Floating floor: screed technology

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In this article, you will learn how to make floating floors. We will tell you about the principle of forming the “pie” of this design, as well as about the functional purpose of each of the layers. The article provides options for different premises and approximate market prices for the material.

What is a floating floor

Floating floors are a system of screeds, insulation materials and floor coverings that are independent of walls and floors. That is, they lean on the base, adjoin the walls, but are not rigidly attached to them. This is achieved through multi-layer technology, which can include layers for various purposes – waterproofing, preparatory, leveling, thermal insulation, engineering and finishing..

Floating floor: screed technology

The combination of materials in the “pie” is accepted for each object separately. There are two fundamentally different options for floating floor devices – “wet” and “dry”. In the first case, cement and gypsum (extremely rare) mortars are used, in the second case, only dry installation. Next, we will consider all possible combinations that meet this technology..

Assigning Floating Floor Layers

Consider a cut of the “pie” taking into account most of the possible material options.

Floating floor base

It can be anything – concrete slab, floor, soil, old durable coating (for example, tiles). The only requirement for the base is that it must be dry and not have a water source (for example, a flooded basement). The floating floor allows finishing even in the case of a moving base – layers, especially sand bedding, compensate for the movement. This is relevant for soil foundations subject to heaving deformations or floor slabs of panel houses.

Floor waterproofing

A must-have layer for all substrates. It cuts off moisture contained in the soil or in a concrete slab, and does not allow subsequent layers to be moistened. It can be rolled dry or welded, sprayed, glued, coated. Waterproofing is mandatory even on old coatings. For example, when re-facing tiles with laminate. This is necessary because the stone material retains moisture better, and after drying the air, it will give it to the laminate. A layer of polyethylene is sufficient to protect the new coating.

Floating floor: screed technology

Prep layer

It is a layer of sand that corrects defects in the base. This unexpectedly simple method is most relevant for soil bases, since it provides effective filling of depressions. Of course, you can use a cement-sand screed, but a sand bed allows you to get the same result without additional costs of cement, work and time. The sand must be dried before use..

Floating floor: screed technology

Leveling layer

Any rigid boards – chipboard, DSP, OSB, magnesite, fiberboard, special gypsum board. One of the options for the “pie” involves laying the slabs directly on the preparation from the sand. Then laminate, parquet board and any other type of dry cladding can be laid on them. This option is popular in rooms with minimal requirements – verandas, balconies, corridors.

Floating floor: screed technology

Insulation and sound insulation

The purpose of this layer is clear from the name. The combined option is very popular – thermal insulation in the form of plates of extruded polystyrene foam, sandwich-polyurethane plates, or other similar modern materials. Usually they have a thermal lock – the edges of the slab, cut in a special way. Another option is pressed hard and semi-hard mineral wool slabs. All these slabs are laid right on the sand.

Special materials can be used as noise and vibration insulation – for example, granular mixtures based on soft balls of the Shumoplast type. This is a great option for uneven subfloors, as the 30mm working layer smooths out any unevenness.

Engineering layer

This is a floor heating system – water or electric. It is not separate or independent – it is a system of pipes or wires included in a cement-sand screed. The engineering layer also includes a foil-clad reflector, which is usually arranged under the heat exchanger..

Final leveling layer

Actually, a preparatory screed for external cladding. In all cases, it is performed with cement-sand, gypsum-cement mortar (with additives) or concrete. It is often done in several stages – covering the engineering layer (rough screed), leveling the surface (final screed), finishing the plane (leveling). At the first stage, a reinforcing mesh is usually laid.

Floating floor: screed technology

Finishing layer

Decorative floor covering – tiles, linoleum, piece elements, etc. Includes a backing.

Damper

The highlight of the technology that makes the floating floor floating. This is a vertical layer of soft material, laid along the perimeter of the walls at their junction with the floor. Or simply a lining placed between the walls and the “pie” of the floor, creating a gap (for dry installation). The main condition is that the damper must guarantee the independence of the floor from the walls along the entire perimeter..

Floating floor: screed technology

Attention! The damper thickness is 10 mm per 1 m distance to the wall (but not less than 10 mm). That is, for a room of 3×3 m, the minimum damper at each wall will be 15 mm.

As a material, special tapes or a canvas of the “Izolon” type 500/300 are used, but you can use ordinary slabs of mineral wool or foam grade 15.

Floating floor options for different rooms

There are several typical techniques for the device of this system, suitable in different cases. We will consider them layer by layer, taking into account the cost of each layer (except for finishing and engineering).

Screed in the apartment

The simplest option is carried out literally in two layers – combined preparation / soundproofing and cement-sand screed. Moreover, in the case of the device of the engineering layer, the preparation can also be foil-coated, that is, it can serve as a reflector. If the preparation is rolled and laid directly on a concrete slab, the edges of the sheet should be brought onto the wall to a height exceeding the thickness of the “pie” by 10–20 mm – this will be the damper.

Floating screed in the apartment on video

If the task is to provide more reliable sound insulation, you should use dense extruded polystyrene foam (PPR) instead of Izolon, fixing it with glue and dowels.

The cost of a 5 mm foil substrate or Izolon is 0.7–0.9 USD. eat2.

Ground screed (in a private house)

Usually done when dismantling the old floor to the base and replacing it with a new one.

Option 1.With insulation

Operating procedure:

  1. Waterproofing. Lay roofing material or polyethylene.
  2. Sand filling with preliminary leveling. Can be done using beacons with tamper – the plane will be more accurate.
  3. Damper device.
  4. Laying of thermal insulation – polystyrene, PPR or mortar with expanded clay (50-200 mm).
  5. Installation of underfloor heating, if necessary. Screed device.

The approximate cost of materials for 1 m3:

  1. Polyfoam – 20 cu e.
  2. PPR – 70 USD e.
  3. Expanded clay – 23 cu e.

Video: floating screed for thermal insulation

Option 2. Without insulation (with “dry cake”)

Items 1, 2 and 3 are identical to the first method.

  1. Laying of leveling boards – chipboard, particle board, fiberboard, OSB, gypsum board – at least 15 mm thick each in two layers.
  2. Laying the finishing layer – laminate, linoleum, parquet board.

Cost of materials for 1 m2:

  1. Chipboard 18 mm – 3 cu e.
  2. DSP 18 mm – 4.6 cu e.
  3. Fibrolite – 7.1 cu e.
  4. OSB 22 mm – 7.4 cu e.
  5. Gypsum plasterboard for KNAUF floor 20 mm – 7 cu. e.

If you decide to arrange a floating floor, try to finish the walls first. In this case, there will be a guarantee of the independence of the elements. Observing this basic principle, you can combine materials depending on your realities and get a consistently high-quality result..

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