Insulation of the old foundation. Repairing an old foundation with your own hands and insulating it. Methods for insulating the foundation part of a wooden house

Why you need to insulate the foundation of a wooden house - there is no need to explain for a long time. Nobody likes it when the cold drags down below. No amount of insulation of plastic windows will help here. We must also add heating costs in a vain attempt to warm up the icy floors and make the temperature in the room bearable in winter. It’s better to choose the insulation method, material, and work once.

Thermal insulation materials

- very important elements of building a new home. When deciding how to insulate the foundation in a private house, you need to choose the right thermal insulation. Thermal insulating materials are cellular or fibrous structures of low density. They can be seen in photographs taken with magnification. Their main characteristics are density and hygroscopicity, on which the quality of thermal insulation depends.

Characteristics of thermal insulators

The lower the density of the material, the better the thermal insulation properties. The density of thermal insulators varies from 50 to 98%.

Photo of fibrous insulation material (mineral wool)

Thermal conductivity is characterized by the thermal conductivity coefficient λ - this is the amount of heat passing in 1 hour through a material measuring 1x1x1 m3 at a temperature difference of 10 degrees.

Water is about 25 times better at conducting heat than air. Therefore, if thermal insulation absorbs water (air in the structure of the material is replaced by water), thermal conductivity will increase sharply, and the material will lose its consumer properties. For this reason, hygroscopic materials must be additionally insulated from moisture.

Vapor permeability, biostability, fire resistance, and frost resistance are also important.

TYPES OF THERMAL INSULATORS:

1. Mineral wool is made from dolomites, marls, and basalts. This is the most popular thermal insulator. Requires waterproofing.
2. Glass wool is made like mineral wool from the same materials as glass. Need waterproofing.
3. Foam glass is sintered from glass powder in the presence of a foaming agent (limestone). Durable, easy to process material with unlimited service life. Vapor and moisture resistant, but the price is high.
4. Foams:

• – a fairly inexpensive option;
• extruded polystyrene foam stronger than polystyrene foam, has the lowest water absorption, durable, non-toxic.
• polyurethane foam– is obtained by spraying liquid components in air and immediately adheres to the surface. Thanks to this, it is possible to thermally insulate an uneven surface without joints. It is convenient to insulate the loggia and basement from the inside.

Photos of foam plastics

Methods for insulating the foundation

How to insulate the foundation of a house largely depends on the design. It can be insulated from the outside or from the inside. Both methods have their advantages and disadvantages. The costs for internal insulation of the basement are much lower, but this method will not save you from freezing, therefore, it is less effective.

External foundation insulation

Advantages of external insulation compared to internal:

• More efficient heat retention in the house;
• extending the service life of utilities;
• protection of the foundation of the house from temperature changes;
• extension of service life.

When building a house with your own hands, the pit must be dug in such a way that there is a distance of 0.5-1 m from the foundation to the edge of the pit. If the house has already been built, it is necessary to dig a trench of the appropriate width close to the wall, clear it of soil and old waterproofing. Then you need to apply a new waterproofing layer, for example, bitumen mastic.

Important! Thermal insulation of the foundation must be carried out in combination with waterproofing. The foundation itself must be protected from moisture, and in some cases the thermal insulation material must also be protected.

Drainage pipes and other utilities can be laid in the dug trench.

The gaps between the foundation slabs are filled with mortar or foam.

Important! If the foundation is shallow, the waterproofing layer must be no less than the height of the foundation. With a buried foundation, the thermal insulation must be no less than the freezing depth.

Filling the lower rims with thermal insulation material

How to properly insulate the foundation of a private house if construction has already been completed? In the absence of a buried foundation and basement, there is nothing left but to insulate the floor and use the ancient method: make a pile.

In the old days, Russian huts were insulated by filling the foundations of the house with earth. The huts were, as a rule, placed on columnar foundations, or even the lower crowns were simply laid directly on the ground. Then, at a distance of up to half a meter from the wall, they built something like formwork and filled the earth between the wall and the formwork.

You can use expanded clay. Its thermal insulation properties are significantly higher than those of earth. But it’s fragile, you can’t sit on such rubble. Since properly insulating the foundation of a private house also means protecting it from dampness, a layer of waterproofing on top would not hurt.

External foundation insulation with expanded clay

If you still decide to expose the foundation, the instructions are as follows:

1. For insulation with expanded clay, a trench 1 m wide is needed.
2. The trench is lined with waterproofing material, such as geotextile.
3. Expanded clay is poured into it, which is also covered with geotextile on top.
4. You need to pour a layer of sand on top.
5. Make a blind area.

External insulation with expanded clay

Foundation insulation with synthetic materials

The width of the trench in this case can be about 0.5 m.

1. Cover the foundation with bitumen mastic.
2. Cover it with thermal insulation boards, gluing it with special glue.
3. If the material is hygroscopic, protect it from dampness with waterproofing.
4. To protect thermal insulation from melt water, it is recommended to raise it above ground level by 30-40 cm.
5. Fill the trench with gravel or sand.
6. The remaining heat insulator is laid on top.
7. Sprinkle with earth, fill with concrete or asphalt.

Insulation of the foundation from the inside

Internal insulation is cheaper and simpler, but there is no protection against freezing, which leads to deformation and cracking of the foundation of the house. Internal thermal insulation can be carried out with expanded clay, polystyrene foam, polyurethane foam, and expanded polystyrene. On top of the insulation layer you need to apply a layer of plaster or cover it with sheets of plasterboard, fiberboard/chipboard.

Backfill insulation

If a house on a columnar foundation is just being built, it is recommended to immediately backfill the insulating material (earth, clay or expanded clay) under the house to the floor level. The same backfill can be done when the foundation is shallow. The soil should be spread in an even layer under the entire house. Expanded clay, whose thermal insulation properties are much higher, can only be placed along the walls in a layer up to half a meter wide.

Simple calculations will show that for a house with an area of ​​100 sq.m., a bedding 0.5 m high will require 50 cubic meters of earth, this is approximately 4-5 KamAZ trucks of soil, which will need to be transferred from place to place and leveled. Therefore, expanded clay is still preferable.

Basement insulation with expanded clay

• waterproof the foundation from the inside. If the basement floor is concrete, waterproof it too;
• make formwork at a distance of about 5 m from the walls;
• pour expanded clay between the formwork and the wall.

Conclusion

Not all work can be done independently. For example, it is better to entrust spraying polyurethane foam to professionals, since this requires a special installation. But it is necessary to know how and what is being done, at least in order to control the work of hired workers.

- this is a necessity, the same can be said about the foundation. This will become especially relevant in areas with very low air temperatures, where the soil freezes to a great depth.

The foundation will give away approximately 10-20% of the total heat of the building, so it’s definitely worth insulating the foundation to keep the heat in the house.

Severe frosts have a detrimental effect on the structure of the foundation, since the soil during the period of freezing will increase in volume and rise along with the building. And this entails deformation and cracks in the walls and foundation. According to the rules, insulation of the foundation must be carried out during the construction of the house.

Most of the cold enters the house through the foundation. If you have a basement in your house, and it is not used as a cellar, then you definitely need it. Insulating the basement from the outside will protect your home from dampness and from heat loss from the basement and first floor, which are heated.

Advantages of an insulated foundation:

• retains heat in the house;
• reduces heating costs;
• prevents frost from affecting the foundation;
• maintains temperature inside the house;
• does not allow condensation;
• provides mechanical protection and waterproofing;
• extends the life of the foundation and affects the longevity of waterproofing.

Which insulation to choose?

Materials for the outside should:

• do not deform due to soil pressure;
• do not allow moisture to pass through.

Mineral wool is not suitable for insulating the foundation, so you need to look for other options.

1. Extruded polystyrene foam.
2. Sprayed polyurethane foam.

These two types of insulation differ in cost and thermal insulation parameters.

Foundation insulation with extruded polystyrene foam has a long service life, since it does not absorb moisture and does not allow water to pass through. The cost of this insulation is significantly lower than polyurethane foam. Advantages of extruded polystyrene foam:

• service life – at least 40 years;
• environmentally friendly product;
• low price;
• high strength;
• good thermal insulation;
• Rodents won't eat it.

Installation of expanded polystyrene

From the outside, the foundation must be insulated correctly and effectively, so thermal insulation slabs are installed to the depth of soil freezing. As a rule, the corner zones of a building require enhanced thermal insulation, so for corners 1.5 meters in both directions, thicker insulation is used.

It is also necessary to insulate the soil around the perimeter of the building; extruded polystyrene foam must be placed under the blind area structure. This will help reduce the degree and depth of soil freezing near the walls of the house.

Before starting work on insulating the foundation, it is necessary to level the surface and waterproof the foundation from the outside. By mounting slabs of extruded polystyrene foam, a sealed shell will be created, so mechanical fastenings will not be suitable here.

The slabs must be attached using glue or by melting a layer of bitumen waterproofing in several places and pressing the slabs to the foundation. Installation of the slabs begins from the bottom up, the seams are filled with polyurethane foam.

Just keep in mind that before installing extruded polystyrene foam, the bitumen waterproofing must dry completely, this will take 5-7 days.

Insulating the foundation of a wooden house from the outside with polyurethane foam can be an ideal option. This insulation can also be used for floors. The material is durable and reliable.

Insulate the foundation and... It is applicable for both ceiling and floor. How is insulation carried out? It is necessary to build formwork near the foundation and pour a mixture of expanded clay and concrete into it.

Insulation of the old foundation

This work is a complex process and is carried out during the warm season. In order to retain heat in the house, it is necessary to carry out high-quality insulation between the lower crown and the foundation. Stages of insulating the old foundation of a wooden house:

1. Dig a hole around the entire perimeter of the house, one to one and a half meters wide and up to 50 centimeters deep.
2. First, fill the trenches 20 centimeters with sand and compact it.
3. Lay polystyrene foam slabs on the sand with a deviation from the base (place a double layer of slabs in the corner areas).
4. Pour sand on top 30 centimeters.

In this way, you will prevent freezing of the soil in the area of ​​the house structure, and the hydro- and thermal insulation will increase.

Olga Rogozina, Ufa.

Thermal insulation is an incredibly important, but also quite complex process. A private house whose foundation is not insulated cannot be called well-equipped.

Therefore, the owner of the building must make the necessary efforts to extend the operational life of his property. It is worth figuring out how to insulate the foundation and what materials to do it with.

Is it necessary to insulate the foundation of a wooden house?

It is unlikely that there is an owner of a country house who likes to have a cold wind constantly blowing across his feet. If you do not insulate the foundation, a similar problem will occur constantly. You also need to take into account that significant amounts of heat escape through a cold floor. As a result, there is an overconsumption of coolant, and heating costs increase.

Thus, the owner must carry out both waterproofing of the foundation and its insulation. It is better if such procedures are carried out during the housing construction stage. The very first task that needs to be solved is the choice of suitable insulation. The most important indicators of thermal insulation materials are hygroscopicity and density. They determine how high quality the insulation will be.

Characteristics of modern insulation materials

The thermal insulation capabilities of a material are determined by its density. As density decreases, heat transfer also decreases. In the case of modern materials, the density can vary significantly. It is in the range of 50-98%. The thermal conductivity coefficient shows how much heat passes through a 1 m3 volume of insulation within an hour. In this case, measurements are taken under conditions when the air temperature on opposite sides of the insulation differs by 10°C. Important indicators of thermal insulation materials include frost and fire resistance, and vapor permeability.

The thermal conductivity coefficient of water is 25 times greater than that of air. The insulation should not absorb moisture, otherwise its quality will deteriorate. If a material with low water resistance is used, it is additionally waterproofed.

There are a lot of popular materials used for insulation. The most famous of them are:

1. Mineral and glass wool. They are inexpensive and provide good surface insulation, but their use requires basement waterproofing.

2. Expanded polystyrene. They are also cheap, but can be damaged by rodents or catch fire.

3. Penoplex. In many ways it is similar to polystyrene foam, although it is more durable and practically does not absorb water. The material does not burn, does not emit harmful substances, and lasts a long time.

It is necessary to carry out thermal insulation of the foundation based on what kind of structure it has. The material can be located outside or inside. Each option comes with certain advantages and disadvantages. But external insulation is considered more effective, since it helps protect the foundation from cooling.

Insulation of the foundation in a wooden house from the outside

When the house is completely built, a trench is dug along its perimeter. The surface of the foundation is covered with a waterproofing material, which can be bitumen mastic. When dealing with a shallow foundation, insulation is placed along its entire height. To increase thermal insulation, an insulated blind area can be installed around the perimeter of the house.

Filling the lower crowns of a log house with thermal insulation

If there is no foundation in the house, and the basement has not been equipped, all that remains is to insulate at least the wooden floor itself. Previously, in ordinary Russian huts they used the method of powdering the base. The essence of the method is that the hut was placed on a columnar foundation or lower crowns that ran along the ground. Formwork was laid half a meter from the walls, and earth was poured into the space between it and the house.

To create an insulated blind area, you must first prepare a trench, the width of which should be up to 1 meter. Such a trench is lined with waterproofing material from the inside, after which expanded clay is poured into it. Another layer of waterproofing is applied on top. You can cover all this with sand and fill the blind area itself. In addition to expanded clay, penoplex can be used, which also provides insulation and is not afraid of water.

External insulation of the foundation with foam plastic, penoplex

A 50 cm wide trench is prepared along the perimeter of the walls. The foundation is treated with bitumen mastic, after which thermal insulation slabs are laid. If you use insulation that is afraid of moisture, it needs to be waterproofed. But it is better to immediately choose a material with moisture-proof qualities. For example, it could be penoplex. After completing such work, sand is poured into the trench. All that remains is to fill the blind area or lay paving stones around the perimeter.

Insulation of the foundation from the inside

Although the cost of internal insulation is low, this option cannot be called successful - the foundation will freeze very much in winter. As a result, the concrete may crack. For internal insulation, mineral wool, expanded polystyrene, and expanded clay are often chosen. The thermal insulation layer is covered with plaster or false walls made of fiberboard are hemmed.

Insulating the foundation of a private house with expanded clay from the inside

At the stage of building a house, it is better to backfill it with expanded clay up to the floor level. This method is also suitable when work is carried out in an old house, if it is built on a shallow strip foundation. Under the entire building, the ground is covered with an equal layer of expanded clay.

Insulation of the foundation from the inside with mineral wool

In houses with concrete floors, waterproofing should be done first. Afterwards, they are backfilled with expanded clay. Place mineral wool on it. Before this, the floor is covered with lags. This technology will allow you to get warm floors in your house and keep the foundation in good condition for a long time.

In contact with

In wooden houses, less effort and money is spent on insulating all structures than in other types of buildings, because wood has low thermal conductivity. But even in log houses there are elements that cannot be made of wood, and often they become conductors of cold entering the house. The largest heat leaks occur through non-insulated parts of the structure. Since the strip foundation is made of monolithic concrete, rubble or concrete blocks with high thermal conductivity, the share of heat loss can exceed 20% of the total, and if there is a basement floor, it is even higher. Let's consider how to insulate the foundation and what materials should be used.

When is it better to insulate the foundation of a wooden house?

It is more convenient and cheaper to insulate the foundation before installing the walls, while the earthen trenches are not yet backfilled, and there are no structures above the base that would interfere with the work. As for insulating an already finished house, the floors of which are too cold, and the walls of the unheated basement are covered with drizzle in winter, then it’s better late than never.

It is most convenient to insulate the foundation before erecting the box

General principles of foundation insulation and materials used

To understand how to properly insulate a foundation from the outside, you need to know that freezing occurs not only above ground level, but also below. Moreover, it is advisable to insulate not only the foundation itself, but also the soil on which the support cushion rests. In this way, it is possible to exclude the impact of frost heaving forces on concrete, which tend to deform the strip structure. Consequently, not only the vertical concrete surface, but also the blind area is subject to insulation. Level - slightly higher than the foundation depth or freezing depth.

To maintain heat in the house, the ground floor should also be insulated. If the floor is monolithic, it is better to fill the space under it not with soil, but with a relatively inexpensive insulation material - expanded clay. Under the frame structure of the floor, waterproofing should be done, insulation should be laid between the frame elements, not forgetting to leave the possibility of ventilation of wood and fibrous materials (mineral wool).

It is also necessary to waterproof the foundation or basement walls, and this should be done in the early stages of construction by laying horizontal roll bitumen waterproofing on the base of the strip foundation. In the second stage, bitumen or polymer-cement insulation is applied to the walls from the outside, and if the house does not have a basement, from the inside too.

The optimal material for external insulation of the foundation is polystyrene foam: relatively inexpensive PSB-50 foam or more durable and durable extruded polystyrene foam (EPS). Although expanded polystyrene does not absorb moisture and is difficult to biodegrade, its surface should be protected from ultraviolet radiation above the ground and exposure to plant roots underground. Below the ground level this can be done with flat asbestos-cement sheets, above with thin-layer plaster reinforced with a polymer mesh.

The thickness of the insulation boards is determined by thermal engineering calculations and the effect that needs to be achieved. The minimum recommended thickness is 5 cm. Any non-hydrophobic, rot-resistant and sufficiently durable materials are suitable for external insulation. It’s not cheap, but foam glass has proven itself, and special boards based on bentonite are also used, which simultaneously provide insulation from moisture.

Foundation thermal insulation technology using extruded polystyrene foam

How to insulate the foundation from the outside using polystyrene foam boards

• Soil preparation

Along the entire perimeter of the foundation, a trench is selected with a depth to the support pad of the concrete strip. If the freezing level is low, then it is enough to dig just below the maximum limit. It is better to rest the slabs on a rigid base; to do this, you should sprinkle the trench with a layer of sand and gravel (10 cm) from below and compact the soil.

The deeper the trench is dug, the higher the thermal insulation of the foundation slabs will be.

• Foundation preparation

The foundation surface must be clean and as level as possible. If vertical waterproofing has not yet been applied, defects must be eliminated with cement mortar or repair compound.

• Foundation waterproofing

The next stage of work is waterproofing the foundation. The insulation itself does not need insulation, but concrete should be protected from moisture, then it will last longer. If there is a basement floor, good waterproofing is especially necessary. Even if we are talking about reconstruction of the foundation and there is no horizontal waterproofing between the sole and the tape, we still recommend doing a vertical one - even such a half-measure will significantly reduce the moisture saturation of the concrete. It doesn’t really matter what material is used: rolled bitumen, liquid rubber or cement-polymer mixtures. The main thing is to adhere to the recommended work technology. It is more difficult to work with rolled materials; you need to have a professional burner and know how to handle it. Mastic and cement compounds are easier to apply; you only need brushes and a spatula.

• Fixing insulation boards

To attach polystyrene foam to the foundation, polyurethane glue or mastic based on bitumen and polymers, cement-polymer compositions are used. Bituminous materials should not contain organic solvents, they destroy polystyrene. The adhesive can be applied to the wall in a continuous layer using a tiler's comb with a large tooth, or, if the walls are not level enough, apply it to the slabs themselves pointwise, at a distance of about 25 cm between points. Install starting from the bottom corner, resting the slabs on a concrete support or sand cushion . Having laid the first row, continue the second so that its seams fall in the middle of the underlying sheets, like brickwork. Connect the slabs with overlapping grooves, but if you have to trim the edge, then be sure to lubricate the joint with mastic or glue. When joining corners, it is recommended to blow out the seam with foam to close any possible cold bridge. If necessary, the slabs are additionally secured with special dowels with a large head (fungi), first filling the holes drilled for the dowels with silicone sealant.

• Laying outer protection

The last stage in installation is to isolate the insulation from external factors. The underground part can be covered with flat slate (ADS), roofing felt. Sometimes it is recommended to simply sprinkle EPS with soil, because it is stronger than PSB. But we still believe that it also needs to be protected, because the roots and shoots of plants grow even through a thick layer of asphalt and split the masonry. You can also install a reliable wall made of solid, well-fired brick, if there is support for it. True, such protection will not be cheap.

Protective brickwork will protect the foam from moisture coming from the soil

External foundation insulation with polyurethane foam

How to insulate the foundation of a wooden house as quickly as possible? For this purpose, sprayed polyurethane foam insulation can be used. Workers will mix the components right at the construction site and apply the liquid composition to the entire external surface within a day. After hardening, polyurethane forms a dense, continuous, seamless coating with characteristics similar to penoplex. True, the cost of insulation will be high.

Due to the absence of seams, sprayed polyurethane provides high thermal insulation

When choosing between external and internal insulation, preference should be given to the first option, since only external insulation closes cold bridges, eliminates the possibility of moisture condensation in the thickness of concrete, reduces humidity in the basement, and increases the service life of building structures.

Without insulation of the foundation, the first floor will always suffer from dampness in the corners and cold.

Video: insulating the foundation with polystyrene foam

How to insulate a crumbling foundation of a village house? Anton Nikolaevich GODIN, Minsk

In earlier times, the construction of foundations was approached more simply - they were built from the materials that were at hand. Therefore, it is quite understandable why these structures began to crumble.

But it would be a big mistake to insulate a foundation that does not provide the necessary strength. Therefore, before doing thermal insulation work, you must first strengthen the old foundation. And to do this, it should be diagnosed, establishing whether it will be able to withstand the weight of the house standing on it in the future?

Foundation repair

To analyze the condition of the foundation from the outside, close to it along the entire perimeter, you need to dig a trench approximately 1 m wide - this is quite enough to inspect the foundation, and subsequently carry out restoration work.

On a note

Such repairs can be done on your own, the only condition is that the house does not sag. If it is warped due to deformation of the foundation, you will have to call a repair team that has the necessary lifting mechanisms. After all, for complex foundation repairs, the house will have to be “hung out.”

As a rule, foundations were previously made either from rubble stone or brick using a continuous strip or columns.

In all cases, it is advisable to pour another one, 30-40 cm wide, next to the existing foundation, connecting them with reinforcement ties. But first, you should identify the weak points of the old foundation, for example, split and fallen stones, cracked bricks, and formed voids.

All these elements need to be replaced. Then, every 30-40 cm, using the existing voids, hammer identical pieces of reinforcement (14-16 mm in cross-section) into the foundation in two rows so that they extend 25-30 cm into the trench. This must be done carefully so as not to destroy the old foundation Houses.

In brickwork, it is best to pre-drill holes according to the diameter of the reinforcement. We recommend placing longitudinal sections of the same reinforcement in two rows on its protruding ends and tying them with wire so that a reinforcement grid is formed.

Formwork is installed along the outside of the trench up to the height of the existing foundation. A sand cushion is poured onto the bottom of the trench, then a layer of gravel. After this, you can begin pouring concrete.

This must be done gradually so that the solution penetrates into all the cavities of the old foundation.

Insulation of the old foundation

But let’s return to the foundation that has already been repaired on our own. When the concrete has set and the formwork can be removed, it is worth starting to insulate the base of the house. Extruded polystyrene foam (EPS), which has greater strength than polystyrene foam, is best suited for this purpose. For this reason, it does not need to be protected from earth pressure.

For Belarus and Russian regions with a temperate climate, a slab thickness of 50 mm is sufficient. They are attached to heated bitumen resin, joint to joint, leaving no gaps. After filling the trench with soil, it is necessary, not reaching the ground level of about 20 cm, to pour a layer of sand, compact it and lay the EPS slabs horizontally flush with the surface, and pour the blind area on top.

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