One of the cheapest methods for constructing a foundation is a strip structure. It can be made as a prefabricated structure (from individual reinforced concrete blocks), or a strip foundation for the house can be poured, done independently with the possible use of ready-made concrete mixtures.
Basic information about strip foundations
Strip foundations can be used in the construction of houses with or without basements. Either way, you get significant savings when choosing this type of foundation.
When constructing a basement, it is advisable to build a foundation in a ready-made pit using double-sided formwork; in this case, the foundation will play the role of basement walls.
A simpler method is to pour the structure into specially prepared trenches. In this case, you can save on the cost of formwork, because it is enough to install only its outer part, which, when using modern materials (formwork using extruded foam), will also become a reliable element of insulation and waterproofing.
The calculation of foundation parameters must be carried out by a civil engineer who will be able to calculate all design parameters depending on the condition of the soil, the presence of groundwater and other factors.
The entire technology of pouring a strip foundation can be divided into several stages:
- Preparing the base, installing formwork
- Manufacturing of reinforcing frame
- Pouring concrete mixture
Let's look at all these stages in more detail.
Preparatory and excavation work
The main issue of preparation is the calculation and purchase of necessary materials. If you decide to prepare the concrete mixture yourself, which will help somewhat reduce the cost of pouring a strip foundation, but will significantly increase the time of its construction, you need to bring the required amount of crushed stone, sand, and cement to the construction site.
In addition, before starting work, it is necessary to purchase formwork material and reinforcement; all this can be imported during the excavation process. In addition, to prepare concrete, you need to make sure you have a concrete mixer, which, in extreme cases, can be rented. But we would still recommend using ready-made concrete mixtures, which will greatly simplify the work.
As already mentioned, concrete can be laid either in trenches or in a foundation pit. In addition to the fact that constructing a pit will simplify the work on arranging the basement, in this case it is possible to arrange additional waterproofing of the building by installing a clay castle over the entire area, which will significantly reduce the access of groundwater to the building.
When performing excavation work, it is necessary to constantly monitor elevations; this will be the basis for the stability of the entire building.
The rules for pouring the foundation do not allow large differences in the base of the structure; of course, a small part can be corrected with the help of bedding, but for large volumes this will not give the desired effect.
In addition, trenches must be monitored along the axes of the building. To do this, they resort to the so-called cast-off, it is performed as follows. 2 m are retreated from the lines of the future walls, supports are mounted to which the boards are attached. Thus, we obtain a structure that follows the entire contour of the building, which facilitates excavation work.
Preparation of the base, installation of formwork
To reduce the impact of seasonal soil heaving, a sand cushion is installed along the entire perimeter of the foundation, which will serve as a shock absorber. It is performed to a height of 10-30 cm, followed by moistening and compaction; at this stage, the elevation marks of the base are finally adjusted.
The next stage is the construction of formwork; it can be made of various materials, in addition, the following types are distinguished:
- Fixed
- Removable
It is recommended to use expanded polystyrene formwork as a permanent formwork, which will act as insulation. Removable formwork is used mainly in large-scale construction and can be installed on a number of objects, although boards removed from the formwork can also be used in a private house.
Basic rules for installing formwork:
- Formwork panels must be installed vertically, this is checked with a plumb line or level.
- All structural elements must be carefully secured, otherwise, under the pressure of the mass of concrete, the formwork may lose its straightness or even collapse, which will lead to loss of concrete.
- When installing, do not forget to insert sleeves under future communications(electricity, water, sewerage).
- It is advisable to cover the surface of the formwork with inexpensive insulating material.
Pouring a strip foundation with your own hands will be more economical with high-quality formwork that prevents leakage of the concrete mixture.
The basis of a strip foundation, which increases its load-bearing capacity, is a frame made of reinforcement. Its diameter and location pitch must correspond to the project; it is not recommended to select such parameters independently.
The distance from the reinforcement to any external surfaces of the foundation must be at least 20 mm, thus forming a protective layer.
Reinforcement elements must be tied with special wire; welding is not permitted, since it deteriorates the structure of the reinforcement. You can tie the frame on the surface and, after installing it in the trench, connect its elements. This method allows you to perform work even in narrow trenches.
That, in principle, is all about the preparatory stages of pouring a strip foundation; you can proceed directly to the process.
The process of laying any foundation involves several stages:
- Site preparation and foundation marking
- Excavation work, trench digging, pillar drilling
- Preparing a pillow for the foundation
- Installation of reinforcement cage and construction of formwork
- Pouring concrete and leveling
I talked about what types of foundations for a house exist today in one of the previous articles, so I won’t dwell on this.
In this article I will talk in detail and step by step about pouring the most popular today - strip foundation and about the distinctive features of the stages of pouring other types.
Pouring the foundation yourself
There are several types of strip foundations, but the do-it-yourself pouring technology is almost the same for everyone.
Pouring concrete into a trench always starts from the corners, and then the remaining voids are filled.
The ideal conditions for pouring the foundation for a house is that the mixer has access to all corners of the house.
The mixer drives up to the corner and the pouring process begins. At this time, one person should hold the gutter, guiding it, and the other (preferably two) should help the concrete to be evenly distributed throughout the trench using a shovel, for example.
In order to expel air from concrete, you need to use a deep vibrator; if you don’t have one, then you need to vibrate using improvised methods. You can vibrate with a bayonet shovel, this vibration is called the bayonet method. A good result can be obtained by tapping with a hammer on the reinforcement frame, or on the formwork (not too much!).
After the trench is filled with concrete, it is necessary to trim the concrete in the right places before “setting” of the concrete occurs. After the concrete has become “Crumble” - it is not advisable to touch it.
As I said that pour the foundation for a house it won’t be difficult, at this stage we examined in detail the pouring of a strip foundation, the stages of which in most cases are suitable for pouring any type of foundation.
Features of pouring a columnar foundation for a house
A distinctive feature of a columnar foundation is that the foundation does not consist of a monolithic tape, but of pillars that are connected by a monolithic tape.
In this regard, after marking, the pillars are drilled using an auto drill or a hand drill; the pillars are reinforced with reinforcement with a diameter of 10-12 mm, with the reinforcement being released 15-20 cm above the level of the pillar.
After pouring the pillars, formwork for the grillage is constructed, connecting all the pillars, a reinforcement frame is created and concrete is poured into the formwork.
It should be recalled that a columnar foundation is constructed for light buildings and in “good” soil.
Features of pouring a slab foundation
A distinctive feature of a monolithic slab is that such a slab is located under the entire structure, and not just under the walls of the house.
In general, building a slab foundation with your own hands is not a difficult process, but it requires a responsible approach, and I believe that it can be moved to a separate article.
One type of monolithic slab is a slab foundation with stiffeners; the technology for pouring this type of foundation is not much different from a conventional one.
Markings are made along the perimeter of the house, then the soil is removed under the future house to the depth of the future slab + the thickness of the sand cushion.
Then it is necessary to build a sand or sand-gravel cushion, followed by compaction.
The reinforcement frame is knitted in two rows in the form of a mesh.
Pouring occurs in much the same way as with any other type of foundation.
Methods for pouring and methods for saving the foundation of a house
Depending on the use of your own labor, you can pour the foundation in three ways:
- Lay the foundation yourself, using only your own labor. This is, of course, a labor-intensive process, but not so much that it cannot be handled on your own. Ideally, 2-3 people will cope with all stages without much effort.
- Partially use someone else’s labor for some stages of pouring the foundation. This method is most common when building houses on your own; it involves the use of hired workers during particularly difficult stages of work. This will allow you to save on your own labor, but financially it will be a little more expensive.
- Entrust the pouring of the foundation for the house to professional workers. This is the most expensive method of pouring, but in this case you will not have to do anything except come to the site and control the process of laying the foundation, because even professionals sometimes do not adhere to strict technology for their own benefit.
- If you hire workers to perform individual stages of pouring the foundation for a house, then you should take into account that the most expensive stage is digging the soil and pouring concrete. If we talk about digging, then it’s up to you to decide whether this is a labor-intensive process and whether it’s worth saving on it. Well, you can save a decent amount on pouring the foundation if you invite a friend to help. In fact, pouring concrete is a dirty, but not very complicated process, which two or three people can easily handle in half a day, saving about 500 rubles each. from a cube of concrete.
- With a strip foundation, you can save on deepening; if you have a not heavy and small house (wooden, for example), then instead of a deep one, you can make a shallow strip foundation.
- You can save money on a slab foundation by making it thinner, but with stiffeners. I talked about a slab foundation with stiffeners in my previous articles.
- When laying a columnar foundation, you can only save on labor, because it is already the least stable compared to its brothers.
- In some cases, fiberglass reinforcement and its use will allow you to save a little on the foundation.
Among other types of foundation, strip foundation is the most common, which is especially true for private construction. Filling will not entail significant financial costs and is not extremely labor-intensive. If you are wondering how to properly pour a strip foundation, then you do not need to have the skills of a specialist, just have the desire and familiarize yourself with some of the rules for carrying out such construction.
The strip foundation is excellent for the construction of buildings in which it is planned to equip the ground floor, basement or underground, which cannot be said about pile-screw foundations. But if the house is supposed to be built on heaving soils, then the construction of a strip foundation will be very expensive, since it is preferable to build these types of foundations on dry soil, which, like wet soil, is not as prone to heaving. It is also impractical to produce to a significant depth, which is especially not required for oversized buildings - bathhouses or garages.
It is impossible to ignore the rules in the process of pouring a strip foundation or any other foundation, since almost 1/3 of the total construction cost is spent on the preparatory work of this part of the building.
It is necessary to familiarize yourself in advance with the rules for constructing a strip foundation. Initially, a soil analysis will have to be carried out, which will determine its type and depth of freezing, this will help to understand whether this type of foundation can be used in a certain area. Afterwards, it will be much more difficult to correct the mistakes made.
Tools and materials
- screws;
- crushed stone;
- sand;
- plumb line;
- shovel;
- nails;
- boards;
- fittings;
- tamping;
- knitting wire.
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Preparatory work
First, markings must be made and ground work must be carried out. The area needs to be cleared of debris. Using a construction project prepared in advance, the internal and external boundaries of the foundation should be marked on the soil surface. This can be done using available means: wooden pegs or reinforcement bars, as well as rope, which can be replaced with wire or fishing line.
Marking for strip foundation.
It is possible to pour a strip foundation correctly if the markings are done correctly, which should be done with perfect evenness in order to avoid more significant labor costs when moving the pegs. You should start marking by determining the axes of the future building. Using a plumb line, you need to mark the first corner, and from it you need to pull the wire to the remaining points of the base at right angles. Each angle must be checked by measuring the diagonals. If the angles match, you can place the pegs in their places so that you can stretch the wire between them. The same technology is used for internal marking. In order to obtain the most suitable base width, you should deviate 40 cm from the outer line.
After completing the marking of the strip foundation, you can proceed to the analysis of surface differences in the territory for development, this will allow you to select the lowest point. Knowing this data, it will be possible to calculate the depth of the trench, which will help to subsequently avoid differences in the heights of the base. If you plan to build an oversized building, it will be possible to build a pit, the depth of which is approximately 0.4 m.
The pit can be dug using a shovel or an excavator. This work should not be carried out “by eye”; it is necessary to check the evenness of the bottom of the trench, using a water level. We should not forget that the walls of the pit must also have ideal dimensions - during the process of arranging the trench it is necessary to ensure their verticality.
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Installation of formwork and reinforcement
The process of making a strip foundation.
The rules for pouring a strip base provide for pouring sand into the trench, which will reduce the load on the base in the off-season; such a cushion will distribute the load over the entire area. The sand should be filled with a layer of 150 mm, but no less, after backfilling, it should be leveled, checking the horizontal level. The pillow should be compacted by sprinkling it with water. The surface of the sand cushion can be covered with crushed stone. It is recommended to waterproof the resulting layers by laying roofing felt or polyethylene film, which will enhance the strength characteristics of the base.
Before pouring, it is necessary to manufacture and install the formwork; available materials are suitable for this, including plywood, boards, remnants of metal tiles, etc. The formwork elements should be fixed with screws or nails, the heads of which should be placed inside, which will make it easier to dismantle the structure, and the base walls will be smoother. The formwork should be installed so that its elements rise 30 cm or more above the soil surface. In the internal space of the formwork along its perimeter, you need to pull the cord at the level to which it is intended to fill.
Formwork diagram for strip foundation.
The pouring process must be accompanied by the arrangement of holes for water supply and sewer pipes, otherwise they will have to be cut through afterwards, which will result in a violation of the integrity of the concrete monolith.
Before pouring the strip foundation, you need to place reinforcement in the formwork. To do this, you need to tie the rods, which should have a cross-section of 12 mm, using knitting wire. It should be knitted so that the sides of the cells are equal to 30 cm. It is preferable not to use welding, since the welding points will be subject to corrosion, and knitting, among other things, can provide flexibility to the structure during ground movements. When laying reinforcement in a trench, it is necessary to ensure that a 5 cm indentation is left on all sides; this will allow the reinforcement to be positioned inside the monolith.
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The process of pouring a strip base
Scheme of foundation corner reinforcement.
The strip foundation should be poured only after it has been determined how much concrete will be needed. This can be determined by multiplying all the dimensions of the base. Concrete mortar can be prepared on your own; for this you need to mix sand (3 parts), crushed stone (5 parts), with 1 part of cement, the mixture should be diluted with water until the composition reaches the optimal consistency. But the best option would be to use factory-produced concrete, since pouring cannot be done on your own in one approach, which will cause the formation of “cold seams” and cold bridges; they will become places where water can seep in, causing destruction of the foundation. If the strip foundation will be poured using a machine, you should ensure that there is access from each corner of the formwork to carry out the pouring process. If the solution is ordered, then before you start pouring you should make sure that it has not yet hardened - if necessary, it will have to be diluted with water.
Rules according to which a strip foundation should be poured:
- Concrete must be poured little by little, each layer should be 20 cm wide.
- After pouring each layer, the solution should be compacted, where special tampers made of wood will be used, this will avoid the formation of voids in the monolithic layer. To do this, you need to tap the formwork walls.
- The strip foundation must be poured to the level of the cord previously fixed.
After the pouring and tamping work has been completed, it is necessary to level the surface of the base using a trowel.
The pouring rules require piercing the foundation in some places, for which you need to use reinforcement, this will free the solution from air.
After completing the steps, you should wait for the foundation to dry completely; this may take approximately 30 days. For this period, there are a certain number of rules that should be followed. If the weather is rainy, the foundation should be covered with polyethylene at night; you can use any other waterproof material; this will help prevent the cement from being washed away. If the weather continues to be sunny during the day, the surface of the base should be watered to prevent cracking of the top layer. The formwork must be dismantled no earlier than 14 days after pouring the base; it is recommended to carry out this work after a month.
You can correctly fill a strip foundation on your own, without resorting to the help of specialists, but to do this, you must follow all the rules so as not to subsequently correct mistakes made during the installation process. After all, some of them will be impossible to fix.
The foundation is the basis of every residential building. The operational characteristics of the building, its stability, strength and safety depend on its strength and reliability. After all, it bears the main load from the entire structure, which is why its competent construction is so important.
If the planned construction is small in size, all the necessary measures can be done independently. For construction or other large-scale construction, it is advisable to turn to professionals.
Preparation of materials
Usually for such work they use high-quality. You can make the mixture yourself, or you can order it ready-made. The process is quite labor-intensive, which explains the heterogeneity of the base filled in individual portions.
The composition of concrete for the manufacture of strip base includes:
- cement, gravel and coarse sand in a standard ratio;
- clean sand (river) for arranging a pillow;
- 2 cm planed board for making;
- and a steel rod 8-12 mm in diameter.
From marking to filling
Site marking
One of the important stages is. First, the site is cleared of foreign objects and small debris. Next, everything from the site is cut off to a depth of approximately 15 cm to limit further rotting processes in the basement of the building.
How is marking done?
- Find the location of the first corner of the building axis. Using a plumb line, pegs are installed: they can serve as suitable pieces of reinforcement.
- Find the following angles, second and third using twine and pegs. They install pegs there too.
- Stretch the cord towards the fourth from the previous ones, make the correct angle along the square, and also place a peg.
- Check the diagonals the resulting rectangle repeating the outer perimeter of the building. They should be even if the corners are built correctly.
- Similarly, outline the internal foundation, as well as its parts for individual components: porch, supports for columns, load-bearing walls.
- Install slats or planks of wood to align the markings in the horizontal plane, a rope is pulled through them.
Land works
Temporary supports must be provided to prevent soil from collapsing!
Formwork
Using a rope, mark the outline for. Install supports at the corners. This requires beams 5 centimeters thick.
The formwork is made from edged boards, which are connected using corners with screws or wooden blocks.
The corners and bars are located outside the formwork, the heads of the screws remain inside.
Armature
Welding violates the corrosion resistance of the material in the places where it is exposed, so its use is not recommended!
The process of pouring a strip foundation for a house
If concrete is ordered, the pouring is carried out at once, simultaneously. Layer-by-layer filling is done if the mass is prepared on its own.
Step-by-step pouring of strip foundation
- First, the concrete is prepared.
The sand is sifted, mixed with cement and water, stirred evenly. The prepared composition is poured into crushed stone, the amount of which is equal to the amount of sand. Mix well so that all the crushed stone is evenly moistened. - Concrete mixture is poured into the self-made formwork.
To ensure high-quality filling and prevent the formation of bubbles, the concrete is pierced with an iron rod and compacted with a wooden beam. It is more convenient to use a special construction mixer or with an attachment for this. - Fill the formwork with concrete mixture to the marked level.
To speed up the settlement of concrete, tap the formwork from the outside. - Smooth the surface concrete with a trowel or rule.
- The concrete surface is sprinkled with sifted dry cement powder.
You can do this evenly through a sieve. This procedure will ensure quick setting of the concrete surface and prevent its cracking or erosion. - Concrete is covered with covering material or regular burlap.
It is left in this form for about a month to ripen. If the weather is hot and dry, then the top cement layer is periodically wetted to avoid drying out.
Only after the final maturation of the concrete monolith can we move on to further construction and begin.
When the formwork is removed, it is necessary to perform high-quality work. This will improve the moisture-insulating and heat-retaining functions of the foundation, as well as increase its service life.
Useful tips
- It is better to make sure in advance that the ordered machine will pour concrete mixture from any angle.
- It is advisable to take care of making an additional tray: the composition will be supplied into it.
- The solution must be checked before pouring - sometimes it hardens a little during transportation.
- In the rain, take care of a reliable shelter, otherwise the top layer of cement may be washed away by jets of water.
To make the foundation correctly, you need to carefully study the options for construction types and their features. The construction of the underground part is carried out taking into account the following requirements:
- economic expediency;
- reliability;
- strength;
- durability;
- sustainability.
Before starting construction work, a soil study should be carried out. The choice of the right type of foundation is influenced by the total weight of the house, the strength of the soil and the groundwater level. A foundation that is carefully made and built in compliance with technology will last a long time and will not cause problems during operation.
Preparatory stage
It’s worth starting with pits or drilling. The main goal of this activity is to find out what soils are located on the site, as well as to find out the level of groundwater. The foundation must be laid in compliance with the rule: the mark of the sole must be at least 50 cm above the level of the water horizon.
How to do soil testing correctly? Two methods are used for this:
- excerpts of pits (deep holes, dimensions in plan are usually 1x2 m);
- manual drilling.
In the first case, the soil on the walls of the pit is examined. They also check to see if water has left the bottom. In the second option, the soil on the tool blades is examined.
Once you have determined what kind of soil is on the site, you will need to find its strength indicators. This can be done using special tables.
The cost of laying the foundation for a house can be up to 30% of the estimate for the entire building. To avoid cost overruns, you need to perform a calculation that will allow you to find the optimal design parameters that will simultaneously guarantee minimum costs, strength and reliability. For your convenience, you can use online payment.
Types of foundations
Building a foundation with your own hands involves the use of several technologies:
- ribbon;
- combined options.
Columnar supports have a low load-bearing capacity. It is possible to install monolithic pillars or assemble them into compact concrete blocks. Both options are great for DIY projects.
There are three types of pile foundation for a house:
- driven (not recommended for private buildings due to the need to attract equipment);
- (suitable for building a brick or concrete house);
- (ideal for light wooden buildings).
Piles make it possible to reduce the amount of excavation work. There is no need to dig trenches or a foundation pit or transport large amounts of soil outside the site. Thanks to this quality, installing this type of foundation is a very economical choice. The main disadvantage will be the impossibility of equipping a basement or underground for utilities. In this case, the base of the building is covered with decorative materials.
Another advantage of piles is the possibility of using them in wetlands. Even if the groundwater level is located close to the ground surface, the supports provide the necessary load-bearing capacity.
The next option is tape. It can be made monolithic or from blocks. The second option is rational to use for mass construction. Strip foundations are:
- recessed (for buildings with a basement, brick and concrete structures);
- (for wooden and frame houses);
- non-buried (technology of pouring foundations for small buildings on a solid foundation).
Before making a tape, it is worth checking the groundwater level and compliance with the rule that the sole cannot be closer than 50 cm to the groundwater horizon. Otherwise, there is a high probability of flooding of the basement, reducing the load-bearing capacity of the foundation and destruction of the materials of the supporting part of the building.
What to do with high groundwater level? If the structure is made independently from brick or stone, screw piles will not be suitable, and for bored piles it will be necessary to lower the water level. An excellent option would be filling. In this case, a non-recessed or slightly recessed base is made. The thickness of the slab is determined depending on the load, on average 300-400 mm.
How to pour a foundation for a house
Monolithic foundation type is the best option for private housing construction. In this case, laying can significantly save on transportation and installation of structures. There is no need to hire a crane to install elements in the designed position or a KamAZ truck to transport concrete blocks and slabs.
Monolithic foundations can be made from factory-made concrete or you can mix the solution yourself using a concrete mixer. The first option is recommended. The fact is that it is very difficult to strictly observe the proportions of the composition in artisanal conditions. For factory-mixed concrete, such a guarantor will be a passport, which indicates the verified indicators of the material.
To make the material yourself, you will need to prepare clean water, cement, sand and crushed stone (or gravel). They are mixed with each other strictly observing proportions, which depend on what grade of concrete needs to be obtained. If you add a little more sand or crushed stone to the composition than required, the strength of the supporting part of the building will suffer.
To properly pour the foundation, you need to familiarize yourself with the basic rules of concreting:
- Concrete must be poured in one go at time intervals of up to 1.5 hours. If you take long breaks in work, the solution sets and concreting joints form, which weaken the structure. The technology allows making horizontal seams if absolutely necessary. It is unacceptable to install vertical seams on a monolithic foundation, since in this case the support of the house will not be able to resist soil deformations.
- The class of concrete is chosen depending on the type of supporting part. For a columnar or pile foundation, class B 15 is sufficient. For tape, grades from B 15 to B 22.5 are needed. Construction of a house foundation using slab technology requires concrete grades B 22.5 or B 25.
- After pouring, the material should gain strength. On average, this takes 28 days. Construction work can continue after the structure reaches 70% of its original strength.
- It is better to carry out work in warm, dry weather. The ideal average daily temperature for concrete hardening is +25°C. At temperatures below +5°C the material practically does not harden. For normal hardening in this case, special additives and heating are used.
- The concrete must be maintained within 1-2 weeks after pouring. It involves wetting the surface with water.
- To mix the mixture yourself, you will need cement, sand, crushed stone (gravel) and clean water. The proportions depend on the strength class. The material is delivered from the factory using a concrete mixer truck - it allows you to extend the life of the solution and deliver it over relatively long distances.
How to pour the foundation correctly? In general, work is performed in this order:
- installation of formwork and reinforcement cage;
- laying waterproofing material in formwork;
- pouring concrete;
- its compaction by vibration or bayonet;
- curing;
- stripping works (if necessary).
To quickly complete the work, it is recommended to order a concrete pump together with a concrete mixer. Concrete manufacturers are usually willing to provide this technique. In this case, it is necessary to use a concrete mixture of grades P3 or P4 in terms of mobility. Otherwise, the equipment breaks down.
Step-by-step instructions for pouring a strip foundation
Concreting is considered using the example of a monolithic tape. To erect the supporting part of the structure, construction is necessary. To do this, use cast-offs and construction cord. You need to show the edges of the tape.
After marking, the soil is excavated. If there is no basement, it is enough to dig a trench. At its bottom you need to make a sand cushion. It performs several functions:
- ground leveling;
- prevention of frost heaving;
The edges of the trench must go exactly along the cord Next stage - . For this purpose, the material included in the estimate is used: boards (removable type) or polystyrene foam (non-removable). The second option serves not only as a form for pouring concrete, but also as insulation of the underground part of the building. When installing the formwork, I raise the base to the desired height.
