Any building needs a reliable, high-quality, well-designed and equipped base. Today, the grillage foundation on stilts, which has an economic advantage in comparison with the traditional strip base, is very popular. The design feature is a horizontal lintel connecting the piles. Rostverk: what it is and what its main purpose is, is described in detail in the article.
Rosterk: what is this element and why is it needed
It is necessary to begin to consider this question with the definition: what is the foundation grill. The internal construction element is a horizontal concrete, steel or wooden lintel connecting the disparate elements of the columnar or pile foundation to each other, as a result of which a level platform is created for the installation of a covering rim. The rostverk perceives the load from the load-bearing structures of the building and evenly distributes it to the supports that transfer the load to the ground.
Such a construction is not inferior in its rigidity and strength to the traditional strip foundation, but the price of the grillage foundation will be much lower, which is associated with lower labor costs and labor-intensive work.
The base structure is created using frame technology, where the pillars or piles are interconnected to form a solid base. The foundation with the grillage is constructed on clay, peat, loess, loamy, heaving and silt soils. Construction of the house can be carried out in areas with ornate relief or on slopes.
Ergonomics, durability and aesthetics of the building depends on the type of grillage, which fits on the columnar or pile foundation. It can be slab, tape and stakanny.
Depending on the location of the grillage relative to the subgrade, the following types of structures are distinguished:
The jumper design can be:
- national team.
Depending on the material of manufacture distinguish grillages:
- reinforced concrete.
The main purpose of the grillage is the perception of the load from the bearing elements of the building and its uniform distribution on the foundation. The most common and economically viable is a pile foundation.
Plate grillage on piles in the form of large-format reinforced concrete slabs set with significant dimensions of the structure around its perimeter. Such a grillage fits on a standard cake 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 base of the grillage;
- concrete preparation in the form of a screed without reinforcement;
Ribbon foundation on piles can be monolithic or modular. 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. Also in the body of the grillage is easier to bury the tip with protruding reinforcement.
Precast tape grillage is used in wood construction technology. Wooden bars are stacked on top and joined in half-wood. This allows you to reduce construction costs and begin construction of the structure the next day after the installation of the foundation.
The precast tape grillage can be made in the form of reinforced concrete beams adjacent to the top of the piles. This design is used primarily for screw piles tied with I-beams or channels.
When the device reinforced bored piles with a grillage can be used stakanny type of construction. The rostver is represented by a kneecap, mounted on a pole, a multiple of 15 cm, and 30 cm wide. Each glass must rest on four piles. Such type of the basis is used at installation of columns. Most often used in agricultural and industrial construction.
Monolithic grillage is the most successful solution for low-rise construction. The element is represented by an integral closed-type structure made of reinforced concrete or concrete. It is poured during construction, in the form of a monolithic slab or beam (tape). In the first embodiment, the design connects all the piles into a single system that covers the entire area of the building. The tape grillage connects piles consistently and is established only under the bearing elements of a structure.
Rostverk, firmly fixing itself to the piles and including them in its thickness, connects the elements of the base. Monolithic tape grillage can be raised, high or deep. It is arranged under adverse geological conditions of the soil. The implementation of such a grillage is of high technical and operational characteristics. However, the design has increased complexity, high cost of work and requires the creation of thick reinforcement.
The precast grillage is represented by a structure made of steel beams interconnected by welding. I-beams and beams are used as connecting elements. Also, the design can be made of wooden bars. This option is used mainly for the construction of non-capital buildings and industrial buildings. The structure is mounted and fixed on the pile heads, which does not require subsequent grouting.
Helpful advice! For the construction of a private house, it is impractical to use the pre-fabricated grillage, because it is associated with a very laborious and costly process.
Prefabricated type has its drawbacks. First of all, the installation process is very laborious, which is associated with a significant weight of metal elements. In some places of the grillage, areas with low strength can be formed, which is associated with low rigidity of welded joints. Due to the formation of corrosion or decay of wood, the construction is short-lived, which is limited to 1020 years of operation.
The intermediate solution between the two previous options is a monolithic precast grillage. The prefabricated structure consists of prefabricated parts that are stacked on piles and are connected to each other by a keyed joint. This is done during construction. Then the whole construction is monolithic.
The most rational solution from the point of view of the integrity of the structure and the stability of its work in the event of various deformations is the device of a high or hanging grillage on bored piles. It is installed above the ground not less than 10 cm. If the distance is shorter, there will be a probability of damage to the integrity of the grillage and its knots with piles, which will lead to the latter being pulled out.
The main disadvantage of this design is the lack of sealing the space between the lower part of the grillage and the ground. Due to the fact that free access of cold air is created, the heat loss at home increases. You can solve the problem by installing shields or additional floor insulation at home.
Helpful advice! This type of grillage is advisable to choose for a subtropical climate, also in the construction of wooden structures.
The sole of the elevated grillage is located at the level of the ground, on which a gravel or sandy pad is laid with a thickness of 10-15 cm, for which the soil layer is removed. This layer helps to reduce the soil moisture under the building and free filtration of water. In this embodiment, the formation of a purged area between the ground and the overlap is excluded.
Recessed foundation tape on bored piles is the most popular option, at the same time, the most irrational. To create it around the perimeter of the future building a shallow trench is pulled out. Next, the piles are installed in such a way that their caps protrude from the bottom of the trench. A sand pillow is set up. After that, a formwork gutter is performed, the bottom of which is located below ground level. Next, create a concrete grillage.
Helpful advice! In spite of the fact that a non-winding space is formed under the buried grillage, daggers, which will take the load from the expanded soil during frosts, can be installed as additional insulation.
Reinforced concrete grillage is characterized by increased strength, reliability, stability of work, rigidity, bearing capacity and durability. This is the most common option. The structure contains reinforcement, which increases the strength characteristics of the grillage, taking over some of the loads. Reinforcement can be performed by creating a full-fledged spatial framework or by laying individual rods.
Important! When forming a reinforced concrete grillage, a sufficient protective layer should be provided for the reinforcement.
Making a concrete grillage is identical to the previous version. The difference is the lack of reinforcement. The entire load is perceived by the concrete structure, which covers the pile heads to a height of at least 10 cm. This option is less durable and durable. Concrete grillage is used in the construction of single-story buildings.
The production of metal grillage is carried out from the rolled steel, represented by I-beams and channels. The result is a solid and rigid structure. But due to the possible corrosion of the metal, especially in places of welded joints, the metal grillage is short-lived. It is used for the construction of single-story buildings.
Wooden grillage is used exclusively for the construction of buildings made of wood. Laying wooden timber through a waterproofing strip on piles, which is used as the roofing material or roofing felt. Before installation, beams should be treated with special compounds and antiseptics, which will prevent the formation of mold and the emergence of various parasites in the wood. The fastening of the timber between them is carried out with the help of bolts and brackets.
A pile foundation is a structure in which the load on the ground is transferred from the structure through piles, which are partially or completely embedded in the ground by posts or bars. For hard and reliable connection of the tops of the piles, a grillage is arranged. It is rational to use this type of foundation when erecting buildings on water-saturated weak soils, on slopes with a steep slope, in areas where the depth of soil freezing exceeds 2 m, also if the weight of the future structure exceeds 350 tons.
Equally important is the creation of a reliable link between the grillage and piles. If there is no firm fixation, this may lead to horizontal displacement of the pillars. As a result, they will not be affected by the design load from the structure, which can sink in this place.
Roaster foundation for a house or other building is the most popular and economically viable option in modern construction. It is characterized by versatility, increased durability and reliability. Qualitatively executed grillage, according to regulatory requirements, is the key to durable construction.