Do I need to insulate the foundation of the house and the better to do it

Thermal insulation of the foundation is just as important a task as the padding of walls and floors with insulation. Frozen soil, especially in regions with a harsh climate, does not protect the base of the building from water and cold, as a result of which the foundation collapses. Thermal insulation works are carried out to provide warmth in the room and to protect the house. You can do this with your own hands, it is only important to choose the right materials and installation technology.

Heat insulator requirements

The base of the building is constantly exposed to atmospheric precipitation, temperature fluctuations, and high loads. For this reason, special requirements are imposed on the choice of thermal insulation:

• low thermal conductivity;
• waterproofness;
• high level of mechanical strength;
• resistance to temperature surges;
• resistance to the formation of mold, fungi, damage from rodents and insects;
• incombustibility.

There are no strict requirements for vapor permeability, but it is recommended to take material with a low level.

Material selection

Mineral wool is not suitable for thermal insulation of foundations. This is due to the property of moisture accumulation and poor mechanical stability. It is better to take polymer insulation. The selection of material also depends on the estimate that is included in the project. Good insulation can also be found among budget materials.

Styrofoam

Polyfoam is widely used in building thermal insulation. It is distinguished by its low weight, correct sheet shape and ease of installation. There are varieties on the market with different densities and thicknesses that can be used in different fields. For insulation of the foundation, the densest materials with a minimum thickness of 50 mm are selected.

The thermal conductivity of the material is more efficient than that of wood, expanded clay or mineral wool. Polyfoam practically does not absorb water and does not shrink, it does not deform over time. Differs in high soundproofing properties. The properties are also not affected by salt or chlorinated water, weak acids, soapy liquids. It can interact with bituminous mastics, adhesive water-soluble agents.

PSB-S-50 and PSB-S-35

For slab foundations and foundations with a large depth, PSB-S-50 expanded polystyrene is used. It can withstand heavy loads and provides high-quality protection against soil swelling. Columnar and standard types of foundations can be insulated with material marked PSB-S-35. The operating temperature ranges are from -60 ° C to + 80 ° C. The dimensions of the slabs are 1 × 0.5 m, 1 × 1 m, 2 × 1 m. The service life reaches 30 years.

Other varieties are not used due to poor density and fragility.

Extruded polystyrene foam

There is a kind of expanded polystyrene, which is made by extrusion. The material obtained in this way has improved characteristics. It is stronger, waterproof, has a low level of vapor permeability and thermal conductivity. Extruded polystyrene foam does not form microorganisms even with prolonged dampness.

The slabs are thinner, but the effect is higher. For insulation in temperate climates, a thickness of 40 mm is chosen; for installation in a cold northern climate, 60 mm are required, which are best laid out in two layers of 30 mm each. Laying is done vertically and horizontally.

Popular manufacturers are Technonikol and Penoplex. Insulation of the foundation with penoplex allows you to obtain a structure service life of more than 40 years.

Polyurethane foam

Has a durable coating without seams, resistant to bad weather conditions and adverse influences. It also performs the functions of steam and waterproofing, making the insulation process easier and cheaper. The material has good adhesion to stone, concrete, brick, wooden blocks and other substrates.

There are two ways to apply polyurethane foam - pouring and spraying. In the first case, the work will be more difficult and costly, therefore it is rarely used. The second method is applicable for insulating roofs, walls, ceilings and other parts of the structure. Before application, all components are mixed with air and the mass is sprayed onto the surface. The disadvantages include the need to purchase special equipment or rent it. The service life is 50 years.

Expanded clay

It has good characteristics, but due to the complexity of the process, it is not used for thermal insulation of foundations from the inside. Also, expanded clay cannot protect the basement from moisture, since it is not a moisture resistant material.

Thermal insulation technology

Thermal insulation of foundations can be carried out at the construction stage or during the operation of the dwelling. Before starting installation work, it is imperative to check and prepare the base. It must be removed from cracks, debris and covered with waterproofing. The effectiveness and durability of the result depends on the quality of preparation.

Insulation of slab foundation

Slab foundations must be insulated during the construction phase as they are located under a layer of reinforced concrete.

The most time consuming stage is earthworks. The foundation is excavated before the soil or base freezes. If possible, it is best to hire a specialized technician to reduce the working time.

The walls of the foundation are cleaned of the ground with a stiff brush. For 10 days, the foundation must be left so that all the moisture is gone. Work should be carried out during warm and dry seasons.

Step-by-step algorithm for warming the foundation:

1. Inspection of dried walls for damage. All defects are eliminated; dust must also be cleaned off. If the thickness of irregularities exceeds 20 mm, the plaster is reinforced with a metal mesh. Then you need to wait for the plaster to dry and then you can proceed to the next stage of insulation.
2. Waterproofing. Better to take coating materials - bitumen mastic, polymers, rubber. A bituminous primer is also used to improve adhesion. It is applied in a thin continuous layer and wait a day until it dries completely. Then the mastic selected for waterproofing is applied.
3. The mastic is mixed with water if the composition is too thick. It is applied with a wide brush or roller in a continuous uniform layer with careful processing of all corners. The layer should not be too thin or too thick. After the first layer has hardened, the second layer is applied. If the area is flooded with groundwater, a third coat should be applied.
4. 5-7 days after the waterproofing has dried, the insulation is installed. For this, special glue ALLFIX, Ceresit CT 83 or Titanium is used. Work is carried out from bottom to top in horizontal rows with the transportation of vertical seams. After applying the glue, the board is applied to the surface. Its location is checked by the building level. Insulation plates for the foundation of the house are laid on the outside as tightly as possible to each other so that the joints are not visible.If the laying is two-layer, the plates are laid in a checkerboard pattern. The joints of the two levels should not coincide, otherwise the insulation efficiency will fall.
5. Fastening of the ground part with dowel-nails or screw method. Fasteners must be done after the solution has completely dried. The deepening reaches 40-50 mm. After the dowel is hammered until it stops.
6. Plastering the surface of the slabs. A fiberglass reinforcing mesh is also placed. It is recommended to cut it into pieces and overlap it by 10 cm.
7. Next, you need to wait a day. After that, a final leveling is performed, and after this layer has dried, the surface is worked off with a float with an emery cloth.
8. At the end, the trench is covered with soil. Leave about 30 cm up to the top. The soil should be tamped so that later the shrinkage is not so noticeable.
9. A layer of sand 10-15 cm thick is laid on top.
10. A waterproofing membrane is placed on top.
11. The last stage is the arrangement of the blind area by pouring a concrete screed.

In the case of using polyurethane foam, leveling and waterproofing are not necessary. After creating a trench and cleaning the walls from the earth, cracks are closed and delamination is removed. After drying, you can apply insulation. When the material hardens, you can fill the trenches with soil and make a blind area.

Thermal insulation of a columnar foundation

If the foundation is made in the form of pillars and piles, the insulation process will be different. To isolate the space between the grillage and the ground, a structure is assembled, which serves as a basement. It does not carry a load, therefore, there are no requirements for mechanical strength.

Pile foundation insulation algorithm:

1. Digging a trench between the foundation posts. It should be narrow with a depth of up to half a meter. A third is covered with sand and gravel.
2. Laying the frame from metal rods. Pouring concrete solution.
3. When the layer is dry, a brick is laid around the perimeter of the foundation. Small air vents remain in the opposite walls to ensure natural ventilation.
4. After the masonry has dried, the selected insulation for the foundation is glued on the outside. Then it is plastered and a reinforcing mesh is placed.
5. Backfilling the trench with soil after complete drying. Compaction of the soil.

At the end, the decorative finish of the frame basement is done. It can be painted, artificial stone or plaster can be applied, siding can be made.

If it is not possible to put a brick filling, a frame made of bars or metal profiles is placed between the foundation supports. The wood must be treated with an antiseptic and dried. Fastening is carried out on metal corners and bolts with self-tapping screws.

Fastening insulation boards

In the case of horizontal insulation of a private house, the slabs can be stacked in one or two layers. Material thickness - 50 or 100 mm. Thermal insulation is done after preparing the pit and filling in the sand cushion.

Algorithm for warming the foundation of the house outside:

1. Compaction of the sand layer over the area and horizontally. The smoother the surface, the better the heat insulator will fit.
2. Laying film and thermal insulation boards. In each subsequent layer, the slabs are shifted so that joints do not form. The shift width is half a sheet.
3. Installation of formwork along the perimeter of the foundation. A reinforcing frame made of steel rods is mounted in it.
4. Next, you need to mix and pour concrete. Wait until the layer is completely dry.
5. Execution of the blind area. The sand is leveled and compacted. You need to make a slight slope from the foundation. Plates are evenly applied to each other, and a waterproofing membrane is placed on top. It should be laid with an overlap of 10-15 cm.
6. Backfilling with sand.

This completes the process of fundamental insulation. If everything is done correctly and according to the instructions, the house will always be warm.

When you can not insulate the foundation

If you refuse to insulate the foundation, you can save money on building materials and the process of thermal insulation. Even before building a house, you need to decide whether insulation is needed for the building. You can consult with professionals, and only then make a final decision.

The base may not be insulated in the following cases:

• The house is in a warm climate. Even in winter, there are no strong and prolonged frosts. In this case, the soil does not freeze, so the foundation does not need to be insulated.
• Uniformity of the soil under the house. In this case, the heaving will be uniform and the house will not decay.
• The underground part is located below the freezing level. The swelling of the soil will not lift the foundation, but will only squeeze the side walls.
• Good drainage around the house. Soil water is drained away so good drainage can be created and swelling can be reduced.
• There is high-quality insulation of the blind area.
• Before the start of construction, a thick layer of expanded clay or dry sand was covered under the foundation. This method is expensive, therefore it is practically not used.

The decision on the need for insulation is decided by the owner of the house. It is necessary to consult with a professional, study the experience of building and insulating houses in the region and note the peculiarities of laying the foundation.