• sand concrete
• plasticizer
• noise insulation PPU 2mm
• cut around the perimeter

In this article, we will talk about things that any customer who plans to perform a screed should know - both about the technology itself and about ways to avoid being deceived by negligent builders.

One of the main requirements of a quality screed is a perfectly flat horizontal surface. How to determine the level of screed?

Stage 1. Determine the horizontal level of the screed

The first thing in this case is to decide on the zero level. In the absence of laser devices, an ordinary water level (it is also called a spirit level) is quite suitable for this purpose. The level used by carpenters is unacceptable for this purpose.

The zero level should be “beat off” in all rooms at once, the height of the beat can be any, although the level equal to 1.3-1.5 m above the floor is considered optimal.

This is done as follows: the first "beat" is made in the room in any place. With the help of a level, it is transferred to all other walls, both inside this room and in other rooms. The result is marks at the same level relative to the "ideal gender" (which in fact does not exist). Marks within each room are sequentially connected to each other by straight lines. This will be our zero level, relative to which we will work. We think it’s not worth saying that the quality of the entire screed will depend on the accuracy of the “beating” of the zero mark. Stage 2. Identification of the maximum level of the existing floor and height difference

We need this in order to correctly select the level of the screed. It should not be higher than the highest point of the floor level. Also at this stage, we will be able to roughly figure out how much material we need to work.

To do this, we measure the height from the zero level to the real floor. We do this as often as possible - the thicker the marks, the better the result will be. In the course of measurements, we make marks on the wall, next to which we write the value. The lower the value, the higher the point is and vice versa.

For example, the minimum value is at around 1.19 m, and the maximum is 1.29 m. Then the height difference will be 10 cm. as it very quickly becomes covered with cracks and begins to crumble. An exception can be made in only one case: a special self-leveling compound of the type will be used for alignment. The minimum and maximum thickness values ​​in this case are indicated on the packaging by the manufacturer.

Sometimes situations arise when different levels of screeds are needed in the same room in different rooms, which is explained by different types of coatings that are planned to be used there in the future.

For example, often in the same apartment parquet is laid in the living rooms, and tiles are laid in the bathroom and kitchen. Laying parquet will require serious calculations, since the parquet itself is a series of several layers of different materials. For example, the total thickness of a parquet can be calculated as follows:

0.2 cm mastic (glue) + 1.3 cm plywood + 0.1 cm parquet glue + 1.5 cm parquet = 3.1 cm.

We remove 1 mm for scraping, we get 3 cm.

For ceramic tiles, the calculations will be as follows:

0.6 cm per adhesive + 1.1 cm tiles = 1.7 cm.

Therefore, at the junction of parquet and tiles, the difference will be 3 cm - 1.7 cm = 1.3 cm.

These are theoretical calculations, but in practice, another 1-2 mm should be added to this number. At the same time, it must be borne in mind that the thickness of the parquet always remains constant, but the thickness of the tiles can be increased due to the thickness of the adhesive base.

Let's talk about the quality of the materials needed to create a screed. Most often, builders use a mixture of cement and sand for this purpose, which is sold ready-made in bags. Sometimes cement and/or a plasticizer may also be added there.

Always ask the builders what kind of mixture they plan to use for the screed in your room. Pay attention to them that in pursuit of a cheap mixture, you can get a poor-quality result, and buying a mixture on the market at the first outlet that comes across can nullify all their efforts. Also, different mixtures can be designed for different construction works.

When buying a mixture, pay attention to its color. An indicator of a high-quality cement mixture is a light gray color without impurities. Red and yellow shades of the mixture gives the excessive content of sand or clay.

If you bought a quality proven mixture, there is no need to add cement to it, as this will negatively affect its properties. The same applies to PVA glue - instead of it, plasticizers must be added in the quantities recommended by their manufacturers.

Stage 4. We prepare the surface for the screed

The screed requires preliminary surface preparation. To begin with, it must be cleaned of dirt, dust, moisture and cement mortar (if any). Delaminations should be removed, uneven surfaces should be leveled with a thick cement mortar (ideally, if it is Non-Shrink Cement - BUTs).

To remove dust, it is best to use a construction vacuum cleaner; in its absence, thorough sweeping with an ordinary broom is also suitable. After that, the floor is primed. At the junction with the walls, a waterproofing gasket is placed in the form of a roofing material tape.

If builders recommend that you do a full waterproofing of the floor, this is not correct. Firstly, such a layer will prevent adhesion, which will reduce the strength of the screed. Secondly, if your apartment is flooded by neighbors from above, all the water will remain in your room. It is better to pay attention to the cracks and get rid of them before the screed.

Stage 5. We expose beacons

Beacons are called guides, with the help of which the screed will be aligned at one level. If they are installed correctly, the screed will be even over the entire surface of the floor. As lighthouses, dense and rigid materials are used - pipes or profiles. The installation method can be different: someone prefers to make small indentations in the solution, someone uses a screw mount. The main requirement for an already installed beacon is its rigid fixation.

The installation of beacons should be done so that they are parallel to each other, and between two adjacent beacons it is possible to support a rail, which will level the solution.

Where screed differences are greatest, plywood formwork can be used to prevent material from penetrating from one area of ​​the screed to another.

Stage 6. Prepare the solution and fill

Today, few builders are engaged in the manual preparation of mortar - more often small concrete mixers come to the rescue. Yes, and this affects the quality of the solution well - the concrete mixer mixes it more thoroughly.

If, nevertheless, the builders stir the solution manually, pay attention that they do not add more water to the solution than it should be according to the instructions - this way they can try to simplify their task and stir the solution more quickly. In this case, the screed will turn out to be less durable, and you will be the loser.

To determine the optimal liquid content in a solution, fairly simple instruments are used. Professional builders with extensive experience can cope without devices, "eyes", and they do it quite accurately. Outwardly, the ideal solution should look like a thick dough. It should not have lumps, it should not crumble or, conversely, be excessively spread over the surface.

Fresh solution must be used within 60-90 minutes. It is impossible to leave the solution for later, pouring a layer of water on top of it. Filling is done in one pass, several stages within the same room are unacceptable.

Tip: when making a screed, pierce the solution as often as possible with a thin metal rod. This will help prevent hollow spaces filled with air.

Stage 7. Properly care for the screed.

Improper care of a fresh screed is the reason for a large number of marriages, although in fact the rules for care are very simple. In the room in which the screed has just been made, it is necessary to maintain a high level of humidity for 7-10 days. This is required so that the solution does not just dry out from dehydration, but rather freezes. If the surface dries, it will be difficult for deeper layers of the mortar to do so.

To prevent premature drying of the screed, it is moistened several times during the day with plain water. On the third or fourth day, beacons are taken out, and the recesses remaining from them are covered with fresh mortar. After that, the screed is covered with a film and left for 12-14 days.

Haste in this matter can be fatal - it is better to wait a few more days than to redo all the work from the very beginning.

Stage 8. We accept the work of builders.

The result obtained can be evaluated in several ways.

1. Visual assessment. A high-quality screed looks like a flat surface of the same color over its entire area. It should not shine and not have cracks.

2. Level check. For this purpose, rail-rules are used. It is applied to the screed in several parts of the room. According to construction standards, the maximum discrepancy between the rule and the screed should not exceed 4 mm.

3. Determining the slope with respect to the horizon. You can use any level to check. A value less than 0.2% is within the normal range, but not more than 0.5 cm (for example, if the room is 4 meters long, the deviation should not exceed 8 mm).

4. Tapping. Perform with a wooden block and listen to the sound. On the entire surface, the sound should be the same - sonorous. A dull sound indicates the presence of voids.

In Russian construction standards, the quality of the screed device is regulated by SNiP 3.04.01-87. In Europe, the DIN 18560 standard is used. Both standards have a number of discrepancies, so if the builders guarantee you a European-quality repair, then you should evaluate the quality of the screed exactly according to the second standard, otherwise it will be a gross violation of your agreements.

If a marriage is found, it is better to call a specialist from the outside for an assessment, since determining the level of damage requires experience and practical training. It is logical if the work of this specialist will be paid for by builders who performed their work poorly.

If you still want to finish the job yourself, heed these tips:

• record all actions and agreements on paper, providing them with signatures on a bilateral basis;
• Take photographs of defective areas if possible.

In the event of an obvious marriage, oblige the builders to eliminate it at their expense. This can be done with a self-leveling compound - not the cheapest way, but quite suitable for the builders to realize their guilt and pay for it in full. If you doubt that the people you hired will be able to cope with this task, hire another team and pay for its work at the expense of the first one.

If there are cracks in the screed, they are primed and covered with BUTS. If there are a lot of cracks, you will need to remove and redo the entire screed. If there are voids in the screed (revealed during tapping), the upper sections are peeled off, removed and filled with the composition again.

What is the minimum thickness of the floor screed according to SNiP?

A layer of cement-sand screed is the basis for the final coating, which is the upper part of the base of the floor. The screed should provide a perfectly flat surface for the finish coat. The quality of the screed determines the life of the floor of the room, strength, and the thickness is of fundamental importance. A reduced layer will not have the necessary strength, and a thickened one will cause an overrun of the mixture. That is why SNIP regulates the requirements for the design, operation, restoration of floors, describes the structure, requirements for elements, including the screed.

Document structure

Building codes and regulations contain requirements for the design of floors intended for public premises, administrative facilities, manufacturing enterprises, and private houses. The document structure contains:

• general requirements for floor design features and its development;
• classification of coatings depending on the strength, thickness of the material;

Today, there are many ways to perform work related to leveling the subfloor for further laying flooring.

• layer requirements;
• a list of measures to protect against water intrusion;
• recommendations on the scope and thickness of the screed;
• litter characteristics;
• requirements for the bases on which the floors are installed.

Basic terms

The rules use terminology, according to which the floor is divided into tiers, component parts with specific names:

• External coating- the outer layer of the floor surface, perceiving the load during operation.
• Interlayer- a floor element that provides elasticity and is located under the top layer.
• Waterproofing contour- a layer that makes it difficult for groundwater or sewage, liquids to access through the floor surface.
• Screed- a leveling layer that serves as the basis for installing the floor, which ensures the flatness of the base, distributes loads, covers various communications.
• bedding- the bottom layer, which evenly distributes the forces from the floor and the weight of the screed to the surface of the base.

All work related to leveling the floor with cement mortars, even if they are done by hand, must meet certain requirements

Solution selection

When deciding on a coating device, make an economically sound, technically competent decision, taking into account the points specified in the standards:

• service life and structural strength;
• rational use of materials, taking into account the characteristics;
• the possibility of mechanization of work, reducing labor costs;
• the influence of negative moments, the ability to violate the integrity of the flooring;
• hygiene and fire resistance.

When designing floors, the standards oblige to take into account the degree of mechanical impact indicated in the table, as well as the level of influence of the liquid on the surface. With abundant moisture, the rules require a floor with a slope of 0.5 to 2%, which is ensured by pouring a layer of varying cross-section.

The main, interlayer and insulating layers of the coating: types and requirements

The choice of coverage for certain types of premises is made in accordance with the recommendations of the tables attached to the standards. They regulate the degree of influence of mechanical, thermal and liquid factors. In particular, the cement-sand surface of the production facility must withstand a specific weight of 50 kgf / cm², a heating temperature of not more than 100 degrees Celsius and exposure to alkaline media with a concentration of up to 8%.

The thickness of the cement-sand composition, according to SNiP, in residential premises should not be less than 30 mm

• Linoleum.
• Wood.
• PVC tiles.
• Parquet.
• Cement concrete base.

The minimum thickness, strength characteristics of the material used for coating are given in the table of the document. When using a common cement-sand mortar as a coating, its minimum thickness at low intensity of exposure is 20 mm, and at moderate intensity - 30 mm. In this case, the strength of the material used should be 200-300 kg / cm².

Bituminous mastic, fine-grained concrete, as well as cement-sand mortars, the minimum thickness of which is 10 mm, are used as a layer.

At a high level of coating loads, the norms oblige to perform waterproofing that protects the floor from exposure to liquids: ordinary water, oils, acids, emulsions, alkalis. As a material used for insulation from moisture, concrete or polymer compositions are used. According to the requirements of the standards, 1-2 protective layers should be applied, depending on the possibility of liquid penetration into the material.

The minimum layer directly depends on the mixture used.

Inspection object: concrete screed

Address of construction expertise: Moscow

The purpose of the construction expertise: to assess the quality of the completed construction and installation works on the installation of the screed for compliance with the requirements of the current regulatory and technical documentation (screed expertise).

Technical means of control used at the facility: DISTO classic/lite laser range finder, Canon digital camera, metric tape measure GOST 7502 - 80, Pulsar ultrasonic tester.

When examining and drawing up an expert opinion, regulatory documents were used.

General provisions for determining quality

The technical inspection of the Customer's object was carried out in order to make an examination of the screed. The basis for the technical survey is the Construction Expertise Contract, which specifies the purpose of the survey and the list of works to be performed. When performing survey work, the obtained data were taken into account, defects were photographed. The results of the survey, which served as the basis for this conclusion, are given as of October 05, 2010.

Diagnostic examination

Inspection of building structures of buildings and structures is carried out, as a rule, in three interconnected stages:

• preparation for the survey;
• preliminary (visual) examination;
• detailed (instrumental) examination.

In accordance with the requirements of SP 13-102-2003 clause 6.1 Preparation for surveys provides for familiarization with the object of the survey, design and executive documentation for the structure and construction of the structure, with documentation for the operation and repairs and reconstruction that took place, with the results of previous surveys.

The expert made an external inspection of the object, with selective fixation on a digital camera, which meets the requirements of SP 13-102-2003, clause 7.2. The basis of the preliminary examination is the inspection of a building or structure and individual structures using measuring instruments and devices (binoculars, cameras, tape measures, calipers , probes, etc.).

Measurement work was carried out in accordance with the requirements of SP 13-102-2003, clause 8.2.1 The purpose of measurement work is to clarify the actual geometric parameters of building structures and their elements, to determine their compliance with the project or deviation from it. Instrumental measurements clarify the spans of structures, their location and pitch in plan, cross-sectional dimensions, height of rooms, marks of characteristic nodes, distances between nodes, etc. Based on the measurement results, plans are drawn up with the actual location of structures, sections of buildings, drawings of working sections of load-bearing structures and junctions of structures and their elements.

Classifier of the main types of defects in construction and building materials industry

• Critical Defect(when performing construction and installation work) - a defect in the presence of which a building, structure, its part or structural element is functionally unsuitable, further work under the conditions of strength and stability is unsafe, or may lead to a decrease in these characteristics during operation. A critical defect is subject to unconditional elimination before the start subsequent work or with the suspension of work.
• Major Defect- a defect, in the presence of which the operational characteristics of construction products and their durability are significantly impaired. A significant defect is subject to elimination before its concealment by subsequent works.

In this case, a defect is every single deviation from design decisions or non-compliance with the requirements of the standards.

The expert carried out a diagnostic survey of the object with the determination of the quality of the construction and installation works performed in accordance with the requirements SNiP. The survey was carried out by the method of measuring quality control.

When assessing the quality of the performed construction and installation works on the device, the following was established:

When tapping the concrete screed coating on numerous areas of the floor surface, changes in the nature of the sound were recorded. This fact indicates a poor-quality base, as a result of which there is no adhesion of the upper floor covering to the base.

Construction expertise comment

According to the Decree of the Government of the Russian Federation N 1025 of August 15, 1997, On the Approval of the Rules for Public Services for the Population in the Russian Federation, “If a law or other regulatory legal act of the Russian Federation adopted in accordance with the law provides for mandatory requirements for the quality of a service (work), the performer is obliged to provide a service (perform work) that meets these requirements.

According to GOST R 52059-2003 Household services. Services for the repair and construction of housing and other buildings. General technical conditions, clause 5.20 “Main work on the repair of basements, cellars, floors of all types, roofs, cladding of external or internal walls with various materials, plastering walls, ceilings, columns, filing ceilings, as well as facing, painting, wallpaper, glass , insulation work must be carried out in accordance with SNiP 3.04.01.

The changes in the nature of the sound detected during the survey when the floor covering is tapped are a violation of the requirements of SNiP 3.04.01-87 “Insulating and finishing coatings”, table 25, according to which “when checking the adhesion of monolithic coatings and coatings made of hard tile materials with underlying floor elements tapping should not be a change in the nature of the sound.

The main requirements for finished floor coverings are given in Table 25:

Table 25

When examining the floor, numerous cracks were recorded in the screed with an opening width of up to 2 mm.

Expert commentary

This fact is a violation of the requirements of SNiP 3.04.01-87 "Insulating and finishing coatings", according to which:

Requirements for finished flooring

4.43. The main requirements for finished floor coverings are given in Table 25.

Table 25

Expert opinion

The presence of cracks indicates a loss of strength and integrity of the floor structure.

When checking cracks using an ultrasonic tester, the maximum depth of their occurrence was set to 35 mm.

Expert commentary

The revealed value of the depth of occurrence of cracks indicates the absence of solidity of the floor.

When examining individual exposed sections of the floor screed, the soundproofing layer was filled with expanded clay with a fraction of 15 mm.

Expert commentary

The revealed fineness of loose soundproofing material - 15 mm, is a deviation from the requirements of "SNiP 3.04.01-87 Insulating and finishing coatings, p.4.20", according to which the fineness of loose soundproofing material should not exceed 10 mm.

SNiP 3.04.01-87 Insulating and finishing coatings

4. Installation of floors general requirements for soundproofing

4.18. Loose soundproofing material (sand, coal slag, etc.) must be free of organic impurities. The use of backfills made of dusty materials is prohibited.

4.19. Gaskets must be laid without gluing to floor slabs, and slabs and mats - dry or with gluing on bituminous mastics. Soundproof pads under the logs must be laid throughout the entire length of the log without breaks. Tape gaskets for room-sized prefabricated screeds should be placed in continuous strips along the perimeter of the premises close to walls and partitions, under the joints of adjacent slabs, and also inside the perimeter - parallel to the larger side of the slab.

4.20. When installing sound insulation, the requirements of Table 18 must be observed.

Table 18

The expert measured the propagation velocity of ultrasound in the floor screed structure to determine the average compressive strength, class and grade of concrete.

Measurements were made by ultrasonic tester Pulsar, according to GOST 17624-87 “Concrete. Ultrasonic method for determining strength. The number and location of controlled sections on the structures are established taking into account the requirements of GOST 18105-86 “Concrete. Strength control rules.

According to the measurements performed, calculations of the average strength of concrete were made, the grade and class of concrete compressive strength were determined.

The results are listed in Table No. 1.

Table #1

According to the results of ultrasonic examination, the strength grade of concrete was M 200.

Construction expertise conclusion

The conclusion of the construction expert on the inspection of the screed

The purpose of the survey: to assess the quality of the completed construction and installation work on the installation of the screed for compliance with the requirements of the current regulatory and technical documentation.

The quality of construction and installation works performed by the Contractor does not meet the requirements of regulatory and technical documents, namely:

The floor covering device was made in violation of the requirements of the current regulatory and technical documents. According to the examination, these violations of regulatory requirements are the result of:

• non-observance of work production technology;
• lack of proper control over the work by the contractor;

As a result of violations of regulatory requirements, this coating cannot provide the design bearing capacity. The fact that part of the floor covering is subject to changes in the nature of the sound when tapped (fixed during the survey) indicates the presence of voids in such areas.

According to the examination, the areas where voids were found are also prone to cracking, which can subsequently lead to the complete destruction of the upper floor covering.

Thus, the audit found that the elimination of the identified violations is not possible without partial dismantling of the upper floor covering in areas with cracks.

To bring the quality of construction and installation works in line with the current regulatory requirements, it is necessary to eliminate the above disadvantages.

To eliminate the shortcomings of the work performed with the screed, we recommend: contact the contracting construction organization with the requirement to bring the quality of the work performed in accordance with current regulatory requirements.

Often, laying flooring and flooring is done on the basis of personal considerations, as well as expediency. But in fact, the project of floors and screeds should be based on a regulatory document that regulates the main technological processes. These documents are constantly used in the construction and design of buildings, but the home master must also know the requirements set out in the SNiP, because floors and screeds have a serious amount of requirements. Let's consider the most basic ones.

Floor screed according to SNiP

When it is necessary to prepare a concrete slab for decorative flooring, a floor screed is made. For this, there is also a separate section in SNiP. If you familiarize yourself with the requirements, recommendations and norms, then the result is the most stable and durable foundations.

Naturally, these standards are mandatory only for capital construction projects, but many are guided by them for home repairs as well.

Determine the function of the screed

If you look at building regulations, then a floor screed is a layer of mortar based on sand and cement, which is poured onto the base base. The main function of the screed is to form the most even basis for the future finishing floor covering. Also, the norms provide for such a floor screed device to ensure a sufficiently high strength of the base to mechanical damage. The SNiP contains all the necessary norms.

The documents

Draft floors should be designed according to special regulatory documents. Previously, SNiP 2.03.13-88 was considered the main document on rough concrete foundations. However, despite the fact that the methods of flooring in residential buildings have not changed, new materials and building technologies began to appear, therefore the standards have changed.

Today, the document SP 29-13330-2011 is in force. It updated the edition of the standards for the arrangement of floors.

Requirements for the tie device

The requirements for floor screed, which are provided for in SNiP, make it possible to obtain a high-quality foundation. It is better to use these norms and requirements in the project for your apartment.

Thus, the minimum layer thickness when laying on a concrete base is 20 mm. If an insulating layer or soundproofing materials are additionally laid, then the thickness will be 40 mm. If a pipeline or other communications will be arranged in the screed, then the layer above the communications should be no less than 20 mm.

If compressible materials are used as heat or sound insulation, then the strength of the sand and cement filling is increased. It should be not less than 2.5 MPa. In this case, the thickness of the screed must exclude any deformation.

The minimum strength index of the solution is 15 MPa, and if a polyurethane self-leveling floor is used as a decorative finishing layer, then the strength is made equal to 20 MPa.

If a self-leveling compound is used, with the help of which smooth surfaces are formed, then the thickness of the layer of this coating should be not less than 2 mm.

To control the coverage plane, the regulation provides for the use of a rule. If it is necessary to check the geometric characteristics of the layer, a tool 2 m long is used.

According to SNiP, it is allowed if the floor screed will have deviations, but not more than the specified values:

• For parquet, laminate, linoleum and self-leveling floors on polymer mixtures, 2 mm per 2 m is allowed;
• For other types of coatings, up to 4 mm per 2 m is allowed.

When performing surface inspections, deviations from these standards are corrected very first, as they have a great influence on how well the finished flooring will be laid.

Technologies and general requirements for the base base

Before laying the sand-cement layer, prepare the base. There are specific guidelines for this in the regulations.

So, the base should be planned according to the profile or marks in the design documents. If it is necessary to add soil, then the layer is maximally compacted and leveled. A mixture of sand and gravel is often used as backfill.

If the floors are laid on the ground, then you can work only when thawing. If the soil surface is weak enough, replacement or additional strengthening is required. It is recommended to strengthen with crushed stone with a fraction of 40-60 mm. In this case, the strength must be at least 200 kgf / m2.

If the base is a concrete slab, then it is cleaned of debris and dust. Then the surface is washed with water. If there are joints between the plates, they are filled with a cement-sand mortar. In this case, the filling depth should not be less than 50%. For these purposes, a solution of grades 150 or more is used.

materials

• sifted sand;
• Cement from M150 for industrial premises and M300-400 for residential premises;
• Gravel and crushed stone with fraction from 5 to 15 mm. The strength index should be from 20 MPa.

Reinforcement

Floor screed reinforcement is used to give the structure greater strength. SNiP recommends the following materials:

• Wire mesh with a cell of 100 × 100 or 150 mm;
• Mesh made of polymeric materials;
• rod frame;
• Fiber reinforcement - fibers of steel, polypropylene, basalt.

This procedure is necessary where the height of the screed is more than 40 mm. For residential premises where a high load on the floors is not provided, screeds up to 70 mm do not reinforce.

The laying of reinforcing materials is carried out at the preparatory stage. In order for the reinforcement to lie correctly, special plastic supports are used.

Screed pouring technologies

The base base is processed according to all the recommendations described earlier. Then it is necessary to treat the surface with primers. After the priming composition has sufficiently polymerized, a cement mortar is prepared in a ratio of 1: 3, where 1 part is cement, and 3 parts of sand.

If sound or heat insulating materials are used, then a damper tape with a thickness of 10 to 25 mm is installed around the perimeter of the room. Also, beacon rails are installed on the floor, and then the screed is poured.

The floor will be ready no sooner than in 24 hours. Do not walk on the ground with your feet. With a large amount of time, it is better to give the screed 30 days. Then you can start sanding and laying the finish coat.