Expanded clay: What does expanded clay do?

Expanded clay

Expanded clay, what is? How is it produced, types of insulation, its technical properties, advantages and disadvantages, properties of choice, and short DIY installation instructions? In addition, there are over two dozen brands of expanded clay in the construction market. The classification is carried out according to the indicator of bulk density (from 250 to 800). Depending on the size and shape of the fragments, are determined in special measuring containers. Larger grains have the lowest bulk density.

The 700 and 800 brands are not available on the market. They are usually produced in a single order as they have not been widely used.

Technical characteristics of expanded clay

The properties of this insulation are confirmed by the national GOST, which controls the quality of building materials with porous structures.

Consider the main characteristics:

  • The strength of expanded clay … This indicator for the material varies and varies by brand and brand. For example, for gravel with a density of 100, the compressive strength is 2-2.5 MPa. And for crushed stone with the same density, this indicator is 1, 2-1, 6 MPa. It should also be noted that the concentration increases as the density of expanded clay increases.
  • Compression factor … This value for quality insulation should not exceed 1, 15. It should be taken into account during transport and long-term storage of the material.
  • Thermal conductivity of expanded clay … This indicator for the material is 0.1-0.18 W / (m * 0С). A layer of this insulation that is 25 centimeters is equivalent to a layer of expanded polystyrene with a thickness of 18 centimeters. And an enlarged pile of clay that is 10 centimeters maintains as much heat as a meter-long brick or 25 centimeters of wood. The higher the density of the material, the lower its thermal insulation properties. This is because the number and size of pores decrease. They contain air – the main thermal insulation.
  • Moisture absorption … Expanded clay is a relatively waterproof material. The water absorption coefficient is 8-20%. However, this only applies to insulation that has a burnt crust. It is she who does not allow moisture to enter the pores. If there is no “protection”, expanded clay absorbs water very well, increases its weight, and loses its insulating properties.
  • Sound insulation … This insulation has good sound insulation and noise control. The material is most effective at absorbing sound when laying on the floor between floors. If there is someone walking or making noise on the top floor, you are unlikely to know. Admittedly, sound insulation with expanded clay will only be effective if the floor surface does not touch the insulation layer, as the friction of the material grains is not at all silent.
  • Fire resistance … Expanded clay is actually fired clay. Numerous tests have proven that the material does not burn in a fire and does not release harmful substances into the air when exposed to fire.
  • Frost resistance … Expanded clay is not afraid of low temperatures, as well as their fluctuations. It is based on frost-resistant material – clay, and thanks to special production technology, it absorbs water very poorly, which means that it will not collapse when water expands into its pores.
  • Chemical resistance … Clay is a chemically inert material and therefore does not react with most building materials and solutions of acids, alkalis, and alcohols.
  • Biological resistance … Mold, and fungi do not multiply in expanded clay. Also, this substance does not attract rodents and insects. In it, they do not arrange nests and holes.
  • Environmentally friendly … Expanded clay is pure natural insulation that does not emit toxic compounds during installation and use.


This insulation has been used for many years and does not lose its popularity, as it is difficult to find peers in terms of price-quality ratio.

Consider the main benefits:

  • Excellent thermal insulation properties… Clay belongs to the category of “warm” natural materials and due to the gas in the structure of expanded clay grains, the thermal conductivity decreases. This thermal insulator is capable of saving up to 80% of heat loss.
  • Lightweight expanded clay … The material is 10 times lighter than concrete. Only foam polymers have less weight among heaters. Therefore, it will not have too much load on the floor, foundation, and roof.
  • Relatively low price … Expanded clay is cheaper than many other heaters. And its installation requires no special tools and teams of professional workshops. All work can be done independently.
  • Environmentally friendly … It is totally natural insulation. It is recommended to use in residential buildings that are built with the “greenhouse” or “eco-house” technology.
  • Indestructibility … The material does not burn, does not support combustion, and does not emit toxic fumes when released into the open-source fire. It is completely fireproof.
  • Easy installation … Even a beginner can create an expanded clay pile. And since the thermal insulation is relatively light, it is quite possible to deal with it alone.
  • Long service life … Expanded clay can be used as a heater for a very long time (100 years or more), but only if it is installed correctly.


Despite its great advantages, expanded clay also has certain disadvantages. They occur especially if an event was selected in low quality or the installation was performed incorrectly.

Disadvantages :

  • Requires substrate when laying horizontally … This is because the material is rather dusty. This is especially true when expanded clay is placed on wooden floors.
  • Absorbs moisture without a protective “crust” on the grains … When wet, such expanded clay becomes unsuitable for insulation. The material dries for a long time. Therefore, it is recommended to place a special waterproof layer on top of the moisture-absorbing insulator.
  • A thick layer of insulation “eats” the height of the room … In order for high-quality heat and sound insulation, it is necessary to lay expanded clay with a thickness of at least 10-15 centimeters. Preferably up to 40 centimeters.
Expanded clay
Expanded clay

Criteria for the selection

It is necessary to choose this insulation, emphasizing certain properties and quality. You can judge the properties of the material according to the labeling on the packaging. The bulk density of expanded clay and grade is usually specified there.

In addition, consider the following suggestions when purchasing insulation:

  • Contact either the factory where the expanded clay is produced or a public representative. Do not buy from dubious sellers, tempted by low prices. Its quality can be very low.
  • Ask the seller to provide a quality certificate for the insulation. It is produced in accordance with GOST 9757-90. Only in accordance with this standard, high-quality clay is used and all fire standards are followed.
  • Pay attention to the situation where the material is stored. It should be stored in a warehouse indoors, but not outdoors, as it may become damp and lose its properties.
  • Check the integrity of the expanded clay parts. High-quality thermal insulation should have as few broken grains, crumbs, and sand as possible. In general, the damaged material should not be more than five percent.
  • The color scale of high-quality expanded clay should be the same for all fragments: shell dark brown and dark (almost black) fragments.

The technique of insulating floors, foundations, ceilings, or ceilings is generally similar.

Let’s consider it step by step:

  • We adjust the base. If this is a floor, then a non-thick layer of cement concrete can be filled. We are waiting for complete drying.
  • We lay the vapor barrier. This could be glass, for example. We glue joints with tape.
  • We put up beams from wooden beams. We see horizontality using construction stages.
  • We fasten the rod with self-tapping screws in 50 cm steps.
  • Pour expanded clay into the gap between the stems with a uniform layer. We ensure that the insulation is in accordance with the surface of the delay.
  • Next, we cover the structure with waterproofing, for example, polyethylene film.
  • On the finished surface, you can lay slabs, slabs, plasterboard, and pour the screw.

In this process, it is permissible not to build structures from delays, but it will be more difficult to check the evenness and uniformity of the expanded clay layer.


Expanded clay is natural ecological insulation that is widely used in private and industrial construction. It can be used to perform high-quality thermal insulation of floors, roofs, ceilings, floors, and even walls. The material has high thermal insulation properties and is resistant to external influences.

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