Materials for dry floor screed: what expanded clay to use, edge strips, top slabs

In construction and renovation projects, dry floor screed is a popular option for producing a smooth and long-lasting floor surface. Using edge strips, top slabs, and expanded clay, among other materials, this technique creates a level, stable base for different kinds of flooring. Every part of the screeding process is essential to maintaining both structural integrity and functionality.

Known for being both strong and lightweight, expanded clay is frequently utilized as the foundation material in dry floor screeds. It is appropriate for both residential and commercial applications because of its superior thermal insulation and soundproofing capabilities. Contractors can customize the screed to meet the unique load-bearing requirements of the project while improving overall energy efficiency by using specific grades of expanded clay.

The crucial elements that delineate the boundaries of the screeded area are edge strips. During installation, these strips act as barriers, keeping the screed mixture inside its designated bounds. Edge strips, which are usually composed of metal or PVC, guarantee uniform thickness and alignment while supporting the screeded floor’s structural integrity and offering a clean edge.

Often referred to as finishing layers, top slabs provide a level, smooth surface that is ideal for installing final flooring components like wood, laminate, or tiles, completing the dry floor screed system. These slabs provide a sturdy base for visually appealing floor coverings and are made to resist normal wear and tear. Selecting the appropriate upper slab guarantees the screeded floor’s long-term durability and aesthetic appeal.

What"s included?

Dry screed is made up of various parts:

1. bottom layer – polyethylene or any polymer film, which is laid directly on the subfloor/concrete slab, etc. with bends on the walls of the room. It guarantees complete tightness and protection (vapor barrier) from moisture.
2. Along the bottom edge of the walls (along the perimeter) to the points of contact with the finishing floor covering – apply specialized edge strips, fixing them to the curved (on the walls below) polymer film. They are necessary to neutralize the dry component from the backfill itself (0.5-1.0 mm). When pressure is applied to the walls, microcracks may appear on them, which the edging tape will not allow. The tape separates the floor layer from the enclosing structure (walls).
3. Second layer, laid on a polymer film – loose and leveling. It may consist of expanded clay, sand or pumice, etc. materials.
4. Third layer is sheet material, moisture-resistant gypsum fiber boards, chipboard, OSB boards, etc. The layer provides a perfectly flat surface, guarantees uniform distribution of loads on the dry screed below.
5. Fourth layer – polyethylene film that protects all elements from negative influences and moisture.

You can then install the final floor covering.

Material requirements

For making dry floor screed, you should only buy premium materials from reputable brands and "time-tested" retail and specialty stores.

The components need to be made in a way that produces a dry floor screed on a subfloor. The specifications (amount, thickness, or footage) of the material to be used in construction projects, along with the products’ shelf life and the ideal temperature range for usage, must all be specified in the instructions.

It is advised to apply layers of each dry screed component in the prescribed order. Layer-laying adjustments may be necessary when installing heated flooring or flooring on the first floor, among other situations.

• after the third layer of expanded clay, a waterproofing film is placed again;
• fine expanded clay sand on it.

The top leveling layer comes next.

In this piece, we examine the necessary components for a dry floor screed, emphasizing the kinds of expanded clay that work well as insulation, the significance of edge strips for preserving structural integrity, and the function of top slabs in producing a smooth, long-lasting finish. We’ll go over useful advice on selecting the best expanded clay for efficient sound and heat insulation, the role edge strips play in maintaining stability and preventing cracks, and how top slabs help create a level surface that is prepared for different floor finishes. Making informed decisions regarding dry floor screed can be facilitated by having a thorough understanding of these materials, regardless of whether you’re building a new space or renovating an existing one.

What materials should be used?

It is necessary to have all the materials ready for work ahead of time, having previously determined how much will be needed based on the room’s perimeter and the floor’s eventual height.

Styling film

The vapor barrier layer’s polyethylene film is applied to the subfloor’s surface after it has been cleared of debris and extends up the walls to the finishing coating level. With so many options available, you can select the best solution for any given situation. types of films used:

• polypropylene;
• polyethylene;
• polyvinyl chloride (PVC);
• synthetic rubber;
• diffuse membranes.

The range of film thicknesses is 200 microns to 1.5–2 mm.

Since the waterproofing layer will be subjected to heavy loads for decades on end, it must not only be completely tight and chemical resistant but also ensure a long service life and strength.

The installation of heated floors is made possible by a broad temperature range (up to +100 C 0). The film must also be exceptionally elastic and stretchable, and it must not rupture when subjected to dynamic forces.

Film must have maximum strength (tensile strength, mechanical damage resistance) and weather resistance in order to be used for dry backfill. Modernized multi-layer, fiberglass, or reinforced film options ensure this.

We can list the TOP 3 renowned film producers as follows:

• Nanoizol (Russia) – high-strength waterproofing, roll 1.5m x 23.3m, price from 1,400-1,700 rubles.;
• Ondutis (France) – innovative, ultra-strong film, membrane for maximum protection of floor screed in rolls of 1.5 m x 50 m, price from 3,800 – 4,500 rubles.;
• Megaizol (Russia) – effective, modern vapor barrier for floors in rolls of 1.6 m x 18.75 m, cost from 1,900 rubles.

The cost of the film increases with its thickness and density. Cost also rises with increased footage.

Edge tapes

The bottoms of the walls are taped around the floor’s perimeter. This substance is made as rolled, foamed polyethylene strips in coil form that come in a variety of sizes, ranging from 50 mm to 150 mm in thickness. In addition, the length varies from 10 to 100 meters. The tape’s primary function is to shield concrete or cement walls from outside influences. The tape material has high ductility, meaning it can expand and contract without deforming.

In addition, the edge tape resists moisture, insulates against heat and sound, and "takes" the strain off the concrete layer.

Experts advise selecting edge tapes from the top three brands listed below:

• KNAUF is known for impeccable, high German quality – expansion tape made of foamed polyethylene, rolls of 20 m with a width of 10 cm, thickness 0.8 mm, price from 400-450 rubles.;
• Izoway (domestic brand) – edge tape is an excellent compensator, will provide moisture, sound, and heat protection, in rolls of 20 m, width 10 cm, thickness 10 mm, cost from 190-200 rubles.;
• VALTEC (Italy) – floor damper tape performs all the necessary protection functions, is durable and strong, in rolls of 25 m, width 10 cm, thickness 8 mm, price from 800-850 rubles.

Choose the material based on its color and intended use.

Dry backfills

Dry backfills remove all unevenness from the subfloor by leveling it as much as possible. A leveling layer is created by manufacturers using a variety of granular materials, either fine or larger in form, such as vermiculite, expanded clay, perlite, or river sand. The following qualities of materials are necessary for backfilling prefabricated floors:

• have excellent flowability – this will ensure excellent leveling;
• differ in optimal grain size – a guarantee of minimal shrinkage under the influence of loads from installed furniture and the movement of people living (in the rooms);
• have porous structures – they provide sound absorption and good thermal insulation;
• the presence of minerals in the raw material – protection against fire;
• minimal hygroscopicity – which minimizes the formation of moisture.

A material that doesn’t shrink over time is ideal for dry backfill.

The material used to backfill the floor needs to be pure, devoid of dust, debris, and impurities.

Expanded clay and its fraction

Among all bulk materials, expanded clay that is the least expensive is thought to be the most well-liked. It is made up of specially fired clay granules, has a low weight, and a high porosity. For backfilling, expanded clay with fraction sizes of 0.5 cm is appropriate. Backfill quality declines when expanded clay with a higher fraction is used. Builders recommend a minimum backfill thickness of 3–4 cm. advantages

• affordable price;
• availability in stores;
• simple installation;
• a light weight.

Long-lasting smooth surface is provided.

One of the drawbacks is that the expanded clay mixture’s functionality may be reduced if it contains fractions of different sizes, even very large ones.

Vermiculite

Material with a natural origin and layered structure. The material is heated (expanded) to fill, forming tiny puff sticks. Because vermiculite is light, it is perfect for backfilling flooring. There is a maximum load of 150–160 kg per 1 m3. Three to four times as much as the load of expanded clay is this. advantages

• the easiest;
• affordable price;
• easy installation.

Reduces the weight on the ceilings and subfloor.

One of the drawbacks is that untreated, unexpanded vermiculite absorbs moisture to the maximum extent possible, making it unsuitable for dry floors.

Perlite

Volcanic-derived raw materials with maximum swelling are perfect for dry floor screed. In the work, perlite and perlite sand are used. One of the material’s benefits is that the raw materials are completely devoid of moisture. One of the drawbacks is the material’s price, which isn’t always readily available in stores. The manufacturer heats the material to 1000 degrees Celsius to create perlite.

Compavit

The product in question is a branded item made by "Vipol" the manufacturer. This ensures superior even filling, high quality, and the absence of contaminants. The material is based on small, uniform fractions up to 4 mm.

Advantages

• more dense structure;
• smooth shapes;
• does not sag over time
• does not cause deformation.

The best heat and noise insulation qualities are the main benefit.

One of the drawbacks is the expense.

It is advised by experts to exclusively buy dry filling from reputable brands.

TOP 3 producers:

1. Knauf. Dry natural backfill (Germany) made of expanded clay for prefabricated floors (dry screed), guarantees high insulating properties without shrinkage. Bags of 40 kg, cost from 2,200-3,200 rubles.
2. RDS-Stroy. A Russian manufacturer offers dry expanded clay sand for creating smooth, durable floors. Provides additional sound insulation and is easy to use. Bags of 40 kg, affordable price 160-170 rubles.
3. Granit-M. The Russian brand guarantees the high quality of the supplied material for dry floors – perlite. Perlite sand levels the surface of the subfloor, provides better heat, noise, and moisture insulation, and is harmless. Bags from 65 kg to 170 kg, cost from 150 rubles. and more.

Upper leveling slabs

The final layer, which may be chipboard or more contemporary material like KNAUF lists, is where the leveling plates are arranged. They are cut to fit the required room perimeter (on a level surface).

Make use of a ruler, knives, an electrician, and a hacksaw. After cleaning the edges of the cut slabs, they are cooked into a single whole on the floor. The finish flooring installation can now begin thanks to the upper leveling plates.

Aligning plates offer the perfect level surface, sound absorption, and microclimate preservation. The ability to arrange warm floors arises.

GVL

This sheet of gypsum fiber contains modified additives, gypsum, and reinforcing materials. A primer is used to impregnate sheets. The material is characterized by its reduced thermal conductivity, homogeneous, strong structure, durability, and inability to ignite. It is advised to use GVL when designing warm floors and when installing carpet, parquet, linoleum, and laminate flooring. placing right away on swollen clay. advantages

• environmental friendliness;
• simple installation;
• universality;
• not fuel and moisture.

Able to withstand loads.

The sheets’ weight, high cost, and fragility after incorrect installation are among their drawbacks.

GVVV

Gypsum fiber sheets that are resistant to moisture are highly advised for first floor layouts, swimming areas, and heated floors. Features are the same as those of the material mentioned above, but moisture resistance is increased.

GSP

Although a new product on the Russian market, the Gypsostrough stove is highly sought after. The material, made of wood chips and gypsum, is easy to assemble, resistant to mechanical damage, and will guarantee longevity and excellent quality.

Advantages

• environmental friendliness;
• high fire safety;
• strength;
• low thermal conductivity.

Superior sound absorption, smooth surface, appropriate for all kinds of coatings.

One of the drawbacks is the expense.

Chipboard

Particle boards ensure a consistent, smooth surface; however, an extra layer of glassine and a moisture and vapor barrier are needed. This option works well for finishing coats applied with tiny nails on solid, parquet boards.

• better heat absorption;
• resistance to mechanical damage.

Cons: Needs another layer of protection.

OSB

The large-sized chips make up the strand board. Hot pressing and longitudinal and transverse fiber distribution are used to give the material strength, durability, and resistance to mechanical stress. The slab is ideal for laying any type of finishing material because it will give the most consistent, even, and dependable coating.

Advantages

• moisture resistance;
• resistance to deformation;
• suitable for bathrooms, kitchens, swimming pools

Lightweight. Cost and availability issues are the downsides.

TOP 3 producers:

1. OSB-3 Murom – high-quality material for floors, walls and ceilings. Perfectly levels the surface, durable. Slab 2.5 m long, 1.25 cm wide, 9 mm thick. Price from 500 rub.
2. GSPV Peshelan – moisture resistant, practical and durable. The material is modern and high quality, fire resistant. Sheets 3 m long, 1.25 m wide, 10 mm thick have a cost of 1,300-1,400 rubles.
3. Knauf-superfloor GVLV – German quality and durability. The boards are moisture resistant, light weight, easy to assemble. Thermal insulation, environmental friendliness. One module measuring 1.2m x 0.6m with a thickness of 2 cm costs from 1,300-1,400 rubles.

The purpose of a leveling plate should be taken into consideration when choosing one.

Necessary equipment

The following supplies and equipment will be needed as work progresses:

• vacuum cleaner, broom – for cleaning the subfloor before work;
• garbage bags;
• laser or hydraulic level – for drawing the contour of the top of the screed along the walls;
• construction stapler for fastening materials;
• ropes, slats or boards to delimit areas;
• construction meter;
• knives;
• mop for evenly distributing expanded clay over the floor surface;
• screwdriver;
• jigsaw;
• glue, fasteners.

Dry backfill leveling needs to be done with extreme caution. Make use of one rail and two sets of guide boards. Commence at the wall across from the doorway. To cut off, you’ll need an edged board. Modules have to be level.

Beacons can also be made out of metal corrugated pipes that have a cross section of 20 x 30 mm and are 2 or 1.5 meters long. as well as metal profiles. They ought to be equal.

Every measurement needs to be precise. The beacons positioned around the room’s perimeter should ideally line up with the laser equipment at the necessary level. An expanded clay backfill that is laid flawlessly every time is the end product.

Why is it important to understand?

Prior to beginning work, make sure you comprehend the specifics:

• determine the area of ​​the room;
• calculate the required amount of materials;
• prepare tools, fasteners.

Choose a premium class or a low-cost installation option to address your financial situation.

The area and necessary backfill layer thickness—which must be at least 3 cm thick—are used to determine the volume of expanded clay. Better thermal and noise insulation are offered by a thicker layer. However, as the floor rises to its maximum, the height of the walls falls, lowering the ceiling in the process.

It is possible to choose insulation materials with a minimum 0.2 mm thickness. The insulation should be larger than the room’s perimeter, accounting for bends and up to 10–20 cm of overlap on the walls.

The size of the room determines how many beacons and guide profiles are required, and the damper tape’s length is equal to the room’s perimeter.

Although you should have some reserve, the upper leveling plates are likewise equal to the area of the room.

Knowing what materials are needed for dry screed will help you choose the right list for the job while keeping your tastes in mind. For instance, it is best to select the materials that are most resistant to moisture if you need to lay dry screed in a bathroom or swimming pool. Additionally, there are suggested options for materials, etc.d. to create heated floors.

Useful video

The following calculation guidelines and the quantity of materials needed for dry screed are covered in the video:

Selecting the appropriate materials for a dry floor screed is essential to getting a long-lasting and functional outcome. For the best insulation and structural integrity, choose the right expanded clay type based on grain size and quality. In order to define the perimeter, support the screed, increase stability, and stop cracking, edge strips are essential.

Whether they are cementitious or gypsum-based, top slabs influence the floor’s durability and ultimate finish. While cementitious slabs offer robustness and resilience in areas prone to moisture, gypsum boards are easier to install and better suited for dry environments. Comprehending these selections of materials enables homeowners and builders to make well-informed decisions that are customized to their individual project requirements.

Contractors and do-it-yourself enthusiasts can create a level and durable floor surface that satisfies both functional and aesthetic requirements by combining the appropriate expanded clay, edge strips, and top slabs. Every part plays a distinct role in the overall performance and quality of the dry floor screed, guaranteeing long-term dependability and satisfaction for any building or remodeling project.

Video on the topic

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