Thermal insulation of the foundation of the house with polystyrene foam, features of insulation, its advantages and disadvantages, the technology of work. Insulation of the foundation with foam is a process aimed at improving the quality of heating a building. It is especially true if there is a basement under the house. Our today's material is about how to properly perform such thermal insulation.
Features of thermal insulation of the base of the building with foam plastic
More than 20% of the heat loss occurs through the ceiling of the underfloor space. They are minimized by well-insulated foundation walls. In addition, thermal insulation protects the base of the house from deformations that appear as a result of cyclic freezing and thawing of heaving soils located in the construction zone.
The most problematic of these are clay and loam, which are the most common soil types in our climatic zone. The mechanism behind their deformations is quite simple.
With the onset of frost, the wet soil gradually freezes, the water in it, turning into ice, expands and thereby increases the volume of the soil. As a result of this process, its heaving and forces arise, acting on the foundation. With the onset of heat, the soil thaws, gets rid of excess moisture and sags along with the base of the building, which leads to deformation of the underground structure and the appearance of cracks on it. Therefore, thermal insulation of the buried part of the house, built on soil prone to heaving, becomes necessary.
In most cases, the installation of insulation on the foundation takes place on top of the waterproofing layer. At the same time, thermal insulation reliably protects the waterproof membrane from mechanical damage that may occur during backfilling or ground movements. If the base of the foundation is located below the depth of soil freezing, there is no need to insulate it.
The most reliable is the insulation of the basement with foam outside, since the notorious "dew point" moves closer to its outer surface, protecting the thermal insulation material from getting wet and thereby preserving its original properties.
Various materials can be used as insulation materials for the foundation: glass and mineral wool, expanded clay, etc. But rigid insulation in the form of slabs made from polystyrene is the most effective. This is due to its ability to maintain its characteristics in any climatic conditions.
The material, which consists of 98% of the cells filled with air, is easy to process, install and relatively inexpensive. It is ideal for insulating underground structures, as it works excellently in a humid environment and has a low thermal conductivity.
Installation of foam plates on the outer surface of the foundation is carried out during the warm season. Although the material itself is capable of withstanding low temperatures, the properties of the adhesive that fix the boards can change in the cold. In addition, drying the substrate in winter will take a longer time.
Advantages and disadvantages of thermal insulation of the foundation with foam
Pasting the foundation with foam plates is one of the most common method of insulating it. This is due to the technical properties of the material.
It has low thermal conductivity, good sound insulation and moisture resistance. The low weight of the foam does not create any particular problems during its installation or transportation. Therefore, the thermal insulation of the foundation can be done by yourself, in addition, the material is easily processed with an ordinary knife and cut with a hand saw.
Thermal insulation, consisting of foam plates, is quite durable, which is an important factor, given the laboriousness of the entire process of warming the foundation. The material is resistant to the overwhelming amount of chemical compounds that are present in the soil and atmosphere.
Due to the cellular structure of the material, which is 98% composed of granules filled with air, foam insulation has the lowest thermal conductivity compared to the same indicator for known basement insulation.
Using foam as insulation for the base of your home is quite affordable. The purchased material will withstand any air temperature and remain stable when exposed to soil moisture.
The only drawback of insulation of the foundation with foam is the need to apply a protective layer to the glued thermal insulation. This is due to the low mechanical strength of the material.
Technology of insulation of the foundation with foam
Strict observance of the rules of thermal insulation of the supporting structure of the house makes it possible to increase the efficiency of its heating, while reducing the energy resources of this process. The sequence of work on warming the foundation with foam plates is a few step-by-step steps.
Selection and calculation of material
The fundamental factor when choosing a foam is its quality. Therefore, the cheapest material with a density of less than 25 kg / m3 it is not recommended to use for thermal insulation of the foundation. A suitable foam must have a low thermal conductivity, withstand well compressive loads from the soil and have a low moisture absorption of about 0.2%, providing it with sufficient frost resistance.
When choosing a product, one should take into account not only its density. Plates must have the correct geometric shape and a minimum deviation from standard dimensions within 10 mm. If they are larger, each element will have to be adjusted in place during installation, which will increase the duration of the work.
The thickness of the foam slabs on the market is 30-120 mm. When choosing a material for this parameter, one should take into account the purpose of the basement of the house, the thickness of the foundation walls and the climatic zone of construction. In regions with a temperate climate, foam plastic with a thickness of at least 50 mm is used for insulating underground structures. The basement, which is planned for arranging a cellar or a bath, is recommended to be insulated from the outside with 100 mm slabs. The corners of the underground part of the house should be insulated with foam plastic 60-100 mm thick, as they freeze in the first place.
The calculation of the thickness of the foam for insulation of the foundation is made using special tables that take into account the parameters of certain brands of this material. For clarity, you can give the following example: a 50 mm thick foam board is comparable in terms of heat retention to a brickwork of 250 mm.
In order to determine the required amount of foam, you should measure the perimeter of the house and the required height of thermal insulation. The obtained values must be multiplied, and then divided by the size of the area of one sample of the material.
Preparation of the foundation for insulation
If the house has been built for a long time, it is necessary to create a workspace to insulate its foundation. This is done with the help of simple tools: shovels and bayonets, a crowbar for extracting large stones from the ground and a brush with metal bristles.
From each of the walls of the house, you need to retreat 1-1, 2 m and dig a trench on the resulting section of the perimeter, while cleaning the outer walls of the foundation from the ground. The depth of the trench should reach the level of the base of the foundation. Remains of dirt adhering to the substrate can be removed with a metal bristle brush.
After that, the surface of the base freed from the soil must dry. The amount of time allotted for this process depends on the weather conditions.
Then the walls must be carefully examined for cracks and large protrusions on them. Cracks should be repaired with normal mortar and ledges should be knocked down with a chisel. All this will ensure a tight fit of the foam plates to the surface of the foundation.
After eliminating defects on the walls of the base, its outer surface must be primed with a primer or acrylic compound. This will ensure the adhesion of the waterproofing to the outside of the underground structure. To do this job you will need a suitable container for diluting the primer and a large paint brush.
The primed and dried surface of the basement walls must be protected from the moisture of the soil with a waterproofing layer before insulating the basement of the house with foam. The material for its creation can be roofing material or liquid rubber.
For pasting the foundation with roll material, you will need a gas burner and a knife. First, it is necessary to cut a sheet of roofing material of the required length vertically, roll it into a roll, and then, rolling and heating the back side of the material with a burner, gradually apply it to the wall. The remaining strips of roofing material are similarly attached. The joints between them must be sealed with bitumen mastic.
If liquid rubber is used as waterproofing, it should be mixed in a bucket with a mixer, and then applied to the surface of the foundation with a wide metal spatula.
Installation of foam on the surface of the foundation
Foam plates are fixed on top of the waterproofing layer using polymer-bitumen mastic or special glue. The binder should not contain acetone, gasoline and other organic solvents, as they have a detrimental effect on the foam, destroying its structure. In addition, for the underground part of the foundation, it is unacceptable to fasten the insulation plates with the help of umbrella dowels, since their installation violates the integrity of the waterproofing, which can lead to leaks of the walls towards the basement.
The installation of thermal insulation of the foundation should be started with the installation of the lower row of foam plates. It requires a rigid stop from below, which can be a protrusion at the base of the base or a backfill of gravel and sand compacted at the bottom of the trench.
The adhesive mixture must be applied to the back of the boards with a notched trowel. Installation of products should be carried out at minimum distances relative to each other. The first row of insulation is leveled horizontally using a building level. The vertical joints of the overlying rows of covering slabs should not coincide, therefore, the products must be placed on the foundation wall in a checkerboard pattern.
If a thickness of an insulating coating of 100 mm is required, you need to use two-layer insulation, that is, two sheets of 50 mm each. In order to avoid the appearance of cold bridges, the joints of the foam sheets in the coating layers are not recommended to be made through, they need to be slightly shifted in relation to each other.
Finishing works on thermal insulation of the foundation
If the insulation, fixed on the foundation, extends beyond the top of the trench with its edges, it must be protected from mechanical damage. To do this, a reinforcing mesh should be installed over the foam plates and secured with glue. After that, the thermal insulation can be covered with plaster, siding or other finishing material.
If the basement of the house is very low, and the foam plates will be completely in the ground, the reinforcement of the surface of the insulation and its finishing will not be needed. In such cases, the trench can be covered with expanded clay as additional thermal insulation for the foundation.
If the house is erected on soil with a high level of subsoil water, after the installation of thermal insulation of the foundation, it is imperative to make a drainage system. Its perforated pipes are located in the trench below the foot of the foundation along its perimeter. The system is installed on a gravel bed, the pipes are backfilled from above with the same material. This is to avoid clogging the drainage with soil particles entering the system along with groundwater.
After the foundation has been insulated and the drainage pipes have been laid, the trench can be backfilled. In order to further protect the foam from unnecessary contact with excessive moisture and insects, it is recommended to lay a plastic wrap, a layer of roofing material or cover the insulation with 1/2 brick masonry before filling the sinuses between the soil and the insulation of the walls.
How to insulate the foundation with foam - watch the video:
The correct application of the technology of warming the foundation with foam plastic makes it possible to perform high-quality thermal insulation, which will reduce the cost of heating the premises in winter, and set the optimal level of humidity in the basement.
