There are several types of floors that are used during the construction of buildings and structures. They have certain advantages and disadvantages. One of the spectacular varieties is the coffered ceiling. It is used less frequently than monolithic slabs. But at the same time, it has a lot of advantages. What is a coffered floor will be discussed later.
General Description
Many people don't know what kind of flooring is called coffered. This is not the most common type of ceilings. Today it is difficult to meet a building project with such an overlap. This is what attracts many builders. The interior using this technology is original.
Any overlap is an important element of the structure. It is responsible for the safety and reliability of the structure, therefore, must comply with the established requirements. Caisson flooring has been known to mankind for a long time. Even in ancient Rome, a similar technology was used in construction. Withof those times, the ceiling of the variety presented has proven itself on the positive side.
In our country, such ceilings are rarely used yet, but they are actively used in buildings in other countries. It consists of beams that are directed towards each other at an angle (not necessarily straight). This approach allows you to create a lightweight design. It has an original appearance and can be used in the arrangement of various buildings.
You can mount the coffered type ceiling with your own hands. Today, for this purpose, a lot of special devices and structural elements are on sale. This greatly facilitates the work of the master. You can purchase everything you need at a hardware store and do the installation yourself.
Historical background
Caisson ceilings (photos are presented in the review) became widespread in the architecture of Ancient Rome and Greece. Flooring was installed between the intersections of the beams. They were decorated with paintings or sculptural elements.
Earlier, floors of the presented type were built of wood. Such designs were also used in other countries, for example, in ancient Egypt. Ceilings of this type have been found in frescoes and ancient mosaics.
The coffered monolithic reinforced concrete slab has become a real breakthrough in the field of architecture and construction. This material has been used in Russia since 1861. Most often, ceilings and columns were built from it.
The first building with reinforced concrete coffered floors was built in 1934. This iswas the building of the Central Union (architect Le Corbusier). The edges of this overlap were directed upwards. The design was made using monolithic technology.
More often the presented technology is used in construction in foreign countries. So, for example, such buildings have long managed to win the attention of the builders of Spain, Germany, England, Italy, etc. Most often, such structures were used and are now used in the construction of administrative buildings.
Main Features
Caisson monolithic flooring is created from panels that are mounted on corner bearing columns. Such plates have the form of ribs or beams intersecting at right angles. With the help of a thin layer of concrete, they are combined into a single system. This is how the ceiling is obtained, resembling a waffle in its appearance.
Most often the plate has a square shape, but it can also have a different configuration, for example, domed.
It is worth noting that ordinary monolithic ceilings involve fixing plates through beams. These are the supporting parts of the structure. Caisson types of floors have special ribs. They take on the function of beams. The ribs in the caisson structure have a pitch of no more than 1.5 m. They form a structure in the form of a grid. This allows you to redistribute the load. This makes the structure stronger. This allows you to reduce the thickness of the layer of monolithic slabs to 5-8 cm.
To ensure greater reliability, reinforcement of coffered floors is carried out. Plates have a thickness of 25-45cm. The height of the ribs that protrude above the base reaches 20-40 cm. At the same time, the proportion established by building codes and rules must be maintained. The height of the rib should not be less than 1/20 of the span length. The dimensions of the coffered ceiling can be different. The largest of them reach dimensions of 35x35 m.
Slabs can be supported on load-bearing columns or walls. In the first option, 4 supports are needed. The columns will hold the structure in the corners.
Benefits
This type of slab has many advantages. This ensures the growing popularity of the presented type of construction projects. In coffered ceilings, ribs form the basis. Thanks to their presence, it is possible to reduce the consumption of cement by 2 times, and reinforcement - by 3 times, compared with a conventional reinforced concrete floor of the same strength.
This feature allows you to expand the possibilities when designing the thickness of the ceiling. Also, its shape can be very original. The configuration can be almost any. You can even create a dome or arch structure.
Today, a technology with a distance between supports for a slab from 10 to 34 m has been developed and applied. In this case, a smaller load acts on walls or columns. This is due to the reduction in the weight of the overlap. This, in turn, leads to a reduction in the total loads that act on the foundation.
Another positive quality is the fact that the coffered floor slab is resistant to earthquake-induced vibrations. ATareas of increased seismic hazard, their use is allowed if there is a span of more than 6 m.
Ribbed varieties of structures are distinguished by a 2-3 times greater bearing capacity. The thickness in this case can be 2 times less than with the arrangement of conventional smooth floors. Fewer load-bearing elements will need to be mounted, which speeds up the construction process. The material consumption of construction is also reduced. Construction costs are significantly reduced. In some cases, this figure reaches 3 times.
Scope of application
Caisson flooring is used in various types of construction. Most often, this type of structure is used in loaded engineering structures. Also, most often they are installed in buildings with a large number of people. These can be shopping, entertainment or sports complexes, cinemas or theaters, educational institutions, etc.
It is worth noting that in large cities of our country, large-scale production is transferred outside the city. From them there are large buildings, which are sometimes even inexpedient, from an economic point of view, to demolish. Therefore, such facilities are being refurbished, turning them into multifunctional centers. Here additional overlaps are created. Most often they are made using caisson technology.
If it is required to equip the production building with overhead cranes, additional ceilings must also be used. The height of such complexes can exceed 10 m. To ensure its proper functioning, they createcoffered types of floors. They are optimal in such conditions in all respects.
The scope of the presented structures is not limited to industrial construction. In private homes, the presented technology can also be used. This allows you to reduce costs, as well as make the original ceiling.
Varieties
There are two types of coffered ceiling according to manufacturing technology. These are monolithic and prefabricated-monolithic varieties of structures. They have characteristic differences.
So, prefabricated monolithic floors consist of prefabricated hollow blocks. Their dimensions are 20x20x60 cm and 30x30x80 cm. They are in sections of a stretched type, in compressed sections of a monolithic slab. Blocks in this case are mounted in the form of a figure closed on all sides. The caisson formwork of the floors in this case is fixed, it consists of beams that remain in the concrete body. The thickness of the monolithic layer of concrete above the beams should be 5-6 cm. In places where the structure is connected to the supports, the slab is solid, since tensile loads act on it in these places. Block and top reinforce.
Monolithic varieties of floors of the presented type are distinguished by an optimal indicator of cement distribution. There is no excess material between the ribs. This significantly reduces the weight of the structure. It has a ribbed structure. In the stretched zones of the section, the mixture is not laid. Here, only the ribs are concreted. Reinforcement passes through them, which increases the strength atstretching. This type of ceiling allows you to significantly save on materials. The overlapped spans can be increased in this case.
Equipment
Before starting construction work, you need to calculate the coffered ceiling. It is created in accordance with the PPR according to the working drawings. To perform the work, you will need to prepare the necessary equipment and materials. The amount of cement and reinforcement depends on the area of \u200b\u200bthe room. Prepared drawings are used for correct calculation.
In the course of work, you will need a grinder, an electric drill, as well as a nozzle in the form of a construction mixer. Cement mortar can be purchased ready-made or made independently using a concrete mixer. The first option is simpler, therefore preferable. But it will be cheaper to make the mixture yourself.
You need to prepare a set of wrenches, a screwdriver and screwdrivers. A chisel and trowel will also come in handy. When working, builders use a spatula, pliers and a hacksaw (including for metal). Measurement is carried out using a tape measure and a pencil. You will also need a plumb line and a building level. Having prepared everything you need, you can get to work. It is performed using special technology.
Formwork preparation
Builders recommend making do-it-yourself coffered ceilings right on the spot. The formwork must be of a special, removable type. In total, 3 of their varieties are suitable for this:
- Standard Skydome type system. It includes plastic elements that allow you to easilyremove the formwork after the concrete has cured. Its surfaces repel the solution, so it does not stick to the mold surfaces. Such formwork is reusable. They also include rails and racks for mounting.
- Combined formwork. To do this, make a temporary flooring of plywood. Elements of conventional formwork are subsequently installed on it.
- The form is made of wooden flooring, as well as self-made plywood formwork. This is most often a one-time design. It can even be made from cardboard covered with a layer of polyethylene.
Pouring concrete
Concrete is poured into prepared molds in two stages. The reinforcement must be mounted so that it is correctly located inside the formwork. Its fixation must be strong so that it does not move when pouring.
Next, special clamps are installed. Reinforcement also needs to be mounted in two passes. First, it is placed in the ribs. The top reinforcement is not laid yet. In this case, clamps are used. When the first batch of concrete is poured (this allows the formation of ribs), you can mount the subsequent frame of metal reinforcement. It has lower and upper longitudinal elements, which are fixed with clamps.
Overlap should be strong enough. The aggregate in the concrete mixture must be fine-grained or conventional. The strength class must be at least B15. Porous concrete with strength class B12, 5 can be used. The water-cement ratio should have an index of 0.5. Pouring is carried out according to the standard method.
With a vibratorneedle type, the mass is compacted in the formwork. The tool must be inserted into the concrete vertically or at a slight incline.
Wooden ceiling
Many modern designers today adopt the presented technique. As a result, a ceiling is created from ribs intersecting with each other. They create a grid on the ceiling. A thin layer unites all structural elements together. For such a ceiling, the bearing qualities are secondary. It should be light and aesthetic.
The ceiling of the presented type has three main structural elements. These are ribs (beams) that provide rigidity, base and decorative elements. As the latter, borders, cornices, patterns, etc. are actively used.
Coffered ceilings can be made not only from wood, but also from plastic. The base is most often made of chipboard, polyurethane sheets, drywall or plywood. Decorative elements cast from gypsum look impressive. Spotlights look good in the cells. Ribs can have different configurations. This provides different light scattering effects. This design looks interesting in different interior styles.
