Foundation slab with heated floor and blind area

Swedish stove technology

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 construction of shallow foundations on heaving soils, described in the 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.

Schematic diagram of an insulated Swedish stove

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.

Installation process

When the concrete floor has been embedded into the pie along the ground, the process of laying the heating circuit can begin.

There are a number of rules:

In order to prevent excessive heating of the coating, proper placement of pipes should be carried out throughout the entire area of the room. More dense installation is carried out around the perimeter, and in the center the contour should be thinner, and the distance from the walls of the room should be at least 15 centimeters;
regardless of the installation scheme chosen, it is necessary to maintain an interval between adjacent pipes of 0.3 meters;
if the pipe is located at the junction of the slab and the ceiling, it should be separated with a special metal sleeve;
The length of the heating circuit should not be allowed to exceed 100 meters, since in such a system the main parameters of coolant circulation will be reduced (read: “How to make a heated floor with your own hands in a private house”).

Laying is done in two main ways:

bifilar - in a spiral
. In this case, uniform heating of the pipes is characteristic due to the alternation of supply and return sections. A low-power pump is used to supply liquid, and laying pipes is very simple by maintaining a 90-degree angle between adjacent sections;
meander - zigzag
. The coolant in such a system cools down as it passes through the circuit, and the surface heats up unevenly. Pipes can turn in the absolutely opposite direction along the way, which affects the complexity of installation. This method is more suitable for rooms with a linear slope, since the coolant will circulate faster and will not have time to cool down. The cabinet with the equipment is installed at the top point of the circuit. Also, this installation method allows you to heat the most spacious rooms.

Regardless of which installation method was chosen, all pipeline branches end in a distribution cabinet located near the room. It is important to take care of the thermal insulation of pipes that pass through neighboring rooms.

The foundation is insulated Swedish slab

An ideal home should be reliable, durable, durable and, most importantly, rational. The current idea of a good home for your family is already associated with energy efficiency and the use of innovative solutions.

At the heart of any home is a foundation that determines its durability and reliability. To build a house, it is proposed to equip the foundation with an insulated Swedish slab (USP).

What it is and what main advantages it has is already known to a wide range of readers, thanks to an advertising company.

However, it is also important to understand the features and disadvantages of USP in order to make an informed choice.

What it is

The insulated Swedish slab is a composite insulated foundation of shallow depth, suitable for the construction of low-rise frame-type houses, log houses, houses made of foam concrete and brick.

The main idea is to isolate the concrete base slab from the ground using insulation like extruded polystyrene foam.

A 200 mm thick insulation layer performs three tasks simultaneously:

Thermal insulation of the foundation slab;
Load distribution on the ground;
Damping of frost heaving of soil.

As with any monolithic slab type foundation, the USP well distributes the load of the house over the entire surface of the building and ensures structural strength, resistance to shrinkage and deformation of wall elements.

The slab itself is well insulated from the ground, which allows you to install a heated floor system directly into the slab, as well as organize a subfloor without additional screeds or add-ons.

As a result, by equipping the foundation with an insulated Swedish slab, the developer receives several design solutions in one element:

a solid foundation that does not depend on the properties of the soil;
thermal insulation of the foundation under the entire structure;
optional underfloor heating system, initially distributed throughout the house;
a finished rough base, on top of which the flooring can be immediately installed.

Extruded polystyrene foam with increased strength and a compressive force at a deformation of 2% of at least 0.2 kPa is used as insulation.

Given the uniform distribution of the load, the foundation is able to withstand tens of tons of load without noticeable subsidence or deformation.

Attention, cold floor!

Some overly thrifty owners do not attach due importance to the problem of low floor temperature in the apartment. Wanting to save on the cost of materials and work, they arbitrarily exclude laying the insulating layer from the technological process. The consequences of such an imprudent decision are felt during the cold season:

the floor covering becomes covered with condensation;
pathogenic organisms such as mold and mildew develop in a humid environment;
the microclimate of the room is disrupted - humidity rises, temperature drops;
heating costs increase;
The service life of the floors is reduced.

To make living indoors comfortable and safe, you should adhere to the work technologies developed by the builders. Only a properly built and well-equipped house with heated floors is a real fortress. Modern materials make it possible to solve this problem quickly and without loss of quality.

Device technology

An insulated Swedish slab is a foundation with a complex multi-layer structure. The rotation order is as follows:

sand cushion made of coarse sand;
geomembrane layer;
drainage system for draining liquid from under the foundation;
sand cushion made of fine and medium sand;
100 mm EPPS insulation around the perimeter and under the blind area;
gravel layer;
EPPS insulation at the base of the foundation with a thickness of 200 mm, with the exception of places for the location of wall supporting structures;
monolithic reinforced concrete slab with reinforcement at the installation site of wall structures and along the entire perimeter of the building.

Creating a concrete base

Pouring a reinforced concrete base is required to create a durable, high-quality floor (for more details: “How to make a concrete floor in a private house with your own hands - instructions”). It is best to mark the surface for pouring using slats 5 cm wide and 2 meters long. It is worth keeping a step between them of about 1 meter, which will allow you to fill the solution in stripes. A square meter of reinforced mesh 3 centimeters thick is placed in the center of the room. Along the perimeter of the room, the junction of the base and the walls is taped with damper tape.

Problems

When choosing an insulated Swedish stove as the foundation of your home, it is important to take into account all the features of this design, some of which can be safely attributed to outright shortcomings.

Execution accuracy

The first feature concerns the foundation construction technology itself. The integrity and reliability of the insulated slab depends on the accuracy of each stage, especially with regard to establishing a common plane when compacting the sand cushion.

It is very risky to equip such a foundation yourself, so it is necessary to turn to firms and contractors with extensive experience and a guarantee of quality.

Consequences of soil heaving

The material for the USHP device is guaranteed to withstand a compressive force at 2% deformation of at least 200 Pa, but this does not mean that after absorbing soil heaving in one year, the material will easily return to its previous shape.

Unfortunately, this technology has not undergone many years of testing and has not been subjected to critical reflection. It is impossible to say precisely that soil heaving will not affect the shape of the insulation and subsequently affect the geometry of the slab.

Rodents

Extruded polystyrene foam is inedible for rodents, especially mice and rats, and is even poisonous. However, it remains an ideal material for making nests and burrows, even for ants and other insects.

Warm floors in a foundation slab are risky

Installing heated floors throughout the entire first floor is a truly excellent solution, but the USHP proposes installing pipes directly into the body of the slab, on which the entire house will then rest. This makes the heated floor completely unrepairable.

If a leak occurs, the foundation will be the first to be damaged, where the water will rush first. And after discovering a problem, it will be impossible to determine where exactly the breakdown is.

Any work to dismantle the base of the slab to eliminate a leak is associated with a violation of the integrity of the foundation, which is simply unacceptable. It is better to abandon built-in heated floors and arrange them separately if necessary.

Location of communications input

It will no longer be possible to move or adjust the position of the sewer pipe or electrical inlet during construction. This is a disadvantage of all slab foundations, so you have to think through the layout very carefully even before starting work on the foundation.

Dry screed for heated floors

It is provided by special bulk compositions that are laid out on top of the waterproofing layer. The dry screed simultaneously acts as a thermal insulation layer. It has the following advantages and disadvantages.

Advantages:

simple installation;
if a wet screed needs to be poured in one go, then in the case of a dry screed, you can stop at any time and then return to work again;
you can immediately begin subsequent work, since there is no need to wait for drying;
Expanded clay is often used, which has excellent thermal insulation properties;
under the backfill layer you can hide wiring and other technical communications.

Flaws:

rodents and other insects often live in dry backfill;
if a coolant leak occurs or water simply penetrates under the floor covering, it will easily seep through the dry screed, which will lead to the formation of mold;
dry screed has poor load-bearing capacity.

Calculation

The task of calculating the cost for an insulated Swedish stove is simplified due to the ready-made design and composition. It is enough to determine the thickness and requirements for each layer according to the construction project.

Insulation is used in most cases with the same thickness of 100 mm around the perimeter and 200 mm under the base of the concrete slab. This size already has a margin of thermal insulation and is suitable for most regions of our country.

When calculating a square meter, the thickness of the sand and gravel cushion, a 200 mm insulation layer and 100 mm of concrete are taken into account. To determine the volume and cost of materials, it is enough to multiply the calculation for a square meter by the total area.

A separate volume of reinforcement ribs for the walls is added to the concrete side and the same volume is subtracted from the insulation. The most difficult thing is to evaluate the additional work on introducing communications, preparing the pit and other individual construction features.

Creating a slab reinforcement frame

For USHP, two types of reinforcement are used: a three-dimensional frame of four reinforcement rods with a diameter of 12 mm or more is placed in the ribs, connected by rectangular frames of 8 reinforcement; A reinforcing mesh of reinforcement with a diameter of 8 mm is laid on the slab.

The rib frames, assembled on a separate table, are placed on plastic supports to create a protective concrete layer. A mesh is thrown over the top and all the reinforcement is tied into a single structure, creating a monolithic frame.

Insulated foundation with warm floor

Often the choice of a home heating system is postponed until the construction of the house itself is completed. When the house is already standing, they choose the type of heating, select equipment and draw a heating scheme according to the layout.

Due to its widespread use, this approach can be called traditional. The design of such houses is simplified; the house design can even be purchased ready-made. Construction costs are divided into stages, which is also convenient. However, the total amount of completed construction is greater than some options for modern construction technologies. We are talking about the technology of an insulated slab foundation with a built-in water heated floor system.

By design, an insulated foundation with a heated floor is a concrete slab laid and covered on all sides with dense insulation. When building a foundation, a drainage system for the site and the house is immediately created. This allows it to be used at high groundwater levels.

Also, when constructing the foundation, a system of water-heated floors is installed in it. That is, already at the stage of building the foundation, two important tasks of comfortable living are solved: heating the house and its drainage. This reduces the time of the full construction cycle, although it slightly increases the cost of construction.

Let us immediately note that a USHP foundation with a heated floor requires individual design, based on the condition of the soil, the depth of groundwater and the load of the house on the foundation. In addition, heated floors require separate design.

Waterproofing layer

The traditional installation of heated floors on the ground implies the presence of a waterproofing layer at the lower level of the base. Thick polyethylene, laid with an overlap, has the lowest cost and quality. It is more practical to use polyvinyl chloride and polymer-bitumen membranes, which contain polyester.

When laying waterproofing, it is important to treat the walls of the room, making a spade 15-20 centimeters high. The protruding parts can be removed using a sharp cutting device upon completion of the work.

Stages of constructing a USP foundation

The technology for constructing a foundation with a heated floor differs significantly from traditional strip foundations, and even more so from modern pile foundations.

Preparatory work on the ground is of great importance in the construction of a USP foundation. To understand the entire construction cycle, we list its stages, based on the construction technology of the specialized company Rekonst LLC.

Stage 1.

The area must be level. The top layer of soil, 300-400 mm, needs to be removed. The result should be a flat area for further construction.

Stage 2.

Marking out the site according to the construction project.

Stage 3.

The construction site should be slightly higher than the surrounding area. To do this, add a layer of sand to the area and level it.

Stage 4.

At the site, according to the project, the sewerage system of the house and the drainage of the site are being installed. Sewer outlets in the house and storm drain points must be prepared.

Stage 5.

Now comes the specific stage of constructing a slab foundation. A special tamping machine is used to tamp the sand and grind it. Tamping is carried out in vibration mode with water poured over the sand.

Stage 6.

According to the project, formwork is installed, removable and non-removable. The formwork is backfilled.

Stage 7.

Layers of geotextiles, waterproofing and rigid insulation made of extruded polypropylene are laid across the construction site. The latter does not react with cement mortars.

Stage 8.

Reinforcing mesh or reinforcement is laid on top of the insulation, with cells of 100 by 100 mm.

Stage 9.

The laid fittings will serve as the basis for laying the water-heated floor pipes. The pipes are laid according to the design with the pipes leading out to the installation sites of the heated floor collectors. Sleeves are placed where pipes pass through partitions. There can be several collectors.

Stage 10.

The final stage is to pour concrete onto the prepared site, creating a foundation with a warm floor.

The result is a ready-made foundation for further construction. The foundation already has a heating system for the house. The stages of installing in-house and storm sewer systems have also been completed.

Monolithic slab + blind area need advice

This topic has 22 replies, 9 voices, and was last updated by zxc 4 years, 2 months. back.

There will be a monolithic slab 8*12, the house will be 1-story. There are options on the Internet: 1) a slab is poured (and then someday a blind area) 2) a slab is poured and at the same time a blind area of different heights is poured. Who did it, how correctly. According to the advertisement, they don’t say anything intelligible, they don’t promise, they don’t know how to do electric shock, they don’t know what layers to lay, but they call the prices astronomical. Some recommend hiring Uzbeks to prepare everything and inviting Russians to pour the concrete. Problems with personnel. Who has contacts of normal specialists at reasonable prices. Thank you in advance.