How to pour a pile-grillage foundation. How to lay grillages on pile foundations. Cleaning and marking the area

It is difficult for a non-specialist to know which foundation to choose for a house. Traditional strip and slab laying is not used in all cases - there are a number of restrictions. In addition, they are quite expensive, which is not always justified economically.

A pile foundation with a grillage will require less investment, therefore, if conditions permit, it is more profitable to use it.

It seems that this is a house “on legs” Source sampochinil.ru

What is a grillage type pile foundation?

Such a foundation is a structure of piles buried in the ground below the freezing depth of the soil, and connected at the top using a metal or concrete strip (grillage). The supports can be combined by one common slab located at ground level or slightly above. The structure, built in accordance with all the rules, is reliable and has a long service life - several decades.

Source domsdelat.ru

Here you can clearly see what a foundation grillage is - this is the entire upper part of any pile foundation, which is also called the “cap”. The purpose of the grillage is to evenly distribute the load from the load-bearing elements of the structure onto the piles and, accordingly, onto the ground.

There are several types of grillage:

• Made. It consists of separate elements, which are a structure of three piles reinforced with a welded frame. To install them, you will need a crane.

Source orchardo.ru

• Monolithic reinforced concrete. It is a solid plate or strip. Poured directly at the construction site.

Source 24stroim-dom.by

• Prefabricated monolithic. An intermediate option, made from prefabricated parts, which in turn are assembled in a factory, and are already cemented in place using locks and key connections.

Advantages and disadvantages of a pile-grillage foundation

Each of the listed types of foundation has advantages and disadvantages that are taken into account during design in order to prevent excessive consumption of materials, deformations and cracks in supporting structures. Among the most common types of foundation, designers have a choice between strip, slab, pile-grillage and pile. If we compare the pros and cons of a pile-grillage foundation with other types of foundations, then SRF wins in many ways.

In fact, the advantages of a pile-grillage foundation far outweigh the disadvantages Source lowcarb-ernaehrung.info

The properties of a foundation with a grillage determine the following advantages of its use:

• applicable for any soil, including mobile and unstable, water-saturated or peaty;
• convenient when building a house in an area with uneven terrain (for example, on a slope);
• does not require large consumption of materials;
• has a significant service life;
• installation is slightly dependent on weather conditions - work is allowed at air temperatures down to -10°C;
• It is stable and has good load-bearing capacity.

On water-saturated soils, building a foundation requires special skill and accurate calculations Source termeszetvedelem.hu

• there are restrictions related to bearing capacity: the foundation is used only for one- and two-story buildings;
• construction of a basement or basement is possible, but involves complex and costly design solutions;
• installation requires high precision, so it is strongly recommended to entrust it to specialists;
• installation work requires the use of special equipment.

Types of pile-grillage foundations according to the method of immersion in the ground

• Driven. The supports are driven into the ground using construction equipment.
• Printed. It involves drilling wells, which are subsequently filled with concrete.
• Screw. It is a method of screwing in piles using special equipment.

A special expense item is the use of special equipment Source blog-potolok.ru

On our website you can find contacts of construction companies that offer foundation design and repair services. You can communicate directly with representatives by visiting the “Low-Rise Country” exhibition of houses.

Types of piles used

Depending on the method of immersion, piles are selected:

• Hammers. For them, wells are prepared in advance, with a depth of 1/3 of the height of the pile. For installation, special construction equipment is used: pressing machine, vibratory hammer, vibratory hammer. Wooden, steel, reinforced concrete and hollow supports are used as driven supports.

Reinforced concrete piles: if the installation technology is followed, the supports will last for many decades Source block-gbi.ru

• Bored. Formwork and reinforcement are placed in the well for strength, then filled with concrete.
• Drilling Wells are drilled in advance, into which reinforced concrete supports are then installed.
• Screw. They are hollow pipes, at the bottom of which there are blades and a pointed tip. The supports are screwed into the ground using special equipment.

Source stroy-dom-pravilno.ru

Piles can have a rectangular or circular cross-section. The materials used for them are concrete, reinforced concrete, steel of various grades, and mostly coniferous wood. Of the tree species, larch is considered the most suitable, containing a large amount of resins that protect the piles from rotting.

Driven metal piles are one of the cheapest and most durable Source blog-potolok.ru

Advantages of piles:

• relative cheapness;
• insignificant time costs for installation;
• independence from groundwater levels;
• reliability (subject to installation technology).

Screw piles are used even in permafrost conditions Source museblog.ru

All of the above types of piles are used when installing a pile-grillage foundation. When choosing piles, the characteristics of the soil and load are taken into account. For private houses, bored and screw piles are most often chosen.

Classification by depth

Depending on the position relative to the ground, there are 3 types of grillage:

• Low or recessed. Its peculiarity is that it is installed below ground level, that is, in the ground. The grillage is placed on a sand cushion.
• Ground. Located at surface level.
• Tall or hanging. It is located above ground level on high supports. If groundwater flows close to the surface, this type of grillage is used.

Source nauka-i-religia.ru

Recessed grillages are used only in cases of extreme necessity, since their installation is comparable in complexity to the installation of a shallow strip foundation: it is necessary to dig a foundation pit, arrange a drainage sand cushion, make formwork, but also install piles.

Unlike buried and above-ground grillages, hanging grillages are not as labor-intensive and, as a result, less expensive.

Stages of installation of a pile foundation with a grillage

The equipment of a pile-grillage foundation is divided into the preparatory stage and the installation itself. At each stage you have to perform several types of work:

Preliminary work

• To build a foundation, you first need project, which is created based on calculations of loads, the expected depth of immersion of piles, and what materials the foundation is planned from.

A project from a professional is a guarantee of safety, long service life, as well as savings in materials and finances Source nl.decorexpro.com

• Then the site is being prepared: debris, topsoil and plant roots are removed.
• Held territory marking: mark the location of supports, grillage, load-bearing structures of partitions.

Attention! Deviation from the project is always the cause of negative consequences, such as curvature of the foundation, the occurrence of unforeseen expenses, and more. Therefore, it is important that the project is drawn up by professionals and is tied to the area.

The work of a “professional” is immediately visible Source blog-potolok.ru

• A trench is dug for the grillage. Its walls and bottom are checked for evenness with a level. After this, a sand cushion is laid and compacted.
• Wells are being drilled for supports, at the bottom of which a sand cushion is also placed. Waterproofing is placed in the pit: you can use a special film, several layers of roofing felt, or plastic pipes.

Technology for installing a pile-grillage foundation

• For the grillage, reinforced concrete beams are used or a monolithic tape is poured. A wooden rectangular formwork is prepared for it, which is secured with supports and lintels. At this stage it is also worth taking care of the sewerage and pipeline.

Photo of a pile-grillage foundation - after the concrete has dried, the formwork is removed Source bestroof.ru

• To increase the strength of the structure, a reinforced frame is placed in the well - 4 metal rods tied with wire. Then the concrete is poured. The tape is also reinforced.
• Next, concrete is poured first into the wells, then into the formwork. The concrete will take at least 10 days to set, after which the formwork will be dismantled.

How is the need for foundation materials calculated?

An accurate calculation can only be performed by a specialist - a civil engineer, who will rely on the requirements of SNiP and a number of indicators such as the strength of supports, grillage, bearing capacity of the foundation, soil resistance force, degree of shrinkage of the support under the influence of vertical load, etc. The specialist will determine the depth of immersion of the supports, their diameter, number, type of grillage and develop a diagram.

For a person without specialized education, calculations for a pile-grillage foundation look something like this Source ask.fm

When calculating the number of supports, they are based primarily on the load on the foundation, which consists of several indicators. Here it is necessary to know the mass of load-bearing walls, partitions, roofs, floor slabs, i.e. the entire mass of the building above the foundation. The payload produced by residents, household items and all other things is also taken into account. In calculations for private houses, an indicator of 150 kg/m² is used.

The last parameter for determining the total load is the weight of the snow mass that can accumulate on the roof in winter. The value generally used is 180 kg/m², but for a number of regions of the country it is slightly different. The resulting sum of loads is multiplied by the safety factor, which is 1.1 (sometimes 1.2 is used). Next, you can calculate the load on one pile.

It would not be out of place to add that online calculators for calculating materials that are widespread on the Internet should be treated very carefully. They may not take into account a number of important parameters.

Video description

For an example of an online calculator, see the video:

Installing additional items

When constructing a pile-grillage foundation, it is necessary to arrange openings for ventilation in the foundation and lay pipes that can be used for heating, sewer, water supply systems and other communications. If you do not take care of the engineering and technical equipment of the house in time, later to install them you will have to partially destroy the grillage.

To preserve the foundation, it is necessary to provide vents for ventilation. Source remontstroy.net

Requirements for creating a high-quality grillage foundation

Since the main loads on the grillage are bending forces, one of the key points when creating a grillage foundation is reinforcement, which significantly increases the strength of the structure.

Source stroidominvest.ru

The second significant point concerns the hardening time of the concrete structure - which is a whole month. The grillage will be able to withstand the proper loads only after the concrete has completely hardened.

Possible mistakes when arranging the foundation

• The piles are not firmly attached to the grillage - thermal expansion during seasonal temperature fluctuations will soon loosen the fastening point.
• The piles are laid at too shallow a depth. Here, both excessive shrinkage of the foundation and squeezing out of loose piles in the layer below the freezing of the ground by forces of soil heaving cannot be ruled out. All this can lead to the destruction of the building.
• Inaccurate calculations. It's just a powder keg - you never know what might happen.

Video description

About the features of a pile strip foundation, watch the video:

These are typical, but not all mistakes that unqualified builders make. There are many stories on the Internet about what went wrong during self-construction, but even knowledge of other people’s mistakes often does not compensate for the presence of real skills and experience. As a result, everyone should mind their own business.

Qualified specialists must calculate and build Source pinterest.com

What does the cost of SRF depend on?

If the project provides for the installation of a pile-grillage foundation, then what the cost of the SRF depends on is determined by a whole group of factors:

• scale of construction;
• type and number of supports, their diameter and length;
• dimensions of the foundation tape;
• use of special equipment;
• region;
• construction company policy.

Online foundation calculator

To find out the approximate cost of a “grillage on piles” foundation, use the following calculator:

Video description

For a clear picture of the cost of a pile-grillage foundation, see the video:

Conclusion

A pile-grillage foundation is considered more reliable than a pile foundation, and more advantageous than a strip foundation, and in some situations it is the only possible one. But only qualified specialists can correctly make calculations and equip it. Otherwise, such a foundation will have insufficient strength or excessive cost, which equally neutralizes all its advantages.

The article talks about the principles of constructing a pile foundation with a grillage, as well as options for tying a foundation made of screw piles. More information about other stages of construction of a pile-screw foundation in the section " ».

A grillage is a structural element that allows you to distribute the loads from the structure along the base.

High and low grillages can be used to frame a foundation made of screw piles.

Pile foundation with high grillage

A high grillage is a beam that unites the pile heads and redistributes the load on them from the structures above, while its base is located above the ground surface.

The greater the distance between the piles, the larger the cross-section of the beam used should be.

A beam, a log, a channel, an I-beam, or an angle (long-rolled beams) can be used as a beam.

Tying a pile-screw foundation with timber or logs

Strapping timber (Fig. 1) is used in the construction of wooden frame buildings.

Picture 1

Beam section:

150x150 with a pitch between piles of 2500-2700 mm;

200x200 mm with a pitch between piles of 3000 mm.

Fastening to the head is carried out using a pin.

Waterproofing is not essential, since metal does not absorb moisture like concrete. However, since condensation can form on metal surfaces, it is still recommended to lay a waterproofing gasket between the supporting platform (head) and the wooden structure.

Log (Fig. 2). This material is resistant to bending, as the wood maintains its integrity. A rounded log gives greater deflection compared to an untreated log, since in this case the integrity of the hard layers of wood is compromised.

Figure 2

The first crown of a log structure can be laid directly on the head. If the foundation is made of concrete, then it should be made of oak or larch, as this will increase the service life of the structure. In the case of a pile-screw foundation, these measures can be abandoned if the height of the grillage is at least 500 mm from the ground level.

Timber/log tying is the most economical and quickly implemented type of connection. To prevent the harness from deforming, the piles must be located at the same level. Otherwise, leveling is performed by partially sawing out the timber/log.

Joining timber/logs (Fig. 3). To connect, cuts are made in proportion to each of the bars at the top and bottom, and the bar/log is folded at a right angle. The joints must be treated with special solutions that protect against moisture and lined with jute.

Figure 3

The use of antiseptics for timber/logs is mandatory only for concrete bases. When constructing a foundation from screw piles, this procedure is advisory, but only if the height of the grillage is at least 500 mm from the ground level.

Tying a pile-screw foundation with a channel or I-beam

The design solution of the metal grillage is determined depending on the loads on the foundation SNiP II-23-81* “Steel Structures”, SP 53-102-2004 “General Rules for the Design of Steel Structures”.

Strapping is done either manually or using special equipment (depending on the standard size of the channel/I-beam).

Channel (Fig. 4 – 7). Lay flat or on edge. The rib option works better for deflection, but due to the torsional moment that arises, in this case it is better to use a welded channel.

Figure 4

Figure 5

Figure 6

Figure 7

If the channel is laid flat (flanges down), then when the pile spacing is more than 2000 mm, it bends even under its own weight, so when choosing this option, the distance between the piles should be designed no more than 2000 mm.

I-beam (Fig. 8). Used for reconstruction of foundations.

Figure 8

In both cases (channel or I-beam), the connection of the structural elements is welded.

Sufficient thickness of long products (from 5 mm), as well as the susceptibility of this part of the structure only to atmospheric corrosion will ensure that its service life meets the requirements of GOST 27751-2014 “Interstate Standard. Reliability of building structures and foundations. Basic provisions”, even without additional anti-corrosion protection. However, after completing the welding work, the structures (at least for aesthetic reasons) should be treated with an anti-corrosion compound.

Screw pile foundation with low grillage

A low grillage (shallow foundation or reinforced concrete strip (Fig. 9) is a distribution beam that unites the pile heads and redistributes the load from the structures above them, and its base is located on the ground surface or below.

Figure 9

The load is distributed not only over the piles, but also onto the ground.

For this type of grillage, all the requirements for concrete foundations are relevant in terms of waterproofing and the use of antiseptics (for wooden and frame-panel structures).

The height of the reinforced concrete grillage is determined by calculation in accordance with SNiP 52-01-2003 “Concrete and reinforced concrete structures. Basic provisions". Reinforcement is made with flat meshes, usually from A-III (A400) reinforcement. Concrete with strength grade B15 or B20 is used.

Domestic builders of private houses usually prefer to make a monolithic strip foundation. But for large soil freezing depths, this option is expensive. After all, in such a situation it has to be laid very deeply, and this means additional significant costs for reinforced concrete. In order to reduce the cost of constructing the foundation of a cottage, private developers are now increasingly beginning to give preference to a pile grillage foundation, the deepening of the support piles of which is much cheaper.

What is a pile foundation with a grillage?

Structurally, a pile-grillage foundation is a series of supports immersed in the ground below the freezing point, and connecting them on top with a “bracing” of steel or reinforced concrete. The first rows of bricks or timber (logs) are already laid on the latter. This design ensures uniform redistribution of loads from both the house and the ground.

Foundation diagram

The point impacts from the piles that arise during heaving disperse throughout the grillage strip of such a foundation. The walls do not experience excess pressure at any one point. Distortions and destruction of masonry on such a foundation are practically excluded.

Types of foundation on piles

The grillage of this type of pile foundation is made of monolithic reinforced concrete or steel channel. The most commonly used concrete structure with reinforcement. It can withstand significant loads. The option where the piping is metal is more intended for light buildings (garages, outbuildings, buildings made of SIP panels and bathhouses).

Pile foundation with metal frame

Pile foundation with monolithic piping

Depending on the type of supports used, the pile-grillage foundation comes in two varieties:

Screw.

Bored.

In the first case, it is an almost complete copy of the foundation on screw piles. Only on the supports is a more powerful monolithic grillage. At the same time, steel “screws” for such a design have to be chosen that are stronger, with larger wall thickness and diameter.

Those who are going to make the foundation with their own hands often prefer to use bored piles in permanent formwork in the form of asbestos-cement pipes. This technology is simpler and cheaper when done independently.

Advantages and disadvantages

The piles of the supporting structure in question, due to their large immersion depth, provide excellent stability to the entire mini strip foundation on top. And they cost much less than a reinforced concrete monolith of the same height. Moreover, if the support pillars are tied on top not with a concrete tape, but with a metal grillage, then you can save a little more. This option is one of the most inexpensive ways to create a support for a private home.

This foundation has the following advantages:

Possibility of arrangement on slopes and in marshy areas;

Relatively cheap construction of a pile grillage structure;

Minimum time spent on foundation construction;

No need to use lifting vehicles;

Simplicity of the technology for installing bored and screw supports, as well as pouring concrete;

Excellent stability indicators in moving heaving areas.

In terms of device speed, a pile foundation with a grillage is inferior only to an analogue made only of screw supports. Plus, a foundation made of wall foundation blocks will be ready to give a head start to the structure in question. In both cases, the high speed of work is due to the lack of concrete work, when it is necessary to wait several weeks until the concrete completes its strength.

If the building site has a slope, then pouring a monolith on it is problematic and expensive. It will be difficult to do without this type of foundation on such a site. Only with the help of piles will it be possible to create a stable and horizontally level base for the structure. This is one of the main advantages of the foundation. All other options are immediately inferior to him on construction sites with complex terrain.

Another undeniable advantage is the extreme simplicity of execution. It’s not difficult to make your own pressed supports from asbestos-cement pipes and concrete inside. It’s even easier to make a reinforced concrete strip of small size and weight on them.

Minor difficulties here can arise only when installing the formwork suspended. It cannot be immersed in the ground. The pillars must raise the grillage part above the ground by at least 30 cm, otherwise, if there is severe heaving, it may “float” from the supports along with the building on top.

There are also disadvantages to a foundation with a concrete grillage on piles, but there are frankly few of them:

Inability to make a basement;

Costs for additional floor insulation.

The underground space of a cottage on a pile foundation with a grillage must be closed from the wind, otherwise constant drafts under the floor will blow all the heat out of the building. To do this, you can use facade panels from various materials or make masonry from beautiful facing bricks. Plus, the floor in such a house will definitely have to be insulated. It is better to immediately include these expenses in the overall estimate for housing construction.

Step-by-step instructions for building a foundation with your own hands

It is best to entrust the calculation and preparation of a foundation project for a house, whether it be a pile-strip foundation, to a professional designer. If the piles are chosen incorrectly in height and thickness, then the reinforced concrete support and the building on it will not last long.

Marking on the site

At the same time, it is also not worth setting parameters “in reserve”; this will only lead to an increase in the cost of work. As such, constructing a foundation of the type in question with your own hands should not cause difficulties. Below is a brief step-by-step instruction that will allow you to quickly understand all the nuances of this process.

To make a foundation from bored piles and a monolithic grillage, you must:

The bottom edge of the supports should be below the freezing point of the soil. In this case, the holes for the piles are made 10–15 cm wider than the asbestos-cement pipes taken. In order for the pillars to stand more firmly in place, an expanding concrete base is installed in their lower part. Holes in the ground for supports are made in width just to fit its dimensions.

Waterproofing of concrete is carried out with roofing felt or mastic. Even flexible shingles made from modified bitumen will do. True, it will cost more than regular roofing felt.

Usage

Comparing the pros and cons of the pile-grillage foundation structure, it is immediately clear that the former are much more numerous than the latter. Such a foundation is suitable for both small outbuildings and one-story private houses made of foam concrete or brick. At the same time, you can do everything yourself without any problems. Not much earthwork and concrete work will have to be done, and the construction of the structure itself is extremely simple.

Any structure needs a reliable, high-quality, well-designed and equipped foundation. Today, a grillage foundation on piles is very popular, which has economic benefits compared to a traditional strip foundation. A special feature of the design is the horizontal lintel connecting the piles. Grillage: what it is and what its main purpose is, is described in detail in the article.

It is necessary to begin to consider this issue with a definition: what is a foundation grillage. The internal building element is a horizontal concrete, steel or wooden lintel that connects the disparate elements of a columnar or pile foundation with each other, resulting in the creation of a flat platform for installation of the flashing crown. The grillage takes the load from the load-bearing structures of the building and evenly distributes it to the supports, which transmit the load to the ground.

This design is not inferior in its rigidity and strength to a traditional strip foundation, but the price of a grillage foundation will be much lower, which is associated with less labor and labor intensity.

The foundation structure is created using frame technology, where pillars or piles are tied together to form a strong foundation. A foundation with a grillage is constructed on clay, peat, loess-like, loamy, heaving and silty soils. The construction of a house can be carried out in areas with ornate terrain or on slopes.

Types of grillage and what types it has

The ergonomics, durability and aesthetics of the building depend on the type of grillage that is laid on a columnar or pile foundation. It can be slab, tape and glass.

Depending on the location of the grillage relative to the subgrade, the following types of structures are distinguished:

• increased;
• high;
• recessed

The jumper design can be:

• monolithic;
• prefabricated monolithic;
• national team.

Depending on the material of manufacture, grillages are distinguished:

• metal;
• wooden;
• concrete;
• reinforced concrete.

Types of element and the main task of the grillage

The main purpose of the grillage is to absorb the load from the load-bearing elements of the building and distribute it evenly on the foundation. The most common and economically justified is a pile foundation.

A slab grillage on piles in the form of large-format reinforced concrete slabs is installed with significant dimensions of the building along its perimeter. This grillage is placed on a standard pie consisting of:

• sand and gravel cushion in the form of two layers of 10 cm each with vibration compaction;
• ring drainage located at the level of the grillage base;
• concrete preparation in the form of a screed without reinforcement;
• waterproofing.

Strip foundations on piles can be monolithic or prefabricated. The first option is used for bored piles. This is due to the fact that the materials have the same linear expansion and technical characteristics. It is also easier to wall up the heads with protruding reinforcement in the body of the grillage.

Prefabricated strip grillage is used in wood construction technology. Wooden beams are laid on the heads and joined into half a tree. This allows you to reduce construction costs and begin construction of the structure the very next day after laying the foundation.

A prefabricated strip grillage can be made in the form of reinforced concrete beams adjacent to the pile cap. This design is used primarily for screw piles tied with I-beams or channels.

When installing reinforced concrete bored piles with a grillage, a glass type of structure can be used. The grillage is represented by a kneecap mounted on a pole, a multiple of 15 cm in height and 30 cm in width. Each glass must be supported by four piles. This type of base is used when installing columns. Most often used in agricultural and industrial construction.

What is a grillage: element design

A monolithic grillage is the most successful solution for low-rise construction. The element is represented by a solid closed-type structure made of reinforced concrete or concrete. It is poured during construction, in the form of a monolithic slab or beam (ribbon). In the first option, the design connects all the piles into a single system that covers the entire area of ​​the building. The tape grillage connects the piles in series and is installed only under the load-bearing elements of the building.

The grillage, securely fixed to the piles and incorporating them into its thickness, connects the base elements. A monolithic strip grillage can be raised, high or recessed. It is arranged under unfavorable geological soil conditions. The implementation of such a grillage is distinguished by high technical and operational characteristics. However, the design has increased labor intensity, high cost of work and requires the creation of dense reinforcement.

The prefabricated grillage is represented by a structure made of steel beams connected to each other by welding. I-beams and beams are used as connecting elements. The structure can also be made of wooden beams. This option is used mainly for the construction of non-permanent structures and industrial buildings. The structure is mounted and secured to the pile heads, which does not require subsequent embedding.

Helpful advice! It is not advisable to use a prefabricated grillage for the construction of a private house, since this is associated with a very labor-intensive and costly process.

The prefabricated type also has its disadvantages. First of all, the installation process is very labor-intensive, which is associated with the significant weight of the metal elements. In some places of the grillage, areas with low strength may form, which is associated with the low rigidity of the welded joints. Due to the formation of corrosion or rotting of wood, the structure is short-lived, which is limited to 1020 years of operation.

An intermediate solution between the two previous options is a monolithic prefabricated grillage. A prefabricated structure consists of prefabricated parts that are laid on piles and connected to each other with a key joint. This is done during construction. Then the entire structure is monolithic.

Optimal grillage location

The most rational solution from the point of view of the integrity of the structure and the stability of its operation in the event of various deformations is considered to be the installation of a high or hanging grillage on bored piles. It is installed above the ground level at least 10 cm. If the distance is less, there is a possibility of damage to the integrity of the grillage and the nodes connecting it to the piles, which will lead to the tearing out of the latter.

The main disadvantage of this design is the lack of sealing of the space between the lower part of the grillage and the ground. Due to the fact that free access of cold air is created, heat loss in the house increases. The problem can be solved by installing panels or additional insulation of the floor of the house.

Helpful advice! It is advisable to choose this type of grillage for a subtropical climate, also when constructing wooden structures.

The base of the raised grillage is located at the ground level, on which a gravel or sand cushion 10-15 cm thick is laid, for which a layer of soil is removed. This layer helps reduce soil moisture under the building and freely filter water. This option eliminates the formation of a blown area between the ground and the ceiling.

A recessed strip foundation on bored piles is the most popular option, but at the same time the most irrational. To create it, a shallow trench is dug around the perimeter of the future building. Next, the piles are installed so that their heads protrude from the bottom of the trench. A sand cushion is installed. After this, a formwork trough is made, the bottom of which is located below ground level. Next, a concrete grillage is created.

Helpful advice! Despite the fact that a windproof space is formed under the recessed grillage, centerboards can be installed as additional insulation, which will take the load from heaving soil during frosts.

What material is the grillage made of?

Reinforced concrete grillage is characterized by increased strength, reliability, stability, rigidity, load-bearing capacity and durability. This is the most common option. The structure contains reinforcement, which increases the strength characteristics of the grillage, taking on part of the load. Reinforcement can be performed by creating a full-fledged spatial frame or laying individual rods.

Important! When forming a reinforced concrete grillage, a sufficient protective layer for the reinforcement must be provided.

The production of a concrete grillage is identical to the previous option. The difference is the lack of reinforcement. The entire load is absorbed by a concrete structure that covers the pile heads to a height of at least 10 cm. This option is less strong and durable. Concrete grillage is used in the construction of one-story buildings.

The production of a metal grillage is carried out from rolled profiles, represented by I-beams and channels. The result is a strong and rigid structure. But due to possible corrosion of the metal, especially in places of welded joints, the metal grillage is short-lived. It is used for the construction of one-story buildings.

Characteristics of a pile foundation with a grillage

A pile foundation is a structure in which the load on the ground from a structure is transmitted through piles, which are represented by pillars or beams partially or completely buried in the ground. For a rigid and reliable connection of the upper parts of the piles, a grillage is installed. It is rational to use this type of foundation when constructing buildings on water-saturated soft soils, on slopes with a steep slope, in areas where the depth of soil freezing exceeds 2 m, and also if the weight of the future structure exceeds 350 tons.

Related article:

Drainage system around the house: drainage device for the foundation of a residential building

Drainage device to protect the foundation part of the building, the specificity of this procedure, the technology for creating a structure with your own hands.

Piles are metal, wood or concrete pointed, long or heeled rods of round or square cross-section. They are immersed in the ground in finished form or made directly into the soil. In its finished form, the pile has a sharp end on one side, with which, with the help of special construction equipment, it is immersed into the thickness of the soil, passing through moving layers, and rests on solid soil. When making piles, holes are drilled in the ground, which are subsequently reinforced and filled with concrete.

Types of pile foundations with grillage

Depending on the method of immersion into the ground, a pile foundation can be driven, driven or screwed. The first option is represented by concrete or reinforced concrete structures. To create them, the reinforcement is prestressed, which increases the crack resistance of the foundation. To install piles in the thickness of the earth, it is necessary to drill the required number of holes of a given diameter and depth. A casing metal or concrete pipe is inserted into each of them. The reinforcement is lowered into it and the entire cavity is filled with concrete.

The design can be made with a closed or open lower end. The main advantage of this type of pile foundation is its high load-bearing capacity, simple technology, reduced cost of work, which is associated with minimal labor costs, and the absence of negative impacts and vibrations on surrounding structures.

The second option involves driving ready-made reinforced concrete piles into the ground. As special equipment, pile drivers, vibratory hammers and hydraulic pile-pressing units can be used, the choice of which depends on the characteristics of the soil, the features and depth of driving piles. This type of foundation is used in permafrost zones. The driving elements can be round, square or trapezoidal. To increase reliability and load-bearing characteristics, piles can be equipped with additional support rings.

Screw grillage foundation: what is it?

A foundation with a grillage on screw piles is one of the new options. The design has good performance characteristics and can be installed on any type of soil. The pile is represented by a hollow pipe, a sharp tip and one or more blades. The tip can be welded or cast.

For each type of soil, a certain type of screw piles is used. For stone areas, narrow-bladed screw piles are used, which have especially strong welded tips and double blades, which ensure reliable adhesion to the ground and prevent the pile from skewing. For thawed and waterlogged soils, piles with a sharp cast tip and medium-sized blades are used, which guarantees easy penetration of the element into the soil without loosening it.

For permafrost soils, piles with small blades are used, which facilitates the rapid introduction of the element into the soil without the risk of distortion. The tip of the pile has a special cutter made of especially strong alloy steel. Such elements are highly expensive.

Options for the location of piles and their types

Piles can be hanging or in the form of racks. In the first option, the load on the surrounding soil is transmitted through friction against the side walls. Such piles are characterized by a developed lateral surface along the entire length with many protrusions, which ensures good load-bearing capacity of the structure. This type is used for soils with a high groundwater level or having a thick layer of weak soil, under which there is a stronger one, but it is still not able to support the rack pile.

Rack piles transfer the load from the structure directly to the strong soil, which is located under the weak layer. The elements are characterized by a smooth surface to which the soil does not cling. The most important criterion for this type of pile is a wide base, which can bear more than 80% of the total load.

Helpful advice! For multi-storey and durable buildings, it is advisable to choose TISE rack piles, which have a significant widening in the lower part of the element, which eliminates further settlement.

Piles in the ground can be located in one of the following ways:

• single;
• tape;
• stripes;
• in the form of a bush;
• field.

The first method is selected for a free-standing support. Depending on the terrain, the pile can be installed inclined. The tape method involves placing piles along the entire perimeter of the structure. For the construction of massive multi-story structures, piles are installed in several rows in the form of strips.

Cluster placement involves installing elements under load-bearing walls and objects with heavy loads. This method is used for the construction of canopies and structures with a large number of columns that hold the roof. For large buildings, piles are installed in a checkerboard pattern.

The choice of pile placement method depends on the construction project. Elements should be located in corners and at the intersections of piers. The optimal distance between piles in a grillage is 2–3 m.

Pros and cons of a pile-grillage foundation

When choosing a foundation for a future structure, it is necessary to study the pros and cons of a pile foundation with a grillage. This design has excellent stability and high load-bearing capacity. This is especially important for building houses on soils that are prone to movement. This type of foundation is often found in seismically active areas, where the foundation will remain motionless during small earthquakes.

Important! Classic piles can withstand loads of up to several tons.

It is advisable to choose a pile-grillage foundation for the construction of structures on soils with a complex structure, especially in mountainous areas, which are characterized by a small layer of loose soil. Manufacturers produce piles of various lengths, which allows you to build foundations on slopes, as well as create curved objects. A pile-grillage foundation is an ideal foundation for the construction of a building from any material.

Due to the fact that the grillage is not in contact with the ground, the possibility of flooding of the structure with groundwater and rodents and various insects entering the house is eliminated. To erect a pile foundation with a grillage, there is no need for preliminary cleaning and leveling of the construction site, which reduces the labor intensity and cost of work. You can build the foundation yourself without using powerful construction equipment, which is especially important in densely built areas or on small plots of land.

However, this design has its drawbacks. When designing this type of foundation, accurate calculations should be performed with the assistance of a specialist. Here you should take into account the length, diameter, weight, number of piles and their exact location.

Important! Pile foundations are not recommended for use for heavy, massive structures, even by increasing the diameter of the pile elements.

Another disadvantage is the labor-intensive repair of the foundation, which will require the construction of retaining walls or the installation of additional piles. The construction of a pile foundation with a grillage eliminates the need for a basement and requires additional insulation of the lower part of the building.

Calculation of pile-grillage foundation

Calculating a pile-grillage foundation is a serious and responsible undertaking. This process is best left to a specialist in this field. To perform the calculation, it is necessary to collect information about the territory for construction: geological structure and physical properties of the soil, hydrogeological and physical-geographical conditions of the area. You can obtain all the necessary information from your local geological exploration service by placing an order in advance.

Based on the data obtained, calculations of the parameters of the selected foundation are performed. The load on the foundation with a grillage is calculated based on the total mass of the structure. Next, the depth of the supports is calculated. Based on the bearing capacity of the foundation and the magnitude of the load, the minimum total area of ​​the supports is determined. Next, the type, diameter and number of piles are selected, which are distributed over the area of ​​the building, according to the selected layout. Next, the dimensions of the grillage are determined by calculation.

Helpful advice! To calculate a pile foundation with a grillage, you can use online calculators or the services of specialists from construction companies.

The calculation of the pile foundation grillage is carried out on the basis of SNiP II-B.1–62. It should be taken into account that the width of the structure should be 10–20 cm thicker than the wall of the building, and the height should be approximately equal to the width. The final stage is the selection of building materials.

Installation of a pile-strip foundation with your own hands

Constructing a grillage on a columnar or pile foundation with your own hands is a feasible and feasible task. It is advisable to choose the first option for the construction of small structures without constant load, such as country houses and gazebos. Pile foundations are the most popular solution for the construction of buildings intended for permanent use.

It is advisable to construct a pile-grillage foundation with your own hands in late spring, early summer or early autumn. The first step is to prepare the site by clearing it of debris and vegetation.

Helpful advice! It is recommended to treat the area for future construction with chemicals, which will prevent the growth of vegetation.

Next, the territory is marked based on the project, indicating the locations of the piles. If screw piles are used, they should be screwed in without first creating holes. To do this, you can use a pipe or a crowbar, which must be inserted into the head of the support. For screw piles, it is more convenient to make a metal or wooden grillage. It is advisable to install a concrete lintel only under a future house made of stone, which requires high rigidity of the base.

Important! The piles must be positioned strictly perpendicular to the ground.

If you are installing bored piles, you will not be able to install them yourself. To create holes in the ground, you need to use special equipment. Bored piles can be made in two ways. The first option involves placing formwork in the form of a metal pipe of the required diameter in each drilled hole. The internal space is reinforced and filled with concrete. The second option eliminates the installation of formwork.

To construct a pile foundation with a grillage, class B7.5-B15 concrete is used, which is the optimal solution for small buildings. For large buildings, concrete of class up to B25 can be used. It is not advisable to use a more durable building material for private housing construction. This is not economically justified, since the safety factor of the material exceeds the load from the building. Reinforcement with a diameter of 12-16 mm of class A400 is placed in each hole.

Laying a pile foundation with a monolithic grillage

For the work you will need the following tools and materials:

• bayonet and picking shovel;
• stakes;
• rope;
• wooden boards or chipboard sheets for formwork;
• set of steel screw piles;
• fittings for reinforcing piles and grillage;
• metal pipes;
• concrete solution;
• plumb line;
• level or hydraulic level;
• roulette;
• specialty chemicals;
• foam boards;
• sand;
• crushed stone;
• bitumen mastic.

The construction of a pile foundation with a monolithic grillage is carried out according to the following algorithm:

• cleaning and leveling the base;
• drilling holes in designated locations of the required depth and size for piles;
• compacting the soil and creating a cushion of medium or coarse sand 30-50 cm thick at the bottom of the holes;
• installation of screw or bored piles according to the work technology;
• preparing a sand cushion for a monolithic grillage;
• formwork installation;
• a frame made of reinforcement is lowered into the pit, consisting of at least 4 rods, the length of which is selected taking into account the height of the strapping;
• performing concrete pouring;
• creation of wooden formwork for a monolithic grillage;
• after the concrete has hardened, the reinforcement frame for the grillage is assembled;
• installation of formwork for strapping;
• concreting the grillage;
• removing the formwork after the concrete has gained the required strength;
• performing waterproofing.

Helpful advice! If an underground space is formed, it is better to cover it with a decorative base or fence.

The grillage is reinforced using rods of class A400, which can be joined into a frame by welding or tied using binding wire. The second option is more labor-intensive, but reliable. When laying the frame, you should leave a distance from the rod to the formwork of at least 3 cm - to create a protective layer of concrete, which will prevent the formation of corrosion.

Helpful advice! At the corners of the building, reinforcement bars must be tied with wire.

Creation of a monolithic foundation grillage on piles

Before installing the grillage, a layer of waterproofing should be laid on the piles. This is necessary in order to eliminate the possibility of the soles of the elements getting wet. Roofing felt, polyethylene films or membranes can be used as a waterproofing material. If a cushion of fine gravel is provided under the base of the grillage, which may compromise the integrity of the waterproofing layer, a concrete footing should be provided.

The next stage is the installation of formwork for the foundation on concrete piles. To do this, markings are carried out in increments of 0.5-0.8 m with driving in pegs with a cross-section of 5x5 cm along the entire perimeter of the building. Next, horizontal wooden boards are laid, in which holes for the piles are pre-cut.

Vertical formwork elements are installed and nailed to horizontal boards. For formwork, it is recommended to use durable wooden boards or chipboard sheets. The inside of the prefabricated formwork should be covered with plastic film. The dimensions of the formwork must exceed the height of the future grillage by at least 5 cm.

Helpful advice! In the case of a low grillage, you can use permanent formwork, which will subsequently become additional thermal insulation for the walls of the premises.

Grillage reinforcement: step-by-step instructions

The next step in constructing a pile foundation grillage is the creation of a reinforcement frame, which must subsequently be completely recessed into concrete on all sides. To do this, it is necessary to lay wooden blocks of any width on the bottom of the formwork in the transverse direction, but with the same thickness of 30-50 mm. The bottom row of reinforcement bars is laid on them, which must be tied together so as to ensure the same distance between the rods.

The upper chord of the reinforcement cage must be suspended from the transverse beams that connect the formwork posts. Then you should tie the lower and upper belts together.

For reinforcement of monolithic tape, class A400 reinforcement is usually used. The number of rods is calculated based on the ratio of the cross-sectional area of ​​the horizontal lintel to the sum of the cross-sections of all rods, which is 1000:1. The following calculation procedure is performed:

• it is necessary to multiply the width by the height of the grillage, dividing the result by 1000;
• the resulting value must be divided by the cross-sectional area of ​​one rod.

The result obtained is the minimum number of bars required for reinforcement.

Helpful advice! The distance between rows of reinforcement should not exceed 150 mm.

Installation of additional elements and concreting the grillage

Before pouring concrete on a horizontal lintel, special pipes should be laid through which utilities will pass, such as water supply, heating, sewerage and communications. Ventilation holes should also be provided in the base.

Important! This stage should not be neglected, since then the integrity of the grillage will have to be compromised.

To create a monolithic grillage, it is recommended to use concrete grades M300 and M500. When filling the formwork with concrete mixture, you should use a vibrating machine that can shake the concrete to eliminate the possibility of cavities, which will increase the strength characteristics of the concrete.

Two hours after pouring the concrete, it is recommended to cover it with film. If it is hot outside, it is periodically necessary to remove the film and moisten the concrete with water so that cracks do not form on its surface. Complete hardening of the structure will not occur earlier than in a week, which depends on the ambient temperature.

If the outside temperature reaches 20 degrees, the formwork can be removed after 4 days, since the concrete base will gain more than half its strength. If the temperature does not rise above 10 degrees, the formwork does not need to be touched for 14 days. When the air temperature is below 10 degrees. it is necessary to provide additional heating and organize insulation of the foundation. After the concrete has completely hardened, you can begin to create a waterproofing layer using bitumen mastic.

Construction of a columnar foundation with a grillage

The construction of the foundation for future construction is carried out according to the following algorithm:

• clearing the area of ​​vegetation followed by treatment with chemicals;
• marking the site based on the project;
• creating holes for future pillars;
• compacting soil at the bottom of the pit;
• creating a sand cushion at least 15 cm high;
• laying geotextiles;
• backfilling with crushed stone;
• performing formwork for each pit;
• covering the formwork system with polyethylene;
• creating a frame for reinforcing piles;
• forming pillars by pouring concrete into holes;
• treating the surface of the pillars with bitumen mastic;
• installation of formwork between reinforced concrete pillars to create a grillage, the height of which should exceed the height of the future structure by 5-10 cm;
• sand cushion device;
• concreting the grillage with structural reinforcement;
• creation of hydro- and thermal insulation.

The main mistakes when constructing a pile-grillage foundation

The first mistake that can significantly affect the reliability and rigidity of the structure is incorrect calculation of the load on the base of the building. Here it is very important to take into account the peculiarities of the type of soil of the area where construction will be carried out.

The next mistake is considered to be small depth or incorrect installation of piles. Free space may form in the soil under the piles, which will cause shrinkage of the foundation. This will undoubtedly lead to a decrease in the air gap under the grillage, which can cause the pile to break in the winter. To eliminate this possibility, piles should be installed below the freezing depth of the soil.

In practice, there are cases where the design does not provide for the creation of an air gap under the grillage. This is especially dangerous in the winter, when the frozen ground expands significantly in different directions, including vertically. This will lead to the formation of excess pressure on the bottom of the grillage, which may cause damage or breakage. To eliminate this, care should be taken to organize an insulating layer in the form of polystyrene foam boards, which will also act as artificial shock absorption.

An equally important point is the creation of a reliable connection between the grillage and the piles. If there is no reliable fixation, this can lead to horizontal displacement of the pillars. As a result, they will not be affected by the design load from the structure, which may sag in this place.

A grillage foundation for a house or other structure is the most popular and economically viable option in modern construction. It is characterized by versatility, increased strength and reliability. A well-made grillage, in accordance with regulatory requirements, is the key to a durable structure.

Since the soils in the Moscow region are predominantly weak, sandy and water-saturated, the construction of a pile foundation with a grillage, or as it is sometimes popularly called a grillage foundation on piles, is common.

Types of grillage

The types of grillage differ in the height level from the soil surface, and the height of the ground area of ​​the piles can be different.

• Recessed– this type of grillage is completely immersed in the ground. The top plane is below the main soil level. The most difficult type of grillage, since it is difficult to provide free space under it.
• Elevated– the concrete strip runs parallel to the ground surface. In some cases it has a slight elevation.
• High– the outer plane of the foundation rises to a significant height from the general ground level. It is a frequently used type, as it has simple installation and is not subject to earth pressure on the foundation. But it requires additional insulation and waterproofing. There is also no possibility of making a basement or underground warehouse.

Rice. Types of pile foundation grillages

The location of the piles under the grillage may vary. For greater strength, they can be arranged in continuous rows, then the grillage will look like a slab. Or, if point reinforced zones are needed, then the piles are installed in bunches. Quite often there are strip installations of piles with a strip grillage.

Types of grillage according to the material used

• Metal

It is a channel or I-beam that performs the function of tying the foundation. This type of grillage completely eliminates the deformation of walls and floors in the form of subsidence or curvature. It has an additional base for permanent formwork and concreting the subfloor on the first floor.

• Concrete

It can withstand the load of a large brick or block house, as it is the most reliable structural device. Its single piles have a common ceiling in the form of a reinforced concrete beam.

• Wood

Applicable only for light country houses. Performs the function of tying the lower crown of a wooden building. Usually installed without creating a basement area.

Pile foundation with monolithic grillage

Making such a foundation yourself is not particularly difficult if the soil does not have any serious nuances, for example, the presence of rock or large layers of sand.
First, the piles are installed according to the intended drawing. In most cases, they are necessarily reinforced and filled with concrete mixture, which is well pushed to the entire depth by mechanical vibration.

Rice. Layout of a monolithic grillage

Since the grillage is a concrete strip encircling the pile field, its cross-section is determined by calculating the constant pressure from the building. All this can be divided into several stages:

• Drawings and markings

Drawing up a drawing plan and carrying out ground markings.

Drilling wells with subsequent driving of pile shafts using special equipment.

Manufacturing of formwork structures for grillage and pile heads, if the latter have an elevation above the ground surface. When the grillage is buried, a trench is dug to pour the concrete mixture.

• Pouring concrete

Direct concreting of the pile structure and grillage using horizontal overlays.

• Freezing

Mandatory curing of the poured monolithic structure until it hardens completely. Dismantling removable formwork (if any).

Technology for constructing a pile foundation with a grillage

Before starting construction, it is necessary to carry out all calculation work on the construction of the foundation. Since installation difficulties may arise, it is better to contact professional staff. After conducting the necessary research, they will provide a full report on the necessary work and its cost.

Price pile foundation with grillage will depend on:

• number of piles;
• diameter, cross-section and total length of pile shafts;
• materials necessary for construction (cement, sand, reinforcement, etc.);
• presence or absence of special equipment.

Step sequence:

• Carrying out marking work on the site

There are two types of markings: “Egyptian triangle” and “two curves”. The first method is to drive slats into the corners on the long side of the future foundation and draw a line between them. Next, knots are tied on the rope at intervals of three, four and five meters. Knots of 3 and 4 meters are connected using a nail. Next, the rope knot is attached to the batten and stretched so that a gap of four meters is on the drawn line. Another line is drawn along a three-meter section of the rope. Then the width of the building is marked on it and the third batten is placed. The last corner is also revealed.

Rice. Foundation marking scheme

The “two curves” method is to determine the equal footage of the installed rail. Markers are placed at these points. The rope is tied at one end to the rail, and the other to the installed mark. The arc is drawn and marked. The same is done with the second mark. From the point where the arcs connect, a line is laid on which the width of the house will be determined. Then the four marks are connected with a cord, and the same marking of the internal fundamental contour is carried out. Only after this, control points for the piles are marked.

Rice. Scheme "two curves" (foundation marking)

• Drilling wells for piles

It is carried out according to calculations that should show the level of soil freezing and the passage of groundwater. The standard depth does not exceed two meters. After drilling is completed, a sand cushion is laid at the bottom of the well and asbestos pipes are installed as formwork. Piles can have not only a round shape, but also a square one. These are used if a small deepening of the foundation is necessary.

• Installation of pile supports

The installation of piles is carried out in strict compliance with the specified parameters. After installation, they are dynamically tested.

• Grillage installation

In turn, it is divided into several stages:

When the grillage is buried, a trench is dug along with the drilling of wells. A sand cushion of at least ten centimeters is placed at the bottom.

Then the formwork itself is installed using chipboards.

Rice. Grillage installation

• Two-level reinforcement

It is carried out using twelve-millimeter rods. They are connected using burnt wire. The bottom of the trench must first be covered with timber boards up to five centimeters wide. The reinforcement should not reach the same distance to the top edge of the formwork.

Rice. Two-level grillage reinforcement

• Concreting the grillage

Produced in one day with the same mixture that was used to fill the piles. The upper plane of the concrete solution must be carefully leveled using a building level. With a recessed grillage, the formwork is removed after 2-5 days, and with a high grillage - at least after a month. Moreover, the concrete must be regularly moistened with water twice a day for two weeks to avoid cracking.

All regulatory requirements regarding the dimensions of foundation elements and materials used are determined on the basis of engineering calculations, also in accordance with SNiP and are included in the construction project.

Foundation on piles with grillage - video

In this video you can watch the creation of a pile-grillage foundation step by step:

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