How To Choose The Right Underfloor Heating Substrate So That It Works

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Video: How To Choose The Right Underfloor Heating Substrate So That It Works

Video: How To Choose The Right Underfloor Heating Substrate So That It Works
Video: Guide: How To Lay Underfloor Heating 2023, September
How To Choose The Right Underfloor Heating Substrate So That It Works
How To Choose The Right Underfloor Heating Substrate So That It Works
  • Underlay for warm water floors
  • Which material should you choose?
  • Styling technique
  • Underlay for warm electric floors
  • What else is recommended
  • Substrate for IR foil underfloor heating
  • Wrong substrate selection errors

Warm floors are currently a very popular option for additional heating. First of all, in private residential buildings and in apartments on the ground floors of apartment buildings, which are located above unheated basements. For their high-quality installation, a foil underfloor heating is often laid.

The market today offers underfloor heating in three versions:

  • Aquatic;
  • Electrical;
  • Infrared (film).

Each of the options mentioned has its own pros and cons that should be considered when choosing. The difference in the design and principles of operation of the floors determines the fact that their installation is carried out using different technologies. One of the few conditions for arranging such floors, regardless of the type chosen, is that in all cases the underfloor heating is pre-laid, on which it is mounted.

For the substrate to work, it must have an aluminum foil thickness of at least 30 microns and have a protective film

Underlay for warm water floors

Before considering the requirements for the substrate material and the technology of its laying, one should understand what it is and for what purposes it is used.

The underfloor heating water substrate is a material laid between the base (the so-called "sub-floor") and the water floor system itself. Its main purpose is to preserve heat and increase the heat transfer coefficient inside the room.


This is achieved due to the fact that the underfloor heating is, in fact, a material with high thermal insulation properties. Its presence does not allow the heat to be spent on floor heating, all of it is directed inside the heated room. The so-called. "Thermos effect". A high-quality substrate combines the properties of a heat insulator with high waterproofing capabilities. What is especially important because coolant.

Learn more about the choice of pipes for the water floor and the installation system.

Which material should you choose?

When choosing a reflective material for a warm floor, the main criterion to pay attention to is the quality and thickness of the substrate. A quality product has the following set of specific performance properties:

  • It must have high waterproofing properties and have the required thermal insulation capabilities;
  • Be environmentally friendly;
  • Possess significant heat reflectivity;
  • Characterized by significant resistance to significant temperature changes;
  • Have certain soundproofing qualities;
  • Resistance to possible deformation;
  • Be simple and easy to install.

The most optimal for those who equip a water heated floor, the substrate is made of foil material.


In addition, the following types of substrates are in demand on the market:

  • Self-adhesive foil-clad PE. The average material thickness is 8 mm. The material is in demand on especially complex surfaces. It is characterized by high heat-reflecting ability, necessary waterproofing ability and significant sound-proofing properties;
  • Laminated single-sided PE. Pros - the required water resistance and high thermal insulation characteristics. Thickness - 8 mm;
  • Foamed PE. With a thickness of 2 mm, it has admissible characteristics for heat and waterproofing;
  • Foil-clad PPP. The material is available in various thicknesses and is characterized as a high quality, highly reflective heat insulator;
  • Tuplex underlays. With a thickness of 3 mm, it demonstrates the maximum heat-reflecting characteristics and waterproofing properties. A significant plus is long service life.

The cost of underfloor heating depends largely on the type of material, the thickness of the underfloor and its design.

If you are going to lay tiles, then you need to cut through the penofol so that the screed is connected to the floor.

Styling technique

The desire of a specialist who installs a warm water floor, the thickness of the cake of which eats up a certain height of the room, is understandable, to minimize it if possible. For this, materials with the minimum permissible thickness are used. The underlay is laid on the previously prepared surface so that the existing reflective coating is directed upwards. The material is laid end-to-end. The seams between the canvases are glued with special tape (metallized). This allows complete insulation of the laid substrate to be achieved.

When the solution comes into contact with the foil surface, the solution destroys the falga, which is why it is so important to use laminated penofol.


Foil underfloor heating, like any other, must be placed on the walls of the room at a distance of at least 50 mm during installation. This will not allow, if the underfloor heating pipes break through, flood the lower room.


In cases where the selected substrate does not have the necessary waterproofing characteristics, a water-heated pie is set up:

  • A layer of waterproofing is applied;
  • The substrate is laid;
  • The warm floor itself is settled on it;
  • Floor pipes are filled with screed;
  • The finishing flooring is laid.

Find out how to choose the right floor for your bathroom.

Underlay for warm electric floors

The underfloor underfloor heating is structurally similar to the options described in the previous section. But almost all models of such underfloor heating do not require preliminary laying of a waterproofing material under the substrate.

The surface is pre-leveled. Then a substrate is laid on it, on which a special mounting tape is attached. The heating cable is attached to it with special brackets.

Important! When installing under electric underfloor heating, it is not recommended to use such material as a foil underfloor heating. This is explained by the fact that metal (foil) is a conductor, and if the contact is broken in the system, the probability of a short circuit is very high.

The most suitable material in this case is a substrate made of the following materials:

  • PP (polypropylene);
  • Penofol (metallized film);
  • Bung;
  • Foamed polymers.

The leader in thermal insulation for warm floors is Energofloor Compact.

What else is recommended

The use of fiberboard and magnesite plates is permissible. In this case, the thickness of the underfloor heating is minimal. These materials are preferred when it is necessary to level the base or increase its sound insulation.

PPE (polyethylene foam) substrates are popular due to their low cost. However, this is not recommended because with constantly operating warm floors, such a substrate is deformed. Therefore, it can only be applied to work, it will not fully work.

When deciding which types of underfloor heating are the best choice for electric floors, penofol is most often chosen. Despite the fact that it is based on foamed PPE (polyethylene foam), the disadvantage inherent in this material was neutralized by lamination. What is a polymer film with metal thread stitching used for? It avoids heat leakage and prevents the PES from overheating to the point of deformation.

Substrate for IR foil underfloor heating

If you plan to equip infrared warm floors, then the main parameters that determine their correct functioning are:

  • Correct installation (in strict accordance with the instructions);
  • Laying the substrate with the heat-reflecting surface facing up.

The underfloor heating film is made of the following materials and taking into account the recommendations below.

  1. Magnesite boards or fiberboard sheets. Before laying them, aluminum foil is laid directly on the pre-equipped screed. And the actual substrate is placed on it. Foil underfloor heating can be used.
  2. If a metallized polymer film is used as a substrate, it should be laid with the reflective side up (towards the film floor with IR resistors). The result is a thin, highly flexible, flexible and environmentally friendly solution.
  3. Insulation is laid over the entire area, on which it is planned to lay an IR foil floor in the future. The backing sheets are laid end-to-end, and the resulting seams are glued with metallized tape. That creates the necessary vapor barrier and gives the substrate the required waterproofing qualities.

Learn more about choosing the right warm infrared floor.

Wrong substrate selection errors

There is one more situation when underfloor heating is used. The price for it is much lower than those set for the options discussed earlier. These are substrates that are installed under the final floor coverings, in particular under the laminate. Laminate underfloor heating protects against warping when overheated and contributes to sound insulation of the floor covering. The video will help you learn about the mistakes in choosing a substrate.



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