The Swedish slab is an insulated monolithic slab foundation of shallow depth. main feature This technology is that the entire foundation of the house is based on a layer of insulation (under the slab). Under warm home the soil does not freeze and does not heave. Such a foundation is suitable for any soil, at any depth. groundwater.
This technology is based on the basic principles of design and device shallow foundations on heaving soils described in Organization standard (STO 36554501-012-2008), developed by the Research, Design, Survey and Design-Technological Institute of Foundations and Underground Structures (NIIOSP) named after. N.M. Gersevanov (FSUE Scientific Research Center "Construction"), FSUE "Fundamentproekt", Moscow State University. M.V. Lomonosov (Faculty of Geology, Doctor of Technical Sciences L.N. Khrustalev) and technical department LLC "PENOPLEX SPb".
The “Swedish stove” technology combines the construction of an insulated monolithic foundation slab and the possibility of laying communications, including a water floor heating system. An integrated approach allows you to get short time insulated base with built-in engineering systems and a flat floor, ready for laying tiles, laminate or other covering.
The main advantages of an insulated Swedish stove:
- The construction of the foundation and the laying of communications are carried out during one technological operation, which makes it possible to reduce construction time.
- The ground surface of the foundation slab is ready for laying flooring;
- The PENOPLEX FOUNDATION® thermal insulation layer, about 20 cm thick, reliably protects against heat loss, which means a significant reduction in home heating costs and an increase in the efficiency of the “warm floor” system;
- The soil under the insulated slab does not freeze, which minimizes the risk of frost heaving problems in foundation soils;
- Laying the foundation does not require heavy equipment or special engineering skills.
Installation features
To provide normal operation insulated Swedish slab (USP) and to prevent frost heaving, it is necessary to provide a groundwater drainage system ( drainage system along the perimeter of the building). An important role is also played by a non-heaving preparation device (a bed of coarse sand, crushed stone). If a combination of layers of crushed stone and sand is used, it is necessary to provide for the separation of these layers with geotextiles (when the fine fraction soil is located above the larger fraction). All necessary communications (water supply, electricity, sewerage, etc.) and inputs must be laid under the slab in advance.
The design of the Swedish slab involves the transfer of all loads from the structure (its own weight, operational loads, snow, etc.) to the insulation layer, which is why to the used thermal insulation material are presented high requirements in terms of strength. The most rational option for use in this design is thermal insulation boards PENOPLEX FOUNDATION®, with almost zero water absorption and high strength for compression.
Instructions for use:
- Step 1. Removing the top layer of soil (usually about 30-40 cm);
- Step 2. Compacting sand and gravel preparation (coarse sand, crushed stone);
- Step 3. Installation of drainage around the perimeter of the structure and pipes engineering communications;
- Step 4. Laying side elements and PENOPLEX FOUNDATION® slabs in the base;
- Step 5. Installation reinforcement cage on stands;
- Step 6. Laying pipes for the floor heating system, connecting them to the collector and pumping air into them;
- Step 7. Filling the monolithic slab with concrete mixture.
The heating system integrated into the foundation design provides comfortable conditions indoors. And the use of durable and absolutely moisture-resistant PENOPLEX FOUNDATION® slabs as foundation preparation will significantly increase the thermal reliability and efficiency of the heated floor system. Can be used as a coolant in the system plain water or antifreeze (if in winter period time in the room it will not be possible to always maintain a positive temperature). Almost all types of pipes can be used as heating pipelines in water heated floor systems: metal-plastic, copper, stainless steel, polybutane, polyethylene, etc.
When laying heating pipes, the following rules are followed:
- Higher thermal power Warm floors are achieved by denser pipe laying. And vice versa, that is, along the outer walls the heating pipes should be laid more densely than in the middle of the room.
- It makes no sense to lay pipes more densely than every 10 cm. More dense laying leads to a significant overuse of pipes, while the heat flow remains practically unchanged. In addition, a thermal bridge effect may occur when the coolant supply temperature becomes equal to the processing temperature.
- The distance between heating pipes should not be more than 25 cm to ensure uniform temperature distribution over the floor surface. To prevent the “temperature zebra” from being perceived by a person’s foot, the maximum temperature difference along the length of the foot should not exceed 4°C.
- The distance between heating pipes and external walls must be at least 15 cm.
- It is not recommended to lay heating circuits (loops) longer than 100 m. This leads to high hydraulic losses.
- Pipes cannot be laid at the junction monolithic slabs. In such cases, it is necessary to place two separate contours on opposite sides of the joint. And pipes crossing the joint must be laid in metal sleeves 30 cm long.
The slab base can withstand significant external influences and is suitable for construction in areas with complex, unstable soils prone to frost heaving, with high level groundwater. Insulating the foundation slab will help to significantly reduce heat loss through the base and reduce the impact of frost heaving of the soil. When the soil moves, the building rises and falls along with the foundation, which protects the house structure from the formation of cracks.
general information
The design of the slab base consists of layers:
- geotextile is covered with overlapping strips on the sand layer, the joints are taped;
- pour crushed stone in a layer of 15-20 cm;
- pour a leveling layer cement mortar, thickness 5-10 cm;
- be sure to isolate the structure from moisture using rolled or coating materials;
- arrange a heat-saving layer;
- cover plastic film stripes overlap by 20 cm;
- lay the reinforcing mesh;
- poured with concrete.
Installation and insulation of slab monolithic foundation expensive due to high consumption building materials. When the soil freezes greater depth and requires significant depth strip foundation, the installation of the slab will be cheaper and less excavation work will be required.
Advantages of a slab foundation
The slab base has the following advantages:
- the concrete slab serves as the floor of the first floor, which further reduces the cost of its installation;
- is an excellent option for the foundation of a house, the construction of which is carried out on floating soils; the slab and the entire house along with it move simultaneously with the soil;
- the slab can be mounted on any type of soil, even on peat bogs and marshy areas;
- the slab is erected above the soil freezing level, thanks to the sand cushion, frost heaving has virtually no effect on the structure;
- reinforced concrete slab is not subject to shrinkage;
- suitable for the construction of buildings up to 3 floors.
Insulating the foundation slab reliably protects it from deformation during seasonal soil heaving and extends the life of the structure.
Advantages of slab insulation
Polystyrene foam, polystyrene foam, and polyurethane foam are used as thermal insulation materials. Mineral wool not suitable due to its low strength and high degree of moisture absorption.
There is a technology for installing a Swedish stove. The main difference is that concrete structure It is built on a layer of heat-saving material, thanks to which the soil under the house does not freeze or heave.
The main advantages of the Swedish stove are:
- the construction of the foundation and the laying of communications are carried out in one technological cycle;
- the heat-saving layer allows you to increase the efficiency of the heated floor;
- installation of the foundation is carried out without the involvement of a large amount of construction equipment.
A drainage system consisting of pipes for draining rain and melt water is provided around the building.
The design of the slab helps to transfer all the loads from the building to the layer of heat-saving material, therefore increased demands are placed on the materials used.
Disadvantages of a slab foundation
A slab foundation is not always the best option. Always do everything in advance necessary calculations and select the most suitable type of foundation for your home.
Disadvantages of the stove:
- not suitable for construction on sloped areas;
- to build a house with a basement on a slab, you need to dig it to a great depth, this will be very expensive;
- it is difficult to repair communications carried out under the foundation slab;
- during construction in winter, additional costs will be required for heating concrete and maintaining desired temperature Location on.
A slab foundation is erected only when it is impossible to install a strip foundation.
Insulation materials
The table shows the materials used to insulate the foundation slab and their characteristics:
| № | Thermal insulation material | Characteristics |
|---|---|---|
| 1 | Styrofoam | Consists of cells filled with air. Available in the form of sheets, it has insufficient density, so its surface needs additional protection. |
| 2 | Extruded polystyrene foam | Able to withstand significant compressive loads without changing its size and structure. It is produced in the form of rectangular sheets with small cells filled with air. Lay the sheets in 1 or 2 layers. The second layer must be laid out so that the seams of the sheets of the first and second row do not intersect. During installation, provide holes for moisture drainage. |
| 3 | Polyurethane foam | It is a type of foamed plastic with many pores filled with air bubbles. The composition is prepared directly at the construction site. The two components are mixed, resulting in a dense, solid foam that is applied to the surface. The slab insulated with polyurethane foam has high thermal and sound insulation properties and can withstand moisture. Refers to low-flammable materials, and some brands are difficult to burn. |
Most often, extruded polystyrene foam is used as insulation under the foundation slab.
Installation of insulated slab
The construction of a monolithic slab foundation requires performing all calculations taking into account geological, climatic conditions and masses of housing construction.
Insulating a slab foundation allows you to save significant money on heating the room during operation.
Site preparation
At the creation stage of the project, it is necessary to take into account that the area for the foundation slab must be wider than the house building by at least 1 m on each side.
Instructions for performing preparatory work:
- The site where construction is taking place is cleared of debris and the root system of trees and shrubs.
- Mark the position of the slab according to the design.
- The fertile layer of soil is cleared and removed. The degree of slab burial depends on geological and climatic conditions. Most often, the thickness of the slab varies from 20 to 30 cm, less often the base is buried by 50 cm.
- They dig a pit and manually level its bottom and side walls.
- Pipes are installed around the perimeter to drain rain and melt water.
- Geotextiles are laid out in overlapping strips. The material should cover the bottom and extend to the entire height of the walls.
- Drive in wooden stakes or metal rods. Pull the cord strictly horizontally. It will serve as a guide for uniform filling of sand and crushed stone.
- Pour sand 20-30 cm thick. Distribute the sand evenly over the entire area, moisten it with water and compact it well.
- Lay out geotextiles.
- Pour crushed stone, distribute it evenly around the perimeter, and compact it thoroughly.
- Conduct all necessary communications. They dig trenches under them in the rubble a little wider than the cross-section of the pipes. The pipeline is laid and a layer of sand is poured on top.
- The sandy surface is leveled.
If the pipeline is laid before the crushed stone compaction stage, the pipes may crack.
Insulation of the slab
Step-by-step instructions for insulating a monolithic foundation slab:
- Mount removable formwork from boards, install supports so that the structure does not fall apart under the weight of concrete.
- A layer of concrete 50 mm thick is poured.
- After the cement mortar has completely hardened, sheets of penoplex are laid on it close to each other and glued. Adhesive composition applied in dots around the perimeter of the sheet and in the center. A layer thickness of 10-20 cm is sufficient. The joints of the row are placed in a checkerboard pattern, offset by 1/3. When laying in two rows, the joints should not intersect.
- Spread thick polyethylene in overlapping strips. The joints are sealed with tape.
- The reinforcement frame is laid and the formwork is filled with concrete.
After the slab has dried, the formwork is dismantled, the side walls are thermally insulated with the same material that was used to lay it under the slab.
The insulated base helps to increase heat saving indoors.
When installing insulation on bitumen insulation, you need to wait until it dries completely. If laid on a damp layer, the materials may be damaged and the effect of thermal insulation and waterproofing will be reduced.
Rules for installing heating pipes
When installing USHP, heating pipes are used. There are the following rules for their installation:
- More dense pipe laying allows you to get more high temperatures heating the room.
- The distance between external walls and pipes should not exceed 150 mm. Closer to the center, the laying step can be increased to 250 mm.
- To minimize hydraulic losses, the length of one loop should not exceed 100 m.
- Do not lay pipes closer than 100 mm from each other.
Heating pipes must not be installed at the junction of monolithic slabs. In this case, it is better to lay two circuits. The pipeline crossing the joint is insulated with steel sleeves 30 cm long.
How to make an insulated Swedish stove with your own hands can be seen in the video:
An insulated foundation slab allows you to reduce heating costs during operation and helps reduce the level of frost heaving in the soil. Thanks to this, the life of the foundation is extended, and living in the house becomes more comfortable.
Insulation is an important part of any construction. It is necessary to insulate all external parts of the building from heat loss: walls, roof, basement and foundation. Insulating the base of a building not only limits heat loss, but also prevents frost heaving of the soil. How to insulate a monolithic foundation? And what are the features of installing insulation on the wall and floor?
Insulation of foundations
Insulation of the foundation is necessary in those parts that are located in the zone of soil freezing. The base and top of the foundation wall are covered with insulation. In addition, heat-insulating slabs are laid under the external blind area around the buildings. These measures help protect the soil and walls from freezing and, therefore, avoid the ground around the house.
Various foundation designs have different ways insulation. Deep strip - only vertical walls near the surface of the ground are insulated, shallow strip - walls and the sole. Pile foundation rests on non-freezing soil, so they only insulate side surfaces piles
Insulation of a monolithic foundation slab is carried out from the sides and bottom. This is necessary due to the location of the slab in the soil freezing zone. A monolithic slab foundation is a shallow structure. Its depth rarely exceeds 50 cm. Therefore, the entire slab is located in the zone of freezing soil and requires high-quality insulation. What materials are used to insulate the foundation slab?
Foundation insulation material: penoplex
Foundation insulation is subject to increased requirements for moisture and water resistance. It comes into contact with wet soil, so in addition to insulation it must prevent moisture from penetrating into the walls of the house. In addition, the foundation insulation must withstand compressive loads.
The ideal material for foundation insulation is extruded polystyrene foam. The trade name of the material is penoplex. It has a closed cell structure, so water and moisture do not penetrate into the material and cause its destruction. Temperature fluctuations around zero create a variable “liquid-ice” state. When moisture is absorbed, the insulation cracks (as a result of freezing and expansion of water in the pores of the material). Therefore, ordinary polystyrene foam (foam plastic) is not used in foundation insulation. Can only be used moisture-resistant types insulation: PPU or penoplex.
Water absorption characteristics In addition to resistance to moisture and steam penetration, penopex insulation can withstand significant compressive loads. Its price is higher than ordinary polystyrene. But it pays off in durability.
How to insulate: from the inside or the outside?
How to properly insulate a foundation with penoplex - from the outside or from the inside? Theoretical calculations show that the location of the insulation with outside protects the wall and slab from freezing. The placement of the insulation inside the wall does not protect the wall and the slab, but it allows you to improve the microclimate in the room. This means that external insulation is the most the best option for any building surfaces.
However, insulation from the outside is not always possible. So for the foundation, external insulation is possible only at the construction stage. Afterwards, the base can only be insulated from heat loss from the inside.
Insulating the foundation slab from the inside gives a noticeable positive result: the house becomes warmer and drier. At the same time, the slab itself continues to freeze in winter time years, so its durability remains short.
If the insulation of the slab was done during construction, then the foundation does not freeze and carries the load of the built house for a long time. How to insulate a slab foundation from the outside?
Penoplex insulation at the construction stage
Insulation during the construction phase involves laying insulation on the ground before pouring concrete. We list the sequence of actions for insulation during construction:
- To eliminate uneven pressure of the foundation on the ground, part of the soil is removed and backfilled with gravel and then sand. A layer of sand is spilled with water and compacted thoroughly.
- After this, a layer of waterproofing and insulation boards are laid.
- Reinforcing rods are placed on top of the insulating material and concrete is poured. In this case, the reinforcement rods are placed in two rows, the bottom row is supported by plastic beacons (so that after pouring the reinforcement is inside the concrete).
In this way, a light, strong and warm foundation is obtained, on which the walls of the building can be erected within a month.
Swedish foundation
Foundation insulated from below with polystyrene slabs and equipped warm pipes, called Swedish. The abbreviation of the foundation sounds like “USHP” or Insulated Swedish Plate.
The thickness of the base slab can vary from 10 to 30 cm (depending on the type of soil and the severity of the structure). The depth of such a foundation is above the soil freezing line. In this case, frost heaving is brought under control and compensated for by external insulation of the slab.
Additional heating arrangement allows you to get a foundation and a warm floor for the house at the same time. This design saves not only weight, but also money. The amount of concrete for casting the base is reduced by a third. Construction costs are reduced.
USHP – Insulated Swedish Plate Advantages of an insulated foundation
Let us list the advantages that make insulation of the foundation slab a necessary element of construction:
- Saving concrete, reducing construction costs.
- Acceleration of house construction time.
- Reducing heat loss and reducing utility bills.
- Improving the indoor microclimate.
- Increasing the durability of the foundation slab and the entire structure.
Such high advantages indicate that an insulated slab foundation is one of best designs foundations of the house.
Insulation of the foundation slab updated: February 26, 2018 by: zoomfund
The Swedish slab is an insulated monolithic slab foundation of shallow depth. The main feature of this technology is that the entire foundation of the house is based on a layer of insulation (under the slab). Under a warm house, the soil does not freeze and does not heave. Such a foundation is suitable for any soil, at any depth of groundwater.
This technology is based on the basic principles of design and device shallow foundations on heaving soils described in Organization standard (STO 36554501-012-2008), developed by the Research, Design, Survey and Design-Technological Institute of Foundations and Underground Structures (NIIOSP) named after. N.M. Gersevanov (FSUE Scientific Research Center "Construction"), FSUE "Fundamentproekt", Moscow State University. M.V. Lomonosov (Faculty of Geology, Doctor of Technical Sciences L.N. Khrustalev) and the technical department of PENOPLEX SPb LLC.
The “Swedish slab” technology combines the construction of an insulated monolithic foundation slab and the possibility of laying communications, including a water floor heating system. An integrated approach allows you to quickly obtain an insulated base with built-in engineering systems and a flat floor, ready for laying tiles, laminate or other covering.
The main advantages of an insulated Swedish stove:
- The construction of the foundation and the laying of communications are carried out during one technological operation, which makes it possible to reduce construction time.
- The ground surface of the foundation slab is ready for laying the floor covering;
- The PENOPLEX FOUNDATION® thermal insulation layer, about 20 cm thick, reliably protects against heat loss, which means a significant reduction in home heating costs and an increase in the efficiency of the “warm floor” system;
- The soil under the insulated slab does not freeze, which minimizes the risk of frost heaving problems in foundation soils;
- Laying the foundation does not require heavy equipment or special engineering skills.
Installation features
To ensure normal operation of the insulated Swedish slab (USP) and prevent frost heaving, it is necessary to provide a groundwater drainage system (drainage system around the perimeter of the structure). An important role is also played by a non-heaving preparation device (a bed of coarse sand, crushed stone). If a combination of layers of crushed stone and sand is used, it is necessary to provide for the separation of these layers with geotextiles (when the fine fraction soil is located above the larger fraction). All necessary communications (water supply, electricity, sewerage, etc.) and inputs must be laid under the slab in advance.
The design of the Swedish slab involves the transfer of all loads from the structure (its own weight, operational loads, snow, etc.) to the insulation layer, which is why high strength requirements are imposed on the heat-insulating material used. The most rational option for use in this design is thermal insulation boards PENOPLEX FOUNDATION®, which have virtually zero water absorption and high compressive strength.
Instructions for use:
- Step 1. Removing the top layer of soil (usually about 30-40 cm);
- Step 2. Compacting sand and gravel preparation (coarse sand, crushed stone);
- Step 3. Installation of drainage around the perimeter of the structure and utility pipes;
- Step 4. Laying side elements and PENOPLEX FOUNDATION® slabs in the base;
- Step 5. Installation of the reinforcement cage on stands;
- Step 6. Laying pipes for the floor heating system, connecting them to the collector and pumping air into them;
- Step 7. Filling the monolithic slab with concrete mixture.
The heating system integrated into the foundation design ensures comfortable indoor conditions. And the use of durable and absolutely moisture-resistant PENOPLEX FOUNDATION® slabs as foundation preparation will significantly increase the thermal reliability and efficiency of the heated floor system. Ordinary water or antifreeze can be used as a coolant in the system (if in winter it is not possible to always maintain a positive temperature in the room). Almost all types of pipes can be used as heating pipelines in water heated floor systems: metal-plastic, copper, stainless steel, polybutane, polyethylene, etc.
When laying heating pipes, the following rules are followed:
- The higher thermal power of heated floors is achieved by denser pipe laying. And vice versa, that is, along the outer walls the heating pipes should be laid more densely than in the middle of the room.
- It makes no sense to lay pipes more densely than every 10 cm. More dense laying leads to a significant overuse of pipes, while the heat flow remains practically unchanged. In addition, a thermal bridge effect may occur when the coolant supply temperature becomes equal to the processing temperature.
- The distance between heating pipes should not be more than 25 cm to ensure uniform temperature distribution over the floor surface. To prevent the “temperature zebra” from being perceived by a person’s foot, the maximum temperature difference along the length of the foot should not exceed 4°C.
- The distance between heating pipes and external walls must be at least 15 cm.
- It is not recommended to lay heating circuits (loops) longer than 100 m. This leads to high hydraulic losses.
- Pipes cannot be laid at the junction of monolithic slabs. In such cases, it is necessary to place two separate contours on opposite sides of the joint. And pipes crossing the joint must be laid in metal sleeves 30 cm long.
The purpose of this article is to go beyond the scope of this project and tell, on behalf of specialists, the basic rules for working with the material that can be useful to everyone.
During construction of this type Extruded polystyrene foam (EPS) was used for the foundation. In a master class format, professional builders will tell you how to choose and how to properly work with extruded polystyrene foam for insulation various types foundations. Namely:
- Why is it necessary to insulate the foundation?
- What to look for when choosing a material for foundation insulation.
- How to properly secure extruded polystyrene foam to the foundation.
- What tool is needed for the job.
Why is it necessary to insulate the foundation?
The foundation is the underground part of the structure that transfers the load from the overlying structures to the prepared soil foundation. Foundations are of the following types:
- Slab, shallow having spatial reinforcement. This gives the structure rigidity and allows it to withstand loads arising from uneven soil movement without internal deformation.
- Tape - laid below the freezing depth, etc. MZLF is a shallow strip foundation, with a base depth above the calculated level of seasonal soil freezing.
- . Insulated Swedish Plate. This foundation is a monolithic concrete slab, mounted on a base insulated with extruded polystyrene foam. A water underfloor heating system and all utilities are integrated into the foundation.
This type of foundation is considered the most technologically advanced and energy efficient. One system combines the foundation and a low-temperature heating system, eliminating the formation of local overheated zones and providing a comfortable radiant heat. In addition, the foundation is not exposed to the forces of frost heaving, because Anti-heaving measures have been taken. Namely, the heaving soil was excavated and replaced with non-heaving soil (sand or crushed stone), a drainage system was installed, the blind area and the base of the slab were insulated.
Up to 20% of heat loss from the total heat loss of the building occurs through the foundation.
Kogut Andrey TechnoNIKOL technical specialist
To achieve maximum energy efficiency of a building, it is necessary to create a closed insulated loop. This means that, in addition to the main structures, such as walls, roof and basement, it is also necessary to thermally insulate the foundation.
In some cases, it is enough to insulate the floor and base, but when organizing the exploited basement thermal insulation of foundation walls is a prerequisite to achieve the required level of comfort and reduce heat loss.
In shallow strip and slab foundations, thermal insulation can reduce the effect of frost heaving. Soil heaving is formed due to the freezing of water in the soil and its subsequent expansion. Various soils have varying degrees heaving. For example, sands allow water to pass through them well, and it does not linger in them. Clay, on the contrary, does not allow water to escape, but due to the presence large quantity small pores have high capillary suction of moisture. Improper design on heaving soils can lead to serious consequences, including destruction of the foundation. If you leave the foundation uninsulated, the heat flow will go down and warm the soil, protecting it from freezing. However, the house may not be heated constantly, and in this case the soil heaves. Thermal insulation of the foundation and blind area is one of the measures to combat frost heaving.
Basic principles for choosing thermal insulation for foundation insulation
So, summarizing all of the above, we conclude: the foundation needs to be insulated. Not every insulation is suitable for this, but only material that can work in aggressive conditions external environment. Those. thermal insulation designed to be “non-removable” must be moisture resistant, have a long service life during which it will not lose its thermal insulation properties, and have strength sufficient to withstand the load from the overlying structures.
Kogut Andrey
Extruded polystyrene foam (EPS) has a low thermal conductivity coefficient of 0.028 W/(m*°C) and a minimum water absorption coefficient of 0.2% by volume. The insulation does not absorb water, is chemically resistant and does not rot. Compressive strength at 2% linear deformation – no less than 150 kPa (~ 15 t/sq. m) and higher. Service life in soils is at least 50 years.
High compressive strength allows the use of EPS in loaded structures (foundations) and ensures the stability of the thermal insulation thickness under load.
The thickness of the thermal insulation layer should be taken based on calculations based on several conditions:
- Purpose of the building (residential, administrative, industrial, etc.).
- The insulation must provide the required heat transfer resistance for a given type of building.
- There should be no seasonal moisture accumulation in the structure.
Calculation thickness of thermal insulation for the foundation is made according to the methodology set out in SP50.13330.2012 “Thermal protection of buildings”. For different regions, the thickness of thermal insulation may vary, depending on climatic conditions. It should also be taken into account that increasing the thickness of thermal insulation increases the energy efficiency of the building and, therefore, leads to lower heating costs.
Choosing specifications thermal insulation, we are guided by the following principles:
- When thermally insulating a strip foundation, when only the vertical wall is insulated, increased strength of the material is not required, because in this case, the EPS takes up loads only from the backfill soil. Therefore, for shallow foundations, brands of extruded polystyrene foam with a compressive strength (at 10% linear deformation) of 150-250 kPa are suitable.
- When laying EPS slabs under the base of the foundation or under the slab, the loads on it increase significantly, and accordingly, the requirements for its strength increase. In this case, it is recommended to use thermal insulation boards with a compressive strength of 250 - 400 kPa.
- A material has been developed specifically for USP with a compressive strength at 10% deformation of 400 kPa and increased slab sizes to increase installation speed. In addition, the increased dimensions of the slabs make it possible to reduce the number of seams and, accordingly, increase the uniformity of the layer.
The nuances of installing extruded polystyrene foam when insulating the foundation
Insulation of the EPPS foundation, depending on its design, should be divided into a number of sequential steps:
- Preparing the base. When insulating an EPS strip foundation, the walls must be smooth, free of dirt and concrete deposits. If necessary, we remove uneven surfaces and cover up sinkholes, chips, etc. cement-sand mortar.
- Choosing a method of fastening EPS. To attach the insulation, we use polymer-cement mixtures or, to speed up installation, special polyurethane adhesive foam.
- Adhesive foam is applied in a strip approximately 3 cm thick along the entire perimeter of the slab, as well as in one strip in the center of the insulation.
- The distance of the adhesive foam strip from the edge of the slab is at least 2 cm.
- Before installing the slab, wait 5-10 minutes and only then glue it to the foundation wall.
- We foam the gaps between the plates (if they exceed 2 mm).
- If mechanical fixation of thermal insulation is provided, then the number of dowels is calculated as follows - for fastening 1 sq. m of thermal insulation on the central part of the foundation requires 5 pieces. fasteners We fix the EPS on the corner parts of the foundation at the rate of 6-8 dowels per 1 sq. m.
- When insulating the base of a strip foundation or monolithic slab, EPS is laid loosely on a prepared base (usually on a compacted sand bed). In this case, it is enough to foam the seams with adhesive foam and, if necessary, fasten adjacent thermal insulation boards together. You can use a nail plate for this.
In this case, special fasteners can be used, which are a spike with teeth for fixation in the material and a flat platform with an adhesive layer.
Together with similar fasteners, gluing is done using adhesive foam for polystyrene foam or to a special adhesive mastic that does not contain solvents. If necessary, the seams are sealed with mounting or adhesive foam.
The layout of EPS slabs during the construction of USHP is carried out as follows. We lay the first layer on the prepared base - a compacted sand cushion - with the seams staggered relative to the adjacent slabs. The side elements are “L” blocks, which are two EPS slabs connected perpendicular to each other.
Typically, such elements are made by installing formwork, but it is possible to use ready-made elements that do not require the use of formwork. Such “L” blocks can be manufactured in a factory, or they can be assembled independently at the work site. For this purpose, a special corner fastener, which consists of angles and screws, and which is mounted at a distance of 300 mm from each other. All elements of corner fasteners are made of high-strength polyamide, which eliminates the formation of cold bridges.
Summarizing
In addition to increasing the energy efficiency of the foundation, EPS insulation increases its service life, because the waterproofing is reliably protected durable material from various mechanical influences. Selecting an option permanent formwork made of extruded polystyrene foam, you can significantly speed up and simplify all work on the construction of the foundation, because there will be no need to assemble and further disassemble wooden formwork, which means the developer will save time and money.