Thermal insulation with the use of polyurethane foam
As is known, the usual blind area simply removes precipitations and melt water during the year, for which the concrete strip is made with a slope from the house. However, if you confine one concrete or asphalt sand-gravel cushion, protect the foundation and socle can only be from moisture, but not from the freezing of the soil. Therefore, if strong frosts in your area are not uncommon, the insulation of the blind area becomes an absolute necessity, as does the insulation of the socle with expanded polystyrene or other suitable insulant. It remains only to decide which materials to use to ensure high-quality thermal insulation. If we talk about modern insulation and do not think about the cost of the material, the ideal option will be polyurethane foam, recommended by many specialists because of the reduction in its use of the terms of work.
The width of the blind should be not less than 60 centimeters, but it is determined, firstly, by the removal of the eaves( the insulated strip should be wider than it by at least 20 centimeters), and secondly, on the type of soil. Usually the blinds are made with a width of the order of 100-120 centimeters, since the width of the thermal barrier is assumed to be appropriate to the depth of freezing of the soil, and at a depth of about 2 meters the temperature is always plus. For insulation with polyurethane foam, a soil is taken out to the depth of the vegetative layer, that is, 15 to 20 centimeters, and the remains of plant roots are taken away to the depth of the centrally located strip along the house, a formwork with a height of up to 40 centimeters is prepared. In the resulting shallow ditch a layer of sand 10 centimeters thick is poured, followed by a careful ramming. Above is poured rubble, the thickness of the layer is up to 15 centimeters, and again tamping.
Now comes the time of polyurethane foam, which is sprayed directly on the gravel, which is necessary only so that the composition bursting under pressure from hundreds of atmospheres does not scatter sand. The layer of foam does not exceed usually 5 centimeters, it freezes after 15 minutes. Concrete can be poured directly on the heater, its thickness should be about 5 centimeters to avoid the appearance of cracks due to temperature expansion. There is no special technology in this process, not counting the gradient from 5 to 10 centimeters per meter, we just need to remember that the is thicker than the concrete layer, the greater the probability of cracking during the blind area of the .If not to exclude, then at least take control of their appearance, it is enough to create artificial seams every couple of meters between individual portions of pouring. Cracks in the future will appear, but it is on these pre-prepared joints.
Thermal insulation of foam with foam as the cheapest method
It is estimated that one running meter of polyurethane foam blind area costs 8500 rubles, when applying a layer of insulation with a thickness of only 5 centimeters. A little expensive? Perhaps, but quickly. If you are not in a hurry and at the same time want to save money for something useful or for the soul, then you better perform the insulation of the blind with foam plastic - the cheapest material from existing insulation.
As the thermal insulation of the blind area, it is best to use extruded polystyrene foam, but it is also possible to do with the usual foamed foam, produced in mats or plates.
In detail, the process of work is as follows: as with the use of polyurethane foam, the primer along the perimeter of the building must be taken out to the depth of the vegetation layer and the width of the future blind area. Then the ground is leveled, which is completely unimportant when the foam is sprayed. As usual, a fifteen centimeter sand pillow 15 centimeters thick, of course, well tamped, is created. But then you will need a mounting foam. The fact is that polyurethane foam immediately and without joints sticks to the plinth, and foam plates leave the gaps of , which must be filled with mounting foam. Ideally, at the same time it would be nice to perform the warming of the base of the house, if it was not done before. Then we provide the screed by laying the reinforced mesh on the angle between the plinth and the plinth, laying the roofing material over the foam plaster for the best waterproofing, and all this is poured with concrete.
Additional insulation of the blind with very deep freezing of the soil
If in your region the winters are very severe, there is a risk that the ground will freeze at depth and under the footprint, thus reaching the basement. Even if the foundation is not deeper, the fact that freezing will go under it, there is nothing good, there can be formed in general permafrost. The best solution is the addition to the blind, stacked from its edge as a continuation, but at an angle of 50-60 degrees to the depth of the soil. Approximate cost of additional insulating strip for extruded and ordinary foam plastic, respectively, 1500 rubles and 500 rubles for the blind area of one side of the country house. But it is better, of course, to use polyurethane foam.
So, as you probably already guessed, the vegetation layer is taken out to the width of the blind area, but further from the edge of the resulting depression begin to dig a ditch depth of about half a meter, with bevels at 50-60 degrees. At the bottom of the ditch lay a strip of geotextile, pour a layer of coarse-grained sand or small gravel, put a drainage pipe on it, cover it with sand and wrap it all in geotextiles, bending its edges. Layers of sand and rubble for the blind area should descend along the slope to the drainage pipe, becoming a cushion for additional insulation. When everything is ready and tamped, we lay the heat-insulating slabs of foam or spray polystyrene foam, we can put geotextiles on top to isolate the atmospheric precipitations absorbed by the soil. The ditch is filled, along the edge of the blind there is a drainage system for draining the wastewater and the work can be considered complete. Do not forget to cover the concrete with polyethylene, so that it does not crack in the very first days from too rapid evaporation of moisture from it.