Warming the foundation of the house outside

Warming the foundation of the house outside

Insulation of the foundation from the outside is a necessary measure for houses located in regions with not the warmest climate. It is especially important to insulate the foundation if the house has a residential basement or utility rooms in the basement. Warming of the foundation solves two main tasks:

  • energy saving
  • protection of foundation constructions.

In the climate of the middle zone of Russia, the foundation must be insulated. In winter, much heat leaves through the floor, and an unheated basement or foundation significantly increases heating costs. If the basement is planned to arrange a warm room, such as a garage or a basement, then without qualitative warming all the more can not do. But even if the basement is simply used for storage, the cold floor does not contribute to more comfortable conditions in the house.

The second task that the foundation insulation decides is its protection against destruction. Over the winter, several cycles of defrost and frost occur, which means that the water turns into ice several times and back into the liquid. Getting into cracks and pores on concrete and freezing, it gradually destroys it. In addition, without thermal insulation on the foundation, condensation forms, concrete becomes more moist, under such conditions it grows old faster, which means it will start to deteriorate faster. It should be remembered that any material is designed for a certain number of cycles of defrosting-freezing, so without insulation it will serve much less.

Warming the foundation of the house from the outside allows you to protect it from the frost heaving of the soil. If the building is on a heaving ground, not only the walls but also the main slab of the basement are insulated. Thanks to the thermal insulation, the foundation will be protected from the destructive effect of ground motion.

Heat and waterproofing of the foundation should be carried out immediately, as it will be ready.

Materials for warming the foundation

  • Styrofoam
  • Expanded clay
  • Liquid polyurethane
  • Extruded polystyrene

All materials for insulation of the foundation from the outside can be divided into two groups:

  • plate
  • for backfilling.

Materials for filling include claydite, slag, straw and other similar materials. This method of insulation is used for a long time. At the moment the most effective clayite is considered. This is a cheap material, but the device for warming the foundation with its use requires a lot of labor, and if you hire workers, it's money.

It will be rational to use claydite not as the main, but as an additional isolation. For an effective heat-insulating layer of expanded clay it is required a lot - its layer should be equal to the freezing depth of the soil plus 5 cm. In the central strip of Russia it is approximately 155 cm. For claydite insulation, the foundation is dug to the very bottom, and the trench is poured in the appropriate width.

Liquid polyurethane

Liquid polyurethane has many advantages:

  • high adhesion to the surface,
  • can be applied to the surface without preparation,
  • absence of seams,
  • excellent moisture resistance,
  • simultaneously is waterproofing,
  • low vapor permeability,
  • service life of more than 40 years,
  • ecological cleanliness,
  • biological neutrality - it does not contain mold, fungi, moss.

The disadvantage of this material is that it is necessary to invite a specialist to buy it or buy special equipment, so the cost of work is quite high. Another disadvantage is that it breaks down from ultraviolet radiation, but for a foundation under the ground it does not matter.


Polyfoam is one of the types of polystyrene. Its use as a heat insulation material is considered optimal for the thermal insulation of the foundation by its own hands for several reasons.

  • Polyfoam - cheap material.
  • It does not absorb water.
  • Durable.
  • Does not change shape over time.
  • Has a very low thermal conductivity due to the large air content.
  • Resistant to temperature changes.

Effective insulation with foam from the outside is impossible without calculating its thickness. It depends on the purpose for which the base of the house is insulated, whether it is planned to make a heated basement. Calculate the thickness of the foam can be based on the fact that 50 mm of polystyrene retains heat in the same way as 250 mm of brick (the wall in one brick). For the thermal insulation of the foundation, a dense foam plastic of PPT-25 and PPT-35 grades is used.

Important! When buying polystyrene, pay attention to its quality. Color and geometry are important here. Correctly stored white foam, grayish or yellowish hue indicates that the material was exposed to ultraviolet light, and the top layer began to decompose. The size of the sheets should not differ by more than 1 cm, otherwise they will have to be adjusted in place.

Extruded polystyrene (expanded polystyrene, foam foam)

Now extruded polystyrene (expanded polystyrene) is considered the most effective slab material for self-insulation of the foundation. It has a lower thermal conductivity than polystyrene, is somewhat more expensive and has a vapor permeability. Usually sheets of expanded polystyrene have a convenient "groove-spike" connection.

Warming the foundation with expanded polystyrene or polystyrene foam

The insulation of the foundation from the outside with foam or foam is produced using the same technology. The thickness of the material should be approximately:

  • for southern regions - 50 mm,
  • for the middle band - 50-100 mm,
  • for northern regions - 100-150 mm.

The foundation must be unearthed to the very foundation. Concrete is cleaned of soil, destroyed parts, if necessary level the surface with a cement-sand mixture. Then it is applied to it with bitumen or a special mastic for waterproofing. You can use roll materials (roofing paper).

It is advisable at the same time to think over and make drainage to divert water from the foundation. This requires a drainage pipe, which is placed below the base of the basement or basement floor. Pour a pillow of gravel with a slope of 5 degrees from the building, put a geotextile wrapped pipe on it and cover it with gravel.

The sheets are glued to glue or glue-foam. The latter is better to choose in packages under the gun, so it is more convenient to apply and the consumption is less. If it is necessary to cover the foundation with foam in two layers, the sheets are staggered so that cold bridges do not form on the seams. The next layer can be glued only after the glue under the previous one has completely dried.

Important! Do not use glue based on solvents that can decompose the foam. Also hot mixes that can melt the material are not recommended.

On the part of the heater, protruding above the ground, glue reinforcing mesh. For this, a layer of glue is applied to the heater and the grid is embedded in it.

Heat insulation of pile-screw foundation

The construction of the house on a pile-screw base assumes that there is an air space between the floor and the ground, where cold air passes unhindered, so it is impossible to do without warming in such a house.

Warming of the pile foundation is made with the help of the following materials:

  • foam plastic,
  • penoplex,
  • extruded polystyrene foam,
  • foam glass,
  • expanded clay.

Even in the process of building a house you need to think about waterproofing grillage. Between it and the lower part of the walls lay a roll waterproofing material. Also grillage is treated with waterproofing compounds, especially if it is wooden. Piles are treated with mastic, which protects them from corrosion.

The simplest and cheapest method is to fill the foundation with soil or expanded clay, but it does not give the best result, use it only if you are very constrained in the means.

If the house is located low above the ground, you can erect the base and insulate it from the outside. The most effective option is full insulation, when the floor is insulated from the outside, and the basement is imitated.

Warming of the floor

You can insulate the outside only the floor - this is the way to choose when the house is located high.

  • On the floor from below attach a vapor barrier film.
  • On top attach a plate heater, for example, expanded polystyrene.
  • Thermal insulation covered with boards.

Warming of the plinth

The plinth can be made by building a thin brick wall or by installing the guides for the basement panels. When constructing a wall, a small concrete strip is poured, which itself acts as a thermal insulation.

If a method with fastening of guides is chosen, then they are bolted or welded to piles. Then, decorate the decorative material in accordance with the technology.

Warm such a socle can be inside or outside with expanded polystyrene. From the outside you can mount DSP plates, and you can fix the finishing material directly to the heater. To protect against rodents, a metal mesh is attached to the insulation layer. If the basement is concrete or brick, then first cover all the cracks and ground the wall. To completely eliminate the blowing, the inside is additionally poured with expanded clay or soil.

As a decorative material and a heater at the same time, it is possible to use plinth thermopanels. They are made on the basis of expanded polystyrene and have a decorative coating and a convenient way of joining.


Warming the foundation is an important measure to protect the base of the house from destruction, to increase its service life and reduce heat loss. Only with good thermal insulation you can equip a heated basement or basement floor. Use for this can be different materials, to warm the tape foundation from the outside, the optimal option is styrofoam or penoplex. For the insulation of the pile or column foundation make an imitation of the socle, which is insulated with the same materials.

  • Foundations for house made of lumber

  • Formwork for foundation

  • The foundation for the veranda to the house with your own hands

  • Foundation for house from road slabs

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