Blind area and insulation of screw foundation. Blind area of ​​the house for different types of modern foundations. Insulation of the blind area for screw piles

Difficult terrain, flooding of the site, weak-bearing soils are a traditional list of factors that complicate, and more often exclude, the possibility of laying traditional types of foundations, including the popular strip and ultra-reliable, but expensive monolithic ones. The outlined range of problems is solved by constructing a foundation on screw piles, which is dominant not only in terms of all-round suitability and all-season use, but also extreme efficiency, as well as speed of construction. A certain disadvantage of a pile foundation, namely, the unsightly free space under the house, is easily eliminated with the help of a decorative base. Such a foundation can be considered a good choice for low-rise construction, which means it is worth taking care of its protection from the eternal “enemies” - low temperatures, melt and rain water. Protection is guaranteed by the blind area for the pile foundation.

Is it worth making a blind area for a pile foundation?

The question is far from idle, but of a fundamental nature. If there is a focus on maintaining the operational characteristics of the building, the construction of a blind area becomes a mandatory procedure. Thanks to this element, it is possible to prevent the corrosive destruction of screw piles, the penetration of moisture into the house from the underground, as well as the destruction of the earth around the load-bearing elements. In addition, the blind area is capable of performing a number of other quite interesting functions.

Stages

What is the blind area of ​​a building and its purpose?

The blind area around the house on screw piles acts as a reliable protective belt or drainage circuit that prevents the destruction of the foundation under the influence of surface water. That is, it should and does, first of all, perform the function of waterproofing. No less important is the ability of the blind area to serve as thermal protection for the building if it is insulated. This feature allows not only to extend the life of structures, but also to significantly reduce heating costs. An additional bonus when constructing a blind area around a house on stilts can be obtained by decorating it. In this case, the residential building receives a more complete, presentable appearance. A less significant, but still useful function of the blind area is to serve as a convenient path for free movement around the perimeter of the building.

Structurally, such an element consists of waterproofing, a gravel-sand cushion, a thermal insulation barrier, and a waterproof coating. Concrete is often used as the latter.

Technical features of the blind area

The main parameters for such an element are regulated by SNiPs, as well as construction practice. Despite the fact that the blind area with a pile foundation is considered one of the simplest construction tasks, its construction should be approached armed with certain knowledge.

• length - protection is necessary for the entire pile foundation, which means the length of the element is equal to the perimeter of the structure;
• width - a prerequisite is a protrusion of 200 mm beyond the end point of the roof overhang, but more often the optimal width is considered to be 1 meter;
• thickness - for a pillow the thickness is chosen to be 20-30 cm, and for a covering from 3 to 150 mm (for concrete 130-150 mm, asphalt 30-40 mm, stone 50-60 mm);
• slope angle - the angle should be maintained at 3-5% (for stone 5-10%), that is, the part of the blind area from the side of the base should be 3-5 cm higher than the outer section.

When and how to make a blind area for the foundation of a house?

The construction of the blind area around the pile foundation must begin after the construction of the basement or first floor. In this case, the pile foundation will immediately receive high-quality protection from surface water. An additional advantage is the ability to move comfortably on a hard, dry path around the house/structure. To understand how to build, it is enough to familiarize yourself with a number of recommendations based on practical experience.

Basic rules for building a blind area of ​​a house

If the question regarding the order of construction of the blind area of ​​a pile-screw foundation has been clarified, then the rules for arranging such a structure require careful detail. The issue of organizing an expansion joint between the base and the drainage circuit itself is considered fundamental. For this, a two-layer roofing material is used or mastic with moisture-proof properties is applied in several layers. Ignoring such an event can lead to the destruction of the decorative layer of the base even with the slightest movement of the soil.

Scheme of arranging a blind area around a pile foundation house:

It is mandatory to install expansion joints along the perimeter of the blind area at intervals of 2-2.5 meters (usually from wooden slats placed on edge). The drainage system is prepared using a separately prepared trench (along the outer edge of the structure) and laying a pipe in it. Sand and gravel are used for backfilling, and geotextiles are used for waterproofing.

Soft blind area around the house on screw piles

This option is acceptable for pile foundations. Its features include the formation of a flexible base from sand and crushed stone with the subsequent laying of paving slabs. The function of the separating layer between sand and crushed stone is performed by geotextiles. Main advantage: low cost.

Blind area for different types of foundation

Shallow strip and monolithic foundations, which are in demand in construction, are equally poorly protected from surface water, and therefore require the installation of a drainage circuit. The design of the protective belt is extremely simple, which allows its construction without the involvement of qualified specialists.

In the case of pile foundations with a grillage lying on the ground or buried, the blind area is constructed according to the same principle as for a strip foundation. When the grillage is located above the ground, a protective element is still required to maintain the operational characteristics of the building and ensure the integrity of the load-bearing elements.

Waterproofing of piles

In the context of the construction of a pile foundation, such an event is of a priority nature. No matter how strong concrete or metal piles are, surface water can cause corrosion of the material and subsequent destruction of the elements.

The optimal case for high-quality and durable waterproofing of piles is the use of moisture-resistant concrete. If metal piles that are hollow inside are used, it is wiser to fill them with concrete with waterproofing additives. Blind areas, as well as proper arrangement of pits, are considered as additional measures for waterproofing piles. The latter are filled up before driving the piles with layers of sand and crushed stone, which makes it possible to form a drainage layer, and roofing felt is placed along the edge of the pit.

The final cost of the element depends on the parameters, materials used, and the type of waterproof coating (for example, asphalt is much more expensive than concrete). But in general, such a protective belt is quite cheap, and the benefits from it are maximum. It is mandatory to make a blind area for all buildings/structures.

Few people know what a foundation blind area is, although they have often seen that there is a narrow strip of concrete, asphalt or paving slabs around buildings.

Why is it needed, and is it possible to do without this structure? Let's try to understand this issue.

Definition of blind area

This strip is called a blind area and, according to building codes, must be installed without fail, since it protects the foundation from the penetration of surface water, which over time causes irreparable damage to it. It is created from waterproof material around the entire perimeter of the building, most often from concrete, asphalt or ceramic paving tiles.

A blind area with a width of at least 0.7 m is installed, with a mandatory slope outward from the wall of the house. In general, the width of the blind area depends on the composition of the soil on the site and the length of the eaves overhangs.

In addition to the main task of protecting the foundation from rain and melt water, the blind area often serves as a pedestrian zone around the house. The presence of a blind area allows you to keep the basement of the building clean.

Jets of rainwater flowing from the roof hit the ground, causing its particles to fly off onto the basement of the house. The sight, after this, is naturally unsightly, and the device of the foundation blind area allows you to avoid this.

Requirements for the blind area

The blind area should be arranged according to the following parameters:

If the foundation is columnar or piled, and the soils are strong, the construction of a blind area can be neglected, but it is imperative to make a waterproof coating in places where rainwater drains from the roofs, if there is no drainage system to remove wastewater from the building.

Types of blind areas

Foundation protection is usually made of concrete, but materials such as:

• Clay is an ancient method of waterproofing surfaces.
• Cobblestone.
• Red fired brick.
• Asphalt.
• Ceramic paving slabs.
• PVP membranes.

PVP membrane

If people are familiar with all materials first-hand, then membranes arouse healthy interest. This is a profiled roll material made from very dense polyethylene. Installation of such a blind area is carried out quickly and with low labor costs.

The membrane is spread directly on the ground, and can be sprinkled with sand or gravel on top. The top covering can be made from any decorative material, up to a natural lawn, for which a layer of earth 20-30 cm high is poured onto a layer of crushed stone and sown with grass seeds.

However, to prevent water accumulation, the membrane is also laid with a slope, and a drainage system is installed on the roof.

Concrete

Before making a concrete foundation blind area, it is necessary to remove the top layer of turf, level the surface and install an enclosing edge made of boards or metal profiles. From the outside, the side is supported with bricks, stones, or pegs are driven in so that, under the weight of concrete, the fencing strip does not fall.

After this, it is necessary to make a backfill of crushed stone and sand. The layer of sand and crushed stone is leveled and thoroughly compacted, after which the reinforcing mesh is laid and the concrete mixture is poured. When leveling the concrete, the required slope of the blind area is made.

When installing a concrete blind area, it is necessary to make expansion joints, for which a 15 mm thick board impregnated with an antiseptic is used.

Proper blind area around the foundation will not allow rain and melt water to seep to the base of the house, thereby extending its service life.

Insulation of the foundation and blind area

If it is necessary to insulate the foundation and blind area, foam or mineral wool slabs are mounted on the outside of the basement of the house. They are attached to the foundation using special dowels, the head of which is shaped like an umbrella. Previously the vertical part of the base is covered with a layer of waterproofing. This can be regular roofing felt or hot bitumen.

Currently, there are ready-made decorative panels made of metal siding with applied foam insulation. Their installation is carried out at a faster pace, combining two processes at once - insulation and finishing.

However, you should know that the insulated base and the foundation blind area perform different functions and cannot replace each other. Insulating the foundation at the basement level makes it possible to better retain heat in the house, while insulating the blind area promotes freezing of the soil to a shallower depth, which ultimately can have a positive effect on the basement of the house, but not on the overall temperature in residential premises .

If a pile-screw foundation was chosen for the construction of the building, at the end of the work the question quite logically arises of how and with what to close the space between the floor of the first floor of the house and the ground. Despite the popular belief that when using a pile-screw foundation, a blind area is not necessary, it is still advisable to do so.

There are several main reasons why it is needed. And among the main ones is the possibility of draining water from the foundation of a building by organizing a slight slope. In addition, the protective structure will provide the building with a finished and aesthetic appearance. A high-quality protective structure, finished with decorative stone or tiles, can become a real decoration of the building. In addition to the above, the following functions should be highlighted:

The blind area of ​​a pile foundation is especially important if the construction was carried out on soft soils.

As practice shows, building a strong, reliable and durable foundation without a protective structure is not possible. Without it, water and moisture will constantly accumulate in the base area, which will lead to devastating consequences over time.

But you can not be afraid of moisture getting on the foundation only if the blind area is made correctly and from reliable building materials.

Technical features of the blind area

Before starting the construction of such a structure as the blind area of ​​a building’s foundation, it is strongly recommended that you study its technical characteristics more closely. This is necessary, first of all, in order to prevent a fatal mistake when choosing a material.

You should approach the choice of the width of the blind area no less competently. On the one hand, it should be sufficient for the necessary protection, and on the other hand, it should not be too wide, so as not to spoil the appearance of the building or take up too much space. Typically, the width is calculated from the size of the cornice. The blind area should be about 20 cm wider than the latter. In this case, the water that drains from the roof during rain will fall directly onto the blind area and be removed along it to the ground, bypassing the base of the building.

Any blind area of ​​a screw or any other foundation includes two main layers: an underlying layer (which is responsible for the stability of the structure, preventing possible failures and subsidence) and a coating that drains water and moisture to the side.

It is important that the thickness of the coating is at least 10 cm, otherwise the structure will gradually be washed away by water. The slope must also be maintained. Without it, there simply will not be a normal outflow of water. The minimum slope should be at least two degrees, but it is better to make it larger, this will allow water to flow more easily in the right direction.

Construction of the blind area

A well-made blind area of ​​a screw foundation is half of an excellent result, and therefore, during the installation of the blind area, it is necessary to delve into all the nuances of the process as thoroughly as possible. Work begins on creating such a structure as a foundation blind area by marking the site. This will make it easier to maintain the desired width around the perimeter of the entire tape. After this comes the turn of earthworks. At this stage, a trench of suitable width and depth is dug.

The next step in the process of constructing a blind area for the base is to form a cushion - first from clay and then from sand. Then a small layer of medium-fraction crushed stone is poured, on top of which a reinforcing mesh is placed. When all of the above work is completed, you can fill the structure with concrete and level it. This is approximately what the installation of the most basic blind area, made of concrete mortar, looks like.

To obtain maximum results, it is not enough to simply build a blind area for a pile foundation. It still needs to be insulated. For this purpose, a horizontal insulation method is used. First of all, the waterproofing layer is laid. The thermal insulation panels used must be highly durable. Otherwise, they may later be damaged due to the severity of the concrete mortar screed.

You can begin lining the blind area of ​​the pile foundation only after the concrete has completely hardened. The cladding of the blind area has nothing to do with its technical characteristics; it performs an exclusively aesthetic function and is performed at will.

Main types of blind area

Depending on the type of material used, the foundation blind area can be:

• from cobblestones;
• made of clay;
• from asphalt;
• from paving stones;
• from paving slabs;
• made of concrete.

Concrete

Concrete blind area is by far the most affordable and easy-to-use material. When performing this type of blind area, it is necessary to provide expansion joints made of wooden planks.

The planks should first be thoroughly coated with a layer of bitumen and placed around the entire perimeter of the building at a distance of 2 to 3 m from one another.

Paving stones

Recently, in private construction, paving stone foundation paving areas are being used more and more often. This material is produced by manufacturers in various colors, a variety of shapes and sizes. To construct such a structure, a layer of sand is placed at the bottom of the trench, the thickness of which can vary within a fairly wide range and depends on the thickness of the paving stones. The sand must be carefully compacted and filled with a mixture of concrete (a layer of about 5 cm is sufficient). After pouring the concrete layer, a reinforcing mesh is laid and concrete is poured again. After the solution has hardened, a dry mixture of concrete and sand is poured onto it, onto which the paving stones are actually laid. At the final stage of the work, the outer edge of the paving stones is framed with a special border.

Paving slabs

Today, paving slabs are available in retail and wholesale sales in a wide range of colors and geometric shapes. Its thickness varies from 4 to 8 cm. This type of blind area has a long service life and is excellent for cladding the blind area of ​​a house. The blind area is made from paving slabs in a similar way to the construction made from paving stones and can easily be done with your own hands.

Conclusion

If you have built a house on stilts and are currently wondering whether the foundation area is needed, it is better to put all your doubts aside if you are interested in ensuring that the foundation of the building lasts for the longest possible period of time.

Some construction experience will be required to complete the job. Only in this case can you count on the fact that the finished blind area will cope with the function assigned to it to the fullest.

The blind area around the house will protect the foundation from moisture and prevent erosion of the soil by melt and rain water.

According to SNiP, the slope of the structure should not exceed 10%.

There are two types of blind areas: a hard structure is based on concreting, and a soft one is made by pouring layers of various building materials.

Today we will look at how a soft blind area around a house is made and its existing types.

The design of the soft blind area consists of building materials laid in layers. Their function is to collect waste water and remove it from the foundation of the house.

Typically, the following materials are used to construct a standard design:

• Waterproofing made of PET film or roofing felt. An alternative, but expensive option is PVC membrane.
• Geotextile fabric is used as a filter material.
• To fill the top layer, use crushed stone, mulched soil or soil with lawn grass, and lay a sidewalk.
• If it is necessary to drain a large amount of water, a drainage pipe is placed inside the blind area.

If we talk about the top layer, then it can be decorated at your own discretion. You can even sow greenery on top.

Decorative crushed stone looks aesthetically pleasing on top, but if it is not available, you can use regular crushed stone, preferably of the middle fraction.

The lowest layer of the structure is traditionally made of pure clay.

In its absence, you can get by with ordinary soil, but then the risk of flooding of the building increases.

Additional measures taken to remove wastewater will help to avoid this.

Geotextile fabric is laid between layers of sand and crushed stone.

It filters passing wastewater, preventing two fractions of adjacent layers from mixing.

Construction according to all the rules of a complex structure cannot be done without insulation. It is made with extruded polystyrene foam or sprayed polyurethane foam.

Existing alternative blind areas

Depending on what is at hand, some owners use their imagination, inventing new types of blind areas. They are slightly different from the traditional one, but they function just as well.

The simplest construction option using PET film has the following sequence:

• A layer of clay is laid around the perimeter of the base of the building.
• Waterproofing is spread on top. Usually PET film is used, although it can be replaced with glass insulation.
• The waterproofing is covered with another layer of clay, about 100 mm thick.
• The top cushion is made of gravel.

A more complex design is obtained using rubemast. This is the same roofing material, only made using new technologies. The order of work is as follows:

• Formwork made of boards or durable sheet material is installed around the building in a pit.
• A sand cushion is poured inside.
• Rubemast is rolled out on the sand so that its edges come out of the trench and overlap the ground.
• The resulting waterproofing is covered with a mixture of gravel and sand.
• The top covering is made of paving stones or any type of paving slabs.

Geotextiles have become widely used in the manufacture of blind areas. The advantage of this material is to prevent the germination of any vegetation on the surface of the structure.

The phased construction of a blind area consists of the following steps:

• A trench with a slight slope is dug along the perimeter of the base of the building to drain water.
• The bottom of the pit is covered with geotextile fabric, running it over the base of the building.
• A layer of crushed stone with a fraction of up to 20 mm is poured on top of the canvas and carefully leveled.
• The extreme part of the trench close to the foundation is covered with a layer of sand. A curb is mounted on top of it.
• The remaining space of the pit is filled up.

Well, the Finns came up with the last, rather interesting idea. It is based on laying drainage pipes. Construction proceeds as follows:

• A trench is dug along the perimeter of the building’s base where the pipeline is laid.
• Pipes are used with holes, placing them at a slope towards the drainage pits.
• The first layer of pipeline backfill is made of gravel. The top is insulated with overlapping sheets of polystyrene foam, after which the entire “pie” is covered with a layer of soil.
• A 400 mm layer of crushed stone is poured onto the ground. The finishing is done with decorative pebbles.

Maybe someone is making another type of blind area, but in any case, the structure for a new house must be laid before the onset of the first winter. Otherwise, after the first winter, the foundation will be covered with small cracks.

Advantages of a soft structure

The construction of a soft blind area differs from a hard concrete one in that it gives the structure special advantages:

• It is not afraid of ground movement caused by winter freezing and spring thawing. If we consider the entire structure in parts, then the foundation has its origin below the freezing level, which makes it motionless. Any blind area is located at the freezing depth. Regardless of the strength of the concrete, soil movement will erode the integrity of the rigid structure, allowing moisture to penetrate underneath the foundation. Repairing new cracks every year leads to new costs. The soft blind area will simply “play” on the heaving soil and fall into place without losing its functionality.
• The soft blind area combines aesthetics and practicality. While protecting the base of the building from moisture, it also decorates the landscape of the yard. This is achieved through the use of a beautiful decorative layer, which looks much more attractive than asphalt or cement screed.
• The surface of the soft blind area can be planted with lawn grass, flowers or any other ornamental vegetation.
• The top decorative layer does not have to be laid at a slope from the building. As a decoration, it may have visible irregularities.
• The use of insulation reduces the depth of freezing around the blind area. This allows you to lay the foundation at a shallower depth when building a house on clay soil.

As you can see, this design has many advantages, but it also cannot do without disadvantages. It is one and is associated with the appearance of weeds on the top layer. Over time, the crushed stone will have to be cleared of weeds, dry grass and leaves. Green space also requires constant care.

Step-by-step laying of the blind area around the foundation

Setting up a soft blind area around the house is quite simple, so you can do all the work yourself. The construction process consists of the following steps:

• A trench is dug under the blind area along the perimeter of the base of the house. 300 mm depth and 600–800 mm width will be sufficient. If it is planned to insulate the structure, then the depth of the pit must be increased by the thickness of the proposed insulation.
• The bottom of the pit is covered with a layer of clay 100 mm thick. You should use only pure clay without various impurities, such as sand or soil. Otherwise, the penetrating water will swell the entire clay layer, and with it the entire blind area. The clay is leveled along the bottom of the trench so that there is a slope of at least 50 mm across the entire width from the foundation.
• The clay layer is compacted tightly and covered with waterproofing made of PET film. Roofing felt is sometimes used instead of film. This is also a good waterproofing agent, but short-lived. The film is spread over the entire bottom of the pit and wrapped onto the foundation. Here you will need to make a fold of approximately 300 mm along the entire length. If the blind area moves away from the base of the building, the fold will act as a compensator.
• The waterproofing on top is protected with a layer of sand 50 mm thick.
• The sand layer is covered with geotextile fabric. Due to its structure, geotextile will allow water to pass through, but will prevent sand from mixing with the fractions of the next layer.
• Crushed stone of the middle fraction with a thickness of about 130 mm is poured on top of the canvas. Between the stones, water will seep up to the waterproofing layer, and then move away from the foundation along it.
• The crushed stone is covered with another layer of geotextile, and the final layer of soft blind area is laid on top of it.

Do not neglect the choice of decorative layer. In addition to his direct duties, he will also serve as a decoration for the landscape of the yard.

Insulation of the structure

When arranging a soft blind area around the house, it would be useful to insulate it. This will bring additional costs, but they are offset by the better functionality of the structure.

Insulation will prevent freezing of the soil around the foundation, which will have a positive effect on the very foundation of the building and the blind area.

For insulation, two types of materials are used:

• extruded polystyrene foam
• spray polyurethane foam

A budget option is polystyrene foam boards. The insulation has increased strength, low water absorption and a long service life.

It is easy to process, allowing you to install it yourself.

When using expanded polystyrene, the depth of the trench is increased by 100 mm. The slabs are laid tightly butt-joint on the bottom layer of waterproofing. If slabs with a thickness of 100 mm are used, it is enough to lay them in one layer.

Sheets 50 mm thick are laid out in two layers.

It is necessary to ensure that the joints of the sheets of the top layer do not coincide with the seams of the insulation of the lower layer.

The polystyrene foam is covered with another layer of waterproofing.

It is installed similarly on the foundation wall.

Top waterproofing will prevent water from penetrating under the insulation.

Expanded polystyrene is resistant to moisture, but water that gets under the sheets when freezing will deform them, which will lead to rapid destruction.

All other layers of soft blind area are laid on the top waterproofing.

As for polyurethane foam, it has the best characteristics. In addition to the fact that its structure has a low water absorption rate, seamless installation eliminates the penetration of water and the creation of cold bridges.

The fact is that the material is sprayed. The foam fills all the voids, and after hardening it forms a single whole coating.

The only drawback is the high cost of the work. Spraying will require special equipment, so you won’t be able to do all the work yourself.

Making a blind area for a pile-screw foundation

Many people ask the question: is a soft blind area around a house on screw piles necessary?

After all, the base of the building is located above ground level, and the piles themselves are protected by a special coating.

There is only one answer - of course, it is required.

Wooden houses are usually built on stilts, and excess dampness under the foundation will not benefit it.

The piles also could use some extra protection, since their coating is not permanent.

It is better to pour a concrete blind area under pile houses, but a properly made soft structure will serve no worse.

The construction process is identical to that for a simple foundation, although there are some nuances:

• The first thing to do is dig a drainage ditch around the house. Perforated pipes or drainage blocks are laid here with a slope towards the drainage wells.
• Soil is removed from the drainage to the screw piles. Further work in the trench is the same as when constructing a blind area under a regular foundation. Only the mounting is different. Instead of a foundation, the piles are covered with the folded edge down to ground level.

It is better to make the top layer from paving stones or paving slabs. This option will allow you to make a sidewalk path around the house. For convenience, the width of the blind area can be increased.

Do not neglect the construction of a blind area around the house. This rather simple structure will benefit the building.

How to properly make a blind area around the house - in the video: