A shallow foundation "insulated Swedish plate" (USP) is a monolithic concrete slab with a water warm floor. This technology has appeared in Sweden, hence the name, has been improved and spread in Germany and other European countries. How to make such a foundation for your home?
Pros and cons of the "Swedish plate"
Advantages of the foundation
- Suitable for any soil, except peat.
- The ground beneath it does not freeze, due to this, the frosty whipping does not act on the foundation.
- The foundation is not buried, so the level of groundwater does not affect it.
- The plate does not form condensation, therefore, there are no conditions for reproduction of mold, moss, fungus.
- For its construction, heavy equipment is not needed except for a mixer for concrete, since it is better to use factory concrete.
- The warm floor and all communications are made in the process of laying the foundation, so time is saved. It is not necessary to make a special sub-space in which the pipes will pass.
- Thanks to heat insulation, heat does not leave the house into the ground, heating costs are reduced.
- The insulation keeps approximately the same temperature of the plate throughout the year, so there are no freezing and thawing cycles that reduce the durability of the concrete.
- The surface of the plate is smooth and smooth, so it can immediately be laid on the floor (parquet, carpet, tile, linoleum, etc.)
However, along with such advantages, difficulties arise, most of which are characteristic of all bases of the plate type.
- First of all, it is necessary to calculate as accurately as possible all communications that will be made inside the slab (water, sewerage, electricity), especially the points of their entry and exit. To calculate the communication it is recommended to contact the specialists.
- The plot must be level, without a slope, otherwise the cost of creating such a foundation will increase significantly.
- In the course of operation in a few years, repairs of the communications laid in the slab may be required. Getting to them will be difficult, it will require costly work.
- In such a house you can not build a high socle, the floor will be low above the ground.
- The Swedish plate for the house, where they do not live in winter, is not justified.
- The building materials required for the construction of UWP are quite expensive.
- "Swedish plate" is not designed for heavy large buildings (more than 2 floors).
To fill the foundation of an ordinary small private house, special knowledge is not required, but this is quite a difficult job, here we need helpers. With observance of the technology, the device of the insulated "Swedish plate" takes from two days to a week, plus the time for the hardening of the concrete. The video shows in stages how UBS is done.
Before pouring the slab, the soil is examined, the surface is cleaned of plants and debris. A layer of soil is removed about 40 cm. The bottom of the excavation is leveled and compacted well. Under the foundation of the USH, a gravel-sand cushion is poured.
First, it is desirable to pour a layer of clay about 10 cm and compact it. Clay plays the role of waterproofing, not allowing moisture from the ground to rise in the half-shell. Then pour small gravel, which will play the role of drainage. It is also condensed. Then put geotextiles on top and pour sand (large, quarry or gravel), which is compacted with a vibrating platform.
A sand cushion is covered with a layer of roofing material or waterproofing film (overlap). The heater will be laid from above.
On the perimeter of the foundation, a trench and a drainage pipe are excavated. This must be done regardless of the level of groundwater, as it may change with time. Also sometimes the drainage pipes are laid under the slab.
Warming and reinforcement
Heat insulation is put on a gravel pillow before pouring the plate, already on it is placed the reinforcement.
Special stands are used for it, so as not to damage the heater, which at the same time becomes a permanent formwork. These stands are on sale, they look like small plastic cups, you can also use ordinary wooden bars, the main thing is to raise the reinforcement by at least 50 mm.
The first grid is made with 10 * 10 cm cells. It is necessary to make two skeletons of steel bars not thinner than 12 mm.
The technology provides stiffeners under the bearing walls. In these places, the insulation is made 10 cm thick, under other areas - 20 cm, that is, one layer instead of two. Due to this groove, a stiffening rib is obtained (see the figure).
As a heater usually take expanded polystyrene (penokleks) - this is a modern material that has important advantages:
- Does not release harmful substances.
- Has a low thermal conductivity.
- It does not have fungi, moss.
- Does not crack.
- Passes the air.
- It has great compressive strength - this property is very important, because a large amount of concrete will apply pressure to the insulation from above.
It is also necessary to insulate the blind with a width of approximately 50 cm. This is done by burying the penoplex plates on the perimeter of the future house, laid in two layers with hydroisection between them. Above, they are covered with sand, then they can be concreted and laid out with tiles.
Water and sewer pipes are laid on a sand and gravel pillow. Previously, it digs the grooves for pipes. After their installation around the perimeter, formwork is installed from the boards, from the inside it is also spread with polystyrene foam. After hardening of concrete, the boards are removed, and the foam foam remains.
Mount the pipes of the warm floor after laying the first frame of the reinforcement. From the edge of the foundation retreat 15 cm.
The warm floor can be laid according to different schemes, which are shown in the figure.
To avoid reducing the pressure in the pipes, the contours do not make a length of more than 100 m. If it is necessary to make several loops, it is better to divide them into shorter ones and connect each one to the collector. The collector should be located in a heated room.
For a warm floor, you can use pipes from:
These materials have durability, strength, and are not subject to corrosion.
The closer the windings of the tube of the warm floor are located, the higher the temperature. According to the norms, the minimum distance between them is 10 cm, the maximum distance is 25 cm. The coils are more densely laid near the walls, in the center of the room - more rarely. After laying the pipes are connected to the manifold and pressurized to identify leaks.
Pressurization is carried out with air at a pressure of 5 atm or water. If air is used, then all compounds are smeared with soapy water so that a leaky area can be found by the appearance of bubbles. According to the technology, when testing the whole pipe must be rolled up and connected to the manifold.
In the future, you may need to build additional communications (wiring, internet, cable TV). Therefore it is advisable to lay several additional channels in advance, in which it will then be possible to pass the wires.
With the concrete pump pour a layer of concrete with a thickness of at least 10 cm, the thickness of the layer depends on the size of the house, that is, from the assumed load on the base. Concrete must be at least M350.
After settling for 2-2.5 hours, the surface is leveled with a concrete batching machine. Concrete freezes and collects a fortress for about a month.
The frozen plate is polished. After this, it will be possible to fill the pipes with water, the temperature of which should be gradually increased within three days.
UWB is a type of foundation, with the use of modern materials. It has many advantages, on it it is possible to build small houses from various materials practically on any ground. It is not suitable for heavy brick or concrete buildings more than two floors and for peat soil.
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