Types and rules for installing floor slabs on a brick wall

The easiest way to cover spans and install horizontal supports is to lay floor slabs. Such slabs come in different types and each of them has its own special characteristics, operating rules, sizes and shapes. It is thanks to the wide selection of floor slabs that they can be used to cover spans of any complexity. However, you should definitely take into account the special criteria for installing floor slabs.

Floor slabs: pros and cons

Precast concrete slabs are primarily designed to delimit floors and dissipate the load, which is then transferred to load-bearing walls and foundations. Due to the considerable number of positive qualities, floor slabs are used both for conventional residential construction and for the construction of industrial buildings.

Most often, slabs with voids are used, the holes in which can have different shapes and diameters. Let's study the main advantages of hollow products:

• Compared to the production of monolithic floors, much less money and labor is spent.
• High strength is achieved due to the reinforcement of the product. The same cannot be said about prefabricated or wooden floors.
• Due to technological voids, heat and noise insulation throughout the building increases.
• Compared to monolithic floors, which greatly load the load-bearing walls and foundation of the building with their weight, hollow core slabs have less weight.

The disadvantages include the possibility of covering only rectangular spans; in other cases, it will be necessary to resort to the use of monolithic floors. You also need to order special equipment to install the slabs.

Support unit design

When constructing a brick building with floors made of flat concrete elements, masonry in the full thickness of the fence is carried out to the design level of the bottom of the ceiling. Then the brick is placed only from the outer part so that a niche is formed where the slab will lie. The process is accompanied by the following:

1. If the depth of support is 12 cm (exactly half a brick), then the niche is made at least 13 cm wide so that the end part of the slab does not rest against the brickwork.
2. Before installing the ceiling, a layer of cement-sand mortar of the same grade that was used during the construction of the masonry is laid on the base.
3. Since the edge zones of the slabs will absorb part of the load from the wall erected above, the voids at the end are tightly sealed with concrete liners so that the product does not collapse from compression.

As a rule, manufacturers of reinforced concrete products provide concrete liners at the factory. If this has not been done, the voids must be filled with M200 concrete mixture under construction site conditions.

In the end walls of the building, the floor slabs rest on the external fences not only with their ends, but also with one side part. Here the depth of support is not standardized, but for reliability, this unit should be designed in such a way that the load from the brickwork does not fall on the first void of the product. Otherwise, squeezing the hollow part may cause its destruction. The support arm should be minimal; its size depends on the design of the slab.

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What are the main types of reinforced concrete slabs?

Factories also produce special slabs that are used for construction in seismically active areas. Such slabs are called ribbed due to the presence of additional stiffeners on both sides.

Required tools and materials

Crane-manipulator for installation of floor slabs
Floor elements made of reinforced concrete are heavy, so truck or tower cranes are used to lift and install them. Electromechanical units are selected taking into account the mass of the panels, the load capacity of the machines, the position of the structures, the type of equipment and devices.

The cranes must be in working order and the mechanical equipment must be in good working order. The condition of machines and devices is confirmed by regulated periodic testing reports. The ceilings can be installed by workers and crane operators of appropriate qualifications, confirmed by certificates. High-altitude installers are equipped with safety belts and shoes with non-slip soles.

Tools and materials:

• electric welding machine, compressor, jackhammer, scaffolding;
• hammers, trowels, levels, hacksaws, crowbars, shovels;
• troughs for mortar to fill joints and areas where slabs are supported;
• sand, gravel, cement, floor panels.

One mounting fixture can be used to work with multiple prefabricated structures to reduce installation time. This will reduce the labor intensity of the process and increase productivity. A four-strand rope sling is used to evenly distribute lifting forces.

People should not be on the slabs while they are being lifted and moved in the air. The installation area is fenced off so that there are no unauthorized workers in it who are not involved in the installation of the floors. The laying of the next floor is done after the installation of the ceiling on the previous tier is completed.

How are floor slabs installed on walls of different materials?

Very often, inexperienced builders have difficulty with how to install reinforced concrete slabs on load-bearing structures. It all depends on the material from which the “box” of the future building was made. Let's study a couple of examples.

Brick walls

When installing reinforced concrete slabs on structures made of brick or concrete, they can be laid directly on load-bearing walls using a special solution of sand and cement approximately 2 cm thick. However, the planting depth must also be taken into account; for brick walls this is 12 cm.

Expanded clay blocks: wall structures

The question of how to lay floor slabs on expanded clay blocks is quite difficult for builders. Since these blocks are not as strong as, for example, bricks, the rules recommend installing a belt of reinforcement on load-bearing structures with a maximum thickness of 20 cm, which will distribute the load more evenly.

Naturally, the slabs are installed only after the belt has gained strength and is able to withstand reinforced concrete slabs. The best support depth for expanded clay blocks is 10-15 cm.

Aerated concrete “box”

As in the case of expanded clay blocks, aerated concrete requires the installation of a reinforcing belt over the entire area of ​​the supporting structure.

Depending on the layer of the reinforcing belt and the size of the slabs, the planting depth for aerated concrete should be in the range of 10-17 cm.

Walls made of porous blocks

In the case of porous blocks, the floor slabs are laid on a so-called cushion of 3 centimeters of mortar and reinforcing mesh. The diameter of the wire used is 4 mm, and the mesh cells are 5x5 cm in size.

There are other layout methods. For example, they make a layer of three layers of hollow brick, on which slabs are subsequently laid.

Armopoyas

Before installing the floors on the main structures, a monolithic reinforced belt is installed. It is carried out along the perimeter of the area of ​​​​the main walls, along their entire width. Formwork is installed along the edge, then a reinforced frame of longitudinal, transverse and vertical reinforcing bars is mounted and filled with concrete.

When constructing an armored belt, the following requirements must be met :

1. The height of the armored belt is from 20 to 40 cm (not less than the height of a standard aerated concrete block).
2. The width must correspond to the width of the supporting element.
3. The thickness of the reinforcement is at least 8 mm. The frame is tightly knitted with wire or fastened by welding.
4. The concrete must match the brand of mortar used for masonry. The recommended grade of concrete used is at least class B15.

The armored belt serves to evenly distribute all loads. It also contains reinforcement fasteners, which are designed for reliable installation of interfloor ceilings. Since the armored belt is a cold concrete layer, it is provided with a thermal insulating coating.

Attention!

Floor slabs are installed only after the monolithic reinforcing belt has completely dried.

Storage of slabs on site

To store slabs on site for a long time, the following rules should be observed:

• If the task is to store a large number of slabs, then the height of one stack should not be more than two and a half meters.

• Laying reinforced concrete slabs on top of each other without wooden spacers is strictly prohibited.

• Wood blocks are installed on both sides with a 20 cm indentation from the edge between each slab.
• The lowest slab should be laid on a large beam so that the slab cannot come into contact with the ground surface.

Correct support of the slabs

We have already described above how to lay slabs on different materials. However, it should also be recalled that designers must specify a standard value when drawing up the technical plan. This value should be 12 cm.

As a rule, in the process of designing the construction of load-bearing structures, designers start from the length of the floor slabs and subtract 24 cm from it, which is equal to the depth of the supports on both sides. The result of this work is the correct amount of emphasis.

Calculation of support parameters

The amount of overlap on the wall depends on the purpose of the building, the width of the wall, the thickness and weight of the ceiling, the seismic activity of the construction area, and the length of the overlapped span. The specific amount of support is calculated by engineers during design. As a rule, to guarantee reliability, taking into account deviations during installation, the maximum value according to SNiP is 120 mm. Laying of PB and PC floor slabs in a brick house is carried out with support on two short sides. The smallest support is presented in the table:

Cell division

You need to pay close attention to the layout of the floor slabs. To calculate this, you need to know exactly the area of ​​the span to be covered and, based on this information, select slabs of the appropriate size.

The maximum length of a reinforced concrete slab can be up to 11 meters, and the width can be from 1 to 1.8 meters.

When drawing up a floor plan, you need to specifically mark openings for communications, for example, ventilation or a chimney. Therefore, we should not forget about monolithic floors, which in the future will need to be carried out directly on site.

Floor installation process

Typically the layout process consists of 5 steps:

• Preparatory stage - this process begins after installing the reinforcing belt or laying the last row of bricks. It is necessary to adjust the height of the structures on which the slabs will be installed. This is done to reduce flexion. Careful preparation and leveling of the wall surface for installation is carried out. In the process of installing reinforced concrete slabs on the foundation, you need to make sure that the waterproofing is reliable.

• Mixing the mortar - a mortar of cement and sand should be mixed in a ratio of 1:3 to a thick consistency. The laying of their solution is laid out in a layer of 1.5 to 3 centimeters for the slab. Some craftsmen, based on their experience, can prepare a pillow for several slabs at the same time. Depending on the material of the load-bearing walls, a reinforcing mesh or a belt of their reinforcement is laid.
• Installation of reinforced concrete slabs - as a rule, the installation process begins from the place closest to the crane or from the places where the communication passes.

• Leveling the slab - this procedure is carried out simultaneously with laying the slab on the load-bearing walls. When the slab is already lying on the wall, it cannot be moved after a couple of minutes and alignment is carried out strictly along the axis of the wall using crowbars. At the end of the installation process, the slings are removed and you can proceed to work with the next slab.
• Anchoring - the procedure involves joining the floor slabs together with ties made of flexible reinforcement of small cross-section. The slabs are joined to the walls using an L-shaped fastening.

Rules for designing interface nodes

When carrying out a detailed design for the installation of floor slabs, in addition to the basic layout of the elements, it is necessary to provide detailing of the nodes , indicating all the nuances when pairing horizontal and vertical elements.

With external walls

The working drawing of the interface between a prefabricated reinforced concrete floor slab and a vertical enclosing structure should show the following details:

• Sectional view of a slab of a given thickness.
• The complete composition of the external wall, including cladding, backfilling and insulation.
• The depth of embedding the structure into the wall.
• Fastening elements to ensure connection (c/p mortar, embedded parts).
• If there is a reinforced concrete belt, a section along this element.
• Scheme of reinforcement of the interface.
• The presence of an elastic insert at the end of the plate.
• Scheme of filling the space between the ceiling and wall cladding.
• If provided for by the project, a diagram of a clean floor with a connection point to the internal part of the vertical enclosing structure.
• When detailing a unit on a typical floor, an image of the overlying external wall.

If the floor slab simultaneously rests on sections of the wall with different designs (for example, at the location of the lintels above window openings), then the assembly must be duplicated for all situations.

With internal carriers

When detailing the support of the slab on internal load-bearing walls, all elements of the drawing are indicated similarly to the algorithm described above. If there are additional design parts, they are also indicated on the unit :

• If the slab is not located in the extreme span, the designer depicts 2 horizontal structures and describes solutions for their connection.
• If the pairing of elements involves twisting or welding, then such parts are also indicated in the project with the designation of the pitch, seam length and other features.
• If there are ventilation ducts located in the thickness of the load-bearing internal wall that affect the installation diagram, such sections are drawn out in a separate drawing.

All additional consumables included in the project are also displayed in the specification for the drawing, indicating their brands and quantities.

Slab cutting

In some cases, it is impossible to lay a solid slab on the site or you simply need to make a technological hole for laying communications. It is in such cases that the technology of cutting reinforced concrete slabs is used. However, it is worth noting that cutting this type of product is an extremely traumatic undertaking. Plus, this leads to a deterioration in the quality of the slab, in particular, the declared strength. It is recommended to order this procedure from the manufacturer or professionals.

Naturally, situations arise when you need to cut a slab quickly and right on the spot; in this case, you need to stock up on a grinder for cutting concrete and an autogen for sawing reinforcement.

Be sure to follow the sequence of actions:

• Apply markings.
• Find a rigid substrate that matches the shape of the slab and place the slab on it.
• Make a cut along the previously drawn lines using a grinder.
• Knock out the cut material using a sledgehammer; you should start from the hollow areas, this will be easier.
• Cut the reinforcement very carefully with an autogen so that the metal does not lose its connection with the concrete.
• Next, you need to fill the voids in the slab with a solution with self-expansion property.

Filling joints between slabs and voids in them

Experienced builders strongly recommend sealing the joints between slabs and void openings. This procedure is performed with the usual solution of sand and cement.

There are several ways to seal the joints between slabs. It depends on the width of the gap:

• Floor deficiencies and large gaps are filled using monolithic pouring technology with reinforcement.

• The average size of the seam is a gap of 2 centimeters; it is filled with high-hardness concrete and longitudinal reinforcement is laid.

• Small gap - up to 2 cm wide, filled with cement.

Waterproofing and insulation

The thermal conductivity of brick is much higher than that of aerated concrete. Therefore, it is recommended to insulate the brick belt. This can be done in various ways, much depends on further options for finishing the internal and external walls of the building. One of the most common insulation options is that the armored belt is hidden behind a thin aerated concrete partition located on the interior side.

After the mortar has set, the top of the masonry is covered with a waterproofing layer of roofing felt or its analogues. This will prevent the formation of condensation on wooden structures supported by an armored belt.

Life hacks and difficulties you may encounter

To lay a slab on a brick wall, its last layer must be bonded. The reinforcing belt can be erected using homemade formwork.

Filling the voids with mortar is required only in those areas that will go outside the building; this protects the structure from severe freezing. Installation of holes for communications must be done on the ground, when there is free access to the slabs, otherwise this may become a problem.

It is necessary to prepare the site for the crane in advance. If the soil at the construction site is loose and crumbly, then this will definitely lead to difficulties. Cranes should not be used near basements; the load on the ground may cause the slab to break. To do this you need to use equipment with a long boom.

If you need to order floor slabs, you should contact IS GROUP. We are ready to provide various designs to any region of the country. Here you can find various road slabs, airfield slabs, FBS blocks, PILES, floor slabs and many other reinforced concrete slabs. Delivery is carried out by rail. If there is no company in your city that can provide you with building materials, then be sure to contact us by phone +7 (495) 175 23 21.

What does the concept mean?

Floors always operate in a building within one floor, taking permanent and temporary loads from their own weight, the mass of floors, equipment, furniture and people using the room.

When external forces are applied, internal forces arise in the element , which determine the geometric section and make it possible to calculate the span structure according to 2 groups of limit states.

At the same time, in the floor slab, along with the loads applied to it, support reactions arise, which are concentrated in places where the elements rest on walls or point vertical structures. These reactions are distributed over the support area and the larger its area, the smaller the load on each cm2 of the vertical element.

Thus, the depth of embedding of the floor in the wall is an important parameter that affects both the value of the supporting transverse force Q in the slab and the axial force N arising in the wall or column. Also, the size of the embedment affects the possibility of local crushing or chipping of the reinforced concrete product during load transfer .