Do-it-yourself pile foundation with a grillage from driven and bored piles

 Do-it-yourself pile foundation with a grillage from driven and bored piles

For a long time, in those areas that are often subject to flooding, people have built houses on piles driven into the ground. The piles were made of logs and driven into the soil by hand - although the process took a lot of time and effort, nevertheless, it made it possible to raise the house by one or two meters and save the property from water. A pile foundation is still often used in cases where a house has to be built on weak soil, highly compressible or weak, that is, on such a soil that is not suitable for an ordinary shallow foundation.

Driven pile foundation structure

The pile foundation (the photo of which you will find in the tab) has many advantages and is considered one of the most reliable among builders. If we compare the columnar and pile foundations, the technology of the latter is much simpler, since there is no need to dig holes, make formwork, fill up the sinuses. When building a pile foundation, you can do without excavation at all - driven piles are driven into the ground using special equipment, and for bored piles, wells can be drilled with a hand-held construction drill.

When building a pile foundation, you can do without excavation at all

On any type of soil, except for those with impenetrable inclusions, it is possible to use driven piles. Driven piles are made of wood (mainly conifers: cedar, pine, larch, oak), steel or reinforced concrete. The end of the wooden pile, which is intended for driving into the ground, is sharpened and protected by a steel tip from possible damage when immersed in the ground. A steel ring is put on the upper end so that the pile does not split from hammer blows. For reinforced concrete piles, the lower end is also sharpened.

Video about the pile foundation

It is quite possible to arrange a pile foundation with your own hands, since you do not have to remove the soil for this: the piles are driven into the ground with the help of special hammers, pressing devices and vibrators. Installed driven piles are cut at the same level, and connected from above with a grillage, which ensures an even distribution of the load on all piles.

The pile foundation can also be made of metal tubular piles that are hollow on the inside. Their main advantage is that they are much lighter than other types of driven piles. In addition, they can be driven very deeply, filling with concrete for stability. This also includes screw piles with a welded-on screw strip, used for a pile-screw foundation.

How bored pile foundations are made

It is better to use bored piles to guarantee the integrity of the foundation on swollen soils. Let this method be more laborious than the one described above, but you do not have to spend money on renting expensive piling equipment: the foundation on bored piles is made by concreting wells drilled in advance.

The pile foundation can also be made of metal tubular piles, hollow inside

Drilling of piles under the foundation can be carried out with a hand drill with a maximum diameter of up to 30 cm and a rod length of more than 5 m. Due to the special arrangement of the cutting blades, drilling requires little effort. The required depth and diameter of the well is calculated based on the characteristics of the soil (most often a depth of about 10 m and a diameter of about 20 cm is enough).

Further construction of pile foundations from bored piles looks like this:

  • along the entire length of the wells, a cover of several layers of roofing material, PVC film or galvanized steel is provided to prevent the piles from pushing out under the influence of soil swelling during frost (nothing will harm the foundation if the soil slides over the protective cover);
  • a reinforcement cage is installed in the wells in the form of connected rods of reinforcement, 3 pieces each, with the removal of the rods above the poured piles to the height of the future grillage - the reinforcement will serve as a link between the rammed pile and the grillage in the future, and will also prevent a possible rupture of the foundation as a result of heaving of the soil;
  • the pile foundation is poured with "heavy" concrete (with quartz sand or crushed rock), filling is continuous in each well in layers, the concrete is compacted by bayonetting.

The poured foundation on piles can be loaded only after a month, when the concrete is finally set.

The poured foundation on piles can be loaded only after a month, when the concrete is finally set

Grillage structure for pile foundation

A pile foundation with a grillage makes the structure more reliable and durable, gives it rigidity. You can make a grillage from prefabricated reinforced concrete elements, or pour a monolithic foundation. A pile foundation with a monolithic grillage is preferable for self-construction, since it is much more convenient to pour concrete than to put heavy reinforced concrete blocks on piles.

There should be a gap between the ground and the bottom of the grillage so that the soil does not lift the grillage itself when swelling, therefore the grillage should in no case be located directly on the ground.

A pile foundation with a grillage makes the structure more reliable and durable, gives it rigidity

The pile grillage foundation is performed as follows:

  • formwork is installed on the piles;
  • inside the formwork, the reinforcement cage is firmly fixed, placing small bars under the lower rods so that the reinforcement is completely immersed in concrete;
  • rods sticking out of bored piles are connected to the reinforcement cage of the grillage for greater foundation reliability;
  • the grillage is poured with concrete (just like in a strip foundation).

The height of the grillage is recommended to be at least 30 cm, and the width is slightly greater than the thickness of the walls of the house (about 40 cm).

Pile foundation: reviews, advantages and disadvantages

Of course, the pile-grillage foundation has a lot of advantages: it allows you to reduce the heat costs of the house, since the grillage does not touch the frozen ground; reduces the level of vibrations, which is especially important in areas located next to the highway or railway; eliminates the need for earthworks; requires less cost than strip foundations.

Video about pile foundations. Pros, cons and recommendations

However, the pile foundation also has drawbacks - it is enough to read the versatile reviews of those who chose this type of foundation for their home. For example, the disadvantages include the fact that the construction of the basement in the house will cause certain difficulties due to the grillage raised above the ground: the space between the piles will have to be filled with something. In addition, the pile foundation is not sufficiently stable on subsidence and swelling soils.

When choosing the foundation for your home, think carefully about all the pros and cons to make the right decision. A pile foundation can be both an ideal option in one case, and a big mistake in another.

How to fill the foundation for a house with your own hands - technique + video

In individual housing construction, strip foundations are most widespread, since they ideally perform their functions on almost all types of soil, are not too difficult for self-filling, and are also relatively inexpensive. Another common type is pile foundations used on moving soils. And the very first stage of arranging such foundations will be an accurate calculation of the required amount of building materials, their purchase and delivery to the construction site. At the same time, it will be reasonable to immediately purchase the entire volume of building materials so as not to be distracted by additional purchases during the work and to have time to complete all the work in one warm season.

Directly at the construction site, for a start, it is worth marking out the territory, i.e. outline the boundaries of the future foundation. It is necessary to make markings taking into account all factors: the occupied area of ​​the future house, its mass, the relief of the land plot, the level of groundwater, etc. To do this, pegs are dug in along the perimeter of the building and along the boundaries of the inner ones, between which a string is stretched in parallel lines. You can check the accuracy of observance of the mutual perpendicularity of all marking lines by comparing the diagonals between the corners of the trench. If they are equal, then all angles are right.

Column foundation

Simple and cheap columnar foundation, is used for small lightweight structures - do-it-yourself gazebos, outbuildings, construction of a bathhouse, etc. The material for the columnar foundation is:

  • rubble stone
  • concrete pillars
  • concrete blocks
  • brick
  • wood.

Making a foundation with your own hands performed on a sand cushion, can be superficial or buried. In the first case, holes 60-90 cm deep are dug in marked places, into which the formwork is installed. The bottom of the pit is well rammed, covered with gravel and sand. The base of the column is reinforced and poured with concrete or laid out with bricks. The disadvantage of brick posts is the large amount of earthwork and the susceptibility of such supports to soil movement.

The foundation device on the soil surface is carried out as follows:

A do-it-yourself unreinforced surface columnar foundation is used for very light structures.

Stages of the device of a monolithic strip foundation

And now we will figure out how to make a monolithic strip foundation without focusing on its depth. This option is most often used in the private sector, since it costs less than a prefab, but is not inferior to it in terms of strength and operational resource.


Creating a right angle on the ground

It doesn't matter what shape, rectangular or square, your house is - what matters is that the corners in it must be 90⁰, otherwise the architectural composition will be broken, and the building will look ugly. Now let's figure out how to correctly make a right angle with improvised means. To do this, in the corner of the future trenches, drive a wooden, or preferably a metal, peg into the ground and tie two cords to it - one 3 m, and the other 4 m (it is better to use aluminum, copper or knitting wire - it does not stretch). If the edges, which are marked in the image above, as currents A and C, are separated by 5 m, then the angle ABC will turn out to be exactly 90⁰.

Mark the trench with threads

To make the trench even, it is best to mark it with nylon threads, as shown in the top photo. Remember that the tape should not be narrower than the bearing wall, but it is even better if it is about 10 cm wider, therefore, a trench must be dug accordingly. After you reach the desired depth, fill the bottom with a 5-10 cm high sand cushion; you can also use granite screening for this purpose.

Reinforcement cage

Let's start with the fact that the reinforcement of the foundation is a prerequisite for the construction of a house, even if it is light, wooden. For this purpose, steel reinforcement is used, where for longitudinal laying, rods with a periodic section with a diameter of 12 mm are used, and for transverse, vertical and horizontal lintels, smooth rods with a diameter of 8-10 mm are used. At the mating points, they are tied with a metal knitting wire (do not weld!).

Now about the parameters of the frame. If the tape is 40 cm wide and 140 cm high, then the frame should be made: L = 300 mm and H = 1300 mm, so that there is 5 cm of margin on each side. The fact is that the corrosion of the metal (rust) will destroy not only the reinforcement, but also the concrete itself, and the 5-centimeter layer will not allow moisture and oxygen to pass through, and the steel will be reliably protected. The value of N can vary from 50 to 80 cm, but a jumper, where the value of T, is not needed in this case. The jumper in such a frame can only be placed on the side, in the middle, and this will be enough.

Concrete preparation

For pouring the foundation, it is best to use grade 300 concrete (if translated into strength class, it will be B22.5), although grade 250 (B20) is also suitable for a one-story house. The proportions of the required ingredients can be found in the table above. It also indicates the amount of water for a certain ratio of cement, sand and crushed stone, but this figure is conditional, since the volume of water is directly related to the moisture content of sand and crushed stone.

Now about the order of mixing the ingredients - this is an important point and the strength of the cement stone depends on it. First, pour 2/3 of the amount of water indicated in the table into the concrete mixer and start the drum. Load cement into a working concrete mixer and mix it until the liquid becomes like thick milk - this will take no more than 2-3 minutes. Then you throw the required proportion of sand there with a shovel, wait until the solution becomes a homogeneous mass, and only then add crushed stone. Add water as needed. So the concrete will turn out to be the grade and strength (class) specified in the table.

Now a few words about sand. If you find that there is clay in the sand - discard it, as it is not suitable for outdoor work. The clay will wash out over time with water and the concrete will collapse. Stones (large) of sand are sown through a sieve, but builders usually use a carapace bed for this purpose - this is very convenient.

Pouring the foundation

Pouring strip foundation

Now we move on to the last phase - to the independent pouring of the strip foundation and its reinforcement. These two functions work together. Here you can go in two ways: the first is to put some stones under the reinforcement cage to create a gap between it and the sand cushion, the second is to pour a layer of concrete 6-7 cm thick, creating a barrier.

It doesn't matter which method you choose, but now you can lower the frame into the trench and start pouring. If you are working with a partner, then it is necessary that one person holds the frame while the other is throwing concrete into the trench - this way you will not allow skewing and all metal bars will be covered with concrete. At this stage, the solution is poured until the tape is level with the ground, and then cover it with polyethylene so that no pieces of soil, dust or sand get in.

After 3-5 days, you can put the formwork for the overground part of the tape - its height will depend solely on your desire. Later you can mount a brick base on it, but if you raise it to a sufficient height, then this part will serve as that very base. Below you can watch a video clip where the strip foundation is being poured.

Video: Ribbon Filling Process

The location of the piles in the grillage

In most cases, the supports in the ground are placed vertically. Sometimes an inclined installation may be required, with several pieces in one place. This method is used if horizontally directed forces can arise. For example, when building on sloped areas.

The location of the piles on the plan of the house

Piles can be located pointwise - under the supports (columns, racks). This arrangement is typical for the construction of awnings or roofing over open areas. Then the supports are placed exactly under the columns holding the roof.

For private houses of small number of storeys, piles are placed in the form of a tape. They are placed in one row, sometimes in two or three, shifting relative to each other.Sometimes in the most loaded parts, for example, in the corners, under areas with a large planned load, they are placed in bushes: several pieces at a short distance from each other.

How to place on the plan of the house yourself

When designing a pile foundation on their own, they usually proceed as follows. On the plan of the building, drawn in compliance with the scale, piles must be laid in the corners and at the intersections with the piers. If they are at a distance of more than 3 meters from each other, intermediate supports are placed between them. It is desirable that the piles are located at a distance of 2 to 3 meters from one another.

First, piles are placed in the corners, then under the abutment of the bearing walls

The principle is simple, but you still need to determine the required pile area. And it needs to be calculated (rather, picked up).

↑ Arrangement of the blind area

When the cladding of the pile foundation is completed, experts unanimously recommend making a blind area around the entire perimeter of the house. The most popular solution is to lay paving slabs on a sand cushion. It is performed (sand cushion) in this way:

  • part of the land around the perimeter of the house to a width of 70-90 cm is removed so that a small slope is obtained to the side from the walls
  • a layer of waterproofing is laid in the resulting trench (roofing material is most often used)
  • a pillow (layer) of sand mixed with cement is poured onto the insulating material
  • the sand-cement layer is well compacted
  • paving slabs are laid on the tamped pillow.

The construction of a fake basement is a need to decorate the appearance of the pile foundation. And we examined the materials for cladding in the article.

Usually, the owners of a new home strive to find a "golden mean" so that it is beautiful and labor costs are kept to the minimum possible.

Facing the base on piles - the finishing process is not difficult, but important. Without finishing it is impossible to qualitatively insulate the basement space, and the house itself just looks unfinished.