Reinforcement of the strip foundation - the rules for the construction of the frame with drawings, diagrams, photos and videos
The strip foundation is the most popular in private construction. It is ideal for the construction of small houses, garages, bathhouses and other outbuildings. All construction work can be done by hand, and the relatively low consumption of materials and the minimum amount of earthworks can reduce the price and production time. Of course, in order for everything to go as it should, you need to know how to properly reinforce the foundation.
Before telling how to properly reinforce the strip foundation, it is worth saying a few words about the choice of reinforcement.
- If you need to reinforce the base for a one-story or two-story house, as well as lighter buildings, you should take reinforcement with a diameter of 10-24 mm. Thicker material will cost too much, and its high strength will not be used. Less thick reinforcement may not withstand the load.
- It is advisable to use special corrugated fittings. It provides the best connection with concrete, guaranteeing its high strength and reliability. A smooth analogue costs a little less, but due to low adhesion it is not suitable for use. The only exception is cross connections. They carry a much lesser burden.
- If the soil is homogeneous over the entire area of \u200b\u200bthe foundation, then material with a cross section of 10-14 millimeters can be used. With heterogeneous soil, the load on the base increases, so it is advisable to invest in rods with a diameter of 16-24 mm.
Of course, buying thick corrugated rebar is quite expensive. But if you decide to reinforce the strip foundation with your own hands, then the amount of work is not too large. So, you will have to overpay a maximum of several hundred rubles - this fully compensates for the high durability and reliability of the finished structure.
With self-calculation and selection of reinforcement for the reinforcing cage of a strip foundation, there is a high probability of error. In the future, it can cause the destruction of the house, so the best solution would be to order a foundation reinforcement project from the designer, and to knit the frame on your own according to the drawing.
How much reinforcement is needed?
Before you go to the store to buy material, you need to find out how much it will take to reinforce the strip foundation. To do this, you should think in advance which scheme of reinforcing the strip foundation will be the best choice and carry out calculations for a particular object.
An example of frame reinforcement for a foundation
When building small houses, garages and baths, the following frame configuration is usually used:
- 2 belts: upper and lower;
- each belt consists of 3-4 reinforcement bars;
- the optimal distance between the rods is 10 centimeters. Please note that the distance from the reinforcement to the edges of the future foundation should be at least 5 centimeters;
- the connection of the belts is carried out using clamps or pieces of reinforcement at a step of 5-30 centimeters, depending on the reinforcement section.
Such a scheme is optimal. Now, knowing the dimensions of the future building, it is not at all difficult to make the appropriate calculations.
Let's say you want to build a spacious frame or wooden dacha with an area of 150 square meters with external walls with a perimeter of 50 meters. Let's do some calculations based on that. When reinforcing the strip foundation, we use the SNiP corresponding and the characteristics described above.
We have two belts with three rods in each. Total - 6 times 50 = 300 meters of main reinforcement. We take into account the number of jumpers that fit in increments of 30 centimeters. To do this, divide 50 meters by 0.3. We get 167 pieces. The transverse jumpers in this base will have a length of 30 centimeters, and vertical - 60 centimeters. For vertical jumpers you will need 167x0.6x2 = 200.4 meters. On horizontal - 167x0.3x2 \u003d 100.2 meters. In total, 300 meters of thick corrugated reinforcement and 300.6 meters of thinner, smooth reinforcement will be required. Having received these numbers, you can safely go to the store for material - the strip foundation without reinforcement will not last long. Some experts recommend taking reinforcement with a margin of 10-15%. After all, a certain amount of material will be needed to strengthen the corner parts of the strip foundation and go to the dock.
How to knit a frame?
The rules for reinforcing the strip foundation force us to abandon the use of welding in favor of knitting, since when using welding, metal rods lose strength at the places of welding joints up to 2-2.5 times. In addition, it is here that corrosion most often appears, which can damage the reinforcement in a few years, significantly reducing the reliability and durability of the base. Only connection by knitting is allowed. This is a rather complicated stage, which will take a lot of time for an insufficiently experienced user. However, a lot here depends on what tool you will use.
Reliable knot for tying reinforcement with wire
The classic tool for knitting reinforcement in a strip foundation is a special crochet hook. Using it, experienced craftsmen can produce up to 12-15 knots per minute (of course, if the knitting wire is prepared and cut in advance). The main advantage of this option is accessibility - a hook can be bought in many stores for a hundred rubles or even cheaper. Minus - the speed of working with it is not great even among the masters. Please note that many hundreds of knittings will have to be done, even if small foundations are to be reinforced.
Wire and hook for knitting a frame
If you want to finish the work as soon as possible, you can use a special knitting gun. Working with it, even an inexperienced user will easily give out 25-30 knots per minute. That is, productivity will increase at least 2 times. Alas, the cost of such equipment is not low - from 50 thousand and above. In addition, to work with it, you need a special wire - the usual one may not work. This further increases the cost. But if it is possible to rent a knitting gun for several hours or a day, feel free to agree to such an offer, just do not forget to find out the maximum diameter of the reinforcement that he can tie. Working with a quality tool, you will spend a maximum of a day on assembling the frame - the correct reinforcement of the strip foundation becomes much easier and faster. When working manually, this process can take a week or more.
How to make a frame?
Before proceeding with the reinforcement of the strip foundation, the drawings of suitable frames should be studied. Indeed, it depends on the strength of the frame whether the base will serve for many decades or whether it will be covered with cracks in the very first spring due to seasonal fluctuations in the level of the soil.
In order not to make mistakes in the manufacture, you need to remember a few rules:
- The overlap (the distance from the place of knitting to the edge of the rod) should be at least 5 centimeters.
- On corner joints, the perpendicularly running rods must be connected to each other - in no case can two separate blocks not connected to each other be used. The ideal solution would be corners made of bent reinforcement - such a foundation reinforcement scheme is the most reliable. But for this you need to have special equipment, if the reinforcement has a diameter of 14 millimeters or more, smaller diameters can be bent at home.
- Connections with wire should be tight - if using a crochet hook, then tighten the wire until it stops so that there is no free space between the clamp and the main reinforcement. Also check with your hand, if the collar moves from touching, you should make an additional tie with wire.
- The overlap during reinforcement should be equal to 40-50 reinforcement diameters. There should be a gap between adjacent connecting rods, and the upper and lower layers, according to the project.
- The reinforcing frame must, in the formwork, stand exactly. It is also necessary to take care of the protective layer of concrete for reinforcement, make it according to the requirements of the drawing. It should be remembered that the minimum protective layer is equal to the diameter of the reinforcement.
Bending of all elements for reinforcing the foundation is performed on a cold one. In no case do not heat the reinforcement, as this will lead to a loss of its strength.
As you can see, the rules are as simple as possible. But some inexperienced builders do not suspect or forget about their existence. This leads to the fact that the technology of reinforcing the strip foundation is violated and its service life is significantly reduced.
Earthworks and preparatory work
One of the advantages of the strip foundation is a relatively small amount of excavation. A couple of people, working a day with short breaks, can easily dig a pit of a suitable size on normal soil. When the pit is ready, you can begin to equip it.
The first step is the manufacture of the foundation pillow. Thanks to it, the negative impact of groundwater on the foundation is reduced, and the load from the foundation itself and the entire building is distributed as evenly as possible over the ground. Here you can use different materials. Most often, sand or gravel is used. They do a good job with their function - the main thing is that the thickness of the pillow is at least 15-20 centimeters.
But some experts recommend a concrete pad. Yes, it costs the most. Expensive cement and the need to reinforce the pillow greatly increase the cost and construction time. But as a result, you get the most reliable foundation for the foundation, which guarantees that it will last for many years. Therefore, we can say with confidence that this money will not be thrown to the wind.
An example of a reinforced strip foundation
If the work is carried out on weak, heaving soil, or if it is planned to build a heavy brick house, but the use of a monolithic foundation is undesirable for some reason, then a strip foundation with a sole can be used. Broadening (glass) can significantly reduce the load on the ground. Of course, do not forget about the reinforcement of the foundation glass - on heaving soils, it will regularly withstand significant tensile and bending loads. It is very important to provide him with sufficient strength.
When using a foundation with a sole, the volume of earthwork increases. In addition, you will have to spend extra money on reinforcing the sole of the strip foundation - if it fails, this will lead to the speedy destruction of the entire structure.
Formwork is installed on top of the finished pillow. When choosing a width, keep in mind that the finished foundation should be 10-15 centimeters thicker than the external load-bearing walls.
The next step is waterproofing. Some builders use roofing material, but this is a rather expensive material. And a lot of weight makes it difficult to install. Therefore, it is quite possible to use building polyethylene. Yes, it is less durable. But after all, it is needed only for a few days - so that the cement milk does not go into the sand. Therefore, cheap and lightweight polyethylene is quite suitable. It is laid on top of the formwork. At the joints, overlap more - at least 10-15 centimeters - and glue with a wide adhesive tape.
This concludes the preparatory work. Now let's talk about pouring and reinforcing the foundation with our own hands.
We install the frame, pour concrete
It is best to assemble the frame from the reinforcement directly in the prepared pit - this allows you to most firmly fix the elements. But if we are talking about reinforcing a deep strip foundation or if the pit is too narrow for work to be carried out directly in it, then you can assemble the frame from the outside above the trench, and then carefully lower it into place. There are usually no problems here and step-by-step instructions are not needed.
The last and one of the most important stages is the pouring of the foundation.
Pouring a strip foundation with a concrete pump
It is advisable to use concrete grade M200 or higher for this. It has high strength to withstand significant loads, and also has a sufficient frost resistance.
It should be said right away that a large amount of material will be needed for work. Make all the necessary calculations in advance - you need to pour concrete in one go, avoiding delamination and other separations. Otherwise, the strength of the base will be significantly reduced, and this will affect the safety of the operation of the house. For the same reason, it is advisable to rent a concrete mixer. Today, many companies offer this service. In addition, renting cheap models is relatively inexpensive - less than a thousand rubles a day. With intensive work during this time it is quite possible to cope with the work. In addition, the presence of a concrete mixer allows you to increase productivity - you just need to throw up sand, cement and pour water, soon getting a finished product that you just need to pour onto the frame installed in the formwork. Working with shovels, such performance cannot be achieved.
After pouring concrete, you must wait 28 days. During this time, the concrete will gain sufficient strength and it will be possible to start building a house, garage or bath.
We recommend watching a video where an experienced civil engineer will talk about the important nuances of reinforcing the foundation. What should be paid attention to when performing work in the first place, so that the foundation of the house is reliable.
Now you know how to reinforce the strip foundation with your own hands. To do this, it is not at all necessary to have highly specialized skills or buy expensive equipment. It is enough to know at least in theory how to reinforce the foundation. Experience will come into the process, and all tools can be replaced with cheap analogues or rented, saving money and time.