So that any building does not need repair for a long time, you need to worry about creating the most reliable foundation. This applies not only to the construction of the foundation, but also to its further insulation.
Thermal insulation is especially needed in cold regions (where the temperature drops well below zero for a long time). First of all, this applies to concrete bases: tape and slab.
Do I need to insulate, and why?
P before considering the methods of work and choosing which technology is better, you need to figure out why the thermal insulation of the base is needed, and whether it is needed at all.The technologies discussed below are equally relevant for those who learn how to insulate the foundation of a wooden house, and for buildings made of concrete, brick, and blocks.
Insulation of the foundation solves several problems at once:
Protects concrete from direct contact with moisture. It destroys the structure itself, and in addition leads to dampness in the basement (if any).
Protects the base from heaving of the soil.
Prevents freezing of a monolithic slab (or strip foundation).
The soil surrounding the foundation contains a certain amount of moisture. In different regions and in different areas, it will differ, but there is always water in the earth. And in contact with concrete, it will accelerate its destruction. The moisture contained in the pores of concrete freezes, turning into ice. Ice occupies a larger volume than water, that is, it expands. Over time, this leads to the appearance and increase of cracks.
Another problem that the insulation of the foundation solves is heaving of the soil. It occurs during a seasonal change in the weather: in sub-zero temperatures, the soil rises, after which (when warming) it sinks back.
This negatively affects the state of the monolithic slab, since constant pressure is applied to the concrete. This is of particular danger if the technology of work was violated when pouring the foundation (which happens often). In this case, the insulation of the foundation allows you to create a kind of protective layer that will take on the pressure of the soil.
The most serious reason why it is necessary to insulate the foundation from the outside is its freezing in winter. In frost, the soil freezes, taking heat from the stove. As a result, the floors in the premises of the first floor become cold, and it becomes cold and damp in the basement (if it is in a private house).
For the reasons mentioned above, we can firmly say whether it is necessary to insulate the foundation, and why. For capital buildings that must stand for more than 10 years, thermal insulation is definitely necessary.
Basic requirements for materials
At foundation heating can not be performed by any material.The main criteria are :
durability: thermal insulation work requires digging a trench around the entire perimeter of a private house, and doing this every few years is difficult and expensive);
water resistance: even in the presence of a protective structure (which covers the insulation from the ground), moisture can penetrate the heat insulator, which will degrade its effectiveness.
List of ways and general stages of work
At heat the foundation of the house from the outsidepossible in several ways :
Plate materials (polystyrene, expanded polystyrene, mineral wool boards).
Bulk materials (expanded clay).
Work can be carried out both at the stage of construction of a private house, and for an already finished building. The second option is better than the first: after construction, the foundation must stand for some time (about six months or a year, ideally, if we are talking about a two- or three-story residential cottage) in order to finally gain its shape. However, during construction, deadlines are very often “burned”, and therefore minimum holding periods are observed, after which work on the construction of walls begins immediately.
Regardless of how the foundation will be insulated, there are general rules and steps:
Ideally, around the entire perimeter, primer coating should be done. This is both cheap and time-consuming, and at the same time it will create additional protection for concrete from moisture.
Work (regardless of which technology is used) is easiest to carry out in the warm season. The weather these days should be dry, because you will have to work in a trench, and soaked earth will greatly complicate the task.
The use of board materials
The most common option is the use of plate materials. These include:
Insulation of the foundation with expanded polystyrene (or mineral wool) is the most popular option among those who wish to cope with the task on their own. Work can be done in two ways:
For self-tapping screws. The insulation sheet is attached to the surface of the plate. About 6-10 self-tapping screws are used per 1 m².
For glue. The plates are glued to the surface with a special solution.
The general rules of operation are as follows:
The insulation begins to be attached from any lower corner, horizontally (i.e., the next sheet is attached to the side, and not from above).
Each next row is mounted with a shift: so that the seams between the heaters do not create a continuous line).
The seams are glued with waterproofing tape (or construction tape).
Insulation of the base with polystyrene foam (video)
Application of sprayed insulation
TO This option includes the use of polyurethane foam. The technology has a significant drawback: do-it-yourself insulation of the foundation is difficult to implement: spraying requires special expensive equipment. Its purchase is unprofitable if thermal insulation of only 1 cottage is planned, even with all additional outbuildings.
For familiarization - let's figure out how to insulate the foundation of a house from the outside in this way:
At the place of work, the insulation itself is prepared (obtained by mixing two components
From a special installation, PPU is sprayed onto the surface, where it instantly hardens, turning into a dense foam.
Of the clear advantages of this method:
saving time (for 1 work shift, 1-2 workers can cover more than one hundred "squares", while fixing foam plastic can take more than 1 day);
does not require surface leveling;
creates a continuous layer (without seams, as between sheets of foam);
polyurethane foam is the “warmest” insulator (thermal conductivity is about 0.03 W / mK).
Base insulation with polyurethane foam (video)
The use of bulk materials
At warming the foundation with your own hands is easiest to do with the help of a bulk insulator - expanded clay.
A trench for such work will require a wider one. Expanded clay, as a heater, does not hold back cold well, and therefore a layer of 5-10 cm (as with the materials above) will no longer be enough. The recommended width of the expanded clay layer is 40-80 cm.
Consider, how to properly insulate foundation like this:
The bottom of the trench dug around the perimeter is covered with a waterproofing film (
Approximately 10-20 cm of rubble is poured to the bottom.
Fitted into rubble drainage pipe (to remove moisture that can enter the expanded clay layer.
The trench is backfilled with expanded clay.
Ideally, it is recommended to make a partition of brick, plastic or metal panels or slate,
and fill up expanded clay between the partition and the foundation. In this case, it will play the role of a barrier, preventing moisture from getting inside (on expanded clay).Installation of insulation protection
After the insulator is fixed on the surface, it is recommended to complete the insulation of the foundation with your own hands with a protective structure. As for expanded clay, it has already been mentioned above.
For polyurethane foam or sheet materials, work is performed as follows:
A wooden or metal frame is mounted - crate. It is attached to the foundation, and the insulation is installed (sprayed) between the frame.
On top of the frame, on the screws, a protective layer is attached. It can be slate, plastic or metal (if the metal is necessarily galvanized or stainless) panels or sheets.
As an option, you can build a brick partition in front of the insulation (as mentioned above).
Users of our portal have accumulated vast experience in building foundations. Starting from tape, pile, monolithic slabs and ending with the popular type -, and willingly share their knowledge with novice developers. was no exception and Turkish945. The user spoke in detail about all stages of the construction of an insulated slab foundation for a garage-workshop-boiler room, 7500x7500 mm in size.
Turkish945 Member FORUMHOUSE
I spent a long time analyzing which foundation to choose. As a result, I settled on the type of UWB. At first I thought about making a plate with stiffeners, then without ribs. But one thing bothered me - whether a 10 cm thick plate would withstand a point load from a TA (heat accumulator). Therefore, I decided not to engage in amateur performances, but to order a foundation project.
After the calculation, it turned out that the thickness of the slab should be increased to 20 cm, otherwise there is no guarantee that it will withstand the expected load. Judging that the savings of 30 thousand rubles. (the difference between the thickness of the slab is 100 and 200 mm) this is an unjustified risk, the user settled on the second version of the foundation.
The foundation is a layer between the building and the base, which redistributes the load from the house to the ground. The foundation should not be built by eye and not according to the principle “so the neighbor did”, but designed on the basis of data from a geological study of the soil (this will make it possible to find out its bearing capacity) and with the further collection of all loads from the building.
Having decided on the foundation project, the user hired an excavator to dig the foundation pit. In total, about 50 cubic meters of soil were selected and taken out. In addition, we managed to negotiate with the excavator and at the same time uproot the bushes and trees on the site. For this work, they gave 15 thousand rubles (at prices in the Moscow Region for 2015).
The height error at the bottom of the pit did not exceed 50 mm. Also Turkish945 asked the users of the portal what to do with the grooves at the bottom of the pit, formed after the work of the bucket: clean or tamp, as is, and then pour the “pillow”?
FORUMHOUSE participants advised to completely remove all loose soil.
The user also conceived with the help of hired workers to dig a trench (400x600 mm) around the perimeter of the foundation for drainage. Then lay the geotextile and start compacting the sand cushion. It was not possible to dig a trench, due to the lack of laborers ready to do this work.
Because Turkish945 from the very beginning he doubted the need for drainage, he decided to completely abandon it, saving 40 thousand rubles. Although this decision, according to our users, is very controversial, work has continued. Over the weekend, the user, with the help of a friend, took all the loosened soil out of the pit on a garden wheelbarrow.
Turkish945
When you look at the pit from above, it seems that there is very little loosened soil, and for two it is an easy job. As a result, we worked 4 hours without a break and were very tired.
Here's what happened after the removal of the soil.
Also, along the way, extruded polystyrene foam was unloaded (19 packs of 120x60x10 cm in size for slab insulation and 2 packs of 1160x580x50 mm for slab sides), which was brought to the site.
Having finished the preparatory stage, the user spread geotextiles at the bottom of the excavation and proceeded to form a sand cushion. To do this, he needed a vibrating plate ( Turkish945 rented it), but there was a hitch with the sand.
Turkish945 ordered sand from one "local" seller, who promised that he would bring eight cubic meters of clean sand at a price of 5 thousand rubles for KamAZ. As a result, sand with a large amount of stones and clay was brought to the construction site.
I had to manually sort out and throw out foreign inclusions. The work dragged on into the evening. The user also agreed with two laborers that on Sunday they would come to lay the sand.
Because the ordered sand is not enough, Turkish945, having received a discount for non-conformity for the first truck, he ordered a second car from the same seller, and ordered a third KamAZ with sand, just in case, from another supplier.
On Sunday morning, it turned out that laborers who had been hired the day before were being delayed. In order not to waste a day, the user got to work.
Turkish945
I rammed the sand with a vibrating plate weighing 85 kg. Made 4 passes in total. One pass took 30-40 minutes. Sand spilled with water.
By this time, two trucks with sand had arrived. The first - with sand from the seller, who deceived on quality, but gave a discount and swore that this would not happen again. The second truck is from a new supplier. Having unloaded two heaps side by side, Turkish945 I saw that the sand was again with clay. In addition, the pile, which, according to the first seller, should be 8 cubic meters in volume, looks exactly the same as the pile from the second seller, but who brought 6 cubic meters of excellent sand.
Bottom line: the first supplier has completely exhausted the credit of trust and said goodbye to him. Without waiting for the unskilled workers, who promised to arrive by this time, the user and his father-in-law began to take away the rest of the sand on their own.
To bring the layer thickness to "0", they drove in pegs with marks of the required level.
By order of the charter, Turkish945 I decided to call the laborers again and find out where they were. Having received the answer that they are already on the way, the work continued. As a result, the "assistants" arrived in the evening, and in ordinary clothes, and when asked how they were going to work in this form, they replied: "We only came to see the scope of work."
Having looked around, the guys immediately declared a price of 1000 rubles per 1 cubic meter of sand. This is about 30 thousand rubles. for two, for 2 days of work. Saying "goodbye", the developer refused their services.
After all the ordeals, Turkish945 found the guys who quickly scattered and compacted the sand at a price of 1500 rubles. per day per person. In total, 40 cubic meters of sand were used for the sand cushion.
Turkish945
We compacted the sand to the state of the slab. It turned out a flat and solid base.
The next stage is the marking of routes for engineering communications. For the convenience of work, the user made a simple device - “beacons”, driving a “weaving” nail into the caps from plastic bottles.
The “beacon” is stuck into the sand, and a roulette ring clings to the nail head.
This allows you to mark the tracks without assistance.
Track lines on the sand were marked with paint sprayed from an aerosol can along a stretched thread.
Having marked the routes, they dug trenches for engineering communications.
The main thing is to observe all the necessary slopes for sewer pipes. 2 cm per 1 linear meter for a pipe with a diameter of 110 mm and 3 cm per 1 linear meter for a pipe with a diameter of 50 mm.
Pipes (under water and heating mains) enter the foundation body in a sleeve - a pipe of a larger diameter. In this case, 110 and 160 mm. Moreover, the entrance of the pipes is deliberately made not at 90, but at 60 degrees. To do this, they took and connected two knees with an angle of 30 degrees.
To check the tightness of communications, you can muffle the outlets and pour water into the pipes. If the liquid level does not change, and there are no leaks at the joints, then the routes can be buried.
Having covered the communications with sand and rammed it, the developer laid out the insulation with the displacement of the plates.
Final variant.
Now we move on to knitting the reinforcing cage. To speed up work Turkish945 I ordered rebar, already sawn to the required dimensions.
Turkish945
When I saw the amount of rebar delivered, I realized that I had made the right decision. And I saved time, and I saved the tool, because I'm not sure that my "Bulgarian" would have withstood such a volume of work.
A special gun was rented for tying rebar, despite the skepticism on the part of portal users about this expensive equipment.
The most frequent complaints: the battery does not hold, does not knit well, the wire gets tangled, but Turkish945 was pleased with the performance of the pistol. According to him, the wire got confused only at the very beginning - the first 10 minutes of work, then, having "filled his hand", he knitted with a pistol without marriage.
As for the speed of work, it took about one hour to tie the reinforcing cage in increments of 25 cm with smoke breaks. And wire spools, costing 120 rubles, are enough for about 170 knots.
Being engaged in independent construction, you need to be prepared for various force majeure circumstances - a sharp change in weather conditions, etc. Arriving at the site one day to finish tying the reinforcing cage, the developer saw the following picture.
Insulation of a monolithic slab, as a technology, has already proven itself in Europe and in the post-Soviet countries. Shallow UWB is in demand in those geographic areas where a harsh climate prevails. The monolithic frame is poured on different types of soil foundations, including heaving ones, with a weak load-bearing capacity. At the same time, the main danger for a monolithic slab is a negative temperature, when the earth base rises, deforming the slab base. This leads to mechanical defects of the structure, unsuitability and accident rate. To avoid this, the insulation of the foundation slab by the horizontal method will help. About whether it is necessary to insulate the foundation, and how to do it, we will consider below.
The benefits of insulation
By insulating the foundation slab, durability and long-term operation are ensured without the need for intermediate repairs. For owners of apartments on the ground floor, houses, cottages, this problem occurs often, a project is needed to insulate the foundation with polystyrene foam. To avoid heat losses, the foundation slab is insulated. In what cases is the foundation insulated:
- ensure the level of waterproofing of the fundamental foundation;
- reduce the rate of thermal insulation losses;
- reduce the cost of heating a dwelling;
- prevent excessive formation of condensate on the surface of the bearing walls of the building. After all, condensate leads to the destruction of buildings, no matter how strange it sounds;
- make living conditions comfortable in an insulated building;
- stabilization of the temperature regime inside the premises, residential building.
Classification of materials for insulation
Very often, homeowners have many difficulties in choosing one or another material; foundation insulation turns into a problem. People get confused in names and properties, they mix thermal insulation characteristics, which only complicates the process for both parties when buying. In order to provide methodological assistance, we will consider the insulation of the slab foundation, materials and characteristics.
The material is selected depending on the characteristics of thermal insulation, climatic conditions of the region. The second point: the involvement of special equipment for spraying a chemical reagent - polyurethane on shallow surfaces. The third factor is the availability of financial resources, since the warming procedure is not cheap.
- Polyurethane foam: foam plexi boards for the foundation are a sought-after material among the rest of the line of heaters. Manufactured from oxygen-foamed plastic. The chemical mixture itself is made directly on the site during construction. There is a procedure for mixing two reagents for insulation. Styrofoam sheets or polyurethane foam have excellent qualities for storing thermal energy in a building, reducing noise levels, and increasing sound insulation. Not subject to the negative effects of moisture, resistant to ignition;
- polystyrene - insulation for foundation slabs at the base contains hygroscopic foam. Extruded foam is also used to insulate facades and other parts of structures. Tiled foam plastic has a low coefficient of strength and instability to mechanical damage on a shallow surface;
- XPS extruded polystyrene foam - insulation for foundation slabs: takes an honorable first place in terms of functionality and application. It is made in a standard rectangular shape. Sheets consist of a cellular structure. The material is able to withstand loads, is not subject to changes, is resistant to temperature changes. It is used for thermal insulation of the foundation with expanded polystyrene, and additional protection is not required. Presence of openings for removal of condensate and moisture.
Plate insulation
In order to insulate the fundamentals, granulated polystyrene foam (polystyrene) is used in shallow concrete. Also called warm concrete. The preparation of insulation for a slab foundation is possible both at the factory and directly at the construction site. It depends on the customer and the possibility of access of construction equipment to the site for insulation of the foundation with polystyrene foam.
In a slab foundation, it is recommended to use PPS with a density of at least 1200D. Project: for one cube of concrete mix: 0.3 tons of M400 cement, one cube of granulated polystyrene foam, 0.8 tons of sand, saponified resin as needed.
When laying concrete, the shrinkage rate is taken into account, one millimeter per meter. The thermal conductivity of the mixture will not be great. We need extruded polystyrene foam under the slab from below, but not from above. The foam must have a layer thickness of not more than 10.0 cm.
What to be guided by when choosing a material for insulation
Since not every product may be suitable for use as a heater, the choice should be guided by the following factors:
- water resistance indicator: the less the foam absorbs water, the longer it retains its useful properties, and vice versa. During the period of negative temperatures, water crystallizes, expands, changes the molecular structure of the element, violates the integrity;
- strength factor: data are important in the construction of a fundamental foundation on moving soil masses, rocks. The points are able to cause deformation, damage the foundation;
- resistance to various environments: each type of soil has features, composition, both chemical and biological. Because of this, the level and concentration of salt increases, which leads to premature destruction of the shallow insulation.
The technology (project) of insulation of the foundation with foam plastic also provides for laying from the inside. But the material must be fire resistant. When ignited, a minimum amount of toxic substances should be released. Often these vapors serve to induce suffocation in asthmatics.
The expiration date of the panel should not be lower than the expiration date of the finishing material. Otherwise, you will be forced to dismantle the layer ahead of schedule.
Foundation insulation is best done with extruded polystyrene foam. Thus, protect the building and keep warm.
Classic design of insulated foundation slab
- Compacted soil surface;
- geotextile layer;
- a layer of sand cushion with a depth of not more than 20.0 cm;
- a layer of crushed stone pillow with a depth of not more than 20.0 cm;
- 10 cm level of occurrence of a shallow concrete slab;
- waterproofing ball;
- a layer of insulation with a thickness of at least 5.0 cm;
- 35 cm monolithic slab;
- grillage made of concrete measuring 50 x 50 cm;
- metal rods of the third class with a diameter of at least 1.2 cm;
- a row of aerated concrete 37.5 cm wide;
- from the front, a row of facing bricks covering aerated concrete;
- ventilation gap 3.0 centimeters;
- waterproofing, insulation, grillage lining on a polystyrene base.
Characteristics of expanded polystyrene
The average life of expanded polystyrene is 30 years. If maintained, the house will last forever. The following factors negatively affect the term:
- the front surface on which the material will be glued is not leveled, there are air gaps, traffic jams;
- PPS plates are not made according to technology, do not have proper protection from the negative effects of ultraviolet radiation;
- before installation, the material lay in open space and was affected by weather conditions.
Heaters, regardless of the name and labeling, have an increased level of ignition. They belong to the third and fourth grade. Currently, most manufacturers add a chemical reagent such as antipyrine to the composition. The main feature is attenuation during ignition. The mark "C" is added to the standard marking.
- Abundant emission of smoke during combustion, during which cyanides and hydrogen bromide fall into the atmosphere;
- minimum water absorption rate;
- increased bending strength;
- warming function - the minimum heat transfer rate;
- interaction with petroleum products.
Neutral interaction with bitumen, cement, gypsum, lime, asphalt.
Insulation of the foundation is a simple project. It is enough to have a construction site with an entrance for equipment. Otherwise, you need to independently prepare the concrete mixture with the obligatory consideration of proportions and ratios. The initial stage may seem costly, but these costs will pay for themselves in full during the first year. Is it worth it to insulate the foundation slab with polystyrene foam sheets, definitely yes.
Some effective building technologies have been created recently. This is due to the appearance on the market of new materials with better or unique characteristics. Some of these techniques can be replicated by the average person with relatively little study of the relevant materials. In this article, we will consider the process of warming with our own hands the foundation of a private residential building, another, relatively small structure.
Why you may need to insulate the foundation slab
Improving the insulation parameters of a building will make it easier and cheaper to operate. Only this fact is quite enough to think about carrying out the corresponding work. Energy resources, despite temporary market fluctuations, will always be of high value. By reducing their consumption, it will be possible to count on significant savings in money.
It should also be noted that the correct engineering calculation will help to move the dew point beyond the contour of the main part of the building. This means that moisture will not condense inside the structures. Thus, after modernization, the conditions for the appearance and development of mold will worsen, hidden corrosion processes will stop.
Separately, it is necessary to consider the heaving of soils. It takes place during the winter. These mechanical influences are capable of creating great pressure on the structural elements of the building. High-quality insulation of the foundation slab will prevent such and other harmful effects listed above.
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Any technology becomes clearer on examples confirming the expediency of its application. In this case, you should pay attention to the foundation "insulated Swedish plate". Here are the main parameters of this foreign technique, which is increasingly used today in domestic private housing construction:
- It is a single structure made of cast concrete with reinforcement and stiffeners. It is installed on a pillow and surrounded by styrofoam boards.
- Sand is initially poured under the main insulation and on the sides of it.
- A system for collecting water and diverting it to drainage is preliminarily installed.
- The blind area along the contour reduces the load on the drainage complex.
- Ensuring comfortable temperature conditions is carried out using the "warm floor" system. It is built into the foundation at the stage of its creation.
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The name itself defines the country of origin of the technology. In Sweden, it has been successfully used for more than half a century, and in Russia, private individuals and construction companies have been using similar methods for about ten years. Such terms are quite sufficient for reasonable conclusions. Practical tests have confirmed the presence of the following features:
- This foundation construction technology is well suited for the construction of 1-2 storey houses. For higher buildings it is necessary to order an individual project. It will then have to be coordinated in all official instances.
- In order to completely eliminate the possibility of flooding the building during the flood period, it is necessary to install sand bedding of the required height. To determine it, you can use statistical data for the desired region with maximum levels. If necessary, additional measures are taken to improve the drainage and waterproofing system.
- On sandy soils, you can save money during the construction process. There is no need for a productive water drainage system.
- Working with concrete, as in all other similar cases, is recommended only during the warm period. It is possible to fill the foundation in winter, but this will be accompanied by increased costs and increase the risk of marriage.
- This design works especially well in combination with a “warm floor”. In particular, when the heating is turned off, even in the cold season, heat will remain in the house for 72 hours.
- A professional company can complete a full cycle of work in 3-4 weeks.
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Material for creating a high-quality insulating layer
You can make a choice based on analogues of materials that are used in Swedish technology. But first, let's rule out the unsuitable options:
- Mineral wools of different types do not have the necessary rigidity, strength and absorb water too well.
- Expanded clay, other materials from granules. They also will not work, as they cannot become a dense, moisture-proof basis for the future foundation.
- Polymeric foam materials that are created directly on the job sites. Some of them can be applied. But the implementation of such a project will require certain skills. You will also need special equipment.
By the method of elimination, we found the "winner" of this correspondence competition. This is foam polystyrene of factory production, penoplex. We list below those characteristics of the material that will be useful for solving the tasks:
- Its method of production implies the release of standardized products. Thus, if you purchase penoplex of a well-known brand, then there will be no doubt that each plate will have the same parameters.
- Accurate dimensions and low weight will facilitate transportation, storage, and installation operations.
- Uniform distribution of closed bubbles in the foam structure provides excellent thermal insulation properties. To produce a full-fledged insulation of a monolithic foundation, it will not be necessary to create a too thick layer.
- This material is durable and waterproof. Many types of plates are made from it with special grooves along the edges, which makes it possible to ensure the tightness of butt joints without additional means.
Warming of the slab foundation
We have found out the main parameters of this technique, so we can proceed to the description of the working operations. Consider the steps that are used to insulate the foundation slab:
- For this group of works, it will be enough to create a layer of high-quality foam plastic with a thickness of not more than 10 cm. It can be formed from two rows of plates that are stacked in a checkerboard pattern with a joint overlap of the joint areas.
- Site preparation should be carried out taking into account the geology of the site, soil characteristics. When creating a recess, the bottom must be made even, so it is recommended to use manual labor in the final stages.
- The sand is backfilled and compacted, after which a temporary formwork is installed, the first layer of concrete is poured without reinforcing elements.
- When the base has hardened, foam boards are laid on it in the order indicated above. They are covered with a thick plastic film on top. The seams between the individual strips are carefully sealed with wide adhesive tape.
- Next, the main foundation of reinforced concrete is created.
- After it hardens, foam boards are attached to the end parts with an adhesive composition.
The key to the longevity of any structure is a reliable foundation on which it is based. The “zero cycle”, that is, the construction of the foundation, is one of the most important stages of construction. Mistakes and shortcomings made during such work, neglect of technological recommendations or unjustified simplification of certain operations can lead to very unpleasant, and sometimes even catastrophic consequences.
One of the most common types of foundations is tape. It is quite versatile, suitable for most residential or commercial buildings, it is highly reliable, stable even on “difficult” soils. But he will show all these qualities only if the concrete tape is reliably protected from negative external influences. Unfortunately, not all novice builders know that the foundation of the house is in particular need of hydro and thermal insulation. One of the solutions to this problems - insulation foundation with polystyrene foam, the technology of which is quite accessible to everyone.
Why is the foundation insulated?
At first glance, it even looks paradoxical - to insulate a monolithic concrete belt, buried in the ground and somewhat rising above the ground in the basement. What's the point if there's no living quarters here? What difference does it make whether the “foundation is warm” or whether it remains open?
Unfortunately, such an amateurish look is not at all uncommon, and many site owners, for the first time in their lives, starting to independently build their own home, ignore the issues of thermal insulation of the foundation and do not even provide for the corresponding costs for these activities. Alas, in this way they are laying a "delayed-action mine" under their dwelling.
- The strip foundation is usually buried in the ground below the freezing level of the soil. It turns out that the temperature of the sole or the lower part of the tape throughout the year is approximately the same, but the upper part of the foundation, depending on the season, undergoes either heating or cooling. This unevenness in a single concrete structure creates the strongest internal stresses due to the difference in linear expansion of different sections. These internal loads lead to a decrease in the strength properties of concrete, to its aging, deformation, and the appearance of cracks. The way out is to ensure the approximate equality of the temperature of the entire tape, for which thermal insulation is necessary.
- An uninsulated foundation becomes the most powerful bridge for the penetration of cold from the outside to the walls and floors of the first floor. Even seemingly reliable thermal insulation of floors and facades will not solve the problem - heat loss will be very large. And this, in turn, is not only an uncomfortable microclimate in the residential area, but also absolutely unnecessary expenses for payment of energy carriers for heating. Conducted heat engineering calculations prove that competent insulation of the foundation provides up to 25 - 30% savings.
- Of course, high-quality concrete mortars have their own operational “reserve” in terms of frost resistance - this is the calculated number of cycles of deep freezing and thawing without loss of strength properties. But you still need to spend this “reserve” wisely, and it is better to protect the foundation to the maximum extent from the influence of negative temperatures.
- The insulated foundation walls will dampen less, as the thermal insulation layer will bring the “dew point” out. This - more one plus insulation tape.
- In addition to insulating the outer walls, conscientious builders also install a horizontal layer of thermal insulation, which will prevent the penetration of cold through the soil to the base of the foundation. This measure is aimed at reducing the likelihood of soil freezing near the belt, which is dangerous for swelling, the appearance of strong internal stresses in the reinforced concrete structure and its deformation.
- And, finally, the thermal insulation mounted on the walls of the foundation also becomes a good additional protection against soil moisture, and in addition, it becomes a barrier that protects the mandatory layer of waterproofing from mechanical damage.
To solve the problem of warming the foundation, a thermal insulation stand is placed on its outer wall - from the base (sole) to the upper edge of the base. No need to rely on the insulation of the foundation from the inside - this will not eliminate external influences in any way, and can only slightly improve the microclimate in the basement.
Start with waterproofing!
Before moving on to the technology of foundation insulation, one cannot help but touch on the issues of its high-quality waterproofing - without this, all the work can be done in vain. Water, in "alliance" with temperature changes, turns into a serious threat to the foundation of the house:
First of all, everyone knows the property of water to expand upon transition to a solid state of aggregation - upon freezing. The penetration of moisture into the pores of concrete at low temperatures can lead to a violation of the integrity of the structure, rupture, cracking, etc. This is especially dangerous in the basement and at a shallow depth of the tape.
- No need to think that soil moisture is pure water. A huge amount of organic and inorganic compounds is dissolved in it, which enters the soil with vehicle exhausts, industrial emissions, agricultural chemicals, spills of oil products or other liquids, etc. Many of these substances are extremely aggressive towards concrete, causing its chemical decomposition, erosion, crumbling and other destructive processes.
- Water itself is a strong oxidizing agent, plus it contains a lot of the mentioned compounds. The penetration of moisture into the thickness of the concrete will necessarily lead to the oxidation of the reinforcing structure - and this is fraught with both a decrease in the design strength and the formation of cavities inside the tape, which then turn into cracking and peeling of the outer layers.
- And in addition to all that has been said - water also causes a gradual washing out of the concrete surface - cavities, shells and other flaws are formed.
It is not necessary to rely on the fact that at the construction site the groundwater is located very deep, and does not pose a particular threat to the foundation. The danger lies much closer:
- Water that falls with atmospheric precipitation or falls on the ground in other ways (spill, melting snow, pipeline failures, etc.) forms the so-called filtration layer, by the way, the most dangerous in terms of aggressive chemical terms. It happens that in the thickness of the soil at a shallow depth there is a waterproof clay layer, which leads to the creation of even a fairly stable surface water horizon - perched water.
The moisture concentration in the filtration layer is a variable value, depending on the time of year and settled weather. The most important role in reducing the negative impact of this layer on the foundation will be played by the organization of proper storm sewers.
- The second level is a fairly constant concentration of capillary moisture in the soil. This is a fairly stable value., which depends on the time of year and the weather. Such moisture does not have a washing out effect, but its capillary penetration into concrete is quite possible if the foundation is not waterproofed.
If the site is characterized by high humidity, for example, is located in a swampy area, then waterproofing is not limited - need to protect the foundation is also the creation of a drainage system.
- Underground aquifers are very dangerous for the foundation. True, they are also quite stable in their location, but in terms of occupancy they depend on the time of year and the amount of precipitation.
If at the construction site there is a tendency for such layers to lie close, then very high-quality waterproofing and a drainage sewerage system will be required - here the effect of water may not be limited to simply penetrating concrete, but also cause serious hydrodynamic loads.
An approximate scheme for waterproofing the foundation is shown in the figure:
1 - sand and gravel pad on which the foundation strip (2) is based. This pillow also plays a role in the overall waterproofing scheme, performing the functions of a kind of drainage.
The diagram shows a block strip foundation, therefore, a layer of horizontal waterproofing (3) is provided between the sole tape and the laying of blocks (4), which excludes capillary penetration of moisture from below. If the foundation is monolithic, then this layer does not exist.
5 - coating waterproofing, on which roll pasting (6) is laid on top. Most often, in private residential construction, tar mastic and modern types of roofing material on a polyester fabric base are used in pairs.
7 - a layer of thermal insulation of the foundation, which in the upper basement is additionally covered with a decorative layer - plaster or facing panels (8).
From the foundation begins the construction of the walls (9) of the building. Pay attention to the obligatory horizontal "cut-off" layer of waterproofing between the foundation and the wall.
To perform waterproofing work, the foundation tape is exposed to the very sole - this will also be required for its further insulation.
Within the framework of this article, it is impossible to talk about all the nuances of waterproofing work - this is a topic for a separate consideration. But still, it would be advisable to give recommendations on the optimal use of waterproofing materials - they are summarized in the table:
| Type of waterproofing and materials used | resistance to cracking (on a five-point scale) | degree of protection against groundwater | room class | |||||
|---|---|---|---|---|---|---|---|---|
| "perch" | soil moisture | ground aquifer | 1 | 2 | 3 | 4 | ||
| Gluing waterproofing with the use of modern bituminous membranes based on polyester | 5 | Yes | Yes | Yes | Yes | Yes | Yes | No |
| Waterproofing using polymer waterproof membranes | 4 | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
| Coating waterproofing using polymer or bitumen-polymer mastics | 4 | Yes | Yes | Yes | Yes | Yes | Yes | No |
| Plastic coating waterproofing using polymer-cement compositions | 3 | Yes | No | Yes | Yes | Yes | No | No |
| Rigid coating waterproofing based on cement compositions | 2 | Yes | No | Yes | Yes | Yes | No | No |
| Impregnating waterproofing that increases the water repellency of concrete | 1 | Yes | Yes | Yes | Yes | Yes | Yes | No |
The table shows 4 classes of buildings:
1 - technical buildings, without electrical networks, with a wall thickness of 150 mm or more. Damp spots and even small leaks are acceptable here.
2 - also technical or auxiliary buildings, but already with a ventilation system. Wall thickness - not less than 200 mm. Moisture spots are no longer acceptable, only slight damp evaporation is possible.
3 - this is the same class that is of interest to private developers - it includes residential buildings, social buildings, etc. The penetration of moisture is no longer allowed in any form. Wall thickness - at least 250 mm. Natural or forced ventilation is required.
4 - objects with a special microclimate, where a strictly controlled level of humidity is required. In a private building, you will not have to meet this.
It should not be concluded from the table that one of the indicated layers is sufficient. Optimal for the foundation, we repeat, will be a combination of coating and gluing waterproofing - this will create a reliable barrier against moisture penetration.
After the foundation has received reliable waterproofing, you can proceed to its insulation.
Expanded polystyrene as insulation for the foundation
Of all the variety of thermal insulation materials, it is polystyrene foam that is the best choice for use precisely in conditions of foundation work - with inevitable contact with moisture, with load soil, etc. . There are other technologies, but if we consider in the context of independent work, without the involvement of craftsmen and special equipment, then, in fact, there is no reasonable alternative.
One of the best representatives of the class of extruded polystyrene foam - "Penoplex"
It should be noted right away that this will not be about expanded polystyrene, which is often called polystyrene foam (it is of little use for such use), but about extrusion types of polystyrene foam. Most often, for the insulation of the foundation, they choose "penoplex" - plates of a certain size and configuration, which are very convenient to work with.
Penoplex prices
penoplex
The advantages of "penoplex" are as follows:
- The density of this material lies in the range from 30 to 45 kg/m³. It is not difficult during installation, but this does not at all mean the low strength of such expanded polystyrene. So, the force for deformation by only 10% reaches from 20 to 50 t/m². Such a heater will not only easily cope with the pressure of the soil on the walls of the foundation tape - it is even laid under the seam or used as an insulating base when pouring a monolithic slab foundation.
- The material has a closed cell structure, which becomes a very good additional waterproofing barrier. Water absorption "Penoplex" does not exceed 0.5% during the first month, and does not change in the future, regardless of the duration of operation.
- Extruded polystyrene foam has one of the lowest thermal conductivity values - a coefficient value of about 0.03 W / m² × ° С.
- "Penoplex" does not lose its outstanding performance characteristics in a very wide temperature range - from - 50 to + 75 ° C .
- The material is not subject to decomposition (except for exposure to organic solvents, which is very unlikely in soil). It does not emit substances harmful to humans or the environment. Its service life in such conditions can be 30 years or more.
Penoplex can be of several modifications designed to insulate certain elements of the building. For example, fire retardant additives are included in some types of additives that increase the fire resistance of the material. This is not required for foundation work. For insulation, "penoplex" of the brand "35C" or "45C" is usually purchased. The numbers in the marking indicate the density of the material.
Release form - panels, most often orange. The size of such plates, 1200 × 600 mm, makes them very convenient for installation. The thickness of the panels is from 20 to 60 mm in increments of 10 mm, as well as 80 or 100 mm.
Plates of this "foam" are equipped with a locking part - lamellas. This is very convenient when laying a single insulating surface - the lamellas, overlapping one another, block the cold bridges at the joints.
Penoplex is the best solution for foundation insulation!
This insulation is produced in several modifications, each of which is designed for thermal insulation of certain elements of the building. Including in this line is presented and "Penoplex-Foundation".
More about - in a special publication of our portal.
How to correctly calculate the insulation of the foundation polystyrene foam
In order for the insulation of the foundation to be of really high quality, it must first be calculated - for a specific building and for the region in which it is being built.
It has already been said that a complete thermal insulation of the foundation should consist of at least two sections - vertical and horizontal.
The vertical section is expanded polystyrene plates fixed directly to the outer walls of the foundation tape - from the sole to the upper end of the basement.
The horizontal section should form a continuous belt around the perimeter of the building. It can be located in different ways - at the level of the sole with shallow tapes, or at another level above the freezing point of the soil. Most often, it is located just below ground level - it becomes a kind of basis for pouring a concrete blind area.
The diagram shows:
- Green dotted line - ground level;
- Blue dotted line - the level of soil freezing, characteristic of a particular area;
1 - sand and gravel cushion under the foundation tape. Its thickness (hп) is about 200 mm;
2 - foundation tape. Depth (hз) can be from 1000 to 15000 mm;
3 - sand filling in the basement of the building. It will subsequently become the basis for laying the insulated floor;
4 - a layer of vertical waterproofing of the foundation;
5 - laid layer of thermal insulation - foam boards;
6 - horizontal section of foundation insulation;
7 - concrete blind area along the perimeter of the building;
8 - finishing of the basement part of the foundation;
9 - vertical "cut-off" layer of basement waterproofing.
10 - the location of the drainage pipe (with her need).
How to correctly calculate how thick the insulation layer should be? The methodology for calculating thermal parameters is quite complicated, but two simple methods can be given that will give the required values with a sufficient level of accuracy.
A. For a vertical section, you can use the formula for the total resistance to heat transfer.
R=df/λb + du/λp
df- the thickness of the walls of the foundation tape;
du- the desired thickness of the insulation;
λb- coefficient of thermal conductivity of concrete (if the foundation is made of another material, accordingly, the value for it is taken);
λp- thermal conductivity coefficient of the insulation;
Because λ - tabular values, foundation thickness df we also know, we need to know the meaning R. A this is also a tabular parameter, which is calculated for various climatic regions of the country.
| Region or city of Russia | R - required heat transfer resistance m²×°K/W |
|---|---|
| Black Sea coast near Sochi | 1.79 |
| Krasnodar region | 2.44 |
| Rostov-on-Don | 2.75 |
| Astrakhan region, Kalmykia | 2.76 |
| Volgograd | 2.91 |
| Central Chernozem region - Voronezh, Lipetsk, Kursk regions. | 3.12 |
| St. Petersburg, northwestern part of the Russian Federation | 3.23 |
| Vladivostok | 3.25 |
| Moscow, central part of the European part | 3.28 |
| Tver, Vologda, Kostroma regions | 3.31 |
| Central Volga region - Samara, Saratov, Ulyanovsk | 3.33 |
| Nizhny Novgorod | 3.36 |
| Tataria | 3.45 |
| Bashkiria | 3.48 |
| South Ural - Chelyabinsk region. | 3.64 |
| Permian | 3.64 |
| Ekaterinburg | 3.65 |
| Omsk region | 3.82 |
| Novosibirsk | 3.93 |
| Irkutsk region | 4.05 |
| Magadan, Kamchatka | 4.33 |
| Krasnoyarsk region | 4.84 |
| Yakutsk | 5.28 |
Now counting T t of the required thickness of the insulation will not be difficult. For example, it is necessary to calculate the thickness of "foam" to insulate a concrete foundation with a thickness of 400 mm for Central Black Earth district (Voronezh).
According to the table we get R = 3,12.
λb for concrete – 1.69 W/m²×° WITH
λp for foam of the selected brand – 0.032 W/m²×° WITH (this parameter must be indicated in the technical documentation of the material)
Substitute in the formula and calculate:
3,12 = 0,4/1,69 + du /0.032
du \u003d (3.12 - 0.4 / 1.69) × 0.032 \u003d 0.0912 m ≈ 100 mm
The result is rounded up, in relation to the available dimensions of the insulation boards. In this case, it would be more rational to use two layers of 50 mm each - the panels laid “in the dressing” will completely block the cold penetration paths.
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