The choice and arrangement of the foundation is of great importance in construction. This is due to the fact that the quality of the constructed object depends entirely on the reliability and strength of the foundation. When choosing its type, it is worth taking into account the number of storeys of the house, the characteristics of the soil and the financial capabilities of the owner of the site. The construction of a pile foundation is especially effective in heaving soils that are subject to deep freezing, namely more than 1.5 m. Piles can also be used in dense soils. We will tell you how to make a pile foundation with your own hands in this article.

Like any other man-made structure, a pile foundation has both advantages and disadvantages. We'll look at them below.

Among the advantages of the design, the following deserve attention:

• Simplicity and high speed of construction.
• Relatively low cost.
• Relevance of use under the condition of heaving soil.
• Possibility of independent construction.
• Some types of foundations can be built regardless of the time of year.

The disadvantages of this design are worth noting:

• If the building is large, the foundation will not be suitable for the foundation. It can only be used for the construction of relatively light houses made of wood, foam/aerated concrete, etc.
• Calculating a pile foundation is not so easy. To make it reliable, it is better to invite a specialist to carry out accurate calculations.

A distinctive feature is the material used to make the piles. So, the piles are different:

• The cross-sectional shape is rectangular or round.
• According to the material used - wood, concrete, metal or reinforced concrete.
• By size – cross-sectional area/length.

As for the deepening method, piles are divided into types:

1. Reinforced concrete drilling rigs. The reinforcement is placed in an already prepared well and filled with concrete.
2. Screw. They are made of metal. The bottom of the pile resembles the shape of a feint. Immersion in the ground is performed using rotational movements. You can do this yourself or using special equipment.
3. Hammers. Based on the name, this type of piles is driven into the ground using special equipment.
4. Boring injection and drilling. A frame of reinforcement is laid in the manufactured wells, which is subsequently filled with concrete. for drilled injection piles the process is the other way around.

Pile foundation may or may not have a grillage (reinforced concrete beam) in its design. As for the grillage, it is laid directly on the piles. Thanks to this device, the weight of the building will be evenly distributed.

Sometimes a combined foundation is made. For example, strip-pile. In appearance it will resemble a grillage, but it will have a greater height. In addition, during the construction of pile- strip foundation, the grillage can be buried in the ground.

Application

Pile foundations are used in industrial and private construction. You can’t do without it on soft soils, namely:

• heaving;
• humus/peat;
• sandy-clay quicksand;
• plastic clay/loamy soils;
• loess-like soils that lose stability when wet.

A pile foundation transfers the load of the mass of the structure to the harder underlying layers of soil.

This foundation on dense soils significantly reduces the volume of excavation work, so it is often chosen in these conditions. Agree, it is easier to drill holes for piles than to dig a foundation pit. In this case, you will need to spend less money and effort on removing excess soil.

Along the perimeter of the bored foundation, wells should be drilled with a distance between them of 1.5 to 2.5 m. This is done in accordance with the depth and diameter of the piles (from 200 to 250 mm). Next, waterproofing material is installed in the wells, then a reinforcement cage, which is subsequently filled with concrete.

The algorithm of actions is as follows:

1. At the first stage, the location of future piles is marked. They should mainly be in the corners of the house, under long sections of walls at a distance of about 1.5–2.5 m from each other.
2. Next, take a garden drill and make holes in the ground Ø200–250 mm, and their depth should be 300–500 mm below freezing of the soil.
3. At the bottom of the wells, a gravel-sand cushion with a thickness of 100–300 mm should be made.
4. It is necessary to lower the roofing felt or other waterproofing material rolled into a pipe to the bottom, which is necessary in order to isolate the pile from direct contact with the soil. For example, an asbestos-cement or PVC pipe can be a worthy replacement for roofing felt.
5. Now the reinforcement cage is installed. It is made from 3 or 4 metal rods Ø 10–12 mm. They need to be tied together with soft knitting wire. If a grillage is provided, the reinforcement should be 150–200 mm higher than the pile. If the lower frame of the house is laid directly on the piles, then the reinforcement should be 40–50 mm below the top of the pile. In this case, be sure to lay down the studs for subsequent fastening of the strapping.
6. After these steps, pour concrete into the prepared wells in portions, thoroughly compacting it, for example, with a vibrator or a wooden stick, piercing the concrete with it.
7. After these manipulations, a grillage is arranged or the lower trim is laid.

Screw piles are metal pipes that are equipped with blades at the bottom and a sharp tip. The blades themselves are:

• welded;
• with a cast tip similar to a geoscrew;
• multi-turn.

The diameter of the piles ranges from 57 to 133 mm, and the length from 1.65 to 3.3 m.

To install piles, markings are first made around the perimeter of the future house, as described in the previous subsection, and then they are installed. You will need 2 assistants, two will screw in the piles, and you need to monitor compliance with the vertical.

First you need to screw in the piles in the corners. To ensure accurate centering of the screw pile, make a small depression at the place where it is buried. Next, the pile is installed vertically. A crowbar commensurate with the diameter is inserted into its technological holes. Pieces of pipes are placed on the scrap on both sides, which will serve as the driving force. If you have to screw in piles with a diameter greater than 89 mm, then it is better to replace the crowbar with a truck axle shaft. This will give you a stronger lever.

Now immerse the screw pile into the ground using rotational movements. It should be buried 300 mm below the soil freezing level. It is not recommended to rush during the screwing process, since the immersion of the pile must be exactly vertical. This indicator can be checked with a plumb line or building level. A vertical deviation of even 2º will require removal of the screw pile and you will have to screw it in in another place. Please note, however, that this disrupts the arrangement of the piles.

To screw piles into dense soil or to great depths, you can make a homemade device from a piece of pipe having an internal diameter larger than the outer diameter of the pile. It needs to be put on the pile, and the steel pin must be inserted into the technological holes of congruent diameter. Then you need to thread pipes into the loops, with the help of which the pile will be screwed in.

After screwing in the last pile, check the height of their above-ground part. All the top bases of the piles must be in the same horizontal plane. It’s easy to check this indicator; this is done with a level/water level. All deviations must be checked, and then marked and leveled with a grinder.

The internal space of the piles is filled with concrete. This increases their strength and also protects the internal space from corrosion. A head, which is a square-shaped steel plate, must be welded to each pile. The head of piles with a diameter of 89–133 mm can have a size of 250x250 mm. Then the foundation is tied.

With the help of strapping, all the piles are combined into a single whole structure, due to which the load of the house is evenly distributed across all the piles.

Strapping must be done if the piles rise above the foundation by more than 600 mm. In addition, this event should be carried out if the house is built of brick, gas/foam concrete. The strapping itself can be made of different materials, for example, timber, reinforced concrete grillage or channel.

Strapping using timber is performed during the construction of relatively light-weight wooden houses and frame structures. In these cases, a beam with a cross-section of 150×150 mm is used. It is attached to the piles with loops made of soft steel wire.

The beam must be installed on a waterproofing material. This can be bitumen-polymer roll waterproofing. In this case, all metal elements are pre-painted with moisture-resistant paint, and those made of wood are pre-painted with an antiseptic.

Vanroots/purlins are connected in two ways:

1. The device of the Gerber plastic hinge.
2. Connection on piles with an oblique cut or a straight joint. In this case, you need to cover the joints with boards that are nailed.

The Gerber plastic hinge makes the frame less sensitive to pile subsidence. In this case, you should make a double external piping of the foundation. The internal trusses of the piping should be made of single timber 150×150 mm. The purlins are connected with galvanized steel clamp plates/angles and galvanized nails.

In some cases, the strapping is done with a channel. Then the metal profile should be laid on piles. At the same time, for its fastening, embedded pins/outlets of rod reinforcement are provided. The channel is subsequently welded to the studs. If you installed metal piles, then it can be welded directly to them.

To metal elements were less susceptible to corrosion, they need to be opened with special compounds/waterproof paint.

Pouring reinforced concrete armored belt

A grillage is another type of framing. If the foundation is intended for building a house made of brick or gas/foam concrete, then a reinforced concrete reinforced belt is the only correct option for tying. It can be prefabricated or monolithic. The last option is used most often.

At the top of the piles along the perimeter of the base of the house, formwork is installed, after which roll waterproofing is laid in it. Then a reinforcement cage is installed in it, after which the whole thing is filled with concrete. The dimensions of the grillage are calculated depending on the thickness of the walls and the weight of the house.

Driving piles in winter

If it is extremely undesirable to carry out work with concrete in winter, then this period is not terrible for the construction of a pile foundation, especially when it comes to screw piles. There are no obvious differences between the construction of a pile foundation in winter and summer. The only thing that needs to be taken into account is the degree of soil freezing. If the ground is frozen enough, you will not be able to screw in the piles yourself.

To prevent severe freezing of the soil, remove snow from the future foundation construction site immediately before starting work.

The foundation is tied in winter using a channel or timber. Making a high-quality reinforced concrete grillage in the cold season is quite problematic. In winter you need to do concrete mixture using warm water, and it is necessary to add a plasticizer to its composition, which increases the fluidity of concrete, prevents it from freezing and speeds up the setting process. After pouring, the grillage will have to be insulated, which will ensure normal conditions for concrete hardening.

So, it is quite possible to make a foundation from any piles yourself. If the above instructions are not enough for you, then we suggest you familiarize yourself with some videos that will more clearly show you the sequence of these processes. If you still have questions on the topic, then ask them to our expert, who will kindly provide you with additional explanations.

Video

This video will tell you about the features of a screw pile foundation.

And this video is dedicated to the process of installing piles.

Despite the fact that pile-strip foundations are used almost everywhere, not every developer knows how to correctly and competently apply the advantages of such technology and reduce negative consequences to a minimum. After all, such foundations are capable of withstanding enormous loads, but this can only be achieved through properly selected building materials, as well as the construction of the foundation should be carried out exclusively according to finished project and not engage in independent activities. Then the foundation will stand for a long time and fulfill its main function - to be a strong and reliable foundation for any structure.

How to make a pile-strip foundation correctly?

First of all, what is it! This is a monolithic concrete structure, which consists of concrete or reinforced concrete piles and a strip grillage that connects the piles to each other and serves as a load-bearing lintel. Accordingly, the construction of such a foundation should begin not with marking the location of the piles, but with a preliminary sketch of the future building. Why is this necessary? This is a simple calculation that includes the following parameters:

• Selecting building materials for the future building, making a sketch of the structure with a detailed specification of all materials for load-bearing walls and floors;
• Calculation of the maximum mass of the designed structure;
• Calculation of the maximum load on existing soil, taking into account horizontal and vertical movements, as well as the possibility of soil displacement through seasonal movements;
• Selecting the type of grillage. As a rule, for massive buildings, a strip grillage is used, which can consist of concrete blocks or brickwork and is mounted under all load-bearing walls;
• Calculation of pile type and diameter. But this is where mistakes are often made, because there are ready-made formulas for calculating the load on piles, but they do not take into account the parameters of the soil condition and the degree of its deformation. If they are not taken into account, then a deflection will occur in a weak spot with further destruction of the structure.

Advantages of pile-strip foundations

• It is possible to erect a building on the slopes of hills;
• Piles are mounted below the level of weak soils and rest against dense rocks;
• A minimum of building materials and equipment is used here;
• Piles can withstand significant soil movements;
• The design allows you to fix yourself inside a strong rock and stay there;
• You can build it yourself.

Flaws

• Carrying out complex calculations that only professionals can do;
• Heavy massive buildings cannot be erected;
• No possibility of construction ground floor or basement.

But now the key factor that makes such foundations popular among developers is the use of factory-standardized building materials. After all, the main element of such a foundation is a pile. It can be metal, wood, concrete or reinforced concrete, but this is a ready-made material, and it is quite expensive. Or you can do it right at the construction site, and this does not require a lot of money and materials.

Just first you need to get a detailed project of the future development.

Materials and equipment for the construction of a pile-strip foundation

• Equipment for drilling a well or driving piles.
• Cement.
• Sand of low fraction.
• Fittings.
• Welding machine or set of bolted connections.
• Hollow piles with anchors for screwing into the ground.
• Small fraction crushed stone or expanded clay.

To reduce the cost of building the foundation as much as possible, it is better to buy hollow metal or concrete piles that only have blades for recessing or threads. Considering. that a pile-strip foundation is a combination of piles and a strip grillage, then you need to take into account several rules at once:

1. Rigid, but at the same time flexible, connection of piles and grillage;
2. Choosing the right building materials;
3. Select the technology for pouring piles and grillage that is optimal for the given climatic conditions;
4. Carry out the construction of the foundation as quickly as possible so that rainwater does not fall on the foundation or increased dampness begins to affect it.

Pouring concrete is often used if bored piles are used in the construction of the foundation, which you can do yourself right on the construction site. And here an important role is played by pouring concrete not only on the pile, but also on the grillage. The filling technology consists of several stages:

1. After marking the construction site, wells are drilled to a level below freezing of the soil. A sand cushion is installed at the bottom of the well and compacted. Then the formwork is installed inside. Attention: the essence of bored piles is that these are products that are made immediately on the site during the construction of a building, so here it is better to use sheets of roofing felt or asbestos pipe as formwork.
2. A ready-made reinforcing belt is installed in the pipe, connected horizontally every 30 cm with rods. The belt should protrude beyond the pile to a height of 30-50 cm.
3. Then formwork is created at the site of the future grillage, all piles at load-bearing corners and intermediate connections are covered. The connection of piles and tape reinforcement is done using bolted connections; welding is not recommended due to the violation of the integrity of the metal. It is better to use spiral-shaped rods as reinforcement; they provide an optimal connection between concrete and steel.
4. Foundation pouring stage.

What you need to know about pouring such a foundation

1. Type of cement. Here you need to use Portland cement of a grade no lower than M-200. This cement is used to create mortar.
2. The solution should be of medium density, but not liquid.
3. Filling must be done simultaneously or over a short time period, first of all piles. But only when all the fittings are installed and connected.
4. It is recommended to pour the supporting structures first and leave for a couple of days until the concrete hardens. It is not recommended to start pouring the grillage immediately after pouring the piles for one reason: it is practically impossible to achieve the tightness of a pipe with a sand cushion and some of the concrete will leak out through the lower edge.
5. As soon as the concrete is set, the grillage is poured simultaneously in several places. Here it is worth using several fairly powerful concrete mixers to automate the process.
6. After pouring the entire grillage, leave it to dry for several days, up to a week inclusive, so that the concrete gains at least half its strength.

Nuances that are possible when pouring a pile-strip foundation

• You need to fill the piles first, and only then the space of the strip grillage;
• The solution should be of medium density, but not thick;
• The reinforcement must be completely covered; protrusion of vertical layers outside the strip grillage is allowed if the design involves transferring the load to load-bearing walls;
• The entire structure cannot be poured in wet or damp weather, otherwise the concrete will gain excess moisture and lose its strength factor.

Thus, when creating a pile-strip foundation from bored piles or hollow metal piles, it is the pouring technology that plays a key role. It is not recommended to use filler in piles; it can only be used in a strip structure. Only a concrete solution of sand, cement grade M-200 or higher, and water should be poured into the pile.

Do-it-yourself poured piles

The construction of a house, like any other structure, must be approached responsibly. Each stage from site planning to building cladding requires attention and precision. The key to a strong and reliable house is a well-built foundation. However, work at this stage may be hampered by various factors, among which the first place is occupied by climate and soil conditions. Under some conditions, constructing a conventional type of foundation may not be possible. In this case, a foundation on piles comes to the rescue.

Description of the pile foundation

A pile foundation is a collection of piles connected to each other. Piles can be steel or wood. The length of the pile is determined by the condition of the soil on the site, but not less than 150-200 cm. Most often, piles in the ground are placed vertically, by screwing or driving. To simplify this process, each pile has a pointed end.

Piles provide support to the structure in those places where the load is maximum. It is also necessary to place piles where the load-bearing walls of the building connect.

It is used to connect piles. The main building is being built on it.

Scope of application of foundations on piles

The use of a pile foundation is related to the characteristics of the area where construction work is expected to take place. Most often, piles are used under the following conditions:

• The presence of weak soil, which prevails in and in wetlands. Weak or unstable soil is one that loses its stability when water penetrates. When building on such soil, it is necessary to transfer the load of the structure to a denser layer located deeper.
• High location groundwater, which have a detrimental effect on the traditional foundation.
• Uneven terrain on the site.
• Movable soil, which also negatively affects many types of foundation.
• Construction in regions with a predominance of constant low temperatures. The construction of buried types of foundation in such an area is simply impossible. A pile foundation reduces the volume of excavation work, such as trenching and removal of released soil.
• The proximity of any bodies of water.
• The small construction budget does not allow hiring workers to build a traditional foundation. The pile foundation is erected quickly and at minimal cost.

Foundation piles on problematic soils ensure the reliability and strength of the structure. However, build large objects It is not recommended on such a foundation. This is explained by the fact that the foundation on piles has a small load-bearing capacity.

How to pour piles under the foundation

To carry out high-quality pouring of piles under the foundation of a house, it is necessary to follow a certain procedure:

1. Prepare the area and mark it. The construction site is leveled using a level. The places where the piles are planned to be installed are marked. It is necessary to have support at the corners of the house, at the junctions of load-bearing walls and partitions.
2. Using a manual or mechanical drill, holes with a diameter of about 30 cm are made for pouring future piles. The depth of the holes is selected in accordance with the type of foundation and soil condition. It is important that the bottom of the hole is below the soil freezing level.
3. Permanent formwork is installed. If the construction budget is sufficient, asbestos-cement or steel pipes can be used. To save money, you can build. To do this, the material must be rolled into a pipe of a given diameter. The prepared formwork is lowered into the hole so that it rests on the sand cushion. The shell formed in this way prevents freezing of the soil and pile during the cold season. In addition, the design prevents moisture from penetrating into the concrete. When using metal and asbestos-cement pipes, treatment with a waterproofing solution is required.
4. The installed formwork is filled with a small amount of liquid concrete mortar and raised slightly. As a result, a cavity is formed under the pipe into which liquid concrete penetrates. After the mixture hardens, a kind of pillow is obtained at the bottom of the hole. It greatly increases the bearing capacity of the foundation.
5. A frame made of reinforcement is installed. For its manufacture, steel rods with a cross section of 8-10 mm are used. Their number directly depends on the thickness of the pile. Most often, 3-4 rods of reinforcement are connected together with soft wire, installing transverse jumpers along the entire length of the frame. The frame is also lowered into the hole. Reinforcement of the well allows you to protect the future pile from the impact of soil from the sides, which can lead to fracture of the pile.
6. The prepared well is filled with high-quality concrete mortar. Concrete must be compacted periodically using a special vibrator. You can use a crowbar or a piece of reinforcement for these purposes. In both cases, the mixture is compacted by removing air. It is best to fill the piles with concrete in one go, this will make the pile a solid monolith.

Since ancient times, in areas that are often subject to flooding, people have built houses on stilts 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, it nevertheless made it possible to raise the house by one or two meters and save property from water. Pile foundations are now quite often used in cases where a house has to be built on weak, highly compressible or low-strength soil, that is, on such soil that for ordinary shallow foundation doesn't fit.

Driven pile foundation design

A pile foundation (photos of which you will find in the tab) has many advantages and is considered one of the most reliable among builders. If we compare columnar and pile foundations, the technology of the latter is much simpler, since there is no need to dig holes, make formwork, or fill in sinuses. When constructing a pile foundation, you can do without excavation work 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 constructing a pile foundation, you can do without excavation work at all.

On any type of soil, except those containing impenetrable inclusions, it is possible to use driven piles. Driven piles are made from wood (mainly coniferous species: cedar, pine, larch, oak), steel or reinforced concrete. The end of the wooden pile that 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 to prevent the pile from splitting due to hammer blows. For reinforced concrete piles, the lower end is also sharpened.

Video about pile foundation

It is quite possible to build a pile foundation with your own hands, since it does not require removing the soil: the piles are driven into the ground using special hammers, pressing devices and vibratory hammers. The installed driven piles are cut at the same level and connected from above with a grillage, which ensures uniform distribution of the load on all piles.

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

How are bored pile foundations made?

To ensure the integrity of the foundation on heaving soils, it is better to use bored piles. Although this method is more labor-intensive compared to the one described above, you do not have to spend money on renting expensive pile-driving equipment: the foundation on bored piles is made by concreting pre-drilled wells.

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

Drilling 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 over 5 m. Thanks to the special arrangement of the cutting blades, drilling requires little effort. The required depth and diameter of the well are calculated based on the characteristics of the soil (most often, a depth of about 10 m and a diameter of about 20 cm are sufficient).

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

• along the entire length of the wells, a cover made of several layers of roofing material, PVC film or galvanized steel is provided to prevent the piles from being pushed out under the influence of swelling of the soil during frosts (nothing will harm the foundation if the soil slides over the protective cover);
• a reinforcing cage is installed in the wells in the form of connected reinforcement rods, 3 pieces each, with the rods extending above the poured piles to the height of the future grillage - the reinforcement will subsequently serve as a connecting link between the cast-in-place pile and the grillage, and will also prevent possible rupture of the foundation as a result of soil heaving;
• The pile foundation is poured with “heavy” concrete (with quartz sand or crushed rock), filling occurs continuously in each well in layers, the concrete is compacted by bayonet.

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

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

Grillage design for a pile foundation

A pile foundation with a grillage makes the structure more reliable and durable, giving 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 independent construction, since it is much more convenient to pour concrete than to place heavy reinforced concrete blocks on the piles.

There must be a gap between the soil and the lower part of the grillage so that when the soil swells, it does not lift the grillage itself; therefore, in no case should the grillage be placed 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 bars so that the reinforcement is completely immersed in concrete;
• the rods protruding from the bored piles are connected to the reinforcement frame of the grillage for greater reliability of the foundation;
• The grillage is filled with concrete (the same as in).

Pile foundation: reviews, advantages and disadvantages

Of course, the pile-grillage foundation has many 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 near a highway or railway; eliminates the need for excavation work; requires less cost than a strip foundation.

Video about pile foundations. Pros, cons and recommendations

However, a pile foundation also has disadvantages - just read the varied reviews of those who chose this type of foundation for their home. For example, the disadvantages include the fact that installing a basement in a 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 stable enough on subsiding and swelling soils.

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

For unstable soils, it is better not to use classic foundations in the form of a strip of reinforced concrete. In order for a house to stand on such a support stably, the technology will have to deepen it too much. And this means an increase in the volume of excavation work and spending on concrete. It would be much more rational to create a combined pile-strip foundation with your own hands, which incorporates the best aspects of both piles and strip construction.

What is a strip foundation on piles?

In terms of structure, a pile-strip foundation is a structure made of piles dug into the ground to a depth below the freezing point, and a reinforced concrete grillage on them. It combines the advantages of two types of foundation structures. The grillage tape serves to evenly redistribute loads. And the buried pile foundation plays the role of anchors, which prevent the reinforced concrete from above from “floating away” during soil heaving and a strong rise in groundwater.

Scheme: 1-reinforced frame, 2-asbestos-cement piles, 3-concrete strip, 4-technical terminals, 5-waterproofing, 6-ventilation holes

A conventional pile-screw foundation is somewhat inferior to the type of supports for houses under consideration in terms of distribution of vertical loads. A reinforced concrete tape laid on piles is more resistant to spot raising or lowering of one of the support pillars. On the other hand, this design outperforms its purely strip counterpart in terms of construction costs, as well as stability on heaving and waterlogged soils.

Types and subtypes of foundation

A strip foundation on piles is ideal in the presence of soils with weak heaving. In such areas it can be used for the construction of two-story brick cottages. But in general, such a design is more intended for light frame or timber buildings.

However, if the site for the house has a slope, then it will be difficult to do without a pile strip foundation. Monolithic slab here it will be too expensive to fill, and other options will not be able to withstand all the loads that arise in the future as well.

Based on the depth of immersion of the grillage into the soil, pile foundations with it are divided into two types:

Shallow.

Not buried.

Non-recessed option

In the first case, the tape is immersed in the soil by 20–50 cm, and in the second, it hangs above the ground. Due to its greater strength, heavier buildings can be erected on a foundation with a shallow grillage. However, if the soil is heavily heaving, then the strip part of the structure on piles will simply be destroyed by heaving. It is not made too high, so it is simply not able to withstand strong loads from rising soil.

Advantages and disadvantages

Among the advantages of a pile-strip foundation are:

Sufficiently high installation speed;

Possibility to erect buildings on construction sites with a slope;

A simple technology that makes it easy to build such a foundation with your own hands;

High resistance to movement of heaving soils;

No need to use special equipment.

If the grillage is not buried, then it is not afraid of heaving and moisture in the soil. In terms of service life, this option outperforms its buried counterpart on piles and its shallow-depth strip foundation. It also beats them in terms of cost and the complexity of the work. You will have to dig several times less, the depth of immersion is the same, but you only need to remove the soil under the support pillars. Plus, all construction materials can be delivered to the site without the use of heavy cargo and lifting equipment.

When independently constructing pile-grillage foundations, bored supports made of asbestos pipes are usually used, which are reinforced and filled with concrete inside. It is this option that is discussed in the step-by-step instructions below. In terms of speed of construction, only a foundation made of FBS or screw piles made of steel can compete with such a foundation for a house.

There are only three disadvantages:

The need for additional floor insulation in the cottage;

Inability to use for arranging a basement or basement;

Building weight restrictions.

All types of pile foundations have one common problem - drafts in the underground. In the far north, piles help avoid heating the permafrost layer. At the same time, in other regions, wind freely flowing under a building is a serious problem.

Step-by-step instructions for building a foundation

When preparing to make a pile-strip foundation, you must either plan in advance for high heating costs, or immediately include insulation of the basement-foundation part of the building in the estimate and project. In the second case, you will need moisture-resistant insulation for the walls and cladding, but the home will definitely be warm.

It will be necessary to construct a false wall around the perimeter of the cottage to cover the pile pillars and prevent drafts between them. To do this, you can take facade panels for exterior finishing or corrugated sheets. If you want something more beautiful and elegant, then there are clinker tiles and decorative bricks. There are many finishing materials for the exterior of a building.

The entire process of constructing a belt on piles can be divided into two stages. First, the pile part is made from bored pipes. And then a strip structure is laid on them. You just need to remember to tie them together with reinforcement before pouring the concrete.

In general, the step-by-step instructions for a strip foundation on concrete piles are divided into five steps:

Preparatory and drawing work

Excavation of earth, installation of asbestos cement pipes and their reinforcement.

Pouring permanent asbestos-cement formwork with concrete.

Creation of strip formwork from boards and bars.

Reinforcing the tape on piles and filling it with concrete mortar.

Waterproofing reinforced concrete.

We draw on paper or in the program the future foundation - tape and piles

Marking wells with “stakes” for the piles of the future foundation

Piles must be immersed to a depth below the freezing level of the soil at the construction site. Holes for them will have to be dug 40–50 cm below this mark. The foundation must rest on a stable soil foundation.

After preparing wells with dimensions 10–15 cm wider than the outer diameter of asbestos-cement pipes, a sand cushion is poured at their bottom 30 cm thick. The pipe formwork is installed precisely on this compacted sand. The diameter of the pipes themselves is selected at the rate of 1/3 of the width of the reinforced concrete grillage.

Next, each pile is reinforced with three or four vertical steel rods with a cross-section of 10–12 mm and a length equal to the sum of the heights of the support and the tape on it. They are placed in the pipe at approximately equal distances from each other and from the asbestos-cement walls. To simplify, they can be tied with wire into the desired structure on the ground before installation.

The next stage is pouring the pipes with concrete solution. This is usually done before reinforcing the foundation strip on the piles. But the instructions given may be slightly modified. Then, first, the reinforcement is laid in the grillage and formwork is made for it, and then the whole thing is poured with concrete. The cells of the reinforcing belt are knitted with a size of 30–40 cm, depending on the width and height of the tape.

We fill the piles to the level of the tape reinforcement. The photo shows a situation where the pile was “overfilled” and had to be drilled out to install the strip frame

We dig up the “tape”, add sand, lay down roofing material and knit tape reinforcement

To perform waterproofing, it is enough to take ordinary roofing material and wrap it around the grillage. This is the cheapest option. You can also use bitumen or polymer mastic. On this, the foundation of the house in the form of a strip on stilts is made. In the future, it will only need to be covered with cladding and, if necessary, insulated.

Done - you can lay out the walls

Where to use?

When comparing the pros and cons of using a pile-strip foundation, first of all you need to focus on the material of the cottage walls and the characteristics of the soil. If a dwelling is being built from lightweight building materials and on water-logged soils, then the support discussed above with a grillage raised above the ground is an ideal option. Such a foundation will last for many years and will definitely not be damaged by heaving, and it is not difficult to make. Fortunately brought step-by-step instruction allows you to avoid unnecessary mistakes.