For normal operation of the building, it is necessary to insulate the foundation of the house from the outside and lay polystyrene foam under the blind area. The heat-insulating circuit solves several problems - expanding the frost-free zone, eliminating swelling, cold bridges and heat losses. The need for measures to eliminate swelling conditions (freezing + moisture + clayey soil) is separately indicated in the standards of SP 22.13330 (foundations), departmental VST, territorial TSN (for example, MF-97 for the Moscow region).

In order for an individual developer to insulate the foundation with their own hands without errors, it must be taken into account that the owner's expenses always consist of a construction estimate and an operating budget. Accordingly, changing any of these items, you can automatically affect the other:

• refusing to insulate the blind area, the foundation, the owner saves on the purchase of polystyrene foam, but heating and repair costs increase;
• by investing in thermal insulation, the developer increases the initial costs, but automatically reduces the operating costs.

By investing money in their own home, a young family gets an advantage at retirement in the form of significantly lower utility bills due to energy savings and the absence of foundation repairs.

Heat distribution diagram next to the foundation. It can be seen that the freezing boundary is moving away from the foundation.

Depending on the operating mode of the building, the budget of the developer and the type of soil, horizontal and vertical insulation contours solve different problems:

• blind area - the EPPS tape laid under it moves the freezing zone outward from the house, swelling is impossible in the layers of soil adjacent to the foundation;
• outer vertical surface of the tape - protection of waterproofing, elimination of a cold bridge, reduction of heat loss through the floor / floors of the house, displacement of the dew point outward for normal operation of the underground floor;
• horizontal layer under the sole of the MZLF - if the building does not have heating or is heated during periodic visits, in order to eliminate the freezing of soils under it, it is necessary to keep the heat of the bowels with a continuous layer of expanded polystyrene.

Important! A set of works to eliminate swelling should be carried out only on clay soils. However, heat losses in a complex basement assembly with multilayer linings, by adjoining various structures made of different materials, can only be prevented by the method of external thermal insulation of the vertical surfaces of the foundation.

Materials and technology of foundation insulation

With the existing variety of heat-insulating materials, do-it-yourself foundation insulation is most often done with high-density extruded polystyrene foam EPS, XPS, Carbon SP from TechnoNIKOL, Penoplex Foundation. Unlike mineral, glass and ecowool, expanded polystyrene retains heat-insulating properties, even when completely immersed in water. For comparison, basalt wool loses 30% of its properties when wet, and begins to slide off vertical surfaces under its own weight. Relying on soft insulation concrete structures is prohibited.

Heaters

To protect the foundation of a private cottage, the following heat-insulating materials are most effective:

• polyurethane foam - PPU marking, sprayed onto the surface, also available in the form of plates, density 50 - 60 kg / m3, thermal conductivity corresponds to 0.028 units, costs twice as much as polystyrene foam;
• extruded polystyrene foam - different designations from manufacturers, plates of different sizes, density 35 - 45 kg / m3, thermal conductivity 0.03, cheaper than the previous option.

Insulation of the foundation with extruded polystyrene foam.

The mounting foam used to fill the joints of the insulation is made of polyurethane foam. Therefore, when using Penoplex, XPS, the quality of the joints is higher than the main surface.

The main disadvantage of expanded polystyrene is low chemical resistance - the material is dissolved by petroleum products. Therefore, it is not recommended to paste over concrete surfaces treated with bituminous mastics, deposited roll materials with a bituminous layer. It is better to use polymeric mastics, membranes or polyethylene films. Polyurethane foam is inert to oil products, acids, alkalis and salt solutions.

Budget foam PSB-S has a density of 15 - 25 kg / m3, thermal conductivity of 0.04 units, vapor permeability of 0.05. This heater is used in cases:

• outer layer of vertical crushable insulation;
• fixed formwork for low grillage (lower horizontal deck).

In the first case, the insulation is necessary to protect the main layer of the heat insulator. In the second option, the foam plastic remains after pouring the grillage under the reinforced concrete structure, is crushed by soils during swelling, so that the heaving forces cannot tear the grillage beams from the pillars or piles, the heads of which are embedded in the structure.

Technology overview

Do-it-yourself insulation of the foundation is carried out according to different schemes, depending on the operating mode, design. Protection against swelling is necessary for columnar, strip and slab foundations. Heaving forces practically do not affect the piles, however, with a low grillage on bored, screw piles, the beams must be placed at least 10 cm above the ground.

The scheme of insulation of the foundation and the blind area outside for a house with constant heating.

There are three main operating modes of the house:

• constant heating - insulation reduces heat loss, expands the zone of non-freezing soil around the building and protects the foundation from the effects of negative temperatures;
• heating is completely absent - it is pointless to eliminate heat loss in this case, however, it is necessary to preserve geothermal heat under the building in order to prevent soil freezing, therefore the blind area + the entire perimeter of the garden house under the sole is insulated;
• heating is turned on periodically (baths and cottages) - since there is occasional heating, it is necessary to reduce heat losses in ceilings and floors, the outer surface of the grillage, tape, slab and blind area is insulated, in the absence of heating, it becomes necessary to preserve the heat of the bowels, so the entire perimeter of the house is insulated under the sole foundation.

In garden houses without heating, laying polystyrene foam at the level of the base of the foundation is not always economically viable:

If the depth of the pillars or MZLF is within 40 cm, it makes sense to make a pit, since the fertile layer will still have to be completely removed in order to make floors on the ground.

If the tape or columnar foundation lies deeper, excavation can be avoided by laying the insulation according to a different scheme:

• under the blind area - the perimeter of soil freezing is moved back;
• under the sole of the foundation - protection against swelling;
• on the inner surface of the tape + under the floor on the ground - the preservation of geothermal heat under the entire foundation structure.

If for some reason it is impossible to fill the sinuses of the pits with non-metallic material, in which there is no clay and, accordingly, frost swelling, instead of the standard insulation of the outer surfaces of the strip foundation, a crush-sliding thermal insulation scheme should be used:

• gluing external concrete vertical surfaces with high-density polystyrene foam;
• covering it with polyethylene (attached only in the basement);
• installation of low-density foam plastic PSB-S close to the film without fastening (pressed by the backfill material).

This option is especially relevant for deep-laid tapes. The area of ​​contact of the side surfaces of the tape with clay soils is huge, the pull-out loads are very significant. When heaving forces occur, the soil crushes the foam plastic, shifts it upward along the slippery film. The main layer of insulation is not harmed; after the spring thawing of the soil, the outer layer shifts down again.

Important! Warming is only one method of eliminating swelling in a set of measures. Therefore, drainage and non-metallic materials in the underlying layer, backfilling of the sinuses cannot be canceled.

In the classical technologies of monolithic foundations (slab, tape, pillars), a screed-footing is used to reduce the lower protective layer of concrete, level the base, eliminate leakage of cement laitance from concrete at the time of pouring.

If the building of a seasonal, periodic operation mode is insulated with a layer of polystyrene foam around the entire perimeter of the pit, then there is no need to make footings. That allows you to reduce the construction budget somewhat.

Foundation insulation errors

Due to lack of experience, individual developers often make mistakes when insulating foundations:

• cold bridges - the thermal insulation circuit must be continuous, the seams must be foamed, the joints of the plates must be displaced with a multilayer circuit in adjacent layers;
• the use of low density materials - PSB-S is allowed only for the lower deck of the grillage, the outer layer of crushable thermal insulation;
• violation of thermal insulation schemes - for basements, MZLF buildings with constant heating, it is necessary to insulate the tape from the outside, without heating and with periodic heating - from the inside;

Cold bridges, nullifying the effectiveness of insulation work, usually occur at the junction points of the basement elements:

• lack of lateral vertical thermal insulation along the perimeter of the floor screed on the ground;
• not insulated concrete preparation;
• lack of expanded polystyrene on the upper horizontal edge of the protruding base;
• incorrect pairing of basement insulation and facade insulation.

Errors in pairing the basement and facade insulation.

Important! It is impossible to correct the cold bridge created as a result of facing the facade with bricks, the bottom row of which is installed directly on the protruding plinth.

Thus, despite the fact that it is recommended to fix the insulation on the outer surfaces of the foundation, this scheme is correct only for dwellings with a constant heating mode. In garden houses, thermal insulation is carried out along the inner edges of the tape. The blind area is always insulated, crumpled thermal insulation is usually necessary for deep-laid tapes.

Many novice builders, from among those who are lucky enough to become the owner of their own suburban area, and who wish to carry out most of the work on their own, at first make many serious mistakes. And one of the fairly common ones is ignoring the issues of reliable and warming of the foundation.

An interesting “picture” is obtained - as a rule, everyone remembers about the external design of the basement part of the wall. In no case belittling the importance of a neat finish, we agree that it will not subsequently determine the level of comfort of living in a house and the durability of building structural elements, but the quality of hydro and thermal insulation affects this directly. Therefore, let's look at a very important topic - the full insulation of the foundation base from the outside. By the way, some thermal insulation technologies for this part of the foundation involve its finishing at the same time.

Why is it generally necessary to insulate the foundation, and the basement in particular?

From a philistine point of view, the very formulation of the problem may not seem quite clear - what is the point in general of insulating the foundation? After all, for the most part, it does not directly adjoin living quarters, and, it would seem, cannot influence the microclimate in them in any way. And if basements are not created, or they do not require maintaining a certain temperature level, then why even start such a thing?

This is an extremely common misconception! The foundation, like other elements of the building structure, needs reliable insulation, and this need is caused by a number of reasons of various properties. And, probably, first of all, the thermal insulation of the foundation is a task aimed at maximizing its strength and durability, on which, of course, the operational life of the building itself directly depends. Let's look at the points, and start with the most common - strip foundation.

First of all, it must be said that really high-quality thermal insulation should provide for comprehensive insulation - both of the vertical walls of the foundation (basement), and the blind area along the perimeter of the building. Otherwise, it would be naive to talk about the effectiveness of such events.

• A massive reinforced concrete foundation without thermal insulation from the outside will always be a powerful accumulator of cold in winter, from which it will spread to adjacent building structures. It is clear that the level of the floors of the premises of the first floor, as a rule, is located above the basement line, and the walls and ceilings have their own insulation. But such a neighborhood always leads to excessive heat losses and, accordingly, to completely unnecessary, extra costs for energy carriers used for heating purposes. Practice shows that even just competent insulation of the foundation alone gives a significant, up to 20 ÷ 25%, savings effect, all other things being equal.

1 - ground level;

2 - the base of the foundation;

3 - basement part of the foundation;

4 - building wall;

5 - overlap (floor) of the first floor;

6 - insulation of the outer wall;

Of course, the scheme is not a dogma, and some of its variations are possible. So, in particular, a layer of horizontal insulation (under the blind areas) can also be located in depth, up to the level of the sole. But even in this case, it must be laid in such a way that no gap is created between it and the vertical thermal insulation of the foundation wall.

We deal with the required thickness of insulation

It is probably clear that the thickness of the foundation insulation must obey certain rules. The same foam boards are produced in a wide range of thicknesses, and it will not be difficult to purchase the necessary material for a single-layer or, if necessary, even a two-layer thermal insulation. But how to find the right thickness?

To do this, you can carry out certain thermal calculations using formulas or even just tabular data.

Vertical thermal insulation of the foundation

Let's start with the vertical layer of insulation. The calculation will be based on the following formula:

Rsum = hf/λf + hу/λу

Rsum- the total resistance to heat transfer (measured in m² × ° K / W), which the building structure must have, in this case, the strip foundation. This is a normalized tabular value established by the Construction Norms and Rules (SNiP) for all regions of Russia, depending on the characteristics of their climate. If you wish, you can find tables for various areas on the Internet, this parameter is probably known to all local construction or design organizations, but it will be even easier to take the value from the diagram below.

Please note that for each of the regions three values ​​​​of this thermal resistance are indicated: for walls and enclosing structures, for coatings and for floors. In this case, we are interested in "for walls" - in the columns these are the upper values ​​highlighted in purple.

hf And λf- parameters characterizing the thermal characteristics of the foundation tape itself: this is the thickness of the tape in meters ( hph) and the coefficient of thermal conductivity of reinforced concrete - a tabular value.

hu And λу- similar parameters of the insulation layer.

This means that if the coefficient of thermal conductivity of the selected insulation material is known, then it is easy to calculate its required thickness with simple arithmetic operations.

And in order not to force the reader to dive into independent calculations, we suggest using a special online calculator, which has already included all the heat engineering dependencies and the necessary tabular values.

Insulation of the foundation from the outside - the necessary work to ensure the safety of heat in the room, protection from moisture, saving energy.

The best solution is to carry out all the manipulations during the construction of the building, but the plan can be carried out after the construction of the building is completed.

For each individual case, its most convenient algorithm has been developed, according to which the foundation of a private house should be insulated from the outside, and materials have been selected to achieve the highest quality and most effective insulation of the foundation.

Variety of materials for thermal insulation

Insulation of the foundation basement from the outside is performed:

Each of the listed materials is ideal for arranging high-quality insulation of the foundation of the house from the outside.

In all cases, it should be remembered that the thermal insulation of the foundation is not necessary in order to increase the flow of warm air penetrating into the room. Every effort should be made to prevent the penetration of cold into the building.

The insulation must be moisture resistant

If you want to avoid material costs and save as much as possible on arranging a warm foundation for the house, many owners of private buildings carry out all the work using the land. The method of backfilling allows you to achieve a positive result, but modern materials guarantee that a reliable and high-quality warm foundation will be created.

When deciding how to insulate the foundation, you must first choose the method of performing the work, because the heat-insulating material can be fixed outside the building or on the inner surface of the base.

Depending on which insulation was chosen and on the method of insulation, the materials for insulation of the foundation are selected, which are necessary to achieve the goal.

You can buy everything you need, knowing how to properly insulate the foundation of a residential building in order to provide the owners with comfortable living conditions. The materials used should not be deformed under the influence of aggressive environments, pass moisture. They must be distinguished by a long service life, resistance to temperature extremes, low weight, strength and high density.

Given all the requirements, experts recommend using as a heater:

• penoplex;
• extruded polystyrene foam;
• sprayed polyurethane foam.

Before you insulate the foundation of the house from the outside with your own hands, it is necessary, in strict accordance with all the requirements, to prepare the base surface, on which the heat-insulating material will later be fixed.

For spraying polyurethane foam, you will have to invite professionals with equipment

Spraying polyurethane foam requires the participation of craftsmen, the use of special equipment, in addition, such a coating is afraid of exposure to ultraviolet rays.

That is why the owners of suburban buildings seek to insulate the foundation of a private house with the help of penoplex, which is cheaper, but strong enough and of high quality.

It is also popular to insulate a house from the outside with polystyrene foam because it does not require the use of special fasteners. For its reliable fixation, it is enough to use an adhesive composition similar to mounting foam. This is foam cement.

Execution of work

Knowing how to insulate the foundation from the outside, you can correctly choose the most suitable material and prepare the foundation.

This stage requires special attention, since the algorithm for performing work depends on the features of the constructed skeleton. In cases where we are talking about pile or columnar, then the construction of a brick wall will be required to fill the gaps between already installed piles or pillars:

1. You will have to dig a trench around the entire perimeter of the house, equip a sand cushion at the bottom of it, which will need to be carefully tamped.
2. The second stage is the laying of a reinforcing mesh, on top of which a concrete base is poured.
3. After 10 days, the concrete will gain strength and you can start laying.

Another option that is being considered when deciding how and how to make a warm foundation is to use slag or expanded clay. Having decided how to insulate the foundation of the house, you can begin to perform calculations and purchase materials.

Surface preparation begins with sealing all detected defects on the outer surface of the foundation base of an already constructed building.

For this purpose, you can use a sand-based plaster mixture, and the largest gaps can be filled with mounting foam. Primer is applied over the plaster. It should be a deep penetration compound that provides high-quality adhesion of materials. For more information about the insulation of the base, see this video:

Having made the final decision on how to insulate the foundation from the outside, you need to take care of arranging high-quality waterproofing. To process the foundation from the outside, coating materials such as bitumen mastic are needed.

Outside, the foundation is insulated in two layers

Now it's time to attach the first layer of polystyrene foam. It is necessary to apply an adhesive composition on it and press it firmly against the surface that we insulate.

All seams and joints are foamed, and after the foam has hardened, it is cut off and the entire pasted area is covered with reinforcing mesh to create a second layer of plaster.

To insulate the foundation from the outside, two layers of polystyrene foam are required. The final decoration will be:

• plates;
• panels;
• plaster and paint;
• tile.

Before choosing the best way to insulate the foundation of a built house, you need to decide how and how to insulate the area under it. To do this, you should know how to insulate the foundation, given that a lot depends on the quality of the floor. The penetration of cold air is possible from the underground or basement. Treatment of old floors, during which it is good to use modern insulating materials. For more information about the stages of work, see this video:

Considering various methods and options for warming the foundation, you can be sure that this process is not as simple as it might seem.

Failure to comply with the nuances of the technological process causes a violation of the microclimate in the room, heat loss, unjustified energy costs.

However, knowledge of the features of each individual structure and the building materials used for its construction will help to succeed. So, for example, a concrete base is insulated only from the outside, because cold air practically does not pass through it, but the false base of a pile foundation requires mandatory insulation of the inner surface.

Insulation of the basement of the foundation from the outside should be considered as a stage of general work on the thermal insulation of the building. Each enclosing surface has its own characteristics in terms of the nature of operation, the physics of heat transfer and the influencing factors. This affects the choice of materials and methods of insulation. What works well on a roof or attic is completely unsuitable for the foundation and its visible part - the basement.

The general scheme of complex insulation of the base of the house

Why is it necessary to insulate the basement

In its “pure form”, the basement is insulated if the house stands on a pile or screw foundation. At a strip or slab foundation, it is customary to carry out thermal insulation of the entire base of the house. The effect of warming only its visible (aerial) part in the conditions of central Russia is purely decorative.

If you look at the map of the depth of soil freezing, you can see that from the western border to the Urals it lies in the range from 1 m to 1.8 m. And in the Moscow region, the soil freezes up to 1 m 40 cm.

It looks like a map with isolines of freezing depth

It turns out that any shallow foundation for several months a year (up to six months, depending on the "severity" of the season) is entirely exposed to negative temperatures. Even the full-length foundation is mostly located in this zone. And this is bad for several reasons:

Thermal conductivity monolithic reinforced concrete is quite high, and the mass and area of ​​contact with cold air and earth is large. It turns out that the entire foundation is a large heat exchanger that is in direct contact with the ceiling and load-bearing walls. And if the walls are made of brick, and the floor is a reinforced concrete slab, then the heat loss is quite significant - up to 20%.

In the underground of the house pass engineering Communication- plumbing and sewerage. When they "rise" from the ground, they have to cross the freezing zone. Not to mention those cases when horizontal laying of communications on the first floor is carried out in the subfield. A cold basement and foundation create not the best conditions for this part of the water supply and sewerage system.

It is even possible to lay pipes on the plinth

And with reliable waterproofing in the micropores of concrete, and even more brick, there is always some moisture. When freezing, it expands, microcracks appear, which increase in size during the next thawing / freezing cycles. The number of such cycles that the material transfers without destruction determines the frost resistance index. No matter how great it is, there comes a point when this fortitude ends.

And the insulation of the foundation basement from the outside reduces heat loss, creates more “comfortable” conditions for the basement and engineering networks passing in the underground, moves the dew point from the wall to the insulation (thereby extending the life of the foundation). It is only important to choose the right way to insulate the basement of the house from the outside.

The pile foundation is not such a powerful heat exchanger, but its insulation will increase the overall level of protection of the house, and especially the first floor, from exposure to cold air.

Video description

Why it is generally necessary to insulate the foundation, as well as other necessary measures, is described in the following video:

The choice of insulation for the basement

The choice of materials for the thermal insulation of the base is not as great as for the walls. Due to its proximity to the ground, its operating conditions are more extreme than near the walls.

When calculating wind loads, it is taken into account that they are significantly lower near the ground. This means that the conditions for weathering excess moisture from materials are worse.

Almost always there is a higher level of intrinsic moisture content of materials. Rain and snow melt have an effect. There is also a capillary rise of water through micropores in concrete, in brick or in the plaster layer of the finish - it is not in vain that they carry out horizontal waterproofing of the basement before building walls. And the conditions for weathering excess moisture near the base are worse than near the walls - the wind speed and pressure are lower near the ground. Therefore, the use of mineral wool for insulation of the basement is eliminated both according to the “wet facade” technology and the ventilated facade technology.

Insulation for the basement of the foundation choose from three types of foam:

expanded polystyrene;

extruded polystyrene foam (EPS);

sprayed polyurethane foam (PPU).

Note! Usually, “in everyday life”, polystyrene means expanded polystyrene, but this is a whole class of cellular plastics from different polymers and varying degrees of rigidity.

In practice, extruded polystyrene foam is most often chosen. Conventional expanded polystyrene and hardened polyurethane foam have lower resistance to mechanical stress, higher water absorption coefficient and higher thermal conductivity.

The thermal conductivity and operational humidity of XPS is better than that of conventional foam

On our website you can find contacts of construction companies that offer foundation repair and insulation services. You can directly communicate with representatives by visiting the exhibition of houses "Low-Rise Country".

basement insulation technology

There are several ways to insulate the basement of a house, depending on its design and finishing method.

Insulation of the basement strip foundation

If we draw parallels with the insulation of the facade, then the basement of the strip foundation is insulated and finished in two ways - using the technology of a "wet" or hinged facade. But of course, the course of work has differences, ranging from the preparation stage to the decorative finish.

Preparatory stage

As mentioned above, the basement is the visible part of the foundation, and it must be insulated in combination with the underground part. This is best done during the construction phase before backfilling. If insulation is carried out separately or during reconstruction, then the foundation must be dug up to the sole and a full range of waterproofing and insulation should be carried out.

Important! Unlike the facade, basement waterproofing is included in the mandatory list of works before insulation.

The width of the trench must be sufficient so that a person can freely work in it.

Carrying out thermal insulation work for the basement of an already standing house is more difficult than during construction

Work procedure this stage is the following:

surface carefully cleared from the earth. Give it time to dry.

Clean up concrete spills("folds" from the irregularities of the formwork) or remove the remnants of the masonry mortar, if the base is made of bricks. Cleaned from dust.

Deep chips and gouges sealed with repair mortar. To do this, use special mixtures, which include modifiers that accelerate the hardening of the solution.

The walls are primed bituminous primer and wait for it to dry completely.

Cover the foundation to its full height roll waterproofing. The work goes from the bottom (from the sole) up, with the overlap of the strips along the horizon, and when building up along the length - vertically. Fixation to the wall occurs with the help of a gas burner, which heats the bitumen on the inner surface of the waterproofing strip. For reliability, the joints are additionally treated with bituminous mastic. And if the house stands on wet soils with a high level of top water, then pasting is carried out in two layers.

Waterproofing should be a continuous layer from the sole of the base and to the entire height of the base

Insulation with expanded polystyrene and EPS

The fundamental difference between how to insulate the basement of a house from the outside with polystyrene foam or XPS and how to insulate the underground part of the foundation lies in the method of attaching the plates.

The slabs are fixed to the surface of the underground part of the foundation exclusively with the help of an adhesive solution. The use of mechanical fasteners will damage the waterproofing, which is basically unacceptable.

As an alternative, you can use fixing the slab to the wall on the molten bitumen of the top layer of rolled waterproofing. But the method itself is quite risky and requires verified accuracy in handling the burner, and in order for the fastening to be reliable, the surface itself must be as even as possible.

Attention! It is necessary to use cold bituminous mastics for insulating joints or fastening insulation boards with extreme caution. Some types of ready-made compositions contain components that are aggressive towards polystyrene.

It is easier to fix the plates with a conventional adhesive solution, a layer of which allows you to compensate for small irregularities in the base. And this is the only way of fastening when the insulation is carried out in two layers.

Two-layer insulation is necessary for the basement

The fastening of the insulation to the above-ground part of the foundation takes place in a combination of glue plus mechanical fasteners (plastic dowel-umbrellas). If the backfill presses the insulation in the underground part, then on the surface the adhesion forces of the adhesive will not be enough for reliable fixation. In addition, there is no water pressure on the surface, which means that there are no conditions for its penetration through the fasteners into the materials from which the base is built.

After the expanded polystyrene plates are fixed over the entire surface of the foundation, backfilling is carried out and a blind area is equipped (insulated if the soils are heaving).

Video description

Once again about the choice between foam and XPS. It is better to choose extruded polystyrene foam. And why - well explained the author of the following video:

Finishing work

There are two types of finishes for the insulated basement of the strip foundation:

Plaster or tile. A layer of adhesive (approximately 3 mm) is applied to the surface of the expanded polystyrene and a fiberglass mesh is pressed into it. Apply another layer of the same thickness of the solution and level the surface. After the base has dried, the base is plastered or tiled.

hinged facade. A crate is mounted from a metal profile. To reduce heat loss, the brackets are blown with mounting foam. Sheathe the frame with panels.

Insulation of the base of the pile foundation

In this case, we are talking about the construction of a small closed subfloor under the floor of the first floor.

There are two types of insulation - external and internal.

External insulation is resorted to when a small wall of ordinary brick is built along the outer perimeter of piles (reinforced concrete or screw). For it, they can even cast a small reinforced concrete foundation. And in this case, the insulation technology is the same as for the base of the strip foundation.

A brick fence on a concrete base does not differ from a wall on a shallow foundation

Internal insulation is carried out when the base (or pick-up) is made in the form of sheathing piles on a wooden or metal frame.

Conclusion

Insulation of the basement from the outside is carried out as part of the complex work on the hydro- and thermal insulation of the foundation. To do this correctly, and not “by eye”, it is necessary to carry out calculations and develop a full-fledged project, taking into account the characteristics of the region, site and base design. And this is a task for specialists. However, as well as the performance of the work itself.

Solving the issues of thermal protection of the building in a complex, among all the options, contractors and owners most often choose the popular method of insulating the foundation of the house from the outside with polystyrene foam. There are other technologies, but unlike wall insulation, not all “usual” heat-insulating materials are used here - the features of operating conditions and a wider range of tasks impose certain restrictions. Since the foundation has not only an underground part, sometimes it is necessary to use a combination of several technologies. How and with what to close the foundation from the outside in order to reduce heat loss, we will consider in this article.

A warm house is the care of the owners Source vikonda.zp.ua

Why insulate the foundation

Thermal losses of the building through the foundation are small - from 5% to 15%. Its position and features of the "physics" of heat transfer affect.

About 15% of losses remain on the foundation and floor, but how much this is in absolute terms depends only on the owner of the house. Source ps-b.ru

There are only three ways to transfer thermal energy: radiation, convection (for gas and liquid media) and heat conduction.

Radiation is clearly not "about the foundation", but about the devices of the heating system. They have a higher temperature than the air and surrounding objects and serve as sources, not "sinks". But the walls of a heated room in the cold season radiate energy into the street in the infrared spectrum. To see this background, just look at them in the thermal imager. It is especially bright in non-insulated areas and "cold bridges".

It's so easy to see how heat escapes through uninsulated walls. Source rte-france.com

Natural convection is characterized by an upward flow of warm air and a downward flow of cold air. Of course, the temperature of the foundation cannot affect this process. Here it is important to insulate the roof and ceiling so that they do not quickly "cool" the warm air.

Of the above three ways of transferring thermal energy, it is “due to” the thermal conductivity of structural materials that a cold foundation affects heat loss and the cost of heating a house. And the thermal conductivity of reinforced concrete, from which the foundation is usually made, is quite high, so its low temperature is transferred to the walls and load-bearing partitions.

The air in the room cools due to the building envelope, which gives off heat to the environment. For the underground part of the foundation - this is soil, for the basement and walls - air. Insulation of the foundation reduces these losses.

Video description

Details about the heat loss of the building and the goals of insulation of the foundation are described in the video material.

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

Technologies and materials

There are only two types of foundation that are subject to insulation: slab and tape. For columnar and pile foundations, we can only talk about the thermal insulation of the floor of the first floor and the fence (basement) - a kind of screen that protects the underground. And directly piles and pillars are not insulated.

Plate

The technology of warming the foundation of the slab is no different from the thermal insulation of concrete floors on the ground:

solid foundation of compacted soil;

geomembrane as protection against capillary rise of groundwater;

crushed stone-sand cushion to improve the bearing capacity of the soil and the correct distribution of the load;

roll waterproofing;

sheet insulation (polystyrene foam or EPS);

XPS is the best material for insulating the foundation of the slab. Source rmnt.ru

On our website you can find contacts of construction companies that offer foundation design and repair services. You can directly communicate with representatives by visiting the exhibition of houses "Low-Rise Country".

The Swedes have slightly improved the technology and already at the stage of pouring the foundations they mount a "warm floor" in the slab. We often do it the old fashioned way - in a screed or under the finishing floor covering. The Scandinavians are “boring” people and already know in advance where they will have not only partitions, but also how the furniture will stand (one of the conditions for the correct operation of the “warm floor”). Our people have a different character - they are not only furniture, but also the inner walls are often moved from place to place.

Strip foundation

Warming of this type of base has a wider choice of materials and technologies:

fixed formwork;

fastening sheets of foam or extruded polystyrene foam;

spraying liquid polyurethane foam;

expanded clay backfill.

Among the insulation for the foundation, only one popular heat-insulating material is missing - mineral wool. When saturated with water, any kind of it loses its thermal insulation properties. And although it not only easily absorbs, but also easily releases moisture, it is impossible to create conditions for its weathering for the foundation.

Places of insulation of the foundation Source anticafe-sandbox.ru

Strip foundation insulation technologies

Each type of insulation has its own characteristics that dictate how it is used.

This is the only method of insulation that is possible only at the stage of construction of a monolithic strip foundation. In fact, this technology can be called "two in one", when the formwork of heat-insulating materials remains as part of the structure after construction is completed. Moreover, fixed formwork solves two problems - how to insulate the foundation of the house from the outside and from the inside.

Structurally, there are two types: block and panel. When pouring the strip foundation, shields are used. The blocks have walls and transverse wide lintels, which reduces the strength of the reinforced concrete base.

Ready-made kits have a set of polymer jumpers that can be used to adjust the width of the foundation Source visualizepicture.com

Such formwork is made from different materials, but most often they insulate the foundation of the house from the outside with polystyrene foam (regular or extruded).

In addition to the "clean" technology, there is a combined one, when the plates are not "connected" to each other, but are attached to a removable formwork.

The combination of removable and non-removable formwork is an increased strength for large volumes of concreting Source pobudova.in.ua

After they backfill the sinuses near the underground part of the foundation, they prepare a “trough” for the blind area from the compacted soil. And then according to the standard scheme: crushed stone, sand, waterproofing film, insulation (expanded polystyrene or XPS boards), formwork, reinforcement and concrete pouring. Instead of concrete, you can use paving slabs or gravel, but the insulation of the blind area, as part of the general work, is a must.

Insulation of the blind area will reduce the effect of heaving of the soil on the foundation Source decorexpro.com

Unlike the previous method, an already existing foundation is insulated. Therefore, there is only external insulation. Work is carried out both during construction and during the reconstruction or repair of a house.

Warming during the construction of a house is much easier than during reconstruction

The most difficult work has to be carried out during the repair. Before insulating the foundation of the house from the outside, it is necessary to dig out and clean the tape from the soil up to the heel. Then the steps go in the following sequence:

• Waterproofing is performed - first, a bituminous primer is applied, then strips of rolled materials are glued (soldered) from the bottom up with overlapping seams.

Note. It is better not to use bituminous mastics in tandem with sheet insulation - they are “fluid” and do not provide reliable fastening of the plates to the adhesive solution.

A cement-based adhesive is prepared, with its help the plates are fixed to the foundation. In the above-ground part, additional fixation with dowels is not necessary - only on the base. Direct fastening of plates using mechanical fasteners without an adhesive solution is unacceptable - the adhesive also serves as a “gasket” between polystyrene foam and bitumen, which is an aggressive medium for the polymer.

After backfilling and making the blind area, the basement is finished: a layer of adhesive solution is applied, reinforced with fiberglass mesh and plastered or tiled.

Video description

With the features of the technology of insulation with polystyrene foam can be found in the video:

Insulation with sprayed polyurethane foam

Among all polymeric heaters, sprayed polyurethane foam is the most expensive type. Its advantage is that the thermal insulation layer has no seams, and the foamed polyurethane has very good adhesion to all types of building materials.

The application of PPU on a surface cleaned of dirt is very fast. There are two types of materials: two-component and one-component.

In the first case, professional equipment is needed, the work of which consists in supplying both components under pressure to the working head, where they are mixed and foamed.

One-component PPU is produced in liter aerosol cans, and even an unprepared beginner can handle them correctly. But this technology is good for a small front of work, or when you need to apply a small layer up to 2 cm thick.

PPU spraying is similar to painting with an airbrush, so it is better to close the cladding of the house. Source ppuspb.ru

If the soils are dry, the level of the top water is low and competent drainage work has been carried out, then the waterproofing of the foundation and the basement can be omitted - there are no seams, and the water absorption of the cured polyurethane foam is small (no more than 2%). When finishing the basement with plaster, reinforcement is not necessary - there are no joints, like foam plates, and, therefore, there are no prerequisites for cracks to occur.

In addition to the price, PPU has another small drawback, which is a consequence of its dignity - good adhesion. When carrying out basement insulation work, it is necessary to protect walls that already have a finish (or do not require it) - this is easier than peeling off hardened foam.

Recently, this bulk material has rarely been used to insulate the foundation. Two factors limit its use: rather high water absorption and thermal conductivity compared to polymeric heaters.

The thickness of bulk thermal insulation can reach 60 cm Source obustroeno.com

The first indicator lies in the range of 8-20% of the volume. Moreover, such water absorption is typical for "fresh" expanded clay - over time it becomes even higher. For comparison, in ordinary foam it is no more than 4%. Therefore, it is necessary to waterproof both the foundation and the entire layer of insulation.

It is impossible to ensure complete “tightness” of expanded clay, and it will take a long time to dry underground, wrapped in a film - its use is not recommended in conditions of high seasonal groundwater rise.

Thermal conductivity also does not meet modern requirements for the thermal protection of buildings - 0.07–0.18 (W / m * ° C) versus 0.02–0.04 for PPU, 0.03–0.04 for PPS / EPS. Therefore, the recommended thickness of bulk thermal insulation for our mid-latitudes lies in the range of 40–60 cm.

The wiring diagram looks like this:

dig a trench of the estimated width (or clear the sinus of the pit) to the heel of the foundation;

a waterproofing film is laid over the entire area of ​​the trench - foundation-bottom-wall;

fall asleep and level expanded clay;

cover with a film on top;

pour a layer of sand;

make a blind area.

Typical scheme for warming the foundation with expanded clay Source sevparitet.ru

The advantage of expanded clay is environmental friendliness and low price. Although, taking into account waterproofing and a large amount of materials, the cost of work in the end will not be so low. In addition, the base will have to be insulated using one of the above methods.

Conclusion

The choice of a specific material and how to insulate the foundation of a house from the outside depends on many conditions - construction or repair, dry or wet soils, the depth of freezing and heaving, the volume and budget of work, the design and depth of the foundation. Therefore, such a task should be solved by professionals.