Floor structures must meet the requirements for strength, fire resistance, sound insulation and thermal insulation. Slab-type reinforced concrete products have all these characteristics. They are used in the construction of industrial, multi-apartment and individual buildings.

They serve as interfloor ceilings, where their lower surface acts as the ceiling, and the upper surface acts as the floor of the upper room. The slabs are also laid on garages, sheds and other outbuildings, thus forming a roof. They are often used as a foundation.

Types of floor slabs

There are 2 types: monolithic floor slabs and hollow core slabs. The former are distinguished by a large margin of safety and load-bearing capacity. Serious disadvantages include their weight, high thermal conductivity and low sound insulation properties. Such products are often used for the construction of public and industrial buildings.

Floor slabs photo

• Hollow-core reinforced concrete products are used in the construction of private houses due to their cheaper cost and light weight compared to monolithic analogues. This factor, of course, does not make it possible to do without special equipment for delivering the PC to the site and installation, but, nevertheless, it makes it possible to significantly reduce the load on load-bearing walls and foundations. And as a result, reduce the costs of their arrangement, using less building material.
• The voids running along the entire length of the concrete product can be round, oval or polygonal in shape. They can be used when laying communications using cable ducts, plastic boxes or corrugated pipes.

Hollow-core floor slabs guarantee:

• good heat and sound insulation qualities;
• fire resistance;
• load distribution on load-bearing walls;
• high mechanical strength;
• durability.

Thanks to the smooth surfaces of the slabs, all further finishing work will be held with not only minimal investment funds for leveling the ceiling (floor), but also with less labor.

Floor slab dimensions

• Floor slabs are produced in lengths from 1880 to 6280 mm in increments of 100 mm.
• The thickness of the floor slab is 220 mm. The standard width of the product is 990, 1190 or 1490 mm, although you can find slabs in other sizes.
• The weight of the floor slab is determined by its dimensions; approximately this figure varies from 500 to 1500 kg. As for the load-bearing capacity of a unit of product, on average it is 800 kg per 1 sq.m.

What you need to know before purchasing a PC

• Traces of rust and grease are not allowed on the surfaces of the product.

• The maximum permissible cracks are 0.1 mm, but better is their complete absence.
• All edges of the slabs should have as smooth surfaces as possible, without bulges or depressions.
• Permissible deviation from the nominal value in length - 10 mm, thickness - 5 mm, width - 5 mm.
• The product must have appropriate quality certificates.

Before you start laying floor slabs, you need to know that:

• the rough side of the slab should be facing up, and the smooth side down;
• products are adjusted on their lower sides;
• Reinforced concrete products should rest on 2 short sides; it is not recommended to place the long side on the wall;
• you will need components for sand-cement mortar;
• The slabs are laid close to each other without gaps;
• The crane services are hourly, so everything necessary is prepared for its arrival so that the work goes without a hitch;
• the slabs should rest only on load-bearing walls, the remaining internal partitions (walls) are erected after the installation of the ceiling;
• for smooth installation, the crane will need at least 2, and preferably 3, people to help;

• Before rough finishing, the voids in the slabs are filled with crushed stone or expanded clay.

Preparing walls before installing floor slabs

• Load-bearing walls are leveled. They must be as even in height as possible, the permissible discrepancy is a maximum of 10 mm. You can identify the difference in heights using a long beam, which is placed on two opposite walls. A building level is placed on top of the timber, and the longer it is, the more accurate the result.
• Thus, all supports under the floor slabs are checked. It is important to take measurements as often as possible. To do this, a beam or beam is installed in the corners of the building, then moves every 1-1.5 m. The corresponding data can be written on the walls with chalk or a marker.
• Next, the highest and lowest point is located and the concrete mixture is laid out using cellular metal mesh. Supports built from foam concrete, slag, gas silicate blocks, in mandatory are intensifying. This can be done using a reinforcing belt with a height of at least 15 cm.
• The reinforced belt evenly distributes the load, prevents deformation of the walls and protects the floor slabs from breaking.

• The formwork is assembled from the most even boards in accordance with the obtained values, that is, the edges can have different meanings in height. You can use a special U-shaped profile. The structure is built around the entire perimeter of the house box, including non-load-bearing walls, especially if the structure is made of lightweight block materials.
• To mix the sand-cement mortar, take 1 bucket of cement (M500) and 3 buckets of sand; enough water is needed so that the mixture is not liquid, but not thick. The sand must be sifted to remove stones, which will contribute to the destruction of the layer under the weight of the slab.
• After pouring, the solution is pierced with a trowel or a piece of reinforcement to prevent the formation of air gaps. Tamping should be given special attention.

• Before laying the floor slabs, it is necessary to seal the voids to prevent freezing. If reinforced concrete products have been stored on a construction site for a long time, then it is recommended to drill one or two holes in the areas where the voids pass through, through which excess moisture will escape. It should be noted that the holes are sealed with concrete mortar, and during installation the slab must be facing downwards.
• Factory voids are filled with expanded clay or simply inserted large pieces one and a half bricks, and the remaining cracks are closed cement mortar. Although in lately factories produce slabs with closed voids.
• The mixture in the formwork must dry well and gain strength; this will take at least 3 weeks.

Crane platform

• The soil where the lifting equipment will stand must be compacted. You cannot install a crane near a house under construction if there is a basement. The supporting “leg” of special equipment creates a very significant load on the ground, which can lead to the collapse of the basement wall.
• For loose or bulk soils, it is recommended to order a crane with a longer boom. If the work is carried out in spring or autumn, when the soil is saturated with moisture, the area under the truck crane is laid out with road slabs (you can use used products). Because equipment can get stuck in the slush under its own weight.

Ruler of slabs

• It is not recommended to cover two spans with one slab. Such a load under certain circumstances can lead to cracking. If this particular installation scheme was chosen, then in this case it is recommended to make a cut with a grinder with a diamond disk (to its depth) exactly in the center of the middle wall.
• If a crack does occur, it will go exactly in the direction of the cut, which is quite acceptable.
• Unfortunately, it is not always possible to cover with entire slabs. Sometimes they have to be lined both in width and length. Here you will need a sledgehammer, an angle grinder with a diamond blade, a crowbar and muscle strength.

• To facilitate the process, use a timber or board of appropriate length. Lumber is placed under the slab strictly along the line of the future cut. At some point, the concrete product will break under its own weight.
• First, a cut is made with a grinder on the upper surface of the slab along the marked line. Next, blows are applied using a sledgehammer along the entire length of the reinforced concrete products. Strikes should be struck as often as possible. If the cut falls on a hollow hole, the slab will break quite quickly.
• When cutting the slab width, you will have to make a lot of effort. Any fittings that come across are cut off with a welding machine or cutter. It is not recommended to use a grinder, as the disc may “bite”. But if only this tool is available, then do not cut the metal rod to the end - leave 2-3 mm. Make the final break with a crowbar or sledgehammer.

When cutting the slab, everything possible consequences fall on your shoulders! No manufacturer will give official permission to carry out this work.

• If whole slabs are not enough to completely cover, and the remaining space is small, then you can avoid the labor-intensive cutting process by using the two methods listed below:
• The last or first slab is not adjacent to the wall along its length. The resulting void between the slab and the supporting wall is filled with bricks or blocks. A cement screed applied upon completion of construction will reliably unite and fasten the masonry to the slab.
• This method is good if the existing concrete panels are laid end-to-end, and the remaining distance is distributed between the two supporting walls and filled in using the described method.

• It should be remembered that if the empty opening is more than 30 cm, then when pouring the screed, reinforcement is performed in this area.
• The slabs are mounted flush against the walls, and an empty gap remains between the slabs themselves. Thick moisture-resistant plywood is attached to the lower surfaces of the reinforced concrete products, and reinforcement must be laid to extend onto the upper surfaces of the slabs.
• Thus, you will get something in the form of formwork, which is filled with concrete mortar. After complete drying, the plywood is dismantled, and a general screed is applied over the slabs.

Installation of floor slabs

• For the work you will need a crane and at least 4 people (crane operator, slinger and 2 assistants). The prepared material is laid out on load-bearing supports with a reinforcing belt. concrete mortar thickness no more than 20 mm. The plate rises in a horizontal position at the desired height. All actions, namely the movement and direction of the load, are carried out under the guidance of the slinger.

The installers accept the floor slab and adjust optimal location. Before removing the slings using crowbars, the concrete panel is directed to the installation site with maximum accuracy:

• a minimum distance of 50 mm is left from the slab to the wall along the long side;
• there should be no gap between the plates;
• The width of the support on each short side of the slabs must be at least 150 mm.

Inspection of concrete floor slabs

• After installing the ceiling, the levelness of the surfaces of adjacent slabs is checked. If the height difference is more than 4 mm, then the slabs must be reinstalled. Precast concrete elements are lifted again by a crane, and according to the position, the solution is removed or added.
• The set concrete layer cannot be diluted with water; the hardened mixture is completely removed, and a freshly mixed one is applied in its place. As soon as the leveling is completed, they proceed to fixing the slabs to each other and to the load-bearing walls.

Anchoring of reinforced concrete floor slabs

Upon completion of the installation work and after the slabs have been leveled, they are anchored. If there is a project, then the documents must contain a special diagram. Otherwise, anchoring is done as follows:

• anchor loops are mounted to load-bearing walls and extend onto the floor slabs by approximately 40-50 cm. As a rule, two fasteners are sufficient for the entire length of the panel (they are placed a meter from the edge of the slabs). In the same way, one anchor is installed across the width;

• if the slabs are joined along their short side, then these sections are fixed diagonally using working holes with reinforcement located in them. If they are not available, you can use special fasteners with L- and U-shapes;
• among themselves concrete slabs fastened at points mounting holes. Metal rods it is necessary to tighten it as much as possible and fix it by welding at least in three points.
• After this, the eyelets and seams between the slabs are filled with fine crushed stone and then sealed with sand-cement mortar. You should not delay this work, as it may get into the holes. construction waste.

Features of floor slab installation technology

• Hollow core slabs are widely used in the construction of low-rise and individual buildings. Although they differ in smaller size and lighter weight from their monolithic counterparts, they nevertheless require thicker walls and a reinforced foundation. In addition, they will not be able to cover architecturally complex structures.
• But, despite these disadvantages, the slabs provide reliable flooring, characterized by for a long time services. Their use is justified in cases where the slabs become the basis for flooring roofing material, that is, they act as a flat roof.

Floor slabs video

When preparing and installing floor slabs, it is important to take into account many technical issues, which means you need to have certain knowledge and skills. If you are unsure of the calculations, contact a specialized organization, where they will draw up a project in accordance with all SNiP requirements.

Reinforced concrete slabs are one of the most common types of floors. They provide high strength and allow you to install a rigid structure in the shortest possible time. Installation of floor slabs is a responsible task that requires certain knowledge in the field of construction. First things first.

Types of floor slabs

Before you start installing a horizontal structure, you need to select a type. Reinforced concrete prefabricated structures are produced in the form of:

• multi-hollow;
• flat (PT);
• tent panels with ribs located along the perimeter;
• with longitudinal ribs.

The most common choice is the use of reinforced concrete hollow-core. They are available in two types, depending on the manufacturing method:

• round hollow (PC);
• continuous molding (CB).

Scheme of a hollow-core floor slab with holes

Round hollow core slabs are time-tested products that have been used in construction for several decades. Many have been developed for them regulatory documents and installation rules. Thickness – 220 mm. Products are installed according to serial sizes, which creates inconvenience during individual construction.

The manufacturing technology of these slabs involves the use of reusable molds for pouring, and before manufacturing non-standard products, you will first need to prepare the formwork. Therefore, the cost of the required size can increase significantly. Typical PC slabs have a length from 2.7 to 9 meters in increments of 0.3 m.

Scheme of reinforced concrete products with dimensions

The width of reinforced concrete products can be:

• 1.0 m;
• 1.2 m;
• 1.5 m;
• 1.8 m.

Structures 1.8 m wide are purchased extremely rarely, because due to heavy weight The installation process in the design position is greatly complicated.

PBs are used in almost the same way as the previous type. But their manufacturing technology allows you to give the product any length. Thickness – 220 mm. The width is the same as the PC series. The disadvantage is little experience in use and poor regulatory documentation.

Flat PTs are often purchased as additional elements for hollow-core slabs. They are available in thicknesses of 80 or 120 mm and are smaller in size, allowing them to cover narrow corridors, storage rooms, bathrooms.

Supporting the slabs

The laying of floor slabs is carried out after the preparation of the project or diagram on which the products are laid out. Floor elements must be selected so that they are sufficiently supported brick wall or expanded clay concrete blocks and laying without gaps in width.

The minimum support for the PB and PC series depends on their length:

• products up to 4 m long – 70 mm;
• products longer than 4 m – 90 mm.

Visual diagram how to correctly and incorrectly support floor slabs

Most often, designers and constructors accept optimal value wall support 120 mm. This value guarantees reliability even with small deviations during installation.

It would be correct to pre-position the load-bearing walls of the house at such a distance that it would be easy to lay the slabs. The distance between the walls is calculated as follows: the length of standard slabs minus 240 mm. The PC and PB series must be laid with support on two short sides without intermediate supports. For example, PC 45.15 has a size of 4.48 m, 24 cm is subtracted from it. It turns out that the distance between the walls should be 4.24 m. In this case, the products will lie with the optimal amount of support.

The minimum support for PT series products on the wall is 80 cm. Installation of such reinforced concrete slabs is possible with support points located on all sides.

The support must not interfere with the passage of ventilation ducts. Optimal carrier thickness interior wall made of brick – 380 mm. 120 mm on each side goes under the reinforced concrete floors, and 140 mm remains in the middle - standard width ventilation duct. In this case, it is necessary to lay it as correctly as possible. Shifting the product towards the ventilation hole will lead to a decrease in its cross-section and insufficient ventilation of the premises.

Summarizing what was said:

• PC and PB series up to 4 m are supported on both sides by at least 7 cm;
• PC and PB series more than 4 m - not less than 9 cm;
• PT series – at least 8 cm on two, three or four sides.

Slab storage

Product storage schemes different types

After the scheme has been developed and the products have been purchased, they need to be placed on the building site for convenient installation in the design position. There are rules for storing materials:

• elements must be laid under a canopy;
• the storage location must be located within the access area of ​​the crane;
• Support points are provided with pads.

Failure to comply with the last rule will result in a break in half. PC, PB and PT products work in such a way that the appearance of intermediate supports or a solid base leads to the appearance of cracks. Laying is done in the following order:

• laid on the ground wooden blocks or boards under the edges of the slab;
• on the boards crane I transfer the ceiling element from the car;
• boards or bars are placed again on the laid slab;
• unload the second slab from the machine;
• repeat points 3 and 4, maximum storage height is 2.5 m.

Masonry requirements

Scheme for calculating floor slabs

In order to correctly install floor slabs, you need to ensure that special requirements to a brick wall:

• evenness of the masonry in the place where the floors are laid;
• laying in three rows until overlapping reinforcing mesh with a cell of 5 by 5 cm made of wire with a diameter of 3-4 mm;
• The top row of the frets on the inside should be bonded.

If the slabs are mounted on expanded clay concrete blocks, an additional monolithic belt is installed under the floors. This design will help to evenly distribute the load from heavy floors onto expanded clay concrete blocks with less strength. The construction technology involves pouring a monolithic concrete strip 15-20 cm thick onto the blocks.

Laying floors

To carry out the work, a minimum of three people will be required: one performs the slinging, and two install them in the design position. If the installers and the crane operator cannot see each other, when installing the slab, another worker will be needed to give commands to the crane.

Scheme of laying reinforced concrete products

Fastening to the crane hook is carried out with a four-branch sling, the branches of which are secured at the corners of the slab. Two people stand on both sides of the support and control its evenness.

When installing a PC, pinching into the wall is carried out in a rigid way, that is, bricks or blocks are laid on both the top and bottom of the slab. When using PB series floors, it is recommended to use hinged fastening. To do this, the slabs are not pinched from above. Many builders install the PB series in the same way as PCs and buildings stand, but it’s not worth the risk, because human life and health depend on the quality of the installation of load-bearing structures.

Another important feature of the use of products from the PB series is that it is prohibited to make technological holes in them.

These punches are needed for heating, water supply and sewerage pipes. Again, many builders, even when constructing multi-story buildings, neglect this. The difficulty is that the behavior of this type of floor under load over time has not been fully studied, since there are no objects built quite a long time ago. The ban on punching holes has reasons, but it is rather preventive.

Slab cutting

Sometimes, in order to install a slab, it is necessary to cut it. The technology involves working with a grinder and a disc on concrete. PC and PT slabs cannot be cut to length, since they have reinforced reinforcement in their support zones. If you support such a cut slab, then one edge will be weakened and serious cracks will appear along it. It is possible to cut PB slabs to length, this is due to the peculiarities of the manufacturing method. A timber or board is placed under the cut site, which will make the work easier.

Separation along the length is carried out along the weakened part of the section - the hole. This method is suitable for PC, but is not recommended for PB, since the width of the walls between the holes is too small.

After installation, the holes in the support areas on the walls are filled with lightweight concrete or clogged with mineral wool. This is necessary to provide additional strength in areas where the walls are pinched.

What to do if it was not possible to distribute the products evenly across the width

Sometimes the dimensions of the room do not correspond to the width of the products, in which case all the spaces are combined into one. This space is covered with a monolithic section. Reinforcement occurs with curved meshes. Along their length, they rest on the top of the ceiling and seem to sag in the middle of the monolithic section. For floors, concrete of at least B 25 is used.

The technology of prefabricated floors using bricks or blocks is quite simple, but requires attention to detail.

The construction of buildings involves the construction of reinforced concrete floors separating interior space into separate zones. Reinforced concrete panels, manufactured at specialized enterprises, are installed between the floors of the house, as well as above the basement of the building. The slabs have increased load-bearing capacity and allow you to quickly form a rigid base. Installation of floor slabs is a serious operation that requires the use of lifting equipment. To perform installation activities, special training and knowledge of technology are required.

Types of reinforced concrete floor slabs

Interfloor panels made of reinforced concrete, widely used in the construction industry, are divided into various types.

The products differ in the following parameters:

• overall dimensions;
• design;
• method of assembling the reinforcement grid;
• manufacturing technology.

Slabs mass-produced at reinforced concrete factories are standardized in size.

The panel dimensions are determined by the requirements of regulatory documents:

• length ranges from 2.5 to 12 m;
• the width ranges from 1 to 1.5 m;
• thickness does not exceed 0.22 m.

Floor structures must meet the requirements for strength, fire resistance, sound insulation and thermal insulation

Standardized product sizes create some difficulties for developers. If houses, baths, saunas and swimming pools are being built, then reinforced concrete panels should be selected depending on the overall dimensions of the building, ensuring reliable support of the floor slabs. By choosing slabs with dimensions corresponding to the distance between the walls, it is easy to quickly build a reinforced concrete floor.

Depending on the design, the floor is assembled from the following types of slabs:

• solid. Solid panels differ from other types of slabs in the absence of internal cavities. The products are characterized by an increased margin of safety, as well as increased weight. The disadvantage of solid slabs is reduced sound and heat insulation characteristics;
• multi-hollow. In the end part of the product, longitudinally located cavities of round or oval cross-section are visible. Products with through cavities are common in the construction industry due to their reduced weight, noise insulation and soundproofing properties;
• tent Stiffening ribs are made along the surfaces of the plates, increasing the strength characteristics and the ability of the products to resist existing loads and deformations. In terms of thermal insulation properties, tent panels are inferior.

The steel rods, which are placed in the mold when concreting the slabs, are connected into a spatial lattice using various methods:

• knitting wire;
• electric welding.

They are used in the construction of industrial, multi-apartment and individual buildings

Depending on the manufacturing method, slabs are divided into the following types:

• PC-grade round-hollow panels, concreted in reusable molds of standard size;
• products of continuous formation, type PB, cut into slabs of the required length.

When planning to build a ceiling, you should pay attention to the dimensions of the products and their design.

How to divide monolithic reinforced concrete panels into parts

When performing installation activities, it becomes necessary to reduce the length of the standard panel. To complete the task, you can use a regular grinder with a diamond wheel designed for cutting concrete. You will also need a disc for cutting steel reinforcement, a sledgehammer and a crowbar.

Carry out work on cutting slabs according to the following algorithm:

1. Mark the required panel size with chalk.
2. Place a backing along the markings to protect the concrete from chipping.
3. Cut the reinforced concrete slab along the chalk line.
4. Apply blows with a sledgehammer to the top plane and end surfaces.

After the unnecessary piece of slab settles under its own weight, perform the following operations:

1. Punch it with a crowbar bottom part concrete panel.
2. Use a grinder to cut the rebar using a metal disc.

First, a cut is made with a grinder on the upper surface of the slab along the marked line

By following the given sequence of operations, it is easy to cut the panel along the longitudinal axis. In this case, using a grinder with a metal circle, you will have to cut the metal mesh used to strengthen the slabs.

How to install floor slabs

Installation of floors is a responsible process that requires special training.

To perform installation operations and laying panels, you will need lifting equipment, tools and materials:

• truck crane;
• rigging equipment;
• scaffolding;
• fastening anchors;
• crowbar and sledgehammer;
• cement mortar;
• trowel;
• building level and plumb line.

Correct laying of floor slabs is carried out on smooth wall surfaces on pre-laid cement mortar. Maintaining the width of the supporting surface will allow you to evenly distribute the load on the load-bearing walls and ensure the stability of the panels.

For the work you will need a crane and at least 4 people

When performing work, adhere to the following algorithm:

1. Check the level of the horizontal end of the main walls and eliminate height differences of more than 15 mm with the solution.
2. Lay the cement mortar on the horizontal end of the walls, ensuring a layer thickness of 20-30 mm.
3. Secure the panel to the sling eyes and move it with a truck crane to the installation site.
4. Adjust the required position of the plate with a crowbar, check the contact patch and lower the product.
5. Disconnect the slings and secure the panel with steel anchors, ensuring a pitch of 180-200 cm.
6. Seal the gap between the end planes of the panels using cement mortar.

On final stage work, seal the end holes in the panels using the following materials:

• mineral wool;
• concrete solution;
• backfill brick.

The end cavities are sealed to a depth of 200-250 mm, followed by filling the end plane with cement mortar.

Laying floor slabs - subtleties of technology

Novice developers do not always have a detailed idea of ​​how to lay panels. The technology for laying floor slabs has certain nuances.

Installers accept the floor slab and adjust the optimal location

Please note the following points:

• installation should be carried out at the end of the main walls of the building with the construction of interior partitions and walls after completion of installation work;
• maintain the amount of support of reinforced concrete slabs on main walls within 10-25 cm;
• ensure reliable fastening of adjacent products using mounting loops;
• control the horizontality of the supporting surface of the load-bearing walls, guaranteeing the absence of drops and steps;
• ensure the uniform consistency of the cement mortar and the absence of rocky inclusions.

Please note that installation of floor slabs is allowed in the following options:

• by two opposite walls on the short sides of the panel;
• at three ends of the walls, forming a U-shaped contour.

Compliance with these requirements will allow you to avoid unforeseen situations.

How to fill small voids when laying floor slabs

During the installation of floor slabs, gaps inevitably form between adjacent slabs, as well as between the outer panels and walls.

Before laying floor slabs, it is necessary to seal voids to avoid freezing

Used following methods seals:

• small gaps between the panels can be easily filled with red brick or blocks of cellular concrete with further leveling of the surface using cement mortar;
• the increased space along the edges of the slabs must be filled with concrete after preliminary installation of the formwork panels and reinforcing grid.

Properly sealed gaps ensure insulation of ceilings and walls, which affects the indoor climate.

Installation of slabs - difficulties encountered

If the rules for transporting and storing panels are violated, unforeseen situations associated with the formation of cracks.

The following recommendations will help prevent cracking:

• store reinforced concrete products on a level surface;
• install wooden spacers of equal thickness between the slabs;
• place the bars strictly vertically;
• do not allow contact hollow core slabs.

In case of minor defects and small cracks, it is allowed to install panels in unloaded areas with sealing of cracks with cement mortar. Slabs with through cracks must be cut into separate pieces and used as short sections.

What to do if you can’t evenly lay out the panels

Considering the significant mass of the panels and increased overall dimensions, it is difficult to ensure the stability of the gaps between the slabs and their uniform laying on the supporting surface. In addition, often the dimensions of the room do not correspond to the dimensions of the slabs, and, as a result, open area. In this situation, the free space should be concreted.

Procedure:

1. Fasten the formwork panels to the bottom plane of the slabs.
2. Lay the reinforcing mesh.
3. Pour the concrete solution.
4. Seal small gaps with cement mixture.

When planning the construction of the floor, select panels according to size and design. Be sure to develop a plan for the floor slabs that will make their installation easier. When installing products, do not lean them on internal ones. If the dimensions of the slabs do not match the dimensions of the box, select the dimensions of the expanded clay block for embedding free space. When using panels for a precast base, you will need. Analyze when planning to build. Recommendations from professionals will help you avoid mistakes.

Do-it-yourself installation of floor slabs.

Currently, in our country, the most popular are three methods of constructing floors in a house. This is the installation of floor slabs, the installation of a monolithic reinforced concrete floor and installation of ceilings on wooden (less often metal) beams. We will definitely talk about all these methods and more. And the first technology we will consider is the installation of ready-made floor slabs.

First, a little about the floor slabs themselves. Depending on their shape, all slabs can be divided into flat and ribbed. Flat ones, in turn, are divided into solid and hollow. We are now interested in empty ones, because... It is this type of slab that is used mainly in low-rise construction.

Hollow core slabs, in turn, are also classified according to various parameters, such as the shape and size of the voids, the thickness of the slabs, the manufacturing technology of the slabs, and the method of reinforcement.

I will not delve into the topic of classification. It is better to look for this information on the websites of manufacturers of reinforced concrete products (reinforced concrete products). We'd better talk directly about installation.

The very first point that you need to pay attention to even at the stage of designing your future home is the opportunity to purchase in your area exactly the slabs of the sizes that are included in the project. Each manufacturer has its own specific range of products and it is always limited. This is really important and I am surprised that very often developers forget about this recommendation and then they have to either cut one or several slabs or make a monolithic section on the floor. We'll talk more about this below.

Storing floor slabs at a construction site.

Of course, it’s great if you have the opportunity to lay floor slabs immediately when they are delivered directly from the truck that brought them. But most often this does not happen. Or the driver insists that you unload the slabs as quickly as possible, because... he is in a hurry for the next order, or the slabs are not laid on the machine in the order you need, or you simply bought them in advance and are not going to lay them yet. In all these cases, the slabs will need to be stored on your site.

Try to choose for this flat surface. Never place slabs directly on the ground. Be sure to put something under the edges of the slab, for example, trimmings wooden beam. There should be only two pads, at a distance of approximately 25-40 cm from the edges. Pads cannot be placed under the middle of the slab.

The slabs can be stored in stacks up to 2.5 meters high. Make the shims for the first slab higher, so that if they are possibly pressed into the ground when laying subsequent slabs, the first slab should never touch the ground, otherwise it could easily break. It is enough to make all subsequent linings even from an inch (2.5 cm). They must be stacked strictly one above the other.

Preparation for installation of floor slabs.

Preparation begins at the moment when the masons cast out the last rows of masonry. The slabs will lie flat and without differences if the top rows of load-bearing walls are level and in the same horizontal plane.

To achieve this, there must be marks in all corners of the room being covered. horizontal level. They are placed during the construction of walls using a level, or a laser level, or a hydraulic level. And when the last row of masonry is done, the distance from the marks to the top of the walls is controlled with a tape measure. It should be the same in all corners. From my experience I can tell you for sure that some masons neglect this, especially when they do backfill masonry at the same time as the face masonry, which is done “under the rod”.

The top row of brickwork of load-bearing walls must be bonded. That is, if you look from the inside of the covered room, then on the load-bearing walls (on which the floor slabs rest) in the very top row of the masonry, only the pokes should be visible.

If the slabs are placed on a load-bearing partition 1.5 bricks thick (that is, the slabs rest on it on both sides), then the top row of such a partition is laid out in one of two ways:

Before laying floor slabs on walls made of various blocks (foam concrete, gas silicate, slag, etc.), it is necessary to make a reinforced concrete belt (usually about 15-20 cm thick). Such a belt is made either by pouring concrete into the formwork, or using special U-shaped blocks along the entire perimeter of the house box, i.e. not only on load-bearing walls, but also on non-load-bearing ones.

When installing hollow core slabs, the holes in them must be sealed. It is much more convenient to do this in advance, while the slabs are still on the ground. In general, SNiP prescribes that voids must be sealed on the side of the slab that rests on outer wall(to reduce the likelihood of the slab freezing), and from the side that rests on the internal partition, only starting from the third floor from the top of the house and below (to increase strength). That is, if, say, the house has basement floor, overlap between the 1st and 2nd floors and attic floor above the 2nd floor, it is mandatory to fill the voids on the side of the load-bearing partitions only in the basement floor.

I will say that we always seal holes when laying slabs. Moreover, recently, more and more often, round-hollow slabs come from factories with the holes already sealed. It's convenient. If the holes are not sealed, we insert a one-and-a-half brick (you can even use half) into them and fill the remaining cracks with mortar.

Also, before installing the slabs, it is necessary to prepare the site for the crane in advance. It’s good if in the place where the crane will stand the soil is, as they say, compacted. It's worse when the soil is bulky. If you have a basement, you should not place the faucet too close to the house, in order to avoid what is shown in the figure below:

In such cases, it is better to order a truck crane with a longer boom. Also, sometimes in the place where the crane will stand, you first have to put several road slabs (usually used ones are found somewhere). Often this has to be done in the fall in rainy and slushy weather, when the area is so “broken” that the crane simply gets stuck on it.

Sufficient for installation of floor slabs three people. One hooks the slabs, two lay them down. If you want, you can do it together, although not always. It happens that when covering, for example, the second floor, the installers and the crane operator do not see each other. Then, at the top, in addition to the 2 people directly laying the slab, there must be another person who will give commands to the crane operator.

Laying begins from the wall on a layer of mortar no more than 2 cm. The mortar should be thick enough so that the slab does not squeeze it completely out of the seam. After the crane operator places the slab on the walls, he first leaves the slings taut. At the same time, using a crowbar, if necessary, it is not difficult to move the slab a little. If the upper surfaces of the load-bearing walls were made smooth, then the slabs will lie smoothly, without differences, as they say, “from the first approach.”

Regarding the amount of support of the slabs on the walls, I will give an extract from the document “Manual for the design of residential buildings. Vol. 3 (to SNiP 2.08.01-85) 6. COLORS:

Paragraph 6.16.: The depth of support of prefabricated slabs on walls, depending on the nature of their support, is recommended to be no less than, mm: when supported along the contour, as well as two long and one short sides - 40; when supported on two sides and the span of slabs is 4.2 m or less, as well as on two short and one long sides - 50; when supported on two sides and the span of the slabs is more than 4.2 m - 70.

When assigning the depth of support for floor slabs, you should also take into account the requirements of SNiP 2.03.01-84 for anchoring reinforcement on supports.

In our practice, we try to make the support no less than 12 cm, fortunately now it is possible to purchase exactly the slabs that are needed. The step of their lengths is 10 cm.

I often hear arguments about whether it is possible to support hollow-core floor slabs on three sides (two short and one long) and how far the long side of the slab can be placed on the wall. From what is written above, it follows that it is possible to support the slabs this way. But this is not entirely true. If you read the specified SNiP, it says that slabs that rest on three sides have a different reinforcement pattern than those that rest on only two sides.

The vast majority of hollow core slabs that are currently produced by concrete factories are designed specifically to be supported on two short sides, so it is not recommended to place them on the wall with their long side. Under a certain load, this can lead to cracking of the slab. The reinforcement scheme and, therefore, the possibility of supporting the slab on a third side must be clarified with the manufacturer.

Another mistake associated with improper loading of the slab is covering two spans at once (see figure below):

Under certain unfavorable conditions, the slab may crack, and the location of the crack is completely unpredictable. If you still use such a scheme, use a grinder to make a cut (to the depth of the disk) on the upper surface of the slab strictly above the middle partition. Thus, if something happens, the crack will pass precisely along this cut, which, in principle, is no longer scary.

Of course, it’s good if we manage to cover ourselves exclusively with whole slabs. But circumstances are different and yet sometimes some slab (or even more than one) has to be cut lengthwise or crosswise. To do this you will need a grinder with a diamond disc for concrete, a sledgehammer, a crowbar and not the weakest guy at a construction site.

To make work easier, it is better to place the slab on a lining. Moreover, this lining is placed exactly under the cut line. At a certain moment, the slab will simply break along this line from its own weight.

First of all, we make a cut on the upper surface of the slab with a grinder along the cut line. Then, striking with a sledgehammer from above, we cut a strip along the top of the slab. It is quite easy to penetrate concrete in void areas. Next, we use a crowbar to break through the lower part of the slab (also through the voids). When cutting a slab lengthwise (we always cut along the hole in the slab), it breaks quite quickly. When chopping across, if the slab does not break after breaking the lower part with a crowbar, use a sledgehammer to strike the vertical partitions of the slab from the side until the victory is achieved.

During the cutting process, we cut the reinforcement that comes across. You can use a grinder, but it’s safer to use welding or a gas cutter, especially when the reinforcement in the slab is pre-stressed. The grinder disc can bite. To prevent this from happening, do not cut the reinforcement completely, leave a couple of millimeters and then tear it apart with a blow from the same sledgehammer.

Several times in our practice we had the opportunity to cut slabs lengthwise. But we have never used, so to speak, “stumps” less than 60 cm wide (less than 3 holes remain), and I do not advise you to. In general, when deciding to cut a slab, you take full responsibility for the possible consequences, because not a single manufacturer will officially tell you that cutting a slab is possible.

Let's now see what can be done if you still don't have enough slabs to completely cover the room:

Method 1- we place the first or last (maybe both) slabs without bringing the long side to the wall. We fill the remaining gap with bricks or blocks, hanging them no more than half from the wall (see figure):

Method 2- we make the so-called “monolithic section”. Plywood formwork is placed underneath the slabs, a reinforcement frame is made (see figure below) and the area between the slabs is filled with concrete.

Anchoring of floor slabs.

After all the slabs are laid, they are anchored. In general, if the construction of a house is carried out according to a project, then it must contain an anchoring scheme. When there is no project, we usually use the circuit shown in the figure:

The anchor is made by bending the end into a loop that clings to the mounting loop of the slab. Before welding the anchors to each other and to the mounting loops, they must be tensioned as much as possible.

After anchoring, we immediately seal all mounting eyes in the slabs and rustications (seams between the slabs) with mortar. Try not to delay this so that construction debris does not get into the rustics, and water does not pour into the eyelets during rain and snow. If you suspect that water has gotten into the slabs (for example, you bought slabs with voids already filled in, and rainwater could have gotten in even while being stored at the factory), it is better to release it. To do this, after installation, simply drill one small hole in the slabs from below with a hammer drill, into the voids where the mounting lugs are located.

It is especially dangerous to find water in voids in winter time when the house is not yet heated (or not completed at all) and the slabs freeze below zero. Water saturates the bottom layer of concrete, and with repeated freezing-thawing cycles, the slab simply begins to collapse.

Another way to secure the slabs is to construct a so-called concrete ring anchor. This is a kind of the same monolithic reinforced belt, only it is not made under the slabs, but in the same plane with them, also around the entire perimeter of the house. More often this method is used on houses made of aerated concrete, foam concrete and other blocks.

Let me make a reservation right away that we have never used it because it is much more labor intensive. I think a ring anchor is justified in more earthquake-prone regions than our Nizhny Novgorod region.

Do-it-yourself installation of floor slabs, HOME

We are considering issues related to the installation of floor slabs. How to store slabs? How to prepare walls for ceiling installation? How to lay and fasten the slabs?

The final operation of the zero cycle is the installation of floor slabs on the foundation, which cannot be done without lifting equipment. For most construction work, TTK maps have been developed to eliminate injuries and ensure the required quality.

The PC layout plan takes into account interfloor technological openings, the range of reinforced concrete products from factories in the region, the configuration of the building, and the presence of ventilation ducts in the internal load-bearing walls. Monolithic areas that will have to be filled locally are indicated separately. Delivery of floor slabs is carried out on semi-trailers only if the length of the products is within 3.2 m. If non-standard panels of greater length are used, they are moved on panel trucks.

The basic rules for laying prefabricated floors are as follows:

• panels can only be laid on foundations leveled in a horizontal plane;
• with a height difference of up to 5 cm, leveling with a screed is allowed; for larger values, only with masonry or an armored belt poured into the formwork;
• support from 6 cm for reinforced concrete, from 12.5 cm for brickwork;
• the thickness of the mortar pastel is 15 - 20 mm with mandatory longitudinal reinforcement with a round rod of 10 - 12 mm (reinforcement A240);
• adjustment of PC products should be carried out with crowbars in the first 10 minutes, always with tensioned slings;
• concrete plugs for voids are installed in the slab before or after laying, depending on the availability of access to the ends of the product;
• anchoring the panels together is mandatory, with load-bearing walls depending on the project.

Attention! It is prohibited to crush PC slabs with crushed bricks or crushed stone to level the lower planes of the basement/underground ceiling. Sand or solution must be sifted before work begins.

Surface preparation

Before placing the slabs on the supporting surface, the foundation is cleaned of mortar, concrete deposits, and dirt. To install the first reinforced concrete product, workers need stepladders, scaffolding, ladders or scaffolding in basement. If a prefabricated floor is being made on a MZLF foundation, these devices are usually not necessary.

Before installation, the quality of waterproofing of the upper edge of the foundation is checked. The film or roll layer must be continuous and be a continuation of the vertical waterproofing of the outer and inner walls.

At the same stage, a solution is prepared at the rate of 2 - 6 buckets for each floor slab, depending on its width. Or you can order a mixture from a mortar unit of guaranteed brand strength. The mortar bed is laid for one/several panels depending on the following factors:

• air temperature - in cold weather the cement-sand mixture can freeze, and in hot weather it can dry out and lose its properties;
• experience of workers - professionals usually apply a bed for 3 - 4 reinforced concrete products, taking into account monolithic areas.

Attention! The working surface of the PC is the bottom edge of the plate, so one specialist with bubble level to control the horizontal in two directions, maintaining the flatness of adjacent panels.

Installation of PC panels

Laying floor slabs begins from the corner closest to the faucet or from the wall with a ventilation duct. In any case, two installers are enough for slinging. Work is usually carried out from the vehicle that delivered the PC product to the site in order to reduce unloading time. To ensure design support, the length of the spans is pre-measured with a tape measure.

The TTK maps indicate in detail how to correctly lay slabs on a foundation with minimal costs time:

• slinging by mounting loops - with sling hooks or special lifting devices;
• supplying the product to the installation site - workers are at a safe distance, unfolding the panel into the design position using hooks in weight;
• laying - after leveling the mortar bed, longitudinal reinforcement is sunk into it in the middle of the supporting surface (3 cm from the edge for reinforced concrete, 6 cm for masonry), the floor slab is leveled on both sides, smoothly lowered into place, the slings remain taut.

If necessary, the reinforced concrete product is adjusted with crowbars during the first 10 minutes relative to the axis of the wall. Then the slings are loosened completely, the lower worker controls the horizontal in two directions.

Attention! Leveling with mortar is carried out by lifting the slab by all mounting loops, and not by one side. If you lift the PC by two loops, spontaneous movement is possible, squeezing out the solution from under the second edge.

When installing the first slab, the foundation cannot be used for workers to walk on, regardless of the width of the tape. It is necessary to use scaffolding, stepladders, and scaffolding. Then the prefabricated floor is mounted according to the layout diagram, the slabs are laid close to each other with their long sides. Concrete (less often polystyrene foam) plugs are usually placed in the voids at the ends after installation of the entire prefabricated basement floor.

Tying slabs with reinforcement

The rules for laying interfloor slabs provide slab anchoring according to the following schemes:

• outer plates - diagonal tying with wire 3 - 5 mm;
• adjacent panels - U-shaped lintels made of smooth reinforcement A240 with a diameter of 10 mm;
• slab/wall – L-shaped anchor with a bend of 30 – 40 cm;
• longitudinal connections - between the slabs resting on the internal load-bearing wall, smooth reinforcement 10 mm.

Thus, the prefabricated horizontal disk of the floor receives additional spatial rigidity and connection with walls made of bricks and concrete blocks.

Attention: The standard support for PC slabs is 6 – 12.5 cm. In the event of seismic activity, the anchors will ensure the evacuation of people from the building, preventing individual slabs from collapsing.

For normal connection of the PC with internal load-bearing walls, it is enough to place 3 longitudinal anchors on each linear meter length. All elements are joined to the mounting loops by welding in accordance with SP 70.13330 for enclosing and load-bearing structures.

Thermal insulation of joints

After laying the slab, the perimeter of the foundation is leveled with brickwork. This material is a cold bridge by default, so it is necessary to lay bars of extruded polystyrene foam or mineral wool. Only in this case will heat loss through the floor be minimal.

Scheme of insulation of the ends of floor slabs.

It is allowed to use solid strips along the entire length of the wall, assembled from pieces of insulation. If there are gaps, you need to fill them polyurethane foam, the characteristics of which are almost similar to the specified heat insulator.

Sealing joints

The above thermal insulation is required exclusively along the outer perimeter of the floor slabs. However, reinforced concrete products have conical longitudinal edges, so there are seams between them. In addition, the width of internal load-bearing walls is usually greater than the supporting surfaces of two adjacent slabs. In the first case, it is enough to fill the longitudinal joints of the floor slabs with M100 mortar. In the second option, it is necessary to monolith the area, connecting the slabs and the foundation. For this, ready-mixed concrete of class B12.5 and higher can be used.

Attention! In areas of internal load-bearing walls, the strip foundation may contain ventilation ducts coming from the underground level. Before laying the mixture on this monolithic area it is necessary to first carry out the masonry to extend the channels to the next floor.

This technology allows you to lay PC slabs on the foundation with minimal time without reducing the strength of the horizontal floor disc. At the same time, a rigid connection with the load-bearing walls is ensured, and the safety of residents during natural disasters is guaranteed.

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