Is insulation under the floor heating necessary?

Why thermal insulation is required

The water circuit heats the floor surface through heat radiation, with the heating direction not only upwards but also downwards. Without installing a thermal insulation layer under the floor heating, a large part of the radiation will be absorbed by the concrete or wooden base. If under the room where you intend to install a heating floor circuit, there is a cold basement or the ground, the heat loss can reach 40%. If there is a heated room underneath, the heat loss will be about 20%.

Reducing the efficiency of underfloor heating system leads to higher energy costs. In addition, the boiler unit is forced to work in high-power mode, which causes faster wear and tear. To avoid problems associated with reducing the service life of equipment, as well as reduce the financial cost of heating, it is necessary to insulate the floor base, using a suitable insulation.

Over the thermal insulation layer, which is mounted on the prepared waterproofed base, it is recommended to lay a roll foil material or immediately use a thermal insulator with a metallized coating. Foil reflects thermal radiation upwards, increasing the efficiency of the heating circuit.

Underfloor heating insulation performs several functions at once:

  • Prevent heat loss through the ceiling and at the same time keep out the cold from below;
  • contributes to the distribution of thermal radiation over the entire surface of the floor covering and, accordingly, an even heating of the room;
  • increases the inertia of the “pie”. after turning off the boiler floor for a long time remains heated, it allows you to save energy carrier;
  • Serves as a sound and vibration insulator, which increases the acoustic comfort in the house.

Insulation is a mandatory element of a warm floor. Without it, the system will not be economical, and most of the energy will be lost to the heating of the underlying floors of the floor or the ground. Especially acute this question arises when the device system on the ground.

So, what heat insulation materials are appropriate to use when installing a water underfloor heating? In general, any material that meets certain characteristics is acceptable. First of all, it should have a sufficient level of thermal insulation, also be resistant to moisture and chemicals from concrete screed, have sufficient rigidity.

In one way or another, these materials meet all of these requirements:

  • expanded polystyrene (foam plastic);
  • Extruded polystyrene foam;
  • Mineral wool boards;
  • polyethylene foam (foamed polyethylene);
  • natural cork.


Styrofoam (EPS) is popularly called Styrofoam. This material is obtained from polystyrene by foaming. In addition to polystyrene itself in the composition of insulation includes a large number of additives and modifiers that improve its properties. Due to the foaming materials, up to 98% of the volume of EPS consists of air bubbles.

Consider the characteristics and properties of polystyrene foam. The heat transfer coefficient, which is the main characteristic of thermal insulating materials, in polystyrene ranges from 0.030 to 0.047 W/m°C. It depends on the manufacturer and the density of the material. EPS is available in different densities, which depends on the stiffness and weight of the material. At the same time, the thermal conductivity of the density depends little.

Advice! For underfloor heating it is recommended to use EPS-35 and higher, with a density of 35 kg / m ³.

Polystyrene foam refers to flammable materials. Also, when heated to a relatively low temperature (about 80 degrees) of it can release harmful substances. Other characteristics of this material include:

  • resistant to fungi and microorganisms, but the material can be destroyed by rodents;
  • EPS poorly absorbs water (not hygroscopic), which is convenient when it is installed in a wet screed.

Styrofoam is easy to use and is often used in underfloor heating systems.

Extruded polystyrene foam

Extruded polystyrene foam (EPPS) is a kind of expanded polystyrene. It is produced in the same way as EPS, the only difference is the method of production of granules. Its characteristics are low thermal conductivity of 0,029-0,034 W/m-C, low hygroscopicity.

Available in different types of EPPS, density from 25 to 45 kg / m ³. In terms of thermal performance and lightness, it surpasses polystyrene to the brand EPS-35 and is similar to the characteristics of high-density EPS.

This material is stiffer, resists mechanical action better than polystyrene, so it is more convenient to use and it destroys less. The main disadvantage its price is higher.

Please note: Both EPPS and regular polystyrene foam is available in a special modification for underfloor heating, in which the top edge of the plate is a system of special grooves and channels for laying the pipe underfloor heating. It simplifies the work.

Mineral wool boards

For underfloor heating systems, sometimes used rigid plates of mineral basalt wool. Its characteristics are similar to the usual mineral wool. The difference in rigidity and ease of installation. The main positive characteristics of mineral wool include:

  • Zero flammability. the material is not affected by high temperatures;
  • high noise insulation characteristics;
  • good thermal insulation properties
  • chemical stability.

Rigid mineral wool boards with a density of 175 to 200 kg/m³, with a heat transfer coefficient of about 0.039 W/m-C, are used for the screed. The main negative property of mineral wool is hygroscopic and vapor permeable. This is why they require careful waterproofing and vapour barrier when installed into a wet screed.

Polyethylene foam

Recently polyethylene foam has been used for thermal insulation of warm floors. It is a roll material with a thickness of 3 to 10 mm. PE foam can also be foiled on one or both sides. Foil coating allows to create a reflective layer for infrared rays. The use of foil enables to reduce the thickness of the necessary thermal insulator.

But there is a nuance: the reflection of infrared rays by such a layer is difficult in a solid body, what is the cement screed. But still, the use of such a material can significantly save on the height of the screed. This will not reduce the height of the room.

According to its thermal and technical characteristics, foamed polyethylene is similar to polystyrene and other materials. The coefficient of thermal conductivity of this material in a dry state is in the range 0,037. 0,049 W/m-°C, but you should bear in mind that foamed polyethylene absorbs water, while its insulating properties are reduced.

It is also important to know that foil can be corroded by chemical materials in the concrete mixture. To eliminate this problem, many manufacturers produce a sheet material that is covered with a special polymer foil on top.

Natural cork

Cork, a natural thermal insulating material, is also used for water underfloor heating systems. Cork has a heat transfer coefficient of 0.034 and is similar to the best artificial materials. The main positive characteristic of cork is its naturalness. It does not contain extraneous chemical additives and harmful substances.

The main disadvantage is that it’s expensive. The use of natural cork in the cement screed floor heating is justified mainly by its naturalness. But the question arises: is it worth pouring expensive and natural material in the cement.

Cork is a relatively hygroscopic material. It can absorb up to 12%. In order to protect against getting wet, the cork insulation must be covered with a thick layer of polyethylene or PVC film with or without foil.

Research. Does it need reflective insulation under under underfloor heating??

I did floor heating in my house and I don’t regret the money I spent. It is comfortable to walk on a warm floor, and it is pleasant for children to lie on it. Low-temperature heating of the entire floor area is much more optimal in terms of heating the room than point radiator heating, in which the temperature of the coolant is several times higher. The radiant energy from underfloor heating provides a more even distribution of heat and creates a pleasant microclimate (“keep your feet warm”) 2. “). But in order for the floor to enjoy the comfort of warmth and comfort for many years, it must be done correctly. Because in the technology of a warm floor (further TP) there are a lot of nuances.

insulation, floor, heating, necessary

Everyone, or at least many people know the standard underfloor heating pie. 1. The base (floor slab, ground, etc.).д.) 2. Insulation (foam plastic/foam board, mineral wool, polyethylene foam) 3. Metal mesh (mesh depends on the distance between the pipes, rod diameter 4-5 mm) 4. TP pipe (if the floor is water) or cable (if electric) 5. Screed (most often CPS with or without plasticizers and/or with fiber) 6. Finish flooring (tile, linoleum, laminate, parquet)

Let’s briefly consider each layer. Insulation. Necessary to prevent heat loss downwards. It is important to achieve that the heat spreads upwards as much as possible. This keeps the temperature of the heat carrier lower and saves energy resources. Most reputable manufacturers of heating systems recommend using polyurethane foam as insulation (primarily extruded / extrusion. a.k.a. EPPS or XPS). Ordinary polystyrene foam with a density of 35 kg/m3 or extruded material hard enough to work normally inside the screed. But its minimum thickness should be 20-30mm. Manufacturers recommend using 30 mm of foam in cases where the heated room below. If there is unheated space or ground below, a thicker layer of insulation is used, 50-80 or even 100 mm. But in practice it is not always possible to increase the thickness of the screed. over, most often it is undesirable to increase it even by 10 mm. Then traditionally use a 3-5 mm layer of polyethylene foam. The commercial name of the polyethylene foam, or otherwise expanded polyethylene (PE or PPE) can be quite different: Penofol, Ecofol, Isolon, Polyfom, Penolon, Porileks, Teplofol, Energofol, Isokom, Vilaterm, Neofol. The essence is the same! In underfloor heating systems, foil-coated or metallized polyethylene foam (foil with a protective film layer, metallized lavsan film, etc.д.). It is believed that the polyethylene foam is able to work effectively as insulation, and the foil to reflect heat. Is this true? Read more.

insulation, floor, heating, necessary

Grid. Mesh performs several functions. a) It is easier to attach a pipe or cable to the mesh. The size of the mesh chosen depending on the required distance between the pipes. Most often it is 15×15 cm, 20×20, 25×25 or 30×30. b) The mesh also serves as reinforcement. But to make it work effectively it is necessary at the time of filling the screed to lift it a little (a few millimeters) from the base c) The grid helps to distribute heat in the heating system more evenly. The pipe heats the metal bars, which in turn transfer the heat to the screed. It is difficult to say without a separate study whether this is a valid claim

The pipe. In water heating systems any pipe can be used: metal-plastic, cross-linked polyethylene, polypropylene, copper and even just metal. But it is most convenient to use metal plastic or cross-linked polyethylene. It is believed that cross-linked polyethylene is more reliable and has a better heat transfer. But if you delve into the topic, it turns out that plastic metal is different and cross-linked polyethylene is a dozen different types. Each particular brand of pipe has its advantages and disadvantages. Cross-linked polyethylene is less flexible in its mass, but the metal plastic tends to fracture on steep radii. Today a quality pipe from European manufacturers is offered for about the same price and everyone chooses on the basis of their own criteria. By and large the difference is not very great. I chose a modern inexpensive metal-plastic, namely metal-polymer pipe Sahna MultiFit Flex (PE-RT/AL/PE-HD) for the price of 36 (summer 2012) per meter. This pipe is very flexible and well bendable. A few words about the position of the pipe in the screed. It is necessary that the thickness of the screed over the pipe is at least 30 mm otherwise the heating will be uneven. Pipes can be laid in a serpentine pattern or in a volute. The snail pipe is preferable as in this case the return pipe is always close to the supply pipe and a more even heating of the room is achieved. The distance between the pipes is determined by calculations, but it must not exceed 30 cm. If you lay the pipe with a step of 30 cm, then at a flow rate of the coolant less than 2.5 l / m, will be felt striped floor heating (tested by my own experience)!). If you choose a pipe spacing of 30 cm, ensure a flow rate of at least 3.5-4 liters/m. The flow rate can be seen if you install a manifold with flow meters. The diameter of the pipe is usually used 16 or 20. For 16 pipes the maximum length of the circuit should not be more than 80-100 meters, and for 20 pipes more than 120 m.

Screed. Here, in general, everything as usual. Many when installing screed with TP pipes use plasticizers or fibers to prevent cracking screed. Practice shows that the usual screed without plasticizers and additives is quite normal with underfloor heating. You can do as a semi-dry, and ordinary screed. The appearance of cracks will depend more on the quality of workmanship, and not on the presence of pipes or cables in the screed.

Finish coating. TA works best with ceramic tiles, as its thermal conductivity of all finishes is the highest. But there are people who successfully use linoleum, carpeting, laminate and even solid board. The lower thermal conductivity of the final coating, the higher will need to maintain the temperature of the coolant (determined by the calculations and experience). If for the tiles will be enough in the off-season 29-35 degrees, then for a solid board the temperature will need to keep 10 degrees higher.

Is foamed polyethylene effective as a thermal insulator carpet pad in the underfloor heating system??

And now I turn, in fact, to the study of the use of polyethylene foam as a thermal insulator and substrate for pipes and cables under the floor heating. As I said above, it is not always possible to increase the thickness of the screed thickness using polystyrene foam. Often for insulation leave only 3-5 mm. And then goes foil polyethylene foam. In my basement I used an extruded polystyrene foam from the company Techno-Nicol, since the bottom of the cold ground. But when installing underfloor heating between the first and second floor I really thought about it. By and large it was not necessary to cut off the heat flow downwards at all in my case. After all, my ground floor is residential and is heated. In addition, a 30 mm layer of polystyrene foam with mounting on my area came out to the amount of about 26,000 Therefore I decided not to use foam. Having a warm ceiling in your own heated basement is not at all superfluous. But whether to apply an underlayment of polyethylene foam? The costs are much lower, but they are there nonetheless. Is it a waste of money or does a thin layer of polyethylene foam insulate the heat flow downwards to some extent. All the heating in my house is automated and divided into zones and circuits with individual regulation. In terms of automation, this means that it is better to minimize the impact of ground floor heating on the heating of the basement, because the nature of heating is different. For example, in the basement due to the high inertia of the ground, the heating is always the last to turn on in the fall. The question of whether to spend 5-6 thousand for a few rolls of polyethylene foam under the TP or not arises sharply. Does it work or not? In such cases, I often resort to the help of the Internet.

But this time I was disappointed. Manufacturers of polyethylene foam with one voice say. foamed polyethylene in underfloor heating systems, be! This miracle material almost completely insulates the flow of heat downwards. On the other hand there are a large number of forums that question the need for this material. People’s arguments are as follows:

The thermal conductivity of polyethylene foam is comparable to that of polystyrene foam. Technical calculations show. In order to effectively block the transmission of heat down through the floor slab, you need to use at least 30 mm of Styrofoam. What is the point of using a 3 or 5 mm layer of polyethylene foam. This is a negligible thickness and will do absolutely nothing. 2. The polyethylene foam (actually polyethylene with air bubbles) will shrink to 1 mm in the screed and stop working. 3. The foil reflects infrared (infrared) radiation, but not inside a solid body. The statement that the foil works as a reflector in the underfloor heating system is untrue and is simply nonsense. In addition, aluminum foil “hurray” corrodes the alkaline medium setting screed, and all kinds of metallized lavsan films, having the form of “aluminum foil” although not corrodes the screed, but are a complete “fuflo” in terms of reflection of infrared radiation.

Such opinions can be met on the pages of forums. Well, it seems quite convincing. But the opinion of forum authorities. this is one thing, but the research carried out. that’s different. Unfortunately, I have not found anywhere in the Internet information about the effectiveness of foil-coated polyethylene in heating systems. And therefore I was tormented by vague doubts, especially against the background of such messages as “I did it without a substrate. it does not, and the neighbor did with the substrate. warms up”. I didn’t want to take a decision based on granny’s fairy tales, so I decided to make my own experiment to find out for sure. To be polyethylene foam in the screed or not to be.

insulation, floor, heating, necessary

To anticipate all sorts of “you’re a fool” in the reviews, I will say that I know the difference between different substrates. Polyethylene foams are of two types: non-cross-linked polyethylene foam (NPE) and cross-linked polyethylene foam (CPT). Cross-linked polyethylene has a number of advantages, but in the context of this study, which aims to establish the effectiveness of 3-5 mm of insulation in underfloor heating systems, there is no significant difference what kind of material. In the Russian market there is also polypropylene NPP foam, which allegedly withstands higher loads than NPE, but its price is three times higher. It is claimed that the LPP is more durable and stable, does not crumple like LPE in the screed. I specifically on this subject was in the store, where a long and closely twisted different insulators in the hands. I have, shall we say, doubts about the fact that the PPP is really 3 times better (judging by the price) than polyethylene foam. I think that most likely they will work similarly in the screed. This study uses the most widely used uncross-linked polyethylene foam at a price of 50 a p.м.

So in my own house I built a kind of test bed in the attic. The base. Normal hollow core PC concrete floor slabs. From the brick I made three small tanks, through which led the metal-plastic pipe of 16 diameter.

The first tank (on the left side of the photo) is placed directly on the floor slab. The second tank (in the center) was placed on a foil-coated polyethylene foam with thickness of 5 mm. Took the cheapest material that was sold under the brand name Isoline at the store. What is the metallized reflective layer, I can not reliably figure out. You know the qualifications of the sellers. The third tank (on the right) was placed on the same 5 mm thick polyethylene foam, but without the reflective layer. Research Objective. Determine what role the polyethylene foam plays in the underfloor heating system and whether the reflective layer plays any role.

The task is set, the cement is kneaded. The layer of screed over the pipe was 35 mm, as this is the most common.

When the screed had cured, I connected the pipe to the manifold and fed it with 39 degree water. To minimize the effect of placing the blocks in sequence, the flow rate in the circuit was more than 5 liters per minute. Measurements showed that the inlet and outlet water temperatures did not actually change.

The measurements were taken with a DS18B20 precision calibrated digital 1-wire thermometer. The temperature values were fed into a database every minute and I was able to follow the process online.

Every 3-5 minutes, just in case, I made alternate measurements manually with an analog sensor connected to a multimeter. Also, I used this sensor to estimate the heating of the test cubes at several points.

The results of measurements were much more interesting than I expected.

The red graph. Screed without thermal insulator 2. Blue graph. Screed with 5 mm thick polyethylene foam without reflective layer 3. Green chart. screed with 5 mm thick polyethylene foam with a reflective layer

The surface of the screed with the foiled PE underneath was on average about 1.5 degrees higher than the surface of the screed without any substrate. This can be clearly seen on the graph. 1.5 degrees. Is that a lot or a little?? I know many people have felt the forehead of a person with a temperature of 38 degrees. Compare with a healthy person’s forehead temperature of 36.6. The difference is not much, but the hand feels quite unambiguous. Approximately the same thing happened in this case. The hand quite definitely felt the higher temperature of the screed with the foil-coated NPE backing. And subjectively it seemed that the temperature was higher by more than a degree and a half, but no. Measurements at different points in the square showed. the difference is about 1.5 degrees. This was also confirmed by repeated measurement with a multimeter. And what about LPE without a reflective layer. And then there is the surprise! The surface temperature of the heated screed is about 0.5-0.7 degrees lower than with foil-coated PE. over, as you can see on the graph, the metallized layer generally plays the same role as the rest of the 5 mm of thermal insulation proper! That is, half of the 1.5 degree difference gives polyethylene foam and half gives polyethylene foam. metallized reflective layer! I didn’t expect that in any way. This proves the validity of using a reflective layer in underfloor heating systems. What are the laws of physics at work in this case? After all, infrared radiation is not transmitted in a solid body. But the fact is. And let the absolute values of this is only 0.7 degrees, but they are.

I must admit that before the experiment I was quite skeptical about the advisability of installing polyethylene foam in the screed under the floor heating. I didn’t believe that the reflective layer played any role. But the conclusions are quite unambiguous. NPE/PPE works! What’s more, somehow it works (and works well!) and a metallized reflective layer of NPPE.

But in which of the three cases is the screed more evenly heated?? There may be surprises here too! Alas, measurements at 7 points of each cube showed that the use of NPE did not affect the more even heating of the screed. The graph of the temperature drop closer to the corners of the cube is absolutely identical in all three cases.

The temperature graph has stabilized after about 2.5 hours of work. Now let’s see what happens after the underfloor heating pump is turned off. How do the graphs behave? After all, in the first case, where the screed is in contact with the floor slab and therefore heats it up more, the inertia should be higher and the screed should cool down more slowly. Let’s check.

It is. The red graph decreased more slowly and eventually the temperature of the first cube became higher. Considering the small surface area and the short running time of the floor heating, the inertia is not very significant, but it’s still there.

Well, what happens if you compare the work of 5 mm of expanded polystyrene with 20 mm of extruded polystyrene foam? Whether there will be a significant effect? I removed the substrate without a reflective layer, and instead installed a layer of polystyrene foam.

Now start the underfloor heating pump again and see what happens. The blue graph shows the temperature of the screed surface where the polystyrene foam was used.

Again, a surprise. Of course, the screed over 2 centimeters of styrofoam warms up better, but only by 0.3-0.4 degrees. I would expect that the difference would be much more noticeable. So it turns out that a 5 mm layer of polyethylene foam with a reflective layer as a thermal insulator in the floor heating system is only slightly inferior to a 20 mm layer of foam plastic.

The alkaline environment of a curing cement screed is thought to corrode aluminum foil. That’s probably true. Therefore, manufacturers produce two varieties of polyethylene foam with a reflective layer: with aluminum foil (traditionally denoted by the letter “F”) and with foil, laminated film, or with a metallized polymer film (most often has the letter “L” in the name). For underfloor heating systems is designed for LPE, a reflective layer which is resistant to alkali and is not destroyed in the cement mortar.

On the second floor I have installed polyethylene foam under the brand EcoFoil. On the first floor I have long chosen in the store and felt, compared a dozen different materials from the category of LDPE. Despite the difference in price (sometimes 2-3 times), I did not see a significant difference. EcoFol was one of the expensive, but I thought that the pores it burst when squeezed with fingers is easier than others, so I bought the cheapest material under the brand name Megaflex. It cost me 49 per m2. Megaflex is cheaper than Isolane and you can’t tell them apart.

Where there is no possibility to use polystyrene as insulation, use polyethylene foam.Metalized polyethylene foam in the underfloor heating system to be, after all! Point.

PS: Advice on the screed for the TP

I have accumulated some life experience during the construction process about screed with underfloor heating pipes. So I want to share this information. It often happens that the screed gives cracks, falls apart into pieces, caves in, walks, and so on. Cracking in the screed to this day, even for experienced builders is an unpredictable process. But there are a number of recommendations that can reduce the risk of cracking.

In the vast majority of cases, the screed TP is floating. This means that it is not in direct contact with the substrate. Between the floor slab and screed is mounted with PPE, foam plastic or just polyethylene film. It is worth saying (but many are perplexed to hear about it) that any floating screed by knocking or walking produces a deaf or even a ringing sound. All because the screed is not connected to the substrate. This is not terrible and is a characteristic feature of floating screeds.

Screed on the extruded polystyrene cracks less than on EPS. This is due to the fact that the EPS. deformable material. Where the situation allows it, it is better to use polystyrene foam. 2. The minimum thickness of the floating screed is 40 mm. And on EPS, I would recommend a thickness of 60 mm or more. The ideal thickness of the screed on a deformable base (eg FPE) with underfloor heating pipes is 80 mm or more. 3. It is believed that the semi-dry screed is stronger than the usual “wet”, and less subject to cracking. 4. Properly care for the screed after it has been installed. NEVER allow draughts. Cover a fresh screed with foil. Keep it moist, but don’t overwater it. In hot weather the screed may dry out faster at the edges, so the edges need additional moisture. Water. This is both a friend and foe of the screed. Lots of water. Cracked, not enough. It will also crack. 5. Be sure to leave a gap between the wall and screed, laying the same EPS. The size of the gap. 5 mm. 6. It is obligatory to arrange expansion joints. The maximum area of the screed in one piece is approximately 20-25 m2. If these gaps do not make, then, say, 50 m2 screed is likely to break itself. 7. Reinforcing with mesh. Not obligatory, but desirable. It is important that the grid is placed 10 mm from the bottom of the screed, and not just lie on the floor, although technically it complicates the work. 8. Use quality materials! Buy cement from trusted suppliers. Sand should be coarse and washed. You can also use high quality sand-concrete (if you can find it). Believe me, it is better to overpay a little or even a lot than to take the cracked screed together with the pipes of a warm floor and fill up again. The strength of the screed does not have to be M-200 or M-300. Practice shows that the honest M-150. It is a very good and strong screed. Only if it is honest M-150. 9. Fiber reinforcement and use of plasticizers. Not necessarily, but if your masters know the quality materials is quite acceptable. Independently, randomly buy plasticizers, use PVA or buy fiber on the market, I do not recommend. What happens as a result is difficult to predict.


For the arrangement of the system of warm floors manufacturers offer consumers a wide range of different materials, which differ in cost, type of raw materials (there are natural and synthetic products), as well as on the quality characteristics inherent in the products.

You can highlight the main materials for thermal insulation:

Cork carpet pad

The raw material is a natural and environmentally friendly product sold in rolls. The specific structure of the material, made in the form of miniature prisms, provides the insulation with a high level of compression strength. Cork has no adhesion to cement.

Experts recommend giving preference to such raw materials only if the laying is possible, based on the height of the ceilings in the room. Such limitation is explained by the fact that installation of cork insulation is connected with floor elevation, approximately 4-5 cm, as the boards needed for such works will be about 30 mm thick. In addition, the installation of cork requires the additional purchase of reflective material.

The positive features of the raw material should include the safe operation of products in residential areas due to the naturalness of the products. The disadvantages of cork insulation are the high cost of raw materials and low hygroscopic index.

Polypropylene is used as insulation for underfloor heating. The material is used in the form of extruded plates, which have a closed cellular structure. This type of raw materials is more popular in comparison with other products for insulating the floor. Due to the high demand for polypropylene high quality raw materials, through which the coating is well amenable to processing, which facilitates the installation of products in areas with complex configuration of the floor. In addition, the products are not hygroscopic.

The positive properties of polypropylene include its high temperature resistance, allowing the use of products at temperatures up to 130C.


The most suitable product for thermal insulation of warm water type floors are products with a thickness of 50 to 100 mm. The material stands out for its good strength characteristics, low cost and minimal weight. In addition, polystyrene foam is hard enough and is characterized by resistance to significant temperature fluctuations, accompanied by drops from negative to positive thermometer values.

It is explained by the peculiarities of the structure of the raw material, it has an air spraying of cells. Products of polystyrene foam retain their appearance and properties when in contact with aggressive environments, including brine solutions and alkalis, in addition, they do not absorb liquids and are easy to install.

There are varieties of insulation materials, which have in their composition polypropylene film.

In addition to the above characteristics of raw materials can be added soundproofing properties, resistance to rot and bioproofing. The service life of polystyrene foam products is counted in dozens of years.

However, it is worth noting that there are some varieties of products, which during operation and heating will emit toxic substances.

Metallized lavsan film

Such products provide quality protection against the negative effects of alkali on the floor covering and cement screed. Aluminum products without an additional layer of polyvinylchloride film, resistant to thermal effect, is not used. The positive feature of products is a high level of reflective properties.

The disadvantages of foil insulation include a low level of insulating qualities. Therefore, when laying products over a basement, standard products with a minimum thickness will not be enough. This can be solved by using solid insulation mats in several layers. During installation, it is necessary to follow the technology of laying sheets so that the seams of the materials below are closed by the seams of the products laid on top of them. This method will reduce heat loss.

Mineral wool

The material is sold as a solid board or vice versa. flexible mat. When you install the wool directly into the screed, it is compressed under load, resulting in lower thermal insulation qualities of raw materials. Experienced craftsmen recommend combining mineral wool with floor structures, which consist of wooden beams.

The advantages of mineral wool should include:

  • The non-combustibility of raw materials and resistance to high temperatures;
  • a good level of soundproofing of the surface;
  • Good thermal insulation characteristics;
  • resistant to chemical compounds.

The disadvantages of products include the presence in the composition of foamed wool, which is hazardous to humans, as well as poor resistance to moisture. But quality floor waterproofing will help to use the products for thermal insulation of warm floors.

Foamed polyethylene

Very often the choice in favor of thermal insulation for underfloor heating is this material. The products are products with a thickness of 3 to 10 mm, which are sold in rolls. On the market are varieties of polyethylene, which additionally include a foil layer, located on one or both sides.

This structure allows you to create a reflective layer for infrared rays. In addition, the presence of the foil provides additional thickness to the insulation, increasing its properties.

Among the disadvantages stands out the inability to reflect IR in a solid body, which is how the cement screed is laid on the floor.

In terms of performance characteristics, the raw material is not inferior to polystyrene foam. However, foamed polyethylene is capable of absorbing moisture, which negatively affects its insulating qualities. In addition, some chemical elements contained in the concrete can destroy the foil layer of insulating products. To exclude the possibility of destruction of insulation in the operation of the floor, most manufacturers began to produce sheets, where the foil is additionally covered with a polymer film.

Types of heat insulation under the floor

Although there is a wide variety of insulation, it can actually be divided into just two categories.


This category includes Styrofoam and polystyrene foam under a warm water floor. The advantage of polystyrene systems is their high strength and ability to withstand mechanical stress.

This group should also include a profile mat for the installation of water underfloor heating. Using a profile system (bosses or guide grooves) is very convenient for laying the pipe.

Profile guide mounting mats for water underfloor heating, after laying the pipe, top filled with a small layer of adhesive mortar. After drying for 1-2 days, you can begin operation of the heating system.

Styrofoam for underfloor heating is an unprofitable option. Plates are easily deformed after laying, and then the insulating capacity of the material is reduced.

Roll-fed thermal insulation

Enjoys well-deserved popularity. Foil reflective thermal insulation for water underfloor heating allows you to reduce the thickness of the “pie”. The foil effectively reflects the thermal radiation.

Foil insulation for water underfloor heating often has a special marking that facilitates installation of the heating circuit. The thickness of the substrate roll type does not exceed 1-1,5 cm.

Mineral insulators are laid rarely, as the top will need to lay a protective layer. To use for a substrate mineral material is inexpedient.

According to customer reviews, one of the best solutions is the purchase of insulation such as Teploisol.

Cork insulation can also be used. Cork insulation has good performance on: compressive strength, sound insulation and lack of adhesion to cement mortar.

When deciding which insulation material to choose, you should be guided by the technical characteristics of the heated room. Possible disadvantages of the substrate, such as cost, thickness, maximum compressive stress, etc., have to be taken into account.д.

Thermal insulation for water underfloor heating

Insulation for underfloor heating contributes to a more even distribution of heat inside the room. A material with specific properties (thermal insulation) is an important component of the underfloor heating “pie”.

In the absence of such a layer, the water heating system functions less efficiently and is not durable in operation.

The expediency of thermal insulation

Any heated floor, as well as the water version must be arranged with the use of insulating materials that are characterized by low thermal conductivity.

  • Uniform distribution of thermal energy around the room, which is important given the configuration of the heating system: a water floor consists of straight/curved sections of pipes, and therefore the floor will give off heat unevenly;
  • Insulation of communications from below reduces the intensity of the outflow of thermal energy outside the room through the ceiling.

In addition, thermal insulation system “warm floor” helps to simplify the installation of heating structures. But this applies to the variant with barrels, as in this case, laying and fastening of pipes is performed faster.

The principle of choice of insulating material

Given that the insulation is made inside the “pie” water floor, the material must be as effective and safe as possible both in terms of composition, and when changing operating conditions (violation of tightness of communication, the formation of fungus, fire situations, etc.).).

Accordingly, the thermal insulation is selected from a number of options for such properties: low thermal conductivity, fire resistance, additionally considered insulation with sound-reflective. Not unimportant is such a quality as moisture resistance. Different types of materials are characterized by different properties, which means that before buying you need to study their features.

Shape of production: sheets/plates, which simplifies the installation of the water floor. The dimensions of the material differ considerably. The main characteristic of any insulation is the thickness. In the case of expanded polystyrene value of this parameter varies from 30 to 120 mm. A common type of this kind of insulation. foam plastic. It is made by extrusion of polystyrene.

Styrofoam should be securely hidden under a layer of cement, or under another reliable coating

The colder the room under the ceiling, the greater the thickness of insulation should be. The main disadvantage, which characterizes the foam plastic, is the low strength. For this reason, at the stage of arrangement of the water floor is often performed by reinforcing the “pie” of the heating system. There is a simpler analogue in properties. expanded plastic. But it is used less often due to the availability of more suitable materials.

The thickness of thermal insulation made of foam or polystyrene foam 100 mm, for warm regions or second floors, can be reduced by 30%.

Features of using mineral wool

For the arrangement of the water floor use insulation with a sufficiently high stiffness. For this reason, mineral mats are generally used. Their main advantage. the possibility of filling the free space due to elasticity. However, this kind of material is not resistant to moisture.

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If mineral mats absorb a lot of water, they will lose their insulating properties. But if during the arrangement of the water floor to provide effective waterproofing this layer of the “pie”, the quality of insulation will not suffer. It is allowed to use basalt and fiberglass type of material.

This type of insulation is also susceptible to moisture, and in addition is not resistant to the formation of fungus. However, cork is characterized by a fairly good ability to reduce the intensity of heat loss.

In the arrangement of the water floor is usually used cork material with a wax coating. But if you compare penoplex or even its less effective analogue foam plastic, cork is somewhat loses on the indicators of heat saving.

It is a special material that is equipped with bosses and a vapor barrier layer. This configuration allows not only to provide thermal insulation and vapor barrier floor, but also to securely and quickly fix the pipes without the need for special fasteners.

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Carpet pad and mats should be universal and easy to install.

Peculiarities of installation of insulation

If under the floor is cold ground, or unheated basement, it is recommended to use a heater that is thick enough to ensure the effective functioning of the heating system (100 mm, 120 mm). For cases where the floor is a warm room, it is enough insulation, the thickness of which is 30-50 mm.

Proper waterproofing of the basement surface, solves the problems associated with phenol release and high humidity.

Depending on the type of material from which the rough base is made, as well as on the type of insulation, the method of fixing the mats/plates is determined. Foamplex is usually fixed by means of adhesive. In this case it is recommended to use the largest possible size plates, because it is desirable to avoid the formation of a large number of gaps. This will lead to the fact that the foam plastic will lose its insulating qualities because of the “cold joints”.

Step by step instructions for laying the mats and thermal insulation

Mineral wool materials are recommended to be stacked between the joists. In this situation, it is sufficient to use mats slightly larger in width than the distance between the joists of the lag system. But the size difference should not be too large, as this will lead to deformation of insulation, and at the same time will worsen the thermal insulating qualities.

On top of a layer of insulation lay a lining, it is preferable to choose for this purpose foiled material on one side, but not aluminum foil. On top of the laying of communications system.

If you have chosen a mineral wool material, from below, before mounting the lag system, you need to fix a layer of waterproofing. This will provide additional protection against moisture. Joints and joints of the moisture-proof foil are sealed with a tape. In the case when the foamlex is mounted, all the connecting joints between the boards must be filled with sealant.

What is the threat of lack of insulation or its insufficient thickness?

In such cases, there is a significant decrease in the effectiveness of the heating system. This means that due to the substantial heat loss the room will not get warmer, and the cost of heating is not reduced.

In turn, the cold microclimate in the living room will lead to the formation of mold on surfaces, furniture and even on things. This is due to the increased humidity along with the insufficiently high room temperature. And in case of temperature changes condensation is formed, which is detrimental to any systems and mechanisms.

Thermal insulation for underfloor heating

Before installing underfloor heating, you need to think about its insulation. Today I will talk about the warm floor in the tile adhesive or screed. Of course, such a warm floor can be put without insulation, directly on the plates or on the screed (if you have it), but the heat loss of such a floor will be much higher. This coating, helps to keep the temperature.

No matter how you turn it, but insulation is a necessary thing. Of course, you can do without it, but you will spend more electricity for heating and maintaining a given temperature. Underfloor heating will heat not only the upper usable layer (tile adhesive and tiles), it will also heat the lower layer, which is under the floor heating, that is deep in the screed or floor slab, this layer is absolutely useless to us and we do not need to spend energy on it. It is desirable to direct the full potential of the floor heating upwards, to the tile surface on which we walk. This is what thermal insulation for underfloor heating is for.

Thermal insulation is a foam-foam with a reflective foil surface, it is this surface and will reflect the heat to the top.


Thermal insulation for underfloor heating (screed or tile adhesive). comes in two varieties. Both types of foam-foam with a reflective surface. However, you can put a softer and higher foamed material in the screed, usually it is 5. 8 mm, the screed is filled with a large layer, and therefore the difference of 5. 8 mm, will not be noticeable. If you take this foam-foam in your hands, it is soft easily crumpled. One meter of this insulation costs from 30 to 60.

But what to do if you already have a screed? On it you are going to put a tile with underfloor heating, and for you it is important every millimeter. You need a different kind, thinner, but more dense, as you have already understood this is the second type of thermal insulation. This is the one I bought for me, since I already have screed in my apartment. This type is less easy to crush in hands, it is much denser and only 2. 3 mm thick. I have 3 mm thick thermal insulation. It can easily be placed under a warm floor, and then cover it with tile adhesive and lay tiles. It practically will not raise the level of tiles, 2.3 mm, it is not essential.

As the manufacturer himself assures, this coating saves electricity,

, expensive because it is stronger and thinner.

Features of electric type floor heating

A well-known fact from the basics of physics: warm air in the room tends to rise to the top, while at the same time it remains cold underneath. Such fluctuations have a negative impact on human health. You can get colds, there is a feeling of discomfort. A healthy body is only when your feet are warm.

The installation of electric underfloor heating promotes even heat distribution, proper heat exchange and a proper microclimate in the room. Creation technology is not complicated, well tested by companies specializing in the service of installation of underfloor heating. It is applicable to all types of premises. Such a floor in operation is safe and does not require maintenance during operation of the system.

When creating an electric underfloor heating, it is necessary to adhere to 5 obligatory conditions:

  • It must occupy at least 70% of the area of the room in which it is installed;
  • Need to use in the arrangement of resistive single. better twin-core heating cable, necessarily shielded, infrared film or special electrician mats;
  • must be selected a quality insulation and properly laid;
  • screed must be made necessarily sand-cement with observance of the necessary proportion, it must be no more than 50 mm thick;
  • As the final floor covering after the installation of the electrical system, you can use ceramic tile, natural and artificial stones, laminate, carpet, parquet and other materials that will match the installed electrical system.

Underfloor heating without insulation

A heating floor without insulation, without insulation and without heat insulation. hni? That is, the overlap, on top of the pipe water underfloor heating, then the screed and the laminate and all.

I guess that’s it: “Ordinary Marketing Bullshit” (OMF) For those who didn’t go to school: IR radiation only penetrates a few microns into a solid. And is completely absorbed by this thin layer. And this means that the IR radiation, re-reflected by the aluminum layer, will move away from it by a few microns, heats the concrete, which in turn heats the aluminum. Hence the unsophisticated conclusion: that with the film that without it, the temperature of the transition of concrete-heat insulator will remain exactly the same. But the application of aluminum foil, costing 3 kopecks, allows you to sell it to suckers for 3 thousand profitability “business” 1000%.

HH: Do not confuse reflector operation in air, and even more so in airless space (for example, on spacecraft, where infrared radiation is the only way to cool the vehicle).

warm the floor under the beds, cabinets, tables. Useless and pointless.

The TP is generally done for comfort, not for heating. And comfort is a constant temperature. But a constant floor temperature cannot compensate for variable external conditions.

You are making a classic mistake: you have two variables but one regulator math and logic denies such cartwheels.

Therefore, 1. Do TP around the bed (it’s just a couple of m2). 2. You put a standard water radiator under the window, with a thermal head).

You have two regulators (TP and radiator), and you can always set two comfortable settings to be comfortable bare heels, and not to be hot in the bedroom.

HH: Electric heating consumes not as much as cable power, but about 20 W/m2 (which is the difference between 22 air and 24 on the floor (my comfort)). So there won’t be any “ruin”.

and yet the problem is? heat? or for comfort?

I personally plan to install it directly on the floor slabs, so that there would be a heat accumulator

heat with comfort. I personally plan directly to the floor slabs, so that the heat accumulator would be

I was planning that too, now they say you can’t do that.

I believe that in the mode “for comfort” the stove will be heated to 23 degrees

23 degrees) n.2 laminate (. ) п.3 floor heating (24 degrees on average. ) п.4 floor slab (. ) п.5 air in the basement (??

Thus, I believe that, yes! there is heat removal from the laminate flooring (whether by ventilation flows) but! The slab (n4) is also insulated from below (n.5 poor heat conductor)

so the proportions 70-30 are somewhat exaggerated

20watt per metre is for a 20 sqm room = 400watt is plenty for “maintaining” the temperature from 20 to 22.

This means that less power is needed, i.e. the system is even more viable

I will not say anything about creepy descending of the heated air somewhere

By the way the idea to insulate the ceiling of the basement I really liked it)

Mm-hmm. The ceiling will be insulated, but the heat will spread to the sides of the walls of the basement. over, concrete is probably the best conductor of heat (of building.materials) the heat loss zone will be about 1 m from the edge of the slab. What is the area of the room there? 20 м2? That’s square 4.5х4.5. So, take 1 meter around the perimeter. What’s left? The square in the center 2.5х2.5 = 6 m2 This is the space you have protected from heat loss, 14 m2 of the side space is leaking onto the basement wall.

It doesn’t work: You need two regulators with one to keep the floor temperature constant (the comote zone is very narrow: 22. 26°C), and the other to keep the air temperature constant (and it depends on dozens of variables, and above all on the outside temperature, which varies from 30 to.30 the heating capacity varies from 0 to 100%).

How are you going to adjust two parameters at once with one knob??

We all used to insulate our homes. The main activities in this direction are related to the installation of insulation materials on the wall panels. The presence of a layer of insulation significantly reduces the intensity of heat transfer between the walls and the outside air. Exactly the preservation of heat inside living quarters is the key to a comfortable stay, even with a powerful heating equipment.

Insulation is a task that concerns not only the structural elements of the house. If you use a waterborne floor, you also can not do without thermal insulation. What is the need for thermal insulation in this case, and what are its functions, let’s analyze in detail.

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