Grillage: what it is and its role in setting the foundation

Any structure needs a reliable, high-quality, well-designed and equipped base. Today very popular rostverkovy foundations on piles which has an economic advantage compared with the conventional tape base. The design feature is a horizontal jumper connecting piles. Grillage: what is it and what is its main purpose, is described in detail in the article.

Grillage What is this item and why it is needed

Consider this question it is necessary to start with a definition: what is the grillage foundation. Internal construction element is a horizontal concrete, steel or wooden bridge linking disparate elements of the columnar or pile foundation together, thereby creating a flat area for mounting the accountant's crown. Grillage supports the load of the load-bearing structures of the building and distributes it to the support, which transmit the load to the ground.

This design of its stiffness and strength are not inferior to the traditional strip foundation, but price rostverkovogo foundation will be much lower, due to lower labor costs and complexity works.

The design of the base frame is constructed using technology where columns or piles are interconnected together to form a solid foundation. The foundation is being built with raft on clay, peat, loess, loamy, heaving and muddy bottoms. Construction of the house can be carried out in areas with ornate relief or on the slopes.

Varieties of raft foundation and what he has types

Ergonomics, durability and aesthetics of the building depends on the type of raft foundation, which is placed on a columnar or pile foundation. It can be slab, strip and glass.

Depending on the location relative to the grillage subgrade distinguish the following types of structures:

• increased;
• tall;
• buried.

jumper design can be:

• monolithic;
• precast-monolithic;
• team.

Depending on the material of manufacture gratings are distinguished:

• metal;
• wood;
• concrete;
• reinforced concrete.

Element types and the main task of the grillage

The main purpose of raft foundation is the perception of the load bearing elements of the building and its uniform distribution in the foundation. The most common and cost-effective is a pile foundation.

Grillage slab on piles in the form of large-size concrete slabs installed at considerable dimensions of the structure along its perimeter. This raft foundation is laid on a standard pie, consisting of:

• sandy cushion in the form of two layers of 10 cm vibrocompaction;
• the annular drainage located at the level of the sole grillage;
• preparing a concrete screed without reinforcement;
• waterproofing.

Strip foundations on piles may be precast or monolithic. A first embodiment is used for bored piles. This is due to the fact that the materials have the same linear expansion and specifications. Also in the body grillage easier to wall up headroom with protruding reinforcement.

Precast tape grillage used in wood construction technology. Wooden boards stacked on the end walls and are joined in a half-tree. This reduces the cost of construction and to start construction of buildings on the very next day after the base unit.

Prefabricated grillage belt may be formed as a reinforced concrete beams, piles adjacent to the end walls. This design is primarily used for screw-driving, bandaged I-beam or a channel.

When the device bored piles with concrete grillage glass type of construction can be used. Grillage represented patella mounted on the column 15 cm in height times width - 30 cm. Each cup should be based on four piles. This type of base is used for mounting columns. Most often used in the s / s and industrial construction.

What is the grillage: design element

Monolithic grillage is the most successful solution for low-rise construction. Element contains the whole structure of a closed type, made of concrete or concrete. It is poured in the construction, in the form of a monolithic plate or beam (ribbons). In the first embodiment connects all pile into a single system that covers the entire area of ​​the building. The belt connects the pile grillage consistently and installed only under the bearing structure elements.

Grillage is securely to the piles and including them in his column, connects the base elements. Monolithic belt grillage can be increased, high or recessed. He gets under unfavorable geological conditions, soil. Performing such grillage has high technical and operational characteristics. However, the structure has a high labor intensity, high cost of works and requires the creation of a dense reinforcement.

Prefabricated represented grillage structure made of steel beams joined together by welding. As the coupling elements used I-beams and beams. Also, the design can be made of wooden beams. This embodiment is preferably used for erecting semi-permanent buildings and industrial buildings. The design is mounted and fixed on the pile heads that does not require subsequent embedment.

Useful advice! For the construction of a private house prefab grillage use is impractical because it is associated with a time-consuming and costly process.

Prefabricated type has its drawbacks. The first installation process is very time-consuming, which is associated with a significant weight of metallic elements. In some places grillage region can be formed with low strength due to the low stiffness of welded joints. In connection with the formation of corrosion or rotting wood construction is short-lived, which is limited in 1020 years of operation.

An intermediate solution between the two previous embodiments is monolithic precast grillage. The assembly consists of prefabricated parts which are stacked in piles and communicate with each other keyed connection. This is done during construction. Then the entire structure concreted.

Optimal location grillage location

The most rational solution from the standpoint of structural integrity and stability of its operation at occurrence of various high deformatsiyschitaetsya device or hanging on bored grillage stilts. It is installed above the ground at least 10 cm. If the distance is less likelihood there rostverkai connection nodes integrity damage it with piles, which will last pull-out.

The main drawback of this design is the lack of sealing the space between the lower part and the ground grillage. Because creates easy access of cold air increases the heat loss of the house. The solution is to use the mounting boards or additional warming of the floor of the house.

Useful advice! This type of raft foundation is expedient to choose for a subtropical climate, and in the construction of wooden structures.

Sole elevated grillage located at ground level, on which is laid sand or gravel airbag 10-15 cm thick, which layer of soil is removed. Such a layer helps reduce soil under the building and moisture free water filtration. This embodiment avoids the formation of blown region between the ground and lapped.

Recessed strip foundation on bored piles is the most popular option, while at the same time and thus irrational. To create the perimeter of the future building pulled a shallow trench. Next, set the pile so that the bottom of the trench sticking their headroom. Arranged sandy pillow. Thereafter the trough-formwork, the bottom of which is located below ground level. Next, create a concrete raft foundation.

Useful advice! Despite the fact that the space is formed under the recessed windproof raft, as additional insulation can be installed drop keels, which will take the load from the ground in an intumescent during frosts.

What material it is made grillage

Reinforced grillage characterized by high durability, reliability, stability, rigidity, load capacity and durability. This is the most common option. As part of the design of reinforcement is present, which increases the strength characteristics of the raft foundation, taking over part of the load. Reinforcement may be performed by creating a full spatial frame or laying the individual rods.

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

Production of concrete grillage identical to the previous embodiment. The difference is the absence of reinforcement. The entire load is taken of the concrete structure, which covers the pile end walls to a height of not less than 10 cm. This embodiment is less strong and durable. Concrete raft foundation is used in the construction of single-storey buildings.

Production of metal grillage is made of a profile rolled represented by I-beams and channels. The result is a sturdy and robust design. However, due to possible corrosion of metal, particularly in the field of welded joints, metallic grillage is short-lived. It is used for the construction of single-storey buildings.

Wooden raft foundation is used exclusively for the construction of structures made of wood. Stacking wooden beams through a waterproof lining on the pile, which is used as roofing felt or roofing felt. Prior to installation of the beam must be treated with special compounds and antiseptic that will eliminate mold growth and the emergence of various parasites in the thick wood. Fastening between the timber together by bolts and brackets.

Characteristics of pile foundation with grillage

Pile foundation - is a structure in which the load from the ground is transmitted through the pile constructions that are presented partly or completely recessed in the ground pillars or beams. For rigid and reliable connection of the upper parts of the piles arranged grillage. This type of foundation is rational to use in the construction of buildings on the water-saturated soft soils on the slopes, with a steep slope, in areas where the depth of soil freezing exceeds 2 m, also, if the weight exceeds the future structure 350 m.

Related article:

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

drainage device to protect the foundation of the building, the specificity of this process, the technology is creating a design with their own hands.

The piles are metal, wood or concrete pointy, long or having a heel rods of round or square section. They sink into the ground as is or are made directly to the soil column. In finished form the pile has on one side a sharp end, which with the help of special construction equipment immersed in soil column, passing moving beds, abuts against the firm ground. In the manufacture of piles in the ground is carried out drilling, which, subsequently, are reinforced and filled with concrete.

Varieties of pile foundations with grillage

By the method of immersion into the soil pile foundation can be printed, precast or screw. The first option presented concrete or reinforced concrete structures. To create these fittings pre-straining, which increases the fracture toughness of the foundation. Device for piles to be drilled earth thicker desired number of holes of a given diameter and depth. In each of them inserted a metal casing or concrete pipe. It falls fittings and all the cavity is filled with concrete.

The structure may be formed with a closed or open lower end. The main advantage of this type of pile foundation is a high load capacity, simple technology, reduced the cost of the work, which is associated with a minimum of effort, lack of negative impacts and vibrations on surrounding structures.

The second option involves plugging into the ground precast concrete piles. The coconut can be used as special equipment, and hydraulic vibrators svaesdavlivayuschie units, the choice of which depends on the characteristics of the ground, and depth features piling. This type of foundation is used in permafrost zones. Driven elements may be round, square or trapezoidal shape. To increase the reliability and performance of the pile carrier may be equipped with additional support rings.

Screw rostverkovy Foundation: what it is

With raft foundation on screw piles it is one of the new options. The construction has a good performance and can be mounted on any type of soil. Pile represented hollow pipe, sharp tip and one or more blades. The tip may be welded or cast.

For each soil type used a certain type of screw piles. For stone areas used narrow-bladed screw piles, which have a particularly strong welded and double blade tips that provides good traction with the ground and prevents skewing piles. For thawed and watered soil pile used with a sharp tip and cast medium sized lobes, which guarantee easy penetration of the element into the ground without loosening.

For use permafrost piles with small blades, which promotes rapid introduction of the element into the ground without risk of warping. The tip of the pile has a special cutter made of high-strength alloy steel. Such elements are characterized by high cost.

Options for the location of piles and their types

Piles may be hanging or in the form of struts. In the first embodiment, the load on the surrounding soil is transmitted through the friction of the side walls. Such piles are characterized by improved lateral surface along the entire length with a plurality of projections that provides good bearing capacity of the structure. This type is used for soils with a high water table or with a thick layer of soft soil by which is more durable, but it is still not able to keep pile-counter.

Piles-rack transfer the load from the construction directly on the solid ground, which is located under the weak layer. The elements are characterized by a smooth surface, for which the soil does not cling. The most important criterion for this type of pile is a broad base which receives more than 80% of the total load.

Useful advice! For multi-storey buildings and durable it is advisable to choose a pile-rack TISE with a significant broadening of the bottom of the element, thus eliminating further draft.

Piles in the ground may be located on one of the following:

• single;
• belt;
• bands;
• in the form of a bush;
• field.

The first method is chosen under-standing support. Depending on the topography pile may be arranged obliquely. Belt process involves placing piles around the perimeter of the buildings. For the construction of massive multi-storey structures used in the installation of piles several rows in the form of strips.

Spray arrangement involves the installation of elements for the load-bearing walls and objects with a large load. This method is used for the construction of sheds and structures with a large number of columns that hold the roof. For large buildings used by the installation of piles staggered.

The choice of method depends on the location of the pile construction project. The elements should be placed in the corners and places crossing piers. The optimal distance is the distance between the piles in the grillage 2-3 m.

Pros and cons of pile-foundation rostverkovogo

Picking up the foundation for the future structure of the need to examine the pros and cons of the pile foundation with the raft. Such a construction has excellent stability and high load carrying capacity. This is especially important for the construction of houses on soils that are prone to shifting of. This type of foundation is common in seismically active zones, where the basis will remain fixed for small earthquakes.

Important! Classic piles are able to withstand loads up to several tons.

Pile-foundation rostverkovy advisable to opt for the construction of buildings on the grounds of complex structure, especially in mountainous terrain, which is characterized by a thin layer of loose ground. Manufacturers produce piles of different length, which allows to build a foundation on the slopes, as well as create curved objects. Rostverkovy pile-foundation is an ideal basis for the construction of buildings of any material.

Due to the fact that the raft foundation is not in contact with the ground, it eliminates the possibility of flooding facilities groundwater entering the house rodents and various insects. For the construction of pile foundation raft with no need for pre-cleaning and alignment of the construction site, which reduces the complexity and cost of the work. Build the foundation can own without the involvement of the powerful construction machinery, which is especially important in a dense housing, or on small plots of land.

However, this design has its drawbacks. In the design of this type of foundation should perform accurate calculations with the assistance of a specialist. It should be taken into account the length, diameter, weight, number of piles and their current location.

Important! Pile foundation is not suitable for heavy, bulky structures even by increasing the diameter of the pile elements.

Another disadvantage is the laborious repair base structures which require retaining walls or installing additional piles. The construction of pile foundation with a basement raft eliminates device and requires no additional warming of the lower part of the building.

Calculation of pile-foundation rostverkovogo

Performing the calculation of pile-rostverkovogo foundation is a serious and responsible action. This process is best left to the person skilled in the art. For the calculation it is necessary to gather information on land for construction: the geological structure and physical properties of soil, hydrogeological and physical and geographical conditions of the area. Get all the necessary information in the local service of exploration, pre-order it.

The obtained data are performed calculations of the parameters of the selected base. The load on the foundation with a raft is calculated based on the total weight of the structure. It then computes the depth of the supports. Based on the bearing capacity of the foundation and the load is determined minimum total area supports. Next selected type, diameter and the number of piles, distributed along the area of ​​the building, according to the selected arrangement pattern. Next determined by calculation grillage dimensions.

Useful advice! For the calculation of pile foundation with a raft, you can use an online calculator or specialist services of construction companies.

Calculation of pile foundation grillage is performed on the basis of SNIP II-V.1-62. Note that the structure width must be 10-20 cm a wall thickness of the structure, and the height should be approximately equal to the value of width. The final stage is the selection of construction material.

The device of pile-strip foundation with his own hands

The construction of raft foundation in the columnar or pole foundations with their own hands is feasible and doable task. The first option is advisable to opt for the construction of small structures without constant load, such as summer houses and arbors. Pile foundation is the most popular solution in the construction of buildings intended for continuous operation.

The device of pile-foundation rostverkovogo own hands it is advisable to carry out in late spring, early summer or early autumn. The first step is to prepare the site, clear it of debris and vegetation.

Useful advice!Territory for future construction is recommended to treat with chemicals that eliminate vegetation growth.

Next executed marking territory on the basis of the project showing the location of piles location. If you use screw piles, they should be screwed without creating holes. You can use a pipe or crowbar, to be inserted in the well head support. For screw-driving is more convenient to metal or wooden raft foundation. Concrete bridge advisable to arrange for a future house of stone, which requires high rigidity base.

Important! Piles must be placed exactly perpendicular to the ground.

When bored piles are arranged, with their own hands to install them will not work. To create holes in the ground need to bring special equipment. Bored piles can be manufactured in two ways. The first option is drilled into each well of the formwork placed in a metal tube of the required diameter. The interior space is reinforced and filled with concrete. The second embodiment eliminates the installation of the formwork.

For the device with the pile foundation concrete grillage used class B7.5-B15, which is optimal for smaller buildings. For parking buildings can be used concrete class to B25. More durable building material is inappropriate to use for private housing. It is not economically justified, because the margin of the material exceeds the load of the building. In each hole diameter is laid armature A400 of 12-16 mm class.

Bookmark pile foundation with a monolithic grillage

To work need these tools and materials:

• Podbornoe bayonet and shovel;
• scrap;
• stakes;
• rope;
• wooden boards or chipboard sheets formwork;
• Kit steel screw piles;
• armature for reinforcement piles and pile cap;
• metal tube;
• concrete mortar;
• plummet;
• level or gidrouroven;
• roulette;
• specialty chemicals;
• Penoplex plate;
• sand;
• gravel;
• mastic asphalt.

Installation of foundation pile with monolithic grillage with the following algorithm:

• cleaning and leveling of the base;
• drilling a hole in target locations required depth and size for piles;
• compaction of soil and the establishment of the cushion of sand or coarse fraction of average thickness of 30-50 cm at the bottom of the holes;
• mounting screw or bored piles according to the technology works;
• preparation of sand bags for monolithic grillage;
• the formwork device;
• is lowered into the pit of the carcass reinforcement, composed of at least four rods, the length of which is chosen with regard strapping height;
• execution of pouring concrete;
• the creation of the wooden formwork for monolithic grillage;
• After hardening of concrete is done collecting the reinforcement cage for the raft foundation;
• installation of formwork for binding;
• concreting of the raft foundation;
• removal of the formwork after concrete attains the desired strength;
• execution of waterproofing.

Useful advice! If the image of the underground space, it is better to close the decorative cap or Zabirko.

Reinforcement grillage performed using A400 grade rods, which may be connected to the frame by welding or connected using a binding wire. The second option is more time consuming, but reliable. When laying the carcass must keep a distance from the rod to the formwork at least 3 cm - to create a protective layer of concrete, which prevents the formation of corrosion.

Useful advice! At the corners of the building reinforcement rods must necessarily wiring.

Creation of monolithic grillage foundation on stilts

Before grillage device should be put on a pile layer waterproofing. This is necessary in order to eliminate the possibility of soaking the sole elements. As the waterproofing material may be roofing felt, plastic film or membrane. If grillage provided beneath the sole of the airbag gravel fines that may compromise the integrity of the waterproofing layer should provide footing.

The next step is shuttering device under the foundation on concrete piles. For this it is performed marks at 0.5-0.8 m Never nail pegs section 5x5 cm around the perimeter of the structure. Next performed laying horizontal wooden boards, in which pre-cut holes for piles.

Mounted vertical formwork elements that are nailed to the horizontal planks. Formwork recommended solid wooden boards or chipboard sheets. Inside the formwork team should lay a polyethylene film. formwork dimensions must exceed the height of the future grillage not less than 5 cm.

Useful advice! In the case of low grillage devices can be used permanent shutteringWhich will be subsequently more insulation to the walls of buildings.

Reinforcement raft foundation: step by step guide

The next stage in the device raft foundation pile foundation is to provide a reinforcing cage, which subsequently must be completely on all sides recessed into the concrete. For this it is necessary to lay on the bottom of the formwork transversely wooden bars of any width, but with the same thickness of 30-50 mm. They fit into the bottom row of the reinforcement bars, which must be linked together so as to provide a uniform distance between the bars.

Upper belt reinforcement cage must be hung to the cross bars that connect the rack casing. This is followed by a tie between the lower and upper belt.

For reinforcing the monolithic tape is commonly used valves class A400. The number of rods is calculated on the basis of the horizontal cross-sectional area ratio jumper to the sum of the cross sections of all the rods, that is 1000: 1. Perform the following procedure for calculating:

• you must multiply the width by the height of the pile cap, dividing the result by 1000;
• the resulting value is divided by the sectional area of ​​the bar.

The result is the minimum number of rods required for reinforcement.

Useful advice! The distance between the rows of valves should not exceed 150 mm.

The apparatus further elements and concreting grillage

Before pouring the concrete horizontal jumper should lay special pipes through which will pass utilities such as electricity, heating, sanitation, and communications. It should also be provided in the bottom ventilation openings.

Important! Should not be neglected according to stage, because then it is necessary to break the integrity of the raft foundation.

To create a monolithic concrete raft foundation is recommended to use the brand M300 and M500. When filling concrete formwork mixture should use a vibrator that is able to settle concrete, to eliminate the possibility of formation of cavities, which will increase the strength characteristics concrete.

Two hours after the pouring of concrete it is recommended to cover with foil. If it is hot outside, it is periodically necessary to remove the film and wet concrete with water to its surface is not formed cracks. Complete solidification structure occurs not earlier than one week, depending on the ambient temperature.

If the outside air temperature reaches 20 deg., The formwork can be removed after 4 days, as a concrete base over half pick strength. If the temperature does not rise above 10 deg., The formwork is not necessary to touch it for 14 days. At temperatures below 10 deg. necessary to provide additional heating and insulation of the basement to organize. After complete hardening of concrete, you can create a waterproofing layer using bituminous mastics.

Apparatus columnar foundation with grillage

Apparatus for future base construction according to the following algorithm:

• cleaning of the territory from vegetation, followed by treatment with chemicals;
• counting section based on the design;
• creating openings for future columns;
• compacting the soil at the bottom of the pit;
• the creation of a sand cushion height of not less than 15 cm;
• laying geo-textiles;
• backfilling with gravel;
• formwork for the execution of each pit;
• Covering polyethylene formwork system;
• creating the framework for reinforcing piles;
• forming pillars by pouring concrete into the hole;
• surface treatment pillars bitumen mastic;
• installation of formwork between concrete pillars to create a raft foundation, the height of which must exceed the height of the future design of 5-10 cm;
• sand cushion device;
• concreting grillage with reinforcement structures;
• creating water and heat insulation.

The main mistakes in the construction of pile-foundation rostverkovogo

The first mistake that can significantly affect the reliability of the design and the cruelty is not performed correctly, load calculations on the basis of the building. It is very important to take into account the singularity of the type of soil the area where the construction will be carried out.

The following error is considered to be a small depth of the pile, or improper installation. The soil under the piles can be formed free space, which will cause shrinkage of base. This will undoubtedly lead to a reduction in air gap under the raft, which can cause failure of the pile in the winter. To exclude this possibility, the pile should be installed below ground freezing depths.

In practice, there are cases that the project does not provide for the creation of an air layer under the raft. This is especially dangerous in winter, when frozen earth greatly expanded in all directions, including vertically. This will lead to the formation of overpressure in the lower part grillage, which may cause damage or breakage. To eliminate it, you should take care of the organization of insulating layer in the form of slabs of expanded polystyrene, which will also play the role of an artificial depreciation.

Equally important is the establishment of a reliable connection between the raft and the piles. If reliable fixation is absent, it can lead to a shift in the horizontal pillars. As a result, they will not impact the design load of the structure, which may prosest at this point.

Rostverkovy foundation under the house or other structure is the most popular and cost-effective option in a modern building. It is characterized by versatility, increased strength and reliability. Qualitatively grillage adapted, in accordance with regulatory requirements, is a guarantee of durability.