Flooring: Surface requirements

The upper layer of the floor (it is also called floor finish) is constantly subjected to the operational effects (stresses). Base finished floor is its base, and any error made when the device can reduce the useful life or destruction of the coating.

In this part of the tutorial we will explain what you need to take into account the nuances in the construction of bases.

 So, we will answer the following questions:

• Which normative documents used in the design of the grounds.
• What are the requirements to the ground.
• What parameters should correspond leveling screed and underlying layer or the base on the ground.

Regulations applied in the design of the base

At first glance it seems that the floor - this is only the visible (or visual) part, which laid floor finish.

In fact, the floor - a complex multi-layer structure consisting of a plurality of stacked layers. "Pie" when viewed from the top down, includes the following main layers:

• Finish - finishing floor directly undergoing influences performance.
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• Screed (base under the coating).
• Underlayment. Basic structure. It distributes the load on the ground.
• Waterproofing.
• Subgrade.

Thus, each layer performs certain strictly predetermined function and durability of a final coating depends on the surface quality. Therefore, before starting the construction of the base should be to develop the project, based on which will be performed on the object. Project documentation is based on the regulations that define the rules and construction standards.

Piotr Smirnov (Engineer Product SIKA Company):

At the device of floors designers refer to the standard documentation. This documentation is called the Building Regulations (SNIP), or the modern name - Code of Practice (COP).

When designing floors typically use two main document, this SP 29.13330.2011 floors and SP 71.13330.2011 Insulation and finishes.

Floor design starts with the selection conditions of its operation, including, and finish. These conditions are determined depending on the functional purpose of the premises or the construction as a whole.

It can be industrial, warehouse, residential, public, administrative or sports facilities. Each of these objects is different load on the cover and, respectively, on the base.

Knowing the purpose of the room, we can understand what kind of load must withstand the topcoat and the base.

Once we have decided on a functional object or premises, where it is planned to arrange the floor, you need to turn to regulatory documentation, which defines the requirements for the grounds and the rules for their preparation, depending on the load and impacts.

Characteristics of the base and regulatory requirements

Regardless of the type of floor finish coating, it should be laid on the flat surface. Irregularities, depressions and other defects will lead to a rapid deterioration of the topcoat that will shorten the life of sex.

The load on the cover is transmitted to the base under it, a coupler, which in turn transfers the load on the underlying carrier layer and beyond, on the ground, the ground plate at the device. Therefore, the base must match the strength and load-bearing characteristics, calculated in its design.

Piotr Smirnov:

The structure of the floor, which is arranged on the ground (storage, logistics, industrial buildings, hangars and shopping centers, underground facilities) includes:

• a packed bed of soil, gravel and sand;
• thin concrete screed for waterproofing layer;
• of rolled waterproofing layer of bituminous materials or special welded membranes;
• carrying concrete backsheet; In most cases, this layer is the foundation for hardening cement finishing coating or coating of a liquid polymer materials;
• coupler (backbone under coating);
• layer (bonding adhesive layer);
• topcoat.

Let us consider what is required to the specification of the above layers.

Ball underlying concrete layer is made on the basis of calculations and in accordance with the requirements of SP (SNP). Concrete class for this design - not less than V22.5.

These recommendations are contained in the technical sheets of the products in most industrial coatings manufacturers.

The thickness of the carrier on the ground underlying layer should be not less than:

• In public buildings - 80 mm (100 mm when the base is under the coating).

• In industrial premises - 100 mm (120 mm if the foundation under the coating).

Piotr Smirnov:

If the scheduled finish polymeric coating, waterproofing under such a base - is required, and when dry hardening cement based mixtures - is highly desirable.

If floors are constructed on prefabricated or monolithic concrete, they include:

• waterproofing layer (for wet rooms);
• leveling screed (directly to the base layer or waterproofing or water-retaining polyethylene film);
• thin layer finishing self-leveling screed (A finishing roller coating or painting);
• topcoat of paint or adhesive interlayer type.

Requirements for Leveling

To understand what is required of the screed, it is necessary to understand why it is needed. Screed - an intermediate layer between the base stacking and finishing the floor surface. Screed leveling out downstream floor layer and gives it rigidity and, if appropriate, sets a certain slope value.

Screed arranged: to level the surface of the underlying layer, if necessary, to cover communications, and as for the distribution of loads on heat and sound insulation layers and provide the rated heat absorption floors.

Among the main technical requirements for screed, can be identified: when its device for separating layer (a polyethylene film or roll waterproofing) under moderate load screed thickness should be not less than 40 mm. The compressive strength of the cement-sand screed - not less than 15 MPa. If it provided elastic thermal or sound insulation, the thickness of tie - at least 40-50 mm. The thickness of the cover screed for pipes, including the heated floors, must be not less than 45 mm larger than the pipeline diameter. In this case it is necessary to provide reinforcing metal netting or antennae fiberglass. The compressive strength of such a tie - at least 20 MPa.

Piotr Smirnov:

If leveling screed manufactured directly on a concrete base and 40 mm in thickness, it is necessary to provide a secure grip with the base by means of the adhesive layer. Thus, at low (consumer) stress, substrate strength (couplers) to be coated should be less than 15 MPa. But in the device of bulk polymer, wood, sports and other special coatings base strength must be at least 20 MPa.

With significant mechanical loads screed thickness adopted for the calculation, but not less than 70 mm. Such ties are made of concrete class V22.5.

Regulatory flatness screed is determined by measuring the gap between two-meter rack and the floor surface. For the majority of the finish flooring (parquet, laminate, ceramic tile, linoleum, carpet coating polymer liquid floors), the gap should not exceed 2 mm (not more than two locations on the 2 meters).

Before laying the final coating, depending on the type of coating material and the adhesive layer is verified substrate moisture.

For laying coatings in rolls and polymer-tile (not aqueous) adhesive, liquid polymer floors for, for wood substrate moisture content should not exceed 4%.

For styling and natural polymeric coating on a roll and a hot plate at humidity aqueous adhesive base must not exceed 2%.

Features of the device subgrade under the counter

On the foundation soil is distributed load, transmitted through the underlying support (support) layer from the overlying layers. Therefore, the soil foundation imposed certain strength and performance requirements. Can not be used as the base under floor sagging, non-cohesive soils with deformation modulus less than 5 MPa. For example, peat, black earth. In the presence of soft soil should be replaced by low compressibility. The thickness of this layer is determined on the basis of calculation.

If the lower portion of the underlying layer is located in the zone of influence of groundwater on their capillary rise (regardless of their season), it is necessary to organize one of the following events:

• to lower the groundwater level;
• increase the level of the floor due to the device ground pads of coarse sand, crushed stone or gravel;
• when concrete underlying layer mount quality waterproofingkapillyaropreryvayuschuyu or to arrange a layer of geosynthetic materials.

It is also necessary to provide (if necessary) protivopuchinistye measures. Such measures may include: replacement of heaving soils to nepuchinisty; lowering of the groundwater below the freezing depth reason not less than 80 cm; additional insulation, which reduces the depth of soil freezing. In addition, the ground under a concrete subbase need douplotnit rubble or gravel to a depth of at least 40 mm.

Subject to the above requirements for reasons even during the construction and finishing works in the home, you can avoid problems with the floors in the course of their operation.

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