7 tips for insulating a house with expanded clay: floor, walls, roof, foundation

8 min

Lightweight, durable and durable expanded clay is made from natural raw materials and has high thermal insulation qualities, and at the same time it is much cheaper than similar materials. He also has some drawbacks, but if all installation conditions are met, they are nullified. We deal with the basic properties of the material and the peculiarities of warming a house with expanded clay, the nuances of its use for thermal insulation of the floor, walls, roof and foundation.

# 1. Expanded clay: production and fractions

For the production of expanded clay, low-melting clay grades with a quartz content of 30% are used. They are processed in special chambers, where they are heated to a temperature of 1050-13000C for 30-40 minutes, as a result of which swelling and the formation of porous granules with a melted hermetic shell, which gives the material the necessary strength, occurs. The more pores in expanded clay, the better.
expanded clay production

In the production process, as a rule, granules of different fractions are obtained:

  • expanded clay sand with granule size up to 5 mm;

  • expanded clay crushed stone – granules resembling cubes in shape;

  • expanded clay gravel – oblong granules.

By the size of the granules, expanded clay of such fractions is isolated: 5-10 mm, 10-20 mm and 20-40 mm.
expanded clay fraction 4

# 2. Advantages and disadvantages of expanded clay

Expanded clay gained wide popularity not only due to its low price, but also due to other advantages:

  • good thermal insulation qualities. The thermal conductivity coefficient is 0.07-0.16 W / m * K. Frankly, this is not the highest result among all heaters, but expanded clay bypasses competitors in many other parameters;
  • excellent sound insulation;
  • high strength and preservation of the original shape under the influence of high and low temperatures;
  • fire resistance and frost resistance, achieved by “hardening” expanded clay during manufacture;
  • light weight. All 1 m3 of expanded clay from 250 to 800 kg;
  • inertness to mold, fungus and rodents;
  • due to flowability, it can fill a cavity of any shape and size; it is used for insulating floors, walls, foundations and roofs;
  • resistance to aggressive chemicals;
  • environmental friendliness;
  • durability;
  • installation can be done independently – no specific technique is required.
    expanded clay

Among the disadvantages:

  • the insulation layer cannot be thin;
  • the tendency of granules to dust formation, therefore, when working with expanded clay, it is better to use a respirator;
  • expanded clay is able to absorb moisture. It gives off the accumulated moisture, but very slowly, so it is better not to use the material in very damp rooms, but in any case, you will have to equip a layer of waterproofing.
    expanded clay 2

No. 3. Physical and technical properties of expanded clay

When choosing expanded clay for home insulation, pay attention to its following properties:

  • The bulk density of the material, which determines the weight of 1 m3 of expanded clay, is indicated in grades and can be from 250 to 800 kg / m3, in total there are 10 grades. Expanded clay grade M400 has a density of 400 kg / m3, for example. The lower the density, the better the thermal insulation qualities;

  • strength. The higher the weight of expanded clay, the greater its strength should be, so that the material does not collapse under the pressure of its own weight. For expanded clay М400, the strength must be at least P50, for expanded clay М450 – P75, etc .;

  • the coefficient of deformation indicates the shrinkage of the material. Permissible value 0.14 mm / m;

  • the thermal conductivity coefficient of good expanded clay is 0.07-0.16 W / m * K, lower quality material has a coefficient of 0.2 W / m * K and higher, it is better not to take it for insulation.
    expanded clay fraction

Due to its properties, expanded clay has a wide range of applications. It is used as a filler in the production of blocks from expanded clay concrete, as a decorative and drainage material, but still the main area is thermal insulation, not only of structures, but even of soil.
expanded clay fraction 2

No. 4. Warming the floor of the house with expanded clay

Expanded clay is one of the most suitable materials for floor insulation, especially if the budget is limited. Insulation can be performed in one of several existing ways.

The classic version provides for the following sequence of actions:

  • thorough cleaning of the floor surface from dust and dirt;
  • laying a layer of a waterproofing agent, which is used as a durable plastic film, for its connection you can use construction tape. The edges of the film should go onto the walls above the level of expanded clay with a screed;
  • it is better to pre-mix expanded clay of different fractions in order to obtain maximum strength and thermal insulation;
    expanded clay floor insulation
  • placing beacons on which a layer of expanded clay will be poured. The first lighthouse is installed at a distance of 2-3 cm from the wall, the rest are mounted parallel to it at a distance of the length of the rule, which will subsequently level the solution. Attention should be paid to this stage, since it depends on how flat the floor will be after the screed is completed. Lighthouses are made of metal profiles or pipes, which are exposed on piles of strong cement, gypsum or alabaster mortar. The guides are carefully aligned using a level;
  • filling of expanded clay, its thorough ramming and leveling. The layer must be at least 10-15 cm in order to achieve thermal insulation qualities, this must be taken into account when calculating the floor level;
  • preparation of cement milk (slurry of cement) and pouring a layer of expanded clay with it. This is necessary to give it strength, otherwise during the subsequent pouring of the screed solution, its level may be violated. You can reinforce the surface with a metal mesh – this will provide it with additional strength;
    expanded clay floor insulation 2
  • pouring the floor with a finishing cement screed with a thickness of about 3 cm. The mortar is poured from the walls, opposite the door and stretched as a rule to obtain a flat surface. Within a week you can walk on such a floor, but it gains final strength after a month. During this time, you can periodically wet the surface with water to prevent cracking.

You can do without the time-consuming process of preparing the mortar and pouring the screed using a simplified dry technology:

  • a vapor barrier is laid on the surface of the main floor;
  • expanded clay is poured over the lighthouses, for reliability it can, of course, be fixed with cement milk;
  • dense gypsum-fiber sheets are laid on expanded clay, which are held together with glue.

The dry method is similar to the option of insulation along the logs:

  • laying a layer of vapor barrier;
  • installation of wooden blocks impregnated with an antiseptic. To obtain a strictly vertical level, wood pads can be used. The bars are fixed to the floor with self-tapping screws in increments of 0.5 m;
  • expanded clay is poured clearly along the upper edge of the bars;
  • covering the structure with a layer of vapor barrier;
  • laying plywood, chipboard, OSB, after which you can mount the finished floor.
    expanded clay floor insulation

No. 5. Warming the walls of the house with expanded clay

To insulate the walls with expanded clay, the three-layer masonry method is used, which is applicable only for newly erected houses: the first layer is the load-bearing wall, the second layer is expanded clay with cement milk, the third layer is the external finish. There are three technologies:

  • masonry with horizontal three-row diaphragms. Together, two parallel walls are erected, one of them is brick thick, the second is half a brick, the distance between them is 15-25 cm.After laying every fifth row, insulation is poured into the cavity, rammed and poured with cement milk, after which the overlap is laid out of the brick in three rows, the corners for greater strength are performed without cavities. After the completion of the work, the outer layer is finished with facing brick, plaster or other material;

  • well masonry involves the erection of two walls at a distance of 15-35 cm from each other and their ligation through a row of jumpers of 70-110 cm. Wells-cavities are covered with expanded clay and filled with cement milk;

  • masonry with embedded parts also involves filling the space between two parallel walls with expanded clay as they are erected. The walls are connected to each other with reinforcement brackets.
    expanded clay wall insulation 2

If the walls of a frame house are insulated, then the expanded clay insulation must be tamped very carefully. The walls of a wooden house are most difficult to insulate with expanded clay. Since its thermal insulation properties are somewhat worse than those of its closest competitor – mineral wool, it is necessary to leave cavities 20-40 cm thick, and this is a significant load on the load-bearing walls, therefore, an additional foundation will have to be made outside. The complexity of the technology and the cost of all additional manipulations practically negates the efficiency of expanded clay insulation, therefore, for wooden houses it is better to consider another option for wall insulation.
expanded clay wall insulation

No. 6. Roof insulation with expanded clay

The process of roof insulation resembles the method of floor insulation with expanded clay. It’s easy to do all the work yourself:

  • vapor barrier flooring. You can use glassine, plastic wrap, foil or styrofoam;
  • some masters advise to fix the vapor barrier layer with soft clay, but you can do without it;
  • filling expanded clay, and it is recommended to take expanded clay gravel, which fills all cavities well, sometimes it is mixed with expanded polystyrene crumbs. Expanded clay is well rammed, after which you can make a screed for greater structural strength;
  • roofing material flooring, which is pressed against a layer of expanded clay. Installation is carried out with an overlap, the seams are insulated with tape or bitumen mastic;
  • laying of roofing material.

expanded clay roof insulation

expanded clay roof insulation 2

No. 7. Warming the foundation with expanded clay

You can also insulate the foundation with expanded clay on your own:

  • the foundation is freed from the soil, a trench about 80-100 cm wide is dug;
  • waterproofing the foundation with hot or cold applied bitumen mastic, or roll roofing material. A special primer must be applied under the mastic, which dries up in 2-3 hours;
  • in places where groundwater is high, it is necessary to arrange drainage around the house to effectively remove moisture and ensure a longer service life of expanded clay, which is afraid of moisture. At some distance from the house, a pit is dug up to a depth below the level of the foundation, geotextile is placed on the bottom, covered with rubble and pipes with holes are laid, the pipes are covered with rubble, covered with the edges of geotextile and covered with sand;
    expanded clay basement insulation
  • laying the film over the waterproofing. It should completely cover the foundation, and from the side of the ground, it should be approximately at the level of the drainage. After that, expanded clay is poured and tamped;
  • installation of a blind area, for which formwork with a height of 10-15 cm is performed along the perimeter of the building, a reinforcing mesh is laid in it and poured with concrete.

Cheap and environmentally friendly expanded clay can become reliable thermal insulation, provided that reliable waterproofing is performed.

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Passionate about DIY for over 10 years and all the new tools, I give you through this blog all my advice, tips, tests in all areas: carpentry, electricity, masonry, gardening, home automation ...


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