Concrete screed

A concrete screed is an essential component of both new and renovated flooring. It offers a level, smooth surface that is perfect for laying different types of flooring, like hardwood, carpet, or tiles. As a foundational layer, the screed helps to evenly distribute weight across the floor and guarantees the final flooring’s stability and durability.

The versatility of concrete screed is one of its main advantages. It can be used in large industrial spaces as well as residential ones, such as kitchens and living rooms. Because of its flexibility, the material can be used in a variety of thicknesses and compositions, depending on the project’s particular needs. Because of its versatility, concrete screed is a necessary part of contemporary building.

Concrete screed provides significant thermal and acoustic insulation qualities in addition to its many practical uses. Accordingly, screed floors can lessen noise transmission between a building’s levels and help maintain comfortable interior temperatures. Because of these qualities, concrete screed is a desirable choice for improving a space’s general usability and comfort.

Concrete screed application is a multi-step process that begins with substrate preparation and continues with screed material mixing and pouring. In order to guarantee that the screed reaches its maximum strength and durability, proper curing and drying times are essential. Despite its apparent simplicity, producing a screed of superior quality demands expertise and close attention to detail.

In the end, concrete screed is essential to the building sector because it provides a dependable and efficient means of laying level, stable flooring. Understanding the significance and advantages of concrete screed can help you make well-informed decisions and get the best results for your flooring needs, whether you’re planning a new commercial build or a home renovation.

Is it possible to create a screed in a steam room??

A typical bathroom is split up into three areas: a steam room, a shower room, and a dressing room. These areas are all hotter and more humid than living rooms.

Installing a subfloor made of full-fledged heavy concrete with both fine (sand) and coarse aggregate (crushed stone), along with plasticizers to help raise the water resistance grade (W) and frost resistance grade (F), would be the best course of action in such circumstances.

Requirements

Several design and functional requirements should be considered when designing and installing floor screeds in bathhouses:

• Binding materials must have an increased water resistance grade – from W6 and above.
• Coarse aggregate must be exclusively granite-based. The use of limestone crushed stone is not allowed, since it is destroyed by moisture.
• Considering that drain traps are installed in wet rooms, a slope of at least 1% – 1.5% is arranged for them. Thus, the thickness of the screed is determined based on the minimum value at the ladder – 40 – 50 mm and the maximum value – at the opposite corner of the room.
• Under the screed, it is necessary to install adhesive waterproofing with a minimum of 400 mm of adjoining walls.
• Concrete for the subfloor must have a compressive strength class of at least B15 – B20, which corresponds to cement grade M300 and higher.
• Many steam rooms are made unheated, which requires the use of concrete for the screed with a frost resistance class of at least F100.
• If effective insulation is installed under the structure, mesh reinforcement is required in the body of the screed to avoid cracks from the formation of bending forces. In this case, the minimum thickness of the subfloor at the drain is at least 70 mm.

As a result, the bathhouse is designated as an item requiring a unique operating mode. The floor screed of the structure is made of regular construction concrete, which is utilized for load-bearing structures.

Regulatory documents

The following regulatory documents provide a description of the bathhouse subfloor requirements mentioned above:

• PP. 3.8 – 3.11 SNiP II-L.13-62* “Baths. Design Standards”.
• SP 63.13330.2018 “Concrete and Reinforced Concrete Structures”.
• SP 29.13330.2011 “Floors. Updated version”.

Every document on the list governs the minimum thickness, the strength of the concrete, the presence of structural components in the screed, and the water and frost resistance grades.

Design and pie

For a dependable, sealed structure that will endure for many years, it’s critical to pay attention to the order and thickness of each layer when laying concrete in a bathroom:

• A concrete bedding layer up to 30 – 40 mm thick is arranged on a reinforced concrete floor slab, foundation slab, or compacted soil.
• A layer is applied over the leveled preparation liquid bitumen mastic.
• Next is a roll-on fused waterproofing with an overlap of material along the length of at least 100 mm.
• Extruded polystyrene foam boards with a thickness of at least 50 mm, grade PSB-S 35.
• A layer of reinforced concrete screed along the slope to the drain – from 70 to 100 – 150 mm, depending on the angle and length of the room. If it is necessary to install a water or electric heated floor, the screed is installed in 2 stages. The first layer is reinforced concrete 70 mm thick, then – heating pipes or a heating mat, on top – a second layer of concrete, reinforced with a mesh, along the slope.
• If defects and irregularities are visible on the surface of the subfloor, protruding elements of large filler, it is advisable to make a leveling layer 10 – 20 mm thick from a self-leveling floor.
• A finishing coating of natural boards or tiles is installed on top of the leveling plane.

Due to the elastic nature of the insulation, the screed is buoyant and necessitates the vibration-absorbing gasket from the damping tape when it is mated with the walls all the way around the room.

What concrete is suitable for creating?

To lay down a screed on the bathroom floor It is appropriate to use heavy concrete with the following constructive parameters:

• Compression class class – at least B15 – B20 (r_B = 196.5 – 261.0 kgf/cm 2), which corresponds to the cement brand from M250 to m300.
• Class of concrete for tension – at least b_t6 – b_t2.0 (r_BT = 21.0 – 26.2 kgf/cm 2).
• Mark for frost resistance – with a heated room – F50 – R75, with an unheating space of the steam room – at least F100.
• Mark for water resistance, regardless of class in strength, not less than W6 (concrete withstands hydrostatic pressure up to 6 atm., when diving in a liquid environment).

Purchasing specific plasticizers that are dosed in a finished mixture in accordance with the instructions is necessary if you want to make a solution by hand and achieve these brands by frost resistance and water resistance.

Instructions for preparing the solution

A specific recipe that accounts for the required additives is used to prepare special concrete for floor screed in a bathroom. This is a comprehensive guide explaining how to prepare high-quality concrete for a subfloor by hand.

For the wet method

A wet screed for a bathhouse is an apparatus on a horizontal surface of heavy concrete mixture that has been pre-prepared, considering the characteristics of the recipe (based on 1 m3 of finished material):

• Cement grade M250 – M300 – 9 bags of 50 kg.
• Medium-sized sand, quartz. Washed river sand is considered the best fine filler, since it has an optimal granulometric composition and does not contain clay impurities. 0.4 m3 of sand is required for 1 m3 of concrete.
• The sand is thoroughly mixed with cement until a homogeneous mass of dark gray color is achieved. When mixing, you need to monitor the formation of lumps and break them up to a loose consistency.
• Crushed stone – granite material with fractions of 20 – 40 mm, in the amount of 0.55 m 3 is required for a screed in a bathhouse .
• After adding crushed stone, the dry material is mixed again until homogeneity is achieved.
• Then water is poured into the dry mixture, in portions, with the mixer running. The total volume of water should not exceed 50% of the amount of cement. As a rule, up to 200 – 250 liters of water are required to achieve mobility P2 – P3, that is, a consistency sufficient for the device of the screed.
• A water-repellent plasticizer and an anti-freeze additive are added to the finished mixture. Most often, such chemical compositions are sold in plastic canisters, and their dosage is indicated in the operating instructions.
• The finished composition is mixed in a mixer for 3 – 5 minutes, after which it can be laid on the installation horizon.

Experts advise against manually mixing because there is a greater chance of an uneven solution being produced.

Use a 150–300 liter portable electric mixer (available for purchase or rental at a construction market) to prepare concrete. The above ratios are taken as a percentage of the calculated indicators per 1 m 2 and depend on the mixer’s volume.

For semi-dry

Semi-dry screed is a hard cement-sand blend that is applied with a pump equipped with a pressure damper on the installation horizon. It is then uniformly spread throughout the room.

The ingredients are added to a specialized mobile mixing station, which is used for mixing:

• Cement – depending on the required strength of the screed. For the device of a screed in a bathhouse, the amount is the same as for standard concrete. The cement grade for semi-dry material should be at least M400 – M500.
• Quarry or river sand.
• Large aggregate is not used for such a screed.
• Reinforcing fiber based on polyurethane – depending on the desired strength of the finished structure – from 3 to 10 kg per 1 m 3 of the finished mixture.
• Water for a rigid mixture is poured no more than 50 – 80 liters per 1 m 3 , but the operator determines its exact amount based on the consistency of the material.
• Plasticizers – the same as for standard concrete.

When deciding to install a semi-dry screed, keep in mind the bathhouse’s relatively small area. You should get in touch with a specialized organization that will bring the necessary equipment to the site and complete the installation in a single day.

If the horizontal surface being finished is smaller than 1000–1500 m2, the cost of renting a machine, pump, and blade smoother independently for the property owner will be significantly higher.

Step-by-step actions for pouring

When constructing and putting in a floor screed by hand in a bathhouse, the property owner needs to adhere to a specific formula:

• The floor surface is prepared for installation – waterproofing is installed, heat-insulating slabs are laid, a drain trap with a sewer pipe is installed.
• According to the required slope, rack beacons are installed over the entire area.
• Concrete is mixed in a mixer, according to the recipe described above.
• Tilting the mixer onto the installation horizon is not recommended, since the heavy mixture can cause damage to the insulation when impacted.
• The mixer is tipped into a stretcher, after which the mixture is spread over the entire area of ​​the room.
• The first layer of concrete is leveled with a thickness of up to 20 – 30 mm.
• A reinforcing mesh is laid on top of the layer with an overlap of cards of at least 1 – 2 cells.
• Next, the concrete mixture is spread in an even layer over the entire installation horizon.
• The master levels the screed between the beacons, smoothes it until a flat surface is achieved and the large aggregate completely disappears from the front plane.

Concrete sets in about three to four hours, so everything needs to be done quickly. Installation of the final batch is permitted after the moisture has completely evaporated, which can take anywhere from 7 to 12 days. This is true even though the material only reaches 100% strength on the 28th day following the commencement of the chemical reaction with cement.

See the article at the provided link for further information about the setup.

Features of the technology, if there is a warm floor

The technology used to install the screed varies slightly if the bathhouse has a heated floor:

• A reflective heat-insulating material is rolled out over the insulation so that all the heating energy is only inside the room.
• Next, the first layer of reinforced screed with a thickness of 60-70 mm is installed. The diameter of the mesh rod should be no more than 4 mm, and the dimensions of the cell – 100×100 or 50×50 mm.
• Pipes for underfloor heating are laid on top of the first layer of screed, as well as outlets to the manifold.
• Pipes are protected from mechanical damage along their entire length from a cement-sand mortar, which is mixed separately in small quantities.
• When the solution has set – 2 – 4 hours after laying, the surface is concreted with a slope and a grid, according to the technology described in the previous version.

It is crucial to shield the drain trap, all pipe outlets, and the floor from the liquid mixture when pouring concrete because, once the concrete hardens inside the pipe body, it is nearly impossible to remove without causing damage to the plastic.

Processing and finishing

Depending on the type of finishing coating, the floor needs to be adjusted after the concrete screed is installed.

In order to do this, a pouring mixture containing water repellents is applied on top of the concrete, aiding in the coating’s increased water resistance.

When applying the finishing coating, tile adhesive may be used to achieve the final alignment in certain situations where the concrete surface is level.

A surface polymer water-repellent liquid (available in hardware stores) is applied to the screed if you intend to decorate a bathhouse in an ethnic style with larch or oak boards on logs. By sealing all of the screed’s pores and preventing moisture from penetrating, the polymer is applied with a roller to help extend the structure’s longevity.

Pros and cons

There are several clear benefits that the owner of the bathhouse gets when laying a concrete screed:

• A properly arranged floor pie contributes to increased energy efficiency of the premises, which enhances the sensations from bath procedures.
• Moisture penetration into adjacent rooms or into the ground is excluded.
• The finishing coating is arranged on a leveled base, which gives the rooms a finished look and improves aesthetic qualities.
• The slope helps to quickly drain water into the sewer.
• A capital structure can be used for several decades, without the need for repair or replacement.

However, a design like that has a number of subjective drawbacks:

• Increased labor intensity of work.
• High retail cost of materials and installation operations.
• A properly arranged screed with the whole pie "eats" at least 250 mm of total space, which is important when arranging a bathhouse in wooden log houses with a ceiling height of no more than 2.5 m.

Usually, the estimated cost includes the mentioned drawbacks first, and the height is calculated by building an additional crown for the log home. In this context, a bathhouse’s concrete screed is a crucial structural component.

Cost of work on the device

When a specialist contacts an installation company, they receive a technical assignment and a plan detailing the premises’ economic and technical performance. An estimate is computed based on the project, and the total amount of work and the ultimate cost are established.

Certain companies provide turnkey services, including materials and labor, for a set fee per square meter of completed screed.

• Standard screed without reinforcement, thickness from 50 to 60 mm – 300 – 350 rubles. per 1 m 2 .
• Reinforced subfloor made of concrete, thickness 70 mm – 400 – 450 rubles. per 1 m 2 .
• Complex pie with insulation, waterproofing and slope – from 700 – 850 rubles. per 1 m 2 .
• Screed device with underfloor heating – from 1000 rubles. per 1 m 2 .
• Compaction of the soil base, in the absence of a floor slab or foundation under the bathhouse space – from 200 rubles. per 1 m 2 .

The technical specifications’ content, the room’s arrangement, the object’s distance from it, the complexity, the amount of work involved, and other elements can all affect the price.

Concrete Screed	Description
Definition	A layer of concrete laid to create a flat, smooth surface
Purpose	Used to level floors and provide a stable base for flooring
Thickness	Typically ranges from 40mm to 100mm
Materials	Concrete, sand, and sometimes reinforcement fibers
Applications	Residential, commercial, and industrial floors
Curing Time	Usually takes 7-28 days to fully cure

For a level and long-lasting surface on which different kinds of floor coverings can be installed, a concrete screed is a crucial component of many flooring systems. A well-laid screed guarantees the longevity and functionality of the floor above it, whether it is for a residential, commercial, or industrial space.

Concrete screed installation calls for meticulous planning and exact execution. This entails picking the appropriate components, combining them in the right amounts, and making sure the substrate is ready. Paying close attention to details during these procedures can help avoid common problems like uneven or cracked surfaces.

Excellent screeds are now more easily achieved thanks to advances in materials science and modern techniques. The convenience and efficiency of innovations like self-leveling compounds and faster-setting mixes are increased. These advancements enhance the screed’s overall quality and durability while also saving time.

In the end, a concrete screed is an essential part of the building process. It offers a strong base for flooring and makes a substantial contribution to a building’s structural integrity. Anyone working on building or renovating projects can guarantee a successful screed installation by knowing the fundamentals and adhering to best practices.

An essential layer in construction is concrete screed, which offers a level, smooth surface for floors and other finishes. It ensures a stable, even base that can tolerate heavy use, extending the life and durability of floors. Convenient to use and adaptable, concrete screed is a crucial element in both residential and commercial projects because it can be customized to various thicknesses and finishes. The secret to getting a faultless, long-lasting floor is knowing the significance and application of concrete screed, whether you’re building new or remodeling an existing space.

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