For warm water floors, one of the most important structural elements is thermal insulation. Neither the heating boiler, nor the quality of the pipes of the heating circuit can have such an impact on the efficiency of the underfloor heating as thermal insulation correctly laid in the floor structure. In the design of any underfloor heating, whether it be electrical or water systems, a layer of insulating material must be laid under the water circuit or under the electric cable. The task assigned to thermal insulation is to create a reflective surface, thanks to which thermal energy goes up. In the absence of a layer of thermal insulation of the proper thickness, the heat from the coolant will rush down, without bearing any benefit for heating.

Traditionally, the most accessible and common materials were used for these purposes. As a rule, this is extruded polystyrene foam, ordinary foam or mineral wool. All these materials are united by a low coefficient of thermal conductivity, due to which the necessary conditions are created for the normal operation of the heating system. More practical and modern materials include mats for underfloor heating. They have recently started using it. Practical application has shown high practical and technological characteristics of materials of this type, which opens up rather broad prospects for them.

Mats for warm floors. Main purpose and scope

Before using mats as a thermal insulation material, you should have a ready-made project or “layer cake” scheme on hand. The entire floor structure, including the concrete screed, must be strong, stable and reliable. This is a prerequisite for the normal functioning of the water heating circuit and the stay of all structural elements of the floor in a normal state. To obtain sufficient strength of the substrate, it is necessary to use materials whose density is more than 25 kg/m3.

Until recently, when installing underfloor heating in residential buildings, foil polystyrene was used, which is easy to use and inexpensive material. However, technology does not stand still. Today, a wide variety of insulating materials have appeared that allow you to make a warm floor faster, cheaper and with the lowest labor costs. Mats for laying under a warm water floor are a universal product. On top of the styrofoam layer there was a layer of foil, which provided greater heat transfer to the floor surface. With universal characteristics, such insulating materials made it possible to quickly install the entire structure.

However, despite all the obvious advantages, foil mats also had a drawback. With direct contact of the foil layer with a concrete screed, a chemical reaction occurred. Liquid concrete corrodes the foil, negating all the effectiveness of using this material.

On a note: to eliminate such a negative effect, it is required to lay an additional plastic film.

Another disadvantage of foil mats is the difficulty of fixing the pipeline on the surface of the heat-insulating layer. In practice, a variety of devices were used for these purposes, starting with the guide mesh, ending with mounting rails, clips and clamps. The emergence of new modifications of finished products has greatly simplified the situation, making the installation of underfloor heating really easy, pleasant and of high quality.

In order to understand what role mats play in the underfloor heating system, it is necessary to know the principle of operation of a warm water floor. Like polystyrene, like mineral wool, these products perform the same function — saving heat. The low thermal conductivity of thermal insulation materials, one of their advantages, does not provide the necessary strength of the thermal insulation layer. A rather significant mechanical load is applied to the thermal insulation layer, which is created by a pipeline with circulating water, a concrete screed or a flooring system. Dynamic loads also affect the state of thermal insulation. Therefore, when choosing a material for your warm floor, focus on a density of 35 kg / m3not less.

Whether you use ordinary polystyrene foam, mineral wool or mats as thermal insulation does not matter. It is important that the finished warm water floor is reliably insulated, the water circuit works normally, and heat spreads over the floor surface without interference.

Against the background of the general costs of organizing underfloor heating, the cost of mats is not critical. Having once invested in good thermal insulation, you will get a reliable and efficient heating system.

Modifications of mats for warm floors

The first thing that is decisive when choosing a material is the functionality of the underfloor heating, the tasks that are set for the heating system. In each individual case, the following mats and their modifications for a water-heated floor are used in the practical plane:

  • foil mats;
  • mats with film;
  • mats are flat;
  • flat mats with bosses, polystyrene foam.

The first option — foil mats are usually used when the water floor is planned to be installed in a limited, small space.

Usually this option is suitable for combined heating. The main heating is carried out by radiators, while in the children’s room or in the bathroom you decide to equip water heated floors. The basis of the material is penofol, foamed polyethylene. The material laid with the foil layer up creates the necessary thermal insulation layer for underfloor heating in small rooms.

Important! Foil mats are not used when laying hot water floors on the first floors. The density and thickness of this heat-insulating material in this case is insufficient to create a full-fledged heat-insulating layer.


It will not be superfluous to recall the inconvenience that you will have to face when working with this material. To install the pipes of the water circuit, you will need a special mesh, clamps and mounting clips.

The second option — film mats, are mounting materials based on high-density polystyrene foam. (30-35 kg/m3). Expanded polystyrene is additionally covered with a polymer film and foil to increase its functionality.

These materials have special markings on the surface that facilitate the further laying of the water circuit pipeline. In comparison with the previous version, film mats are effective and often used in work. Due to the high density of the material, the mounting brackets used to fix the water circuit loops are firmly held in it.

Film mats, under a warm water floor, perfectly interact with a concrete screed, which fits perfectly on the film surface of the mats. This modification is often used in the installation of heating systems, where a warm water floor plays a major role. The laying process is facilitated thanks to the existing lamella system.

The third option is flat mats or slabs of expanded polystyrene, 40-50 mm thick.

Here the main emphasis is on the density of expanded polystyrene. It should not be less than 40 kg/m3. Typically, this type of thermal insulation is used in single rooms, where, according to the project, it is planned to equip water heating with warm floors. These mats do a great job. The structure of the material is quite strong and stable. In terms of service life, this material has no equal.

On a note: A properly laid water-heated floor can last 30-40 years. Thermal insulation for the entire period of operation, made of expanded polystyrene plates, does not lose its basic qualities at all.

Installation of pipes of the heating circuit on the surface of the finished thermal insulation is carried out by means of special brackets. Unlike film polystyrene foam plates, here you will have to make your own markings for the future laying of the pipeline. During installation, the plates are covered with a special polyethylene film as a vapor barrier layer.

The fourth option is polystyrene foam mats, flat and with bosses. This is a completely new thermal insulation material used today for laying water floors. Products are manufactured using new technology. As a result of hydropellent stamping, bosses are obtained on the surface of the plate. These figured protrusions are located on the entire surface of the product in even rows.


For the installation of a warm floor, this type of thermal insulation is a real find. Without preliminary marking, you can lay the pipes of the water loop in accordance with any chosen scheme. There is no need to use special fasteners to fix the pipeline. After laying the heating circuit, you can begin to start the system, carry out pressure testing of all heating equipment.

The fifth option — profile mounting plates are distinguished by their versatility. It is almost a ready-to-use substrate for underfloor heating. Unlike the previous options, here we can talk about the material with the highest density, more than 40 kg / m3. The thickness of such sheets varies between 10-35 mm. Each sheet is equipped with rows of rectangular protrusions, in the form of cubes or cylinders. The protrusions have a height of 20-25 mm. Even rows of protrusions and their number allow you to easily lay the heating pipes of the water floor directly on the mats in any direction and any configuration. The distance between the protrusions allows you to work with pipes with a diameter of 10-20 mm.

Note: when using profile mounting plates, the probability of shifting the pipes of the heating loop during the installation of the screed is reduced to zero.

It should also be recalled that today ordinary and laminated boards are produced, i.e. those that have an additional film coating on top. Laminated mats are ready for installation without the need for additional vapor barrier film.

Mat characteristics

Having become acquainted with the varieties of heat-insulating materials, with the modifications of the mats used in the installation of warm water floors, we can draw some conclusions. In conclusion, we give some technological characteristics and material parameters, thanks to which you will be able to make the right choice.

For reference:

  • expanded polystyrene, which is used in mats, must have a density of at least 40 kg per m3which creates the entire structure the necessary margin of safety and rigidity;
  • the thermal conductivity coefficient for all mats varies in the range of 0.037 — 0.052 W / m x K (meters x per Kelvin);
  • a number of materials, especially for profile mounting mats, have good sound insulation. The noise reduction index for mats with a thickness of 20 mm reaches 23 dB;
  • waterproofing in mats, except for laminated products, is provided by special locks installed at the ends of each slab. With the help of these locks, you can achieve a solid, extensive surface area. Slots in this case are practically absent;
  • domestic and foreign industries produce materials of the following sizes:

100×100 cm; 80 x 60 cm; on products with bosses and curly protrusions, it is allowed to install a water circuit loop with a pitch of 50 mm or more.


With all due respect to the self-made decision, choosing mineral wool or polystyrene for the installation of warm water floors, it is best to give preference to finished products. Profiled, flat, and on top of that, laminated mats will significantly speed up the entire process of work, ensure the reliability of the entire puff cake structure for the entire life of the warm floors in your home.

Using thermal insulation for installation, you will achieve an almost complete absence of heat loss during the operation of the heating circuit. Sparing no expense, investing once in modern, high-quality materials, you will provide yourself with a reliable heating system for many years to come. You should not be afraid of a situation where you can flood the neighbors on the floor below. All the heat radiated by the heating circuit will go upwards, evenly heating the entire floor surface.

Laminated boards are equally suitable for wet and dry screed. The choice of mat thickness is determined by the thickness of the future screed and the type of flooring.

In some cases, with sufficient insulation of the subfloor for apartments, products with bosses can be used. When it is important for you to maintain the height of the ceilings in the bathroom or in the kitchen, such products will be very convenient and useful.


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