Concrete withstands bending influences well, but cannot cope with bending on its own. To ensure the bearing ability, do the reinforcement of the foundation with your own hands. To a greater extent this applies to tape and slab structures. In piles and poles, metal is laid more for structural reasons than for real necessity.
Reinforcement Rules
Reinforcement of the strip foundation and any other is carried out taking into account the following rules:
- for working fittings use rods of a class not lower than A400;
- it is not recommended to use welding to connect the rods, since it weakens the cross section;
- without fail, a metal frame of reinforcement must be connected at the corners, welding is not allowed here;
- even for clamps, smooth reinforcement is not recommended;
- it is necessary to strictly observe the protective layer of concrete, equal to 4 cm, this will protect the metal from corrosion (rust);
- in the manufacture of frames, the rods in the longitudinal direction are connected with an overlap, which is assumed to be at least 20 diameters of the rods and at least 25 cm;
- with a frequent arrangement of metal, it is worth controlling the size of the aggregate in concrete: it should not get stuck between the rods.
Properly prepared reinforcing cage is half the success. It is he who will save the foundation in the case of uneven deformations that create bending loads. It is worthwhile to consider the issue in more detail using the example of a strip foundation with your own hands.
What reinforcement is needed for the design
The reinforcement of the strip foundation assumes the presence of three groups of rods:
- workers who are laid along the tape;
- transverse horizontal;
- transverse vertical.
Cross reinforcement under the strip foundation is also called clamps. Its main purpose is to connect working rods into a single whole. Reinforcement of the strip foundation is carried out in strict accordance with regulatory documents. What kind of reinforcement is needed for the foundation? Complex calculations are performed to give an accurate answer.
In order not to hire professionals, you can do with a simplified option. The technology of reinforcing the strip foundation for a small house allows you to assign sections constructively. This is because the tape takes up relatively small loads and works primarily on compression.
To make a reinforcing frame, use structural, that is, minimally acceptable, section sizes:
- For working reinforcement - 0.1% of the cross-sectional area of the foundation under the house. Moreover, if the side of the tape is 3 meters or less, the minimum allowable value is taken to be 10 mm. If the side of the building has a length of more than 3 m, then the diameter of the working reinforcement cannot be less than 12 mm. the use of rods with a cross section greater than 40 mm is not permitted.
- Horizontal clamps cannot be smaller than one quarter of the diameter. For design reasons, a size of 6 mm is prescribed.
- The diameter of the vertical reinforcement depends on the height of the tape for the foundation of the house. For shallow ones, the dimensions of which are 80 cm or less, rods from 6 mm are suitable.
The rules for reinforcing a strip foundation of a recessed type provide for the use of rods from 8 mm or more.
If a building is being built of brick, it is worth laying rebar with a small margin. This option will give confidence in the reliability of the design.
Reinforcement knitting
The scheme of reinforcing the strip foundation involves connecting the rods by the bonding method. The bonded frame is more durable than welded. This is because it increases the likelihood of burning metal. But this rule does not apply to prefabricated elements. Outside the construction site, it is possible to connect parts without significant loss of strength.
To increase the speed of work, it is allowed to reinforce the foundation in straight sections with a welding method. But corners can only be reinforced using knitting wire. These sections of the structure are the most responsible, so you should not rush.
Before knitting reinforcement for a strip foundation, you need to prepare materials and tools. There are two ways that metal bonding is performed:
- special hook;
- knitting machine (gun).
The first option is available, but suitable only for small volumes. Laying the reinforcement in the strip foundation in this case will take a lot of time. Annealed wire is used for the connection, the diameter of which is 0.8-1.4 mm. The use of other materials is not allowed.
The scheme of knitting reinforcement for the strip foundation
To build your home, you need to show patience and care. You should not save time and money, as this can cause trouble during operation. With the connection of the rods along the length of the problems should not arise. In this case, the process is quite simple, it is only important to observe the minimum amount of overlap.
But how to knit reinforcement for the strip foundation in the corners? There are two types of corner joints: between two perpendicular structures and at the junction of one wall to another.
Both options have several technologies for performing work. For corner walls use the following:
- Hard foot. To perform work at the end of each rod make a "foot" at a right angle. In this case, the rod resembles a poker. The length of the foot should be at least 35 diameters, it is better to prescribe more. The bent part of the rod is attached to the corresponding perpendicular section. Thus, it turns out that the external rods of the frame of one wall are connected to the external ones of the other wall, and the internal ones are welded to the external ones.
- With the use of L-shaped clamps. The principle of action is similar to the previous option. But in this case, they do not make a foot, but take an L-shaped element, the side of which has a length of at least 50 diameters of the working reinforcement. One side is tied to the frame of one wall, and the second to the frame perpendicular. In this case, the inner rods must be connected to the external. The step of the clamps should be three quarters of the height of the basement wall.
- With the use of U-shaped clamps. At an angle, you need two elements, the length of the sides of which will be 50 diameters of the reinforcement. Each of their clamps is welded to two parallel rods and to one perpendicular rod.
How to reinforce the strip foundation at obtuse angles. For this, the outer rod is bent to the desired degree value and an additional one is attached to it as a reinforcement. Internal elements are attached to the external.
To lay the reinforcement in the places where one wall adjoins the other, use approximately the same methods as in the previous case:
- overlap;
- L-shaped clamps;
- U-shaped clamps.
The size of overlaps and joints is taken equal to 50 diameters. When performing work, it is worth remembering the most common mistakes:
- right angle binding;
- lack of communication between external and internal elements;
- longitudinal rods connect a viscous crosshair.
Do not repeat these mistakes when building your own home.
Using a crochet hook
Before reinforcing the strip foundation, it is worth learning how to use the working tool. A special gun is rarely used for private housing construction, polishing such equipment requires additional costs. Investing in a tool is beneficial only for fulfilling orders, and not when building one house.
For this reason, the most common tool for knitting in private housing construction has become a hook. It will be easier to use it if you prepare special templates in advance. Such a part works like a workbench and greatly facilitates the work. Things will go faster. To make a template, wooden blocks are required, the width of which is about 30-50 cm, and the length can not be more than 3 m, since such a workbench is inconvenient to use.
In a wooden fixture, you need to drill grooves and holes that will repeat the outlines of the rods in the frame. In such holes, pieces of knitting wire 20 cm long are laid out in advance, and then reinforcement rods are fixed.
In order to understand the technology of knitting, you can consider examples. During construction, two options will be required: for the crosshairs (when the elements are perpendicular to each other) and for the overlap joints. In the strip foundation, the second technology is often needed, when erecting a slab structure, the first will be most relevant.
To connect the stacked frame into a single unit when overlapping, use the hook in the following order:
- the connections are made in several places along the length of the joint, the location of the wire is assigned so that it is in the deepened part of the profile of the reinforcement;
- the wire is folded in half and laid under the junction;
- with a hook pry a loop;
- the free end is brought to the tool and imposed on it with a slight bend;
- start to turn the hook, twisting the wire;
- carefully take out the tool.
For one lap joint, the procedure is repeated 3-5 times. Connecting elements at a time, as is done with cross-abutment, is not enough. Knitting reinforcement under the strip foundation in this case will be unreliable, since fixing at one point does not prevent the movement of elements.
Proper connection of the frame will guarantee the reliability, strength and durability of the supporting part of the building.