, with the problem ground, additional measures may be needed: drainage for groundwater drainage, soil compaction. Before starting work, it is advisable to conduct a geological survey of the site. It costs about 2500 rubles, and will save you from many unpleasant surprises.
Types of foundations
The depth of occurrence is distinguished:
- shallow (0.4-0.7 m);
- recessed (1,2-1,5 m).
According to the construction the foundation can be:
- Tape. The finely stripped ribbon foundation is widely used in individual housing developments, since the cost of the foundation under the house in this case is much lower than other types of grounds, and the bearing capacity is sufficient for most soils. It is not necessary to lay it below the freezing level of the ground, since it is "floating".
- Monolithic. It is built for heavy structures, and also if there is a basement under the house. Suitable for complex soils with deep freezing. The cost of the foundation under the house with the basement is significantly increased due to the expense of excavation and concrete.
- Columnar: pour concrete pillars into the ground at a distance of about 1.5 meters, they are mounted grillage.
- The pile. Variety is the foundation on screw piles. Great advantage in the speed of erection, as well as in the ability to perform rapid winter construction of the foundation under the house. Its cost for buildings with a small area is comparable to the cost of the ribbon foundation.
- Butovy - from stones, cemented with concrete solution.
- Block - from reinforced concrete blocks, fastened with reinforcement and filled with concrete.
How to determine what kind of foundation is needed to build a house
The type and depth of the foundation is determined by the specialist onthe stage of project development. This takes into account the geological exploration data and the weight of the structure. It is clear that the cost of the foundation for a wooden house is much lower than for a two-story brick mansion. The lowest cost will be the erection of a foundation on stony and dry sandy soils, with a sufficient depth of groundwater, with a low level of freezing in the winter. You will have to pay for the foundation if the soils are heavy, with a low bearing capacity (clay, loam), with a high level of groundwater, with deep freezing of the soil during the winter period (margin of frost heaving).
The bearing force of soils is decreasing:
For examples, let's see how to calculate the costfoundation under the house. Take the characteristics for the middle zone of Russia: the depth of freezing of the soil is 80 cm, the base is 50 cm high, the groundwater is below the freezing depth by 1.5 meters. The house is one-storey, with one internal bearing wall, size - 10 x 10 meters.
Lay the base around the perimeter of the house and underbearing walls. Fine-grained belt bases are suitable for use for almost all types of soils. The cost of the ribbon foundation under the house in this case is minimal. They are raised under frame houses and wooden buildings. The buried type of the base is equipped with brick, aerated concrete and concrete houses. "Floating" reinforced concrete strip well compensates for all soil movements and has a large footprint.
Calculation of the cost of the ribbon foundation
The cost of the ribbon foundation under the house consists of the following items:
- Excavation: excavating a trench. Length: 4 * 10 m + 10 m = 50 m. Width: 50 cm + 10 cm = 60 cm. The depth is 120 cm. The volume is equal to 36 cubic meters. Cost manually: 36 * 500 rubles = 18000 rubles. Here, as agreed. It is cheaper to dig an excavator (calculation from the running meter): 50 m * 200 rubles = 10000 rubles.
- The device of sand cushion (20 cm). The volume of sand: 0.2 * 0.6 * 50 m = 6 cubic meters. At a price of 600 rubles, 3600 rubles will turn out.
- The device of a crushed stone pillow (15 sm). 0,15 * 0,6 * 50 m = 4,5 cubic meters. Multiply by 1500 rubles, we get 6750 rubles.
- Formwork device: board width of 15 cm, thickness 20 mm, length - 6 m. Approximately 2.5 cubic meters. taking into account the scraps. 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 cubic meters. At the price of concrete with a delivery of 2000 rubles per cubic meter. will be 65,000 rubles.
The total cost of the ribbon foundation in our case is 105,350 rubles.
This type of foundation is equipped with heavyat home, since it has a high load-bearing capacity. It is the most durable and durable, its only minus compared to non-continuous ones - there is no place for technical scouts under the house. If it is necessary to hide communications, an additional tape grill is also equipped.
Calculation of the cost of a monolithic foundation
When estimating the cost of a monolithic base, a thickness of 30 cm is taken into account:
- Excavation - excavation excavation. Volume: 10 m * 10 m * 0.65 m = 65 cubic meters. Cost: 65 * 300 rubles = 19,500 rubles.
- The device of sand cushion (20 cm). 20 cubic meters. * 600 rubles = 12,000 rubles.
- The device of a crushed stone pillow (15 sm). Crushed stone needs 15 cubic meters. It will cost 2,2500 rubles.
- Formwork device. Board 20 mm, volume: 40 m * 40 cm * 20 mm = 3.52 cubic meters. The cost is 12320 rubles.
- Reinforcement. Reinforcing mesh with a cell 20 cm, it is necessary 1020 m. The cost is 25500 rubles.
- The cost of pouring the foundation under the house: 10 m * 10 m * 0.3 = 30 m3. The price is 2000 rubles per 1 cubic meter. The total cost is 60,000 rubles.
The total cost of a monolithic foundation is 151820 rubles.
The foundation is laid below the depth of freezing. It has proved itself well in heterogeneous, swampy and "floating" soils. Metal piles with a screw tape welded to the rod are screwed into the ground at a distance of about 2.5 meters from each other. Pile blades should be supported by a dense layer of soil. On top of the build a concrete or metal grillage, connecting the supports between each other. To equip this type of foundation, you do not need to align the area, all communications are freely placed inside. It is not suitable for rocky grounds, construction of houses with a basement, for it it is necessary to erect an additional plinth.
Calculation of the cost of pile-screw foundation
Calculation of the cost of the foundation under the house on the screw piles produced as follows.
- The cost of piles. Piles 2,5 m long, 14 pcs. * 1850 rubles = 25900 rubles.
- Screwing the piles, in principle, can be performedyourself. When referring to construction firms, the installation of one pile will cost about 1500 rubles. In this case, the pile-screw foundation will cost about 50 thousand rubles.
- Welding: cutting piles, welding the head.
- Arrangement of grillage. There are two options: weld the metal channel, or fill the reinforced tape. We will calculate the variant with a concrete reinforced tape grillage height 50 cm, width 0.5 cm: concrete 12.5 cubic meters. will cost 25,000 rubles, formwork - about 3,000 rubles.
In total, the pile-screw foundation will have to pay 53,900 rubles. Add the transportation costs and how much welding work will cost you.
The cost of building any foundation is also added to the cost of hydro and thermal insulation. Currently, the market presents a variety of materials that meet the various needs of customers.