The strip foundation is most often used in the construction of a wide variety of buildings. In addition to its simplicity and reliability, it is distinguished by the ease of transformation into monolithic foundationwhich is considered to be even more durable.
Content:
- What is a strip foundation ↓
- Description ↓
- Scope of application ↓
- Laying technology ↓
- Estimated cost ↓
- Calculation ↓
- Online calculator ↓
- Self-calculation by formulas ↓
- Calculation example ↓
What is a strip foundation
The strip-type foundation is a frame structure made of concrete and reinforcement. This structure has a rectangular shape, is solid and intersects in the corners with itself.
Description
Such a foundation is located along the entire house, taking into account the load-bearing walls inside. Usually, a part of the foundation with a height of about 10 centimeters protrudes above the ground. The rest of this element of the house is underground in a trench dug earlier. It is important that the surface of the foundation is larger than the width of the walls, only then the foundation of the building will be reliable.
Despite its popularity, such a foundation requires voluminous and time-consuming land work. In addition, the arrangement of the strip base cannot be called economical in the use of materials. But this option is suitable for heavy houses, for example, made of bricks, and is very easy to build.
The tape-type foundation also performs well on soils with the possibility of uneven shrinkage. If necessary, basement equipment - the walls of the foundation can also serve as the walls of the basement at the same time (at the same time, do not forget to check the possibility of arranging an underground basement at the level groundwater).
On average, the service life of such a base varies from 30 to 80 years, depending on the materials used and the quality of construction work.
Scope of application
Among the main areas of application of strip foundations, it is worth highlighting:
- Houses with heavy walls made of stone or brick (with a density of more than 1300 kilograms per cubic meter).
- Houses with heavy reinforced concrete or metal floors.
- In the case of construction on soil prone to uneven settlement. With the help of the strip foundation, the loads will be redistributed, and the walls will not crack and collapse.
- If there is an underground floor or basement in the construction plan.
Laying technology
As a rule, for the construction of a strip-type foundation, the main building materials are reinforced concrete and rubble concrete. The foundation construction technology itself provides for the following stages:
- The preparatory stage of construction, which consists in marking the site for the future construction, freeing up space on the construction site and purchase (delivery) of all required construction materials. Particular attention should be paid to the marking of the site; the quality of the entire foundation will also depend on its quality. On a construction site cleared of foreign debris and objects, it is necessary to mark the axis of the building and fix the corners with beacons. Particular attention must be paid to the perpendicularity of all marked sides. The dimensions of the construction site must exceed the final dimensions of the house by several meters.
- Digging a trench. The trench itself can be dug manually or with an excavator. If you are using a technique, it is important to level and tamp the bottom of the trench by hand. All debris must be removed from the trench.
- The pit fence is being installed.
- The bottom of the trench is covered with a layer of sand or gravel (12-20 cm).
- Waterproofing of the future foundation is carried out by laying waterproofing material.
- From boards about 40 mm wide the formwork of the foundation is being built (collapsible metal structures can be used).
- Reliable fixing of the formwork is carried out (using spacers). In this case, it is necessary to achieve a strictly vertical position of this element.
- In parallel with the installation of the formwork, the foundation reinforcement is laid (the reinforcement parameters are indicated in the construction project, taking into account what loads must be withstood).
- The foundation is poured with concrete. It is advisable to perform this operation from a height of no more than one and a half meters. Concrete is poured in successive layers up to 20 cm high, with each layer being compacted before pouring the next.
- One week after pouring the concrete, the formwork is removed.
- Work is underway on waterproofing foundation (by using bituminous mastic roofing material is glued).
- The final stage, at which backfilling of the foundation sinuses with sand occurs.
Estimated cost
The tape-type foundation is a reliable foundation for any building. Therefore, there are times when its cost can be more than half of the cost of the entire construction as a whole. Among the factors affecting the cost are:
- soil quality at the construction site;
- groundwater level;
- building area;
- the material used for the walls and the structure of the building;
- additional reinforcement requirements.
The cost of the strip foundation consists of the costs of carrying out the entire range of work and the cost of the materials used (the volume of concrete and reinforcement). If you count all the work provided for by the technology for arranging such a foundation, and the approximate cost of materials, on average, a running meter of a tape-type foundation will cost 6,000 rubles.
Calculation
To calculate the strip foundation, it is necessary to take into account all the features of the soil and the building itself. Based on this data, the possible loads and the required volumes of materials are calculated. Based on the volume of materials and the approximate cost of work, the price of the foundation is formed. For the calculation, you can use online calculators or independently calculate everything using formulas and tables.
Online calculator
One of the popular sites for calculating strip foundations is http://stroy-calc.ru/raschet-lentochnogo-fundamenta.
With the help of this site, where it is enough to indicate the dimensions of the house and the proposed materials for construction, you can easily calculate such parameters as:
- length and width of the foundation;
- foundation support area to determine the required amount of materials for waterproofing;
- lateral area of the foundation, to determine the amount of materials for thermal insulation;
- the volume of concrete for pouring the foundation;
- the weight of the concrete and the load exerted by the structure on the soil;
- rebar diameter;
- number of rows of reinforcement laying;
- total length and weight of the reinforcement (you may like option with fiberglass reinforcement);
- the thickness of the formwork and the required number of boards;
How to calculate the cubic area of the foundation is described in the next article.
Self-calculation by formulas
To start an independent calculation of the tape-type foundation, it is necessary to determine the initial data: the terrain, the size of the house, etc. First you need to calculate the depth of the base of the building.
To determine the depth of the foundation, it is necessary to know the characteristics of the soil at the construction site and the characteristics of the house itself. When erecting massive houses with heavy brick walls, it is necessary to deepen the foundation by 30 cm more than the soil freezing boundary.
Thus, the total height of the foundation with the outer part will be the boundary of soil freezing plus 60 cm. If the building is not very massive, it will be enough to deepen the foundation by 50 cm. The width of the strip is usually taken as standard (equal to 40 cm).
To complete the calculation, it is necessary to calculate the area of the base of the foundation so that the building can withstand all the loads. For this, you can use the following formula:
S> k (n) * F / k (c) * R
k (n) - safety factor, which is 20% (k = 1.2); F is the estimated load from the house and the foundation on the soil, plus the load from snowfall in winter, floors, etc .;
k (c) is the working coefficient, which is looked at in the table depending on the conditions and materials of work (for example, for clay soil and rigid structures it is 1); R - soil resistance indicated in the tables in accordance with the type of soil.
All tables are compiled according to the requirements of sanitary standards. You can find them both in the norms and building requirements themselves, and on the Internet. The only calculated parameter will be the total load.
Calculation example
Let's give an example of calculation. In the case of depth, no questions arise. For example, take an area where the soil freezing boundary is 130 cm, then the depth of the foundation is 160 cm.
In the case of calculating the area, we take:
k (n) = 1.2; F –150000kg (determined as the total value of data from tables of pressure of wall and foundation materials, snow pressure for the region);
k (c) = 1.1; R = 2.5.
In this case, according to the formula, we get an area equal to 6, 5454 square meters. We round it up and get 6.6 square meters.
The cost of a strip foundation can be more than half the cost of an entire home, but it will be a reliable foundation. The main expense item for such a foundation is materials. You can use formulas or online calculators to calculate materials. If you are unsure of your ability to calculate and want to save time, it is better to use online services.