Screw foundation with own hands

The foundation on the basis of screw piles is one of the best solutions in low-rise construction. Its main advantage is ease of manufacture. In addition to this, it is considered universal: it is used for the construction of various types of low-rise buildings and structures. But the main advantage - it gives the opportunity to build on any, even uneven sites. Such a foundation is suitable for different climatic conditions and guarantees increased reliability of the structure even on very difficult soils. Among other things, it is not difficult to make a screw foundation with your own hands, and it will be suitable for any soil except stony. In this case, it is not possible to screw metal supports to the required depth.

Read more about the advantages of screw pile bases

First you need to briefly list all the advantages of screw bases, and then you can examine each section in detail. So, the advantages of screw piles:

1. High strength and real durability.
2. Relative cheapness.
3. Simplicity and speed even self-installation.
4. High reliability on loose sedimentary soils.
5. Possibility of successful use on slopes.

In practice, it is established that concrete bases are much faster destroyed than a pile foundation. This is because the reinforced concrete foundation is much more susceptible to sedimentary deformations. This circumstance leads to a significant decrease in their bearing capacity.

If you compare all the costs of a foundation device on screw piles with the cost of constructing a strip foundation, you can conclude that the pile is much cheaper, which saves money for other types of construction work.

If we talk about the speed of mounting the pile foundation, then here is the advantage. It takes only one day to screw in the required number of piles under a small house or other structure. This is all due to the fact that:

• No need to dig trenches or any pits.
• Do not need any special equipment for manual installation of small piles. Completely with this work will cope 2 or 3 people.
• There is no need for a long wait, as concrete in the foundation is not applied.
• No special skills and knowledge are needed to screw into the pile.

On unstable or sedimentary soils it is possible to use only pile foundation type. After all, only he is able to reach the dense layers of the rock and fix them with the ends of the piles. Piles are indispensable on the slopes, because with sufficient bias would have to use a huge amount of concrete when building a monolith.

The main disadvantages of screw piles

The foundations on screw piles and disadvantages are not devoid:

• Inevitable corrosion of metal.
• Certain restrictions in the field of application.
• Absolute impossibility of installing piles next to the existing walls of the structure.
• Some limitations in the bearing properties of piles.

Metal corrosion is inherent in all metal products, and piles are no exception. Moreover, when building a building on piles, an air layer is formed between the ground level and the bottom of the structure. It is here that the condensate accumulates, capable of destroying the metal structure of the piles. For the above-ground part, this problem is successfully solved by treating metal products with anticorrosive compounds or using galvanized elements. In any case, the underground part in 20-25 years will be thinned by the action of moisture and chemically active minerals. This will cause the structure to sink under its own weight.

The inability to screw piles in the immediate vicinity of the existing structure is due to the fact that a long steel pipe is used for this purpose, which is put into the head. To rotate the pile, a circle with a diameter equal to the length of this pipe is required. The tractor does not solve the problem either, because the tractor will not be able to maneuver effectively near the wall either.

Based on the above, it can be concluded that the screw piles are good for buildings whose lifespan is not planned for more than 25 years. Only they can be used on some types of soil. Screw piles are designed for the construction of low-rise small structures of light materials. In any case, before the construction of a building on screw piles, they need to be cleverly calculated.

Screw foundation with own hands

Any screw pile is a steel pipe with thick walls of circular cross-section. The lower part is pointed and equipped with screw blades. In the upper part there is a massive head, on which, after installing all the piles, mount the strapping of the building. The same head sometimes serves to screw the pile into the ground. It can be done manually with a long pipe or by using attachments for the tractor.

How to make the correct calculation of the pile foundation

First you need to conduct a survey of the land where the building is planned to be built on screw piles. To calculate the foundation, several steps are required:

• Determination of the ultimate strength of each pile in accordance with known mechanical properties and geometric dimensions of the material.
• Calculate the maximum weight load that soil can withstand.
• Determination of the load-carrying capacity of a piling foundation.

If the prepared screw piles are standard, they are steel pipes having a diameter of about 100 mm and a wall thickness of 4 mm. They are equipped with screw blades, the diameter of which is 300 mm. In this case, the bearing capacity of any support will be:

• Up to 9 tons on sandy loam and sandy soils.
• Up to 4 tons in alumina.
• Up to 6 tons in extremely loose rocks with a clay content of not more than 10%.

After this, determine the allowable load on the ground. For this, it is necessary to take into account not only its type, but even the composition and characteristics of the soil in the construction site. Among other things, it is very necessary to correctly determine the maximum and minimum level of occurrence of groundwater. These actions require geological surveys on the site, which involves serious costs. However, it is always possible to take into account the experience of building sites in the neighborhood or find background information on the physical characteristics of the soil in the area where the land is located. Pile foundations are calculated taking into account:

• The maximum possible weight of the building together with all communications, equipment and furniture
• The greatest load from snow on the roof.
• Wind loads in this region.

It's important to remember! Piles must be located at a distance of not less than 1.5 and not more than 3 m from each other. The places of their installation are placed in accordance with the loads specified in the layout of the facility in its various parts.

Layout of the land plot

The foundation on the screw piles is very reliable and durable. This solution has a high resistance to climate change and ground movements. However, one important condition must be met: its installation must be done as competently and correctly as possible. The error in the distance between the piles and the vertical section should not exceed 1-2 cm. Otherwise, in the future, you can face very serious problems, such as the sagging of the grillage, the breaking of the bearing capacity of the walls, the skewing of the building, and other troubles.

There is a good method of calculation, which is perfect for buildings with any complexity planning. Note that any foundations on screw piles are positioned so that the load on both of them and on the ground is distributed fairly evenly. Therefore, you need to take a plan for the future building and break it into rectangles. On their sides and diagonals it is necessary to have blocks of screw supports, taking into account the required distance between them. When marking, it must be remembered that each pile must be in the center of each bearing beam of the building.

Let's give an example. Having broken the whole plan of the building into separate rectangles and determining the size of each of them, we can calculate the necessary number of piles and distribute them across the entire area, taking into account the uniformity of the load on the foundation. Having finished the planning, you need to transfer the drawing to the terrain with the preservation of the scale and insert pegs into the ground at the points of installation of the piles.

Acquisition of material

Both ready-made piles and parts for their manufacture are on sale. For obvious reasons, finished products cost a little more. In any case, it is necessary to demand from the seller a quality certificate for any purchased products. If it does not exist, then we simply pass by. After all, the guaranteed strength and reliability will ensure our safety.

The standard length of screw piles is 2.5 m, and the depth of screwing must be at least 1.5 m. However, when the soil is freezing to a great depth, the supports should be installed at least 200 mm below this level. It should also be taken into account that only 1 m of piles will be above the ground, so if you want to raise the base of the building above - buy pipes longer. We take similar measures to buy piles on an uneven plot.

We make mounting of supports, headers for them and grillage of

For the correct installation of the screw foundation itself, we need to drill a technological hole for each screw pile to a depth of at least 50 cm. For this purpose, you can use a manual, electric or gasoline drill with a suitable length of nozzle. It is best to screw the piles in winter. If there are technological holes, then piles in the frozen ground will not be very difficult. In addition, at this time of year the material is sold at a decent discount.

First they install the corner piles. For this, a pipe with a screw at the end is inserted into the pit and using a lever from a long pipe, two people are screwed into the ground to the required depth. If necessary, you can use a kind of extension cable - a metal profiled tube with ears, which is put on the top end of the pile.

During the tightening process, one should not forget about vertical control, which is performed using a hydraulic level or a plumb line every 2-3 turns. Alternately screwed all the corner supports, proceed to the intermediate. They screw them in the same way as the corner ones. It is only necessary to take into account the mutual arrangement of the supports. They should be conveniently screwed using the levers manually.

pipe Piling of a pile foundation

When installing a foundation on screw piles, it must be remembered that the supports will carry a grillage, that is, a strapping. It can be made of wood from a bar of 150x150 mm, metal or concrete. For its correct and convenient installation, we need to weld the heads at the top of the racks. It is important to ensure that they are exactly on the same horizontal level.

But before installing the heads in the pipe, pour concrete solution. It not only adds extra strength to the piles, but also protects their inner surface from corrosion. In fact, unlike the outer one, it was not processed in any way. Speaking of the heads, it should be mentioned that they are flat metal platforms that are welded to small lengths of a round pipe, the inner diameter of which is slightly larger than the outside diameter of the pile. This headline is simply worn on the pile and welded to it. The welded seam must be treated with an anti-corrosion compound and painted. This design of the heads helps to easily adjust the level at which the grillage will be mounted. After its installation, we can state that our pile-and-screw foundation is completely ready.

As you can see, the construction of a foundation of screw piles is not too wise work. It can be performed by almost everyone who is not afraid to perform manual physical work independently.