How to properly reinforce a strip foundation with your own hands, making a reinforcement frame

Requirements for concrete

The best materials should be used to complete the reinforcement correctly. Concrete is chosen based on its class and brand in compliance with the necessary indicators. Tension (Rbt, n), transverse fracture, and axial compression (Rb, n) are the three primary components of concrete structure strength. correction factors for reliability in the 1.0–1.5 range.

Reinforcement requirements

A strip foundation’s required reinforcement must be determined by performing calculations and taking into account the primary material types. Heat-treated reinforcement that has been mechanically strengthened and hot-rolled is used to complete the task. Maximum loads are used to determine the class, which also takes into consideration tensile properties, plasticity, weldability, corrosion resistance, temperature tolerance, etc.

The three main grades of rods are very strong rope (K), cold-formed wire (ђр), and hot-rolled rod (A). Rods of yield strength class A400 (AIII) with a sickle-shaped pattern resembling a "herringbone" are chosen for foundation frames.

To ensure proper reinforcement, the following kinds of rods must be used:

• Workers – for laying along the perimeter
• Transverse vertical
• Transverse horizontal (clamps)
• Additional – usually knitting wire is used instead

It’s important to keep a few guidelines in mind when deciding which kind of reinforcement to use. Rods with a diameter of 10–24 millimeters are appropriate for reinforcing the base of one- and two-story buildings as well as light structures. It is unlikely that thicker (and far more expensive) reinforcement will be used because of its strength properties.

Because they offer superior adherence to the concrete solution, the rods must be corrugated, and their thickness must precisely match the values listed in the documents. Although smooth rods are less expensive, you cannot build a sturdy and dependable reinforcement cage with them. They are limited to use in transverse joints with relatively light loads.

If the soil is uniform, you can use a material with a diameter of 10–14 millimeters for the strip foundation frame; if the soil is not uniform, it is better to use 16–24. The working reinforcement of the monolithic foundation is composed of rods measuring at least 12 millimeters but no more than 40 if the building’s side is more than three meters.

According to technology, the horizontal clamps’ diameter must be at least 25% of the working rods; typically, 6 millimeters are taken. For low-damaged foundations measuring 80 centimeters or less, the cross-section of the vertical rods must be at least 6 millimeters. After you’ve considered all the options, you can decide what diameter of rods are required for various tasks.

Reinforcement requirements

Prior to reinforcing, you must determine the dimensions of the frame, create a drawing, and create a diagram that includes all of the structures and work. The foundation’s geometric measurements have to allow for the freedom of reinforcing location. The frame is entirely covered in concrete, which shields it from corrosion and other outside factors.

The rods must be spaced apart at least sufficiently to allow for proper joining and adherence to all technological regulations. As per SNiP 3.03.01, only reinforcement of the highest caliber is employed in the work. Rods are bent with the use of specialized tools. The diameter and other physical characteristics of the rods are matched by the bending radius.

Video manual machine for bending reinforcement

And yet another helpful video

Video how to bend reinforcement work on a homemade machine

Calculation of the size, quantity and diameter of reinforcement

Determining the exact amount of reinforcement required to ensure the durability and dependability of the reinforcement frame is crucial. With the building’s dimensions in hand, you can meticulously compute every step.

Typical small house frame configuration:

• Lower and upper row of belt
• 3-4 rods for each row
• The actual distance between the rods is about 10 centimeters. The distance from the rods to the edges of the base should be at least 5 centimeters.
• The belts are connected with clamps or rod sections with a step of 5-30 centimeters.

Therefore, the external wall’s perimeter is 50 meters if a 150 square meter building needs to be constructed. You must consider all of the following when determining the appropriate amount of reinforcement: After multiplying two belts of a longitudinal row of three rods by fifty meters, the result is 300 meters of main rods. There are 167 pieces per 50 meters if the lintels are laid with a step of 30 centimeters. The vertical lintels are 60 centimeters long (167×0.6 = 200.4 meters) and the transverse lintels are 30 centimeters long (167×0.3 = 100.2 meters).

It turns out that the answer to the question of how much reinforcement is required to strengthen a 150 square meter house with a 50 meter wall perimeter is 300.6 additional thin rods and 300 meters of thick corrugated rods. Add 10–15% more for joining and stock.

Rules for reinforcing strip foundations

• Working rods must correspond to at least class A400.
• Welding for connecting the rods is not used due to the likelihood of weakening the cross-section of the element.
• The frame is tied at the corners, not welded.
• It is better not to take smooth reinforcement even for clamps.
• The layer of external protective concrete should be at least 4 centimeters, which will guarantee effective protection against rust.
• In the longitudinal direction, the rods in the frame are connected with an overlap equal to at least 25 centimeters and at least 20 diameters of the rods.
• Standards require that with frequent placement of metal rods, the filler in the concrete solution is not very large and does not get stuck between the rods.
• How to properly lay reinforcement in a trench – this can be done in two ways: create a frame outside the foundation or directly in the trench. The methods of reinforcement are almost equivalent, but for work in the trench you will have to involve someone, while the construction of the frame separately on the site can be done independently.
• Knitting is carried out with a special hook or knitting machine.

• Many people wonder what kind of wire is used for knitting – the answer is simple: soft thin wire of not very high strength. It needs to be pulled tight, a strong knot is obtained in 2-3 turns of the hook.
• The overlap (distance from the edge of the rod to the knitting point) should be at least 5 centimeters.
• All wire connections should be as tight as possible, without free space between the clamps and the frame, no element should move.

How to knit reinforcement mesh yourself

The opportunity to learn how to construct a frame correctly and give the foundation the required properties will be provided by the following detailed instructions. Knitting prefabricated reinforcement for a ground strip foundation is the simplest method. Straight sections of the mesh are made outside the structure, but the corners are knitted after the frame is lowered into the trench.

1. First, you need to cut pieces of rods. It is better to start knitting from the shortest section of the foundation to gain a little experience. You need to cut as little as possible, trying to use the entire length of the working rods. If we take as an example a strip foundation 40 centimeters wide and 120 centimeters high, then the following indicators are obtained.
2. From all sides, the metal is poured with a layer of concrete with a thickness of at least 5 centimeters. Pure size of the frame in height – a maximum of 110 centimeters, width – 30. Add 2 centimeters to knit on both sides for overlap. It turns out that the blanks for horizontal jumpers should be about 34 centimeters long, vertical – about 144 centimeters. This is for high foundations, but usually use a base of about 80 centimeters high.
3. 2 rods are placed on an even platform, at a distance of 20 cm from the ends, horizontal spacers are knitted on both extreme sides: folded the wire, put them under the mounting site and tightened with scrolling the hook.
4. At a distance of about 50 centimeters, all horizontal struts are attached in turn, the structure is put aside, another one is made – these are the lower and upper frames that need to be tied together: adjust the stops for both grids between the rods and vertically at the ends 2 struts, attach the remaining pieces. The same should be done with all straight sections of the structure.
5. Then, at least 5-centimeter-high pads are placed on the bottom of the trench, the side supports and mesh are installed correctly. Now, each corner and joint should be tied, creating a single frame. The overlap of the ends of the rods should be at least 50 rod diameters.
6. Next, the lower turn is tied, the vertical posts are attached, and the upper frame is attached to them. Then, on all surfaces of the formwork, you need to check the distances, indents, and overlaps at the joints so that everything is done correctly and clearly.
7. Connecting the rods along the length usually does not cause problems, but fastening the frame parts in the corners should be done in accordance with established standards. There are two ways: between two perpendicular structures or at the point where one wall adjoins another.

Technologies for tying corners:

1) Rigid paw: knit a paw that is at least 35 rod diameters long and join the bent portion to the perpendicular section at the end of each rod at a right angle. The wall frame’s outer rods are attached to one another in this manner, and the inner rods are welded to the outer ones as well.

2) G-shaped clamps: Using a clamp at least 50 diameters of reinforcement in length, attach one side to a wall’s frame and fasten the other side with a perpendicular instead of a paw. The clamps have a step of ¾ of the wall height, and the outer and inner rods are connected.

3) U-shaped clamps: Two U-shaped clamps that are at least 50 diameters long and welded to two parallel and one perpendicular rods are required for each corner.

The joints are made with comparable fastening techniques.

Any building project needs a solid and long-lasting strip foundation, and you can save time and money by doing it yourself. You must construct a strong reinforcement frame in order to adequately reinforce a strip foundation. This entails making the appropriate material selections, being aware of the proper rebar spacing and placement, and tightening everything down. You can make sure your foundation is strong enough to support your structure for many years to come by using the appropriate tools and following a methodical process.

Knitting reinforcement using a special device – a knitting machine

A few 20-millimeter-thick boards must be used to make this tool. Four boards must be cut along the length of the reinforcement, and two boards must be connected at a distance equal to the pitch of the vertical posts to create two identical templates. Create two vertical supports that are the same height as the reinforcement mesh after that. Since the supports are built with lateral corner stops, it is best to work in a level area.

The device is used as follows: two boards are knocked down and the legs of the stops are installed on them; the two upper boards are then fixed to the upper shelf of the stops. That’s it; the reinforcement mesh arrangement is now complete, allowing for rapid knitting. Installing the rods on each steel lintel and positioning the vertical reinforcement spacers on the designated locations, securing them with nails, is sufficient to complete the frame’s perimeter. After that, all you need to knit is a hook and wire. When numerous identical mesh sections are to be created, such a device is pertinent.

Video on how to knit reinforcement using a device

How to knit reinforced mesh in a trench

Because working in a trench is more challenging, you must prepare everything beforehand. At least five centimeters of height, with a pitch equal to the mesh width, are occupied by special apparatuses or regular stones at the bottom of the trench. The stones are arranged in long rods, with spacers tied horizontally. The second person grasps the ends of the rods and works them into the desired position.

The reinforcement is tied with a step between the spacers of 50 cm. We install pegs and begin to tie the monolithic structure. This is done on all straight sections. Parts of the frame should not touch the formwork, they should be at a distance of several centimeters from the formwork.

One can tie the corners in multiple ways that are currently available. It’s crucial to pay attention to how long the overlaps are when installing vertical rods. Here, larger-diameter rods are frequently employed to increase the material’s strength. After the tying is finished, concrete mortar is poured all at once, covered with polyethylene, and periodically sprayed with water using a sprayer during the drying process.

Welding reinforcement for reinforcement

Knitting is preferable to welding in most connection locations because the final structure will be stronger. Welding is only feasible on straight sections and requires specialized equipment and a great deal of experience.

For the foundation to be genuinely dependable, it is also essential to ensure that the earthworks beneath the tape are correctly executed, stacking multiple layers of materials (not just for the foundation’s top and base, but also for filling).

Practical advice

You can choose reinforcement over rods with a smaller diameter in areas without a heavy load. This is an acceptable option if it does not compromise strength but can lower labor costs. Two factors should be taken into account when selecting the diameter reinforcement for the job: the cost of the work and the desired balance between price and quality. Thick reinforcement is simply unnecessary in some situations, but the cost of the entire construction will go up dramatically if you choose a more expensive material.

The formwork’s frame arrangement needs to be uniform. Prior to constructing the structure, it is imperative that all dimensions be thoroughly examined to rule out distortions, deformations, and non-compliance with the specifications.

Video reinforcement of monolithic strip foundations of shallow laying

And here’s one more video:

Step	Description
1. Plan	Determine the dimensions and layout of your strip foundation, including depth and width.
2. Prepare the Trench	Excavate the trench according to your plan, ensuring it is level and free of debris.
3.

Correct strip foundation reinforcement is essential to the longevity and stability of your building. By taking the time to build a sturdy reinforcement frame, you can avoid common problems like shifting and cracking, which can later require expensive repairs.

Make sure you follow the right procedures when constructing your reinforcement frame: figure out how much steel you’ll need, cut the rebar to the proper lengths, and carefully assemble the frame. The efficiency of the frame depends on the bars being securely tied and spaced correctly.

The general performance of your foundation can be significantly improved by using high-quality materials and verifying your measurements twice. Take your time; it will be worthwhile in the end to pay close attention to detail during the reinforcement stage.

Rebuilding a strip foundation may seem difficult at first, but it is completely possible with the correct support and perseverance. You’ll be well on your way to building a solid, dependable foundation for your building project if you adhere to these recommendations.

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