Insulation of the foundation of an old wooden house outside

Insulation of the foundation of an old wooden house outside Insulation of the foundation of a wooden house outside with your own hands

Quite often in the old or just built building gets cool during the winter period. This is due to the fact that no thermal insulation was carried out during the construction of the base. To save heat, you need to insulate the old wooden foundation of the house with your own hands.

The selection of the method will depend on the type of base and the materials used.

General information

Why do you need to insulate the foundation from the outside

Insulation of the outer type for the base solves several problems at once:

  • Insulation of the foundation of an old wooden house outside Will trap heat inside the house.

  • Can play the role of waterproofing, and thus protects the basement (if any) from the formation of condensation.
  • Save money on heating.
  • Preserves the integrity of the foundation when heaving from frost.

It will be much better than internal insulation, since the latter can only be used with good ventilation of the basement. Otherwise, the dew point will shift and the base will be exposed to low temperature and humidity levels.

When insulating a house outside, such moments are excluded. Depending on the selection of the base (columnar, tape, monolithic or pile), the material that is required to sheathe the base of the house from wood is also selected. The insulation process must be carried out during the construction of the base.

Types of heaters

For such work, as a rule, they use expanded polystyrene, polystyrene or polyurethane foam, and also use expanded clay. Such materials are highly resistant to temperature changes, have a low degree of waterproofing, and have low thermal conductivity.

Expanded polystyrene

Thermal insulation plates from extruded expanded polystyrene are produced in different sizes and thicknesses. The material has huge advantages:

  • Almost completely waterproof - water absorption is not more than 0.2%.
  • Low thermal conductivity - 0. 032 W / m * K at a temperature of + 20 .

    .. + 30 degrees, and with a thickness of 3 cm corresponds to laying bricks with a thickness of 0.55 meters.

  • High indicators of resistance to deformation.

  • Resistance to certain chemical compositions.
  • Resistance to temperature changes from -50 to +75 degrees.
  • Operational period of 50 years or more.
  • Light weight.
  • Small thickness.

  • Safe for health.

The disadvantages include flammability (class G 4 ) and degradability in the sun under the influence of ultraviolet rays. For this reason, when using such plates, it is imperative to make a decorative finish on the base of a wooden house from the street side. When working with expanded polystyrene, it is required to exclude its contact with:

  • Solvents for oil-type paint.
  • Plasticizers containing coal tar (glues and putties).

  • Acetone.
  • Toluene and petroleum formulations.
  • Ethyl acetate used to remove paint and varnish material.
  • Certain wood protection compounds.

The material has a homogeneous and smooth structure, even at the fracture, and the dyeing is smooth and have an extremely high resistance to mechanical pressure.

When purchasing, you should pay attention to this, and, if possible, check.

Polyurethane foam

Do-it-yourself insulation of the foundation of a wooden house is possible with polyurethane foam. On the other hand, polyurethane foam can be used where it is not possible to use tiled basement insulation, for example, with a non-standard configuration, an old stone base or a house belonging to architectural monuments. Another polyurethane foam (PPU) is effective when working with a huge area of ​​the foundation, when it is difficult to guarantee complete sealing of all seams when using tile materials. speed of foam application is another plus of polyurethane foam.

Moreover, it has the following characteristics:

  • The price is 3 times higher than the cost of foam and EPS.
  • Fire hazard G 1 -G 4 .
  • Exceptionally good adhesion to the substrate.
  • Moisture permeability up to 1%.
  • Resistant to all types of organic solvents, alkalis and acids with medium concentration.

  • Compressive strength is up to 140 kPa (will correspond to foam, but still inferior to EPS).
  • Sound insulation.

An additional agent is required to protect against UV rays, as otherwise sun damage will occur within 3 days. In addition to foam, there are other types of plates, and in terms of technical characteristics they are similar to EPS, but they are lined with aluminum foil and are used mainly for internal basement insulation without a new decorative type finish.

Expanded clay

The material is made of light grains, which are obtained by firing clay rocks.

Lightweight elements (0.5 to 4 cm in diameter) will create air layers that form side by side, near the outside of the foundation. To do this, at a certain distance from it, it is required to make a wall using boards for basement finishing, and expanded clay of medium or large fraction is poured into the resulting cavity. Also, in parallel, it is required to carry out drainage work and waterproofing, since the material has a high ability to absorb moisture. The positive properties include a low price, ease of work, rodents do not live in it, will not rot, and still does not burn and does not collapse under the influence of frost.


Expanded polystyrene is inexpensive, non-hygroscopic, durable, does not undergo deformation, resistant to different temperatures. If you need to finish the basement of a wooden house, you need to choose this particular material. The only drawback of the insulation will be its fragility, which means that it is important to handle them carefully.The thickness of the sheets can be from 2 to 10 cm, and the standard size is 1 * 2 meters. The material has:

  • A certain degree of water absorption.

  • Medium flammability, approx. G
  • Low heat conduction.
  • Resistance to chemical composition, including lime, hydrogen peroxide, acids, gypsum, with the exception of nitric and acetic high concentrations.
  • Environmental safety.
  • Resistant to bacteria.

In addition, it is not resistant to UV, acetone, benzene, toluene, termites and rodents.


Features insulation of various types of foundations

Insulation of the foundation of a wooden house outside is always needed. Depending on the type and condition of the soil, the option of the foundation is also selected, and therefore the method of insulation.

Column foundation

The presence of a large layer of air under the house will provide excellent ventilation and a minimum level of humidity. But in cold weather, the supports will remove heat from the ground and contribute to its heaving.

Moreover, from temperature changes, they will begin to collapse. To avoid this:

  • Insulate the ground near the deepened part of the pillars.
  • Thermal insulation is required on the surface of the supports.
  • The space between the house and the ground is isolated from cool air and drafts.

It would be more expedient to insulate the supports during their installation.

This is done using expanded clay, the thickness of the layer around the pillar under it must be at least 0.25 meters. Moreover, it is important to arrange drainage and insulation of the EPSP surface. If the supports are made by concrete pouring, then it is also better to use EPS plates for formwork.

Strip foundation

Such a base is a tape of reinforced concrete that passes under all walls of the bearing type and goes into the ground to different depths.

The external type of insulation of the strip foundation is horizontal, vertical and even mixed. In the first case, the plates are needed to protect the base, and in the second, the insulation of the blind area (especially with a shallow deepening) so that there is no heaving, the third is used in places with a positive temperature in winter and the absence of floor insulation on the ground. the wood plinth is still insulated both vertically and horizontally, because the plinth is exposed to external influences of the environment.

Pile base

This type of foundation also needs insulation, since a reinforced concrete or metal grillage is a cold accumulator, and this leads to large heat loss at home. It is not just the underground space that needs insulation, but even the piles themselves, filled with concrete.

They are insulated by analogy with columnar supports. After that, it is important to close the pile foundation from the outside with a tiled insulation with further decorative type finishing. This will help protect communications from freezing and improve the aesthetic perception of the structure.

Monolithic base

We have already examined the insulation of the strip foundation of a wooden house outside, and now we will consider the features of monolithic bases. Before pouring the reinforced concrete monolith, equip a pillow in which a layer of insulation is placed:

  • Reinforced concrete slab.

  • Polyethylene protective film.
  • Insulation.
  • Waterproofing.
  • Concrete preparation.
  • Rubble.

  • Geotextile.
  • Sand.
  • Earth.

This cake makes it possible to greatly reduce heat loss at home. the presence of a layer of heat-saving materials makes the warm floor more efficient.

It is possible to insulate the monolith only before pouring the foundation.

Step-by-step instructions for insulation

The strip foundation will be the most popular in the construction of houses made of wood. Its insulation will take place as follows:

  1. Insulation of the foundation of an old wooden house outside The most laborious step - you need to dig the foundation around the entire perimeter to a width of 1 meter and depth to the level of freezing.
  2. Next, the bottom of the trench should be tamped down and a layer of sand and gravel should be poured.
  3. The foundation walls are cleaned with a metal brush and dried for a couple of weeks in the sun.

  4. Defects in the base are identified and eliminated, while cracks are expanded and repaired, the surface must be leveled as needed. you can use a reinforcing mesh (if the irregularities are more than 2 cm).
  5. Carry out waterproofing.
  6. Install insulation.
  7. The trenches must be covered with earth, not reaching 0.

    3 meters to the ground level. It needs to be tamped and covered with a sandy layer (0.15 meters), and then tamped again. After that, waterproofing is laid with a small slope from the house - insulation.

  8. Pour the blind area of ​​concrete.

The final step is to do the decorative trim.


In the role of waterproofing, it is most convenient to use bitumen, polymer or rubber mastics based on water. Organic solvents can degrade tile insulation. Before applying the mastic, the surface should be treated with a bituminous primer to improve adhesion. After 24 hours, apply the waterproofing with a wide brush in a couple of layers - the second is applied after the first has hardened.

A week is allotted for perfect drying, and then they begin to warm.

Installation of insulation

Attach the insulation with an adhesive, and glue them in horizontal rows, starting from the bottom. Vertical ligation of the joints is extremely important. The grooves should be tightly aligned and the joints almost invisible. If you envisage laying two layers, then the seams of the lower row are covered with external plates.

The underground part will not require additional reinforcement, and the underground part does not need to be additionally fastened, since it will be pressed down by the soil, and the upper part, after the adhesive has dried, needs to be fastened by means of dowel-nails, which are equipped with wide caps.To avoid damage, plaster is applied on top with reinforcement through a fiberglass mesh. After 24 hours, they are leveled and then rubbed with sandpaper.


If ordinary plaster does not suit you, then you can finish the foundation:

  • Basement siding ..


  • Thermal base / plinth panels.
  • Clinker tiles.
  • Artificial stone panels.
  • Natural stone slabs.

The best and most modern material is glass magnesite. It does not burn, is resistant to frost, does not deteriorate and does not lose its decorative qualities under the influence of ultraviolet rays. A special advantage of the material is the liquid, which makes it possible to use glass magnesite on slightly uneven surfaces. The thickness of the material is only 0.8 cm, but this does not detract from the strength and does not make the cladding heavier in general.


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