The simple design of the reinforcement plays a significant role in pouring the strip foundation for the building. The strength of the foundation, and hence the durability of the entire structure, depends on the quality characteristics of the reinforcing rods. What reinforcement is needed for a strip foundation?
The construction of low-rise buildings requires a strip base. Such a base is easy to build, and it is also the most economical option. The advantage of the strip base is that it can be poured without the use of special construction equipment. In addition, this type of foundation is able to withstand significant loads, which allows you to build several floors.
Strip foundations can be divided into:
- prefabricated structures;
- shallow, suitable for the construction of structures made of wood and other light materials;
- deeply buried, which are used in the construction of brick houses with two or three floors.
Depending on what you wantAs a result, you need to correctly calculate the amount of concrete needed as a base pour, and also decide what reinforcement is needed for the strip foundation of the house.
Selecting the type of reinforcement
What reinforcement is used for the strip foundation? To date, the most popular types of rods are:
- Steel, with a diameter of at least 5 mm for the transverse rails and 10 for the longitudinal ones. The strength of the entire strip structure will depend on which brand of reinforcement is needed for the strip foundation. Class A steel bars with a yield strength of 400 are used. The following differences in grades can be visually determined - A 240 has a smooth surface, A 300 has an annular pattern, A 400 has a herringbone pattern. Lower quality rods are not recommended.
- Fiberglass rods are corrosion resistant, non-conductive. Often such material is used for buildings where it is important to avoid radio interference. The strength of quality rods is not inferior to metal.
For laying the main longitudinal elements of the reinforcement, only rods with a ribbed surface are used, as this guarantees a better adhesion to the concrete. Smooth rods are used when creating side jumpers.
It is strictly forbidden to use the following materials as reinforcement:
- metal pipes;
- chain-link mesh;
- metal profile;
- iron cables.
Mismatchrequirements for reinforcement for a strip foundation can lead to subsidence of the base and further destruction of the entire structure.
Rebar diameter for foundation
The diameter of the reinforcement for the strip foundation determines the subsequent strength of the entire structure. In order to choose the right size of reinforcement, the parameters of the future structure should be taken into account. For example, the maximum diameter with a shallow base and light construction of the whole house will be a waste of money. Rebar is often used for the strip foundation of a house with a diameter of 8-12 mm, this is considered optimal for medium loads.
Which reinforcement parameters should be considered:
- the cross-sectional size of the steel bar should be 0.1% of the cross-sectional area of the foundation;
- when calculating the diameter, the length of the foundation tape and its width are taken into account;
- with a foundation length of more than 3 m, steel bars with a diameter of 10-12 mm are located longitudinally, while 5-6 mm is sufficient as a transverse reinforcement.
The diameter is determined individually, taking into account the characteristics of the building - building material, dimensions, number of floors.
Standard reinforcement pattern
After you have decided what reinforcement is needed for the strip foundation of the house, you should figure out how to install it. For this, there is a universal reinforcement scheme that is suitable for almost any structure on a strip foundation.
- To the bottom in advancedug trench laid out bricks 5 cm high.
- Steel bars of large diameter are laid longitudinally on the bricks.
- In increments of approximately 50 cm, horizontal jumpers of a smaller diameter are attached to the laid bars.
- Vertical rods are attached to the corners of the formed cells.
- Long rods are tied to the vertical reinforcement.
In order for the structure to be as strong as possible, the technology specified in SNiP 52-01-2003 should be followed.
The connection of the rods to each other can be done by welding or wire knitting. The second method is much more economical, although the quality is not inferior to classical welding. For its implementation, a knitting wire is used, from which loops are formed. Rods are threaded through them, after which the free edge of the wire is twisted several times. The use of a special hook greatly simplifies the task.
When constructing a reinforcing structure, due attention should be paid to reinforcing the corners, which account for most of the weight of the structure. Corner reinforcement is also done to prevent unwanted cracks or stretching of the structure.
Angle rods must not be placed perpendicular to each other, their corners must be bent. It is important to ensure overlap and connect all the rods with radius elements. The amount of overlap of the rods that are used in the corner zone should not exceed 25 cm. In case of correctreinforcing the corners during the filling of the trench with concrete, the reinforcing contour will not be destroyed.
Strengthening the various zones of the strip foundation requires the correct calculation of the number of steel bars. Its shortage can lead to the need to purchase the right amount of material, which threatens with a temporary delay in construction.
Calculation of the amount of reinforcement
Collecting a frame from reinforcement for a strip foundation requires a careful calculation of the amount of material needed. In order to simplify the task as much as possible and not use complex calculation formulas, you can simply pre-determine the perimeter of the future structure. Then, taking into account the number of rows of steel bars, the number of longitudinal rods is determined.
The amount of transverse reinforcement is calculated by taking into account the height of the tape and the step between the steel bars. When calculating the amount of reinforcing material needed, add to the total amount the stock of material to form joints between the bars.
Filling the foundation
After determining what diameter of reinforcement is needed for the strip foundation and its bundle, you can start pouring the foundation itself. It is important to mix the solution thoroughly until a homogeneous consistency. If it is not possible to do it yourself, you can order a ready-made one.
Filling should be done at a time, periodically bayoneting the solution with a metal rod to avoid voids that will significantly degrade the quality of the base.
Drying outthe mortar should be made naturally over several weeks with periodic wetting of the surface to prevent cracking of the concrete. Construction can only be continued a few weeks after pouring.
Need for reinforcement
Some builders question the need to reinforce the strip base, citing the fact that high-quality concrete already has sufficient strength. However, it is not. The base without additional reinforcement is unstable to soil movements.
The reinforcing frame is used to distribute the load on the base, as different parts of the house may have different weights. This design is especially needed for a strip foundation, which will support a heavy brick building with several floors.
You can start buying building materials. if you have finally decided what kind of reinforcement is needed for the strip foundation. Rarely steel bars are measured in linear meters, as when calculating the required amount for construction. Sellers calculate quantities in kilograms.
In order to correctly calculate the required weight of a building material, experts recommend using tables from GOST 5781-82 or GOST 2590-88, which indicate the weight of a unit of steel bar. The numbers in both documents are the same, so the use of one or another GOST depends only on personal convenience.
Essential tool for the job
When self-constructing a strip base, the following tools may be required:
- water level, which is used when constructing a ditch, it will help to align the walls in a strictly vertical position;
- to tie steel bars, you may need pliers and wire cutters, or a special knitting tool that will allow you to complete the work faster;
- grinder or grinder equipped with diamond cutting wheels for cutting steel bars;
- to assemble wooden formwork you will need a hammer, a screwdriver, as well as long nails or self-tapping screws;
- for self-mixing the concrete mortar, you may need a concrete mixer, which will allow you to achieve a uniform consistency, and also save a lot of time and effort, if it is not available, you can order a ready-made mortar with delivery or knead manually using a large trough and a shovel.
In addition to these tools, you may need auxiliary ones - buckets, trowels, shovels, a construction wheelbarrow. Often they are purchased as needed.
A competent frame for a strip base can significantly increase the operational life of a building. It will also eliminate the need for frequent repairs that may be needed due to the destruction of an incorrectly erected building.