How to insulate the foundation of a wooden house from the outside with your own hands

Insulation of the foundation of a wooden house
Many owners of wooden houses are faced with the fact that in winter the floor freezes on the 1st floor. This phenomenon can only be eliminated in one way - to insulate the foundation of a wooden house from the outside. The foundation of a wooden house is built from different materials. The method of insulating the foundation of a wooden house depends on the type of supporting structure of the building. Modern thermal insulation materials are used to insulate the foundation of the house. This article presents options for insulating foundations of various designs.

Why do you need to insulate the foundation from the outside?

The foundation of a wooden house is a supporting structure that is in direct contact with the natural foundation and the structure itself. In addition to its supporting function, the foundation protects housing from the negative influences of the soil. It is important that the base of a wooden house does not cause heat leakage from the home.

The foundation of the house is constantly exposed to moisture penetration from the soil and changes in ambient temperature. In winter, moisture that gets into the body of the base of the structure freezes and destroys the supporting mass. The cold begins to penetrate into the home through cracks. As a result, the floors in the house will always be cold in winter. That is why it is necessary to insulate the base of a wooden house.

It is impossible to insulate an old foundation from below, but its walls are quite accessible for thermal insulation. Since supporting structures can be of different types, the thermal insulation of the foundation from the outside is carried out in different ways.

Video description

Details about the heat loss of the building and the purposes of insulating the foundation are described in the video

But there is another function of thermal insulation of the foundation of a house - increasing the service life of the foundation. Building materials have such a criterion as frost resistance. Its numerical expression means how many freezing cycles (assuming water saturation) must pass before signs of destruction appear. Therefore, for regions with cold and long winters, insulation and waterproofing of the foundation is a prerequisite to ensure the strength and durability of the structure.

Materials for foundation insulation

Insulation of the foundation must be done at the stage of its construction. Although there are circumstances when careless builders did not take care of this in due time. And now the owners of the house have to re-insulate the base of the wooden house.

The time comes, and homeowners think about which insulation to choose. Among the wide variety of heat-insulating agents, it is necessary to highlight materials suitable for insulating foundations:

expanded polystyrene;
polyurethane foam;
expanded clay;
Styrofoam.

All these materials have low thermal conductivity and high resistance to temperature changes.

Expanded polystyrene

Penoplex plates (expanded polystyrene)
This material has high thermal insulation properties, moisture resistance and insusceptibility to low temperatures. Thanks to these qualities, extruded polystyrene foam has gained great popularity as external insulation for the foundations of wooden houses. Expanded polystyrene is convenient for insulating strip foundations and plinths.

The material has a fine-cell structure. It is produced by exposing polymer granules to high temperature and pressure in carbon dioxide. Insulation comes on sale in the form of a slab material called penoplex. The service life of polystyrene is about 40 years.

Manufacturers often call expanded polystyrene boards penoplex. Penoplex with a thickness of 50 mm corresponds in heat-shielding properties to 75 mm of foam plastic and 95 mm of mineral wool.

Video on insulating the foundation with penoplex:

Polyurethane foam

The polymer is sprayed onto the foundation walls using special equipment. Once on the treated surface, polyurethane foam greatly increases in volume. In terms of its thermal insulation properties, a 50 mm layer of polymer is similar to a 120 mm thick sheet of expanded polystyrene.

Insulation of the foundation with polyurethane foam

The hardened foam on the walls of the base of the building forms a seamless, dense coating. Unlike sheet insulation, the sprayed outer covering does not require additional sealing of the seams. In addition, the polymer has high adhesion and “sticks” to almost any surface.

Expanded clay

Expanded clay granules are produced by firing a foamed clay solution. Expanded clay has high thermal insulation qualities. This is one of the cheapest thermal insulation building materials.

Lining the external walls of the foundation with expanded clay prevents the base of a wooden house from freezing, even in the conditions of the Far North. The only drawback of the material is its low commercial availability.

Styrofoam

Polystyrene foam is essentially the same polystyrene foam, but has not been extruded (pressure treated at high temperatures). Foam boards are used to insulate the foundation and basement of a house. To prevent heat leakage from a wooden house from below, foam plastic with a thickness of 40 to 120 mm is used.

Polymer boards are easy to process. Most often they are attached to the foundation walls using bitumen mastic. Foam plastic is also fixed to the wall with dowels - fungi.

Polystyrene foam, along with its high thermal insulation qualities, is a very fragile material, so the outside walls of the foundation lined with foam plastic necessarily need a final protective coating.

Advantages, cost, technical characteristics

Expanded polystyrene has the following indicators:

Thermal insulation. This material retains heat well. But compared to mineral wool it is lower. The level varies from 0.028 to 0.034 W x m x Kelvin. The high density of polystyrene foam ensures good heat conductivity.
Moisture resistance, vapor permeability. Depending on the type of material, it has varying degrees of vapor permeability. For example, the extruded material parameter is zero. Foam has from 0.019 to 0.015 kg per meter-hour - Pascal. Regarding resistance to moisture, when a sheet of polystyrene foam is immersed in a container of water, only 4% of the total liquid will be absorbed. In the case of a denser material texture - ten times less.
Strength. According to this characteristic, extruded material is the leader. Here it has no competitors: strong molecular bonds create strong, high-quality material.
Impact resistance. Only direct rays of the sun have a destructive effect on it; this should be taken into account when using it.
The service life is quite long. When the temperature changes, it retains its original properties and is not subject to deformation.
Environmentally friendly. The product is susceptible to oxidation. Even after installation of the material, an oxidation process occurs. It is associated with the inability of the material to polymerize during the production process, which is why it occurs later.

We advise you to study - Creating a modern interior in a minimalist style

Insulation in slabs

The main criterion for insulation remains the ability to protect the room from the cold. This is exactly what needs to be taken into account when deciding to insulate the foundation.

Before making a choice in favor of expanded polystyrene, you should carefully familiarize yourself with its advantages and disadvantages.

The benefits include:

Possibility of use in various forms. When melted, it is easy to give the desired shape.
Expanded polystyrene has a wide range of colors
Suitable as a material for insulating any buildings.
Economical to use.
Wide scope of application.
Recyclable.

The disadvantages of the material are:

Ease of ignition.
Obsolete types of material contain harmful substances released when heated to high temperatures.
A long period of decomposition, and therefore environmentalists oppose its use.
High processing costs.
Easily broken.

Ease of ignition

Like any material, the feasibility of its use also depends on the financial burden. The cost consists of several indicators:

Brands, type of material.
Manufacturer's brand.
Densities.
Sizes of the finished product.

The scheme for determining the cost of insulation in the end will depend on the area of residence. In order to save money, many people insulate the foundation with their own hands. If you plan to additionally insulate the base, you will have to increase the consumption of material, which incurs additional costs. The total cost can be calculated according to the following scheme: the number of sheets is multiplied by the cost of insulation per square meter. Extruded will cost more than usual, but its thermal insulation quality is better.

Methods for insulating the foundation of a wooden house

Mostly wooden houses are built on strip, column and pile foundations. In each case, it is necessary to cover the base and basement of the house with insulation.

Strip foundation

This type of foundation can be made monolithic or constructed from prefabricated reinforced concrete blocks. Also, the support strip under a wooden house is made of rubble stone or flagstone.

The technology for how to insulate the foundation of a wooden house from the outside with your own hands is as follows:

A trench is dug along the perimeter of a wooden house to the depth of soil freezing.
The foundation walls are cleaned of soil residues and covered with bitumen mastic.
The insulation boards are installed on a vertical surface, heating the bitumen waterproofing layer with a burner.
A reinforcing metal or polymer mesh is fixed to the insulation.
All surfaces are primed, puttied and plastered.
Insulation is laid on the sandy cushion of the blind area.
The blind area is concreted, asphalted, lined with ceramics or stone.

Scheme for insulating the strip foundation of a wooden house.
The concrete monolith of the supporting strip of the house with a thickness of 40 - 50 cm does not need insulation. The physical characteristics of such a reinforced concrete mass have sufficient heat-insulating properties.

Columnar foundation

As a matter of fact, it makes no sense to insulate the columnar foundation itself. The main heat leakage occurs through the space between the bottom of a wooden house and the ground. The constant movement of air masses underground creates an outflow of heat from the lower floor of the building.

To prevent this negative phenomenon, the outer perimeter of the underground is covered with vertical fences. Fences can be made from a variety of materials: from wooden panels to reinforced concrete slabs. Enclose the base with siding (thin-sheet metal or polymer panels). Siding performs a purely enclosing function.

Due to the enclosed space, drafts stop and the underground air temperature stabilizes in the positive range, and this ultimately leads to effective insulation of a wooden house.

The basement fence is erected from brick, wild stone or other masonry material. It is important that the masonry of the fence is not rigidly connected to the columnar supports. Due to various geological movements, the pillars can move the masonry of the fence. In this case, the wall of the base may crack and collapse.

A hermetically sealed space inside the base can lead to increased air humidity. This in turn will create a favorable environment for the growth of fungi and mold. To prevent the air in the underground from stagnating, it is imperative to make vents in the basement enclosure - small openings that provide natural ventilation for the underground.

For greater reliability of thermal insulation of the base of the house, polyurethane foam is sprayed onto the internal surfaces of the fence.

Pile foundation

The principle of insulating the pile foundation of a wooden house is the same as in the previous case. The house, located on stilts, also has an open underground, which must be closed from the outside environment.

Wooden houses are supported on both wooden and reinforced concrete and screw piles. To insulate the basement of a house on a pile foundation, wooden panels, polymer or metal siding are most often used.

How to organize water drainage from the base?

Melt and rain water lead to the destruction of the foundation over time. Often even proper insulation cannot save in such a situation. Therefore, it is important to organize the drainage of liquid from the base of the house. For this purpose, an open or closed drainage system is made.

The easiest way to do it yourself is open drainage. It consists of ditches about 0.5 meters wide and 1 m deep, dug along the entire perimeter of the building. The walls of such a trench are beveled at an angle of 30 degrees for better water drainage. Liquid from the pits should move to the drainage well. Therefore, the efficiency of such a system is much higher if the site has a slope.

Closed drainage has recently become the most popular. It consists of pipes that are dug into the ground outside the building around the perimeter. They are laid at an angle to allow water to flow independently into the drainage well. Pipes must be wrapped with geotextiles.

Features of foundation insulation with expanded clay

The method of insulating the foundation with expanded clay has its own characteristics. Since, unlike slab insulation, expanded clay is a bulk material, they do it this way:

a trench around a wooden house is made 20 - 30 cm wide; the depth of the ditch is made just below the soil freezing mark;
sand 10 cm thick is poured onto the bottom of the trench; then make a layer of crushed stone or gravel of the same thickness;
sheets of roofing material are attached to the walls along the outer perimeter of the trench;
the ditch is filled with expanded clay; pour the granules in layers of 30-40 cm; each layer is compacted;
the top of the insulation is covered with a cement screed;
a half-brick thick wall is placed along the screed; masonry is carried out to the height of the building’s base;
a metal mesh is laid across three rows of bricks, connecting the masonry and the base of the house;
the space between the masonry and the base is filled with expanded clay;
a blind area made of cement mortar is installed on top of the masonry; the screed is covered with a galvanized sheet.

Insulation of the base with expanded clay
If the roof insulation is not done simultaneously with the thermal insulation of the supporting structures of the building, then the thermal insulation of the foundation will not bring the desired result. The heat will go up, the floors and walls in the home will remain cold.

The base of a wooden house must be insulated, since the owners try to eliminate the cold in living quarters by increasing the load on the heating system of the house, and this results in exorbitant financial costs for heating the home. In this regard, it is better to properly insulate the foundation once and live in a warm house for many winters without incurring unnecessary expenses for heating the house.

Requirements for insulation

To obtain a high-quality result, it is not enough just to carry out all activities professionally.

Important factors are also the correct choice of consumables and their high quality.

It is quite difficult to choose insulation that is optimally suited for a specific purpose, both in quality and financially. After all, today you can find many options for insulation in different price categories and from different manufacturers.

Do-it-yourself installation of extruded polystyrene foam on a plinth

Therefore, when choosing, you should pay special attention to the following qualities of the material:

Low hygroscopicity. This parameter is very important, as it determines the degree of moisture absorption. At a high rate, the material will absorb moisture and as a result will collapse, which will lead to the destruction of the base itself.
High strength. The thermal insulator must withstand heavy loads of underground compressive forces. For example, the impact of soil, which increases in volume when frozen.
Low thermal conductivity. The thermal insulator must have a reduced thermal conductivity coefficient to ensure good thermal insulation.
Long service life. The thermal insulator should have approximately the same service life as the building, because replacing it is a rather labor-intensive process.

Taking into account all these requirements, you can choose the most suitable material for insulating the outside of your house with your own hands.

Coating waterproofing and penoplex

Polyurethane foam

You can insulate the foundation of a house by spraying. The base is treated externally with a liquid product. When working, special equipment is used. It takes a minimum amount of time for the material to harden. The insulation provides high-quality protection for the foundation.

Advantages of polyurethane foam:

Thermal insulation is characterized by maximum efficiency, since the product is applied in a monolithic layer without gaps;
Foam penetrates into all cracks and small gaps;
The hardening time of the material is minimal, so you can quickly finish lining the base;
Provides protection from moisture;
The insulation is able to interact with any materials: brick, concrete, wood.

Polyurethane foam is considered the best insulation. It wins against the background of polystyrene foam and penoplex. Difficulties arise only when applying the product. You need to have special equipment to process the foundation.