The blind area is an extremely important event. They perform these works after the construction of the house is completed, therefore sometimes insufficient attention is paid to them, a hundred is unacceptable, since the construction of the blind area performs the extremely important task of protecting the foundation from atmospheric moisture. The following describes how the blind area should be done with your own hands, step-by-step instructions for each type of protective strip and recommendations for choosing materials.
Concrete blind area
Today it is the most popular way to protect the foundation, but it has a fairly large number of disadvantages, so if you have the financial ability to choose a more expensive and reliable option, it is better to resort to it. Most often, this type of blind area is characteristic of mass urban construction.
The disadvantages include:
- the need to mix concrete or purchase it at the factory (there is a need to use a concrete mixer);
- concrete gains strength within 4 weeks, half and this time it needs care (wetting every 2-3 hours), which increases the complexity and increases the construction time;
- the likelihood of cracks on the surface;
- the difficulty of access to the storm sewage system and drainage. Since in order to inspect or repair them, you will need to remove the coating, and then lay down a new one.
Production of an element from concrete is carried out in the following order:
- Calculation of the thickness of the entire structure, in which it is required to take into account all the layers. This value is needed in order to determine the depth of the trench along the perimeter of the foundation.
- Determination of geometric dimensions. On average, the width should be taken within 90-100 cm. The slope for concrete is 3-5% (for piece materials - 5%, therefore, in order not to get confused in the values, it is recommended to remember the total - 5%).
- Marking out the terrain. For this, the limits of the future design along the perimeter of the foundation are indicated with pegs with a cord stretched over them.
- Then they tear off the trench. The dimensions in the plan are already limited by the marking, it remains only to dig out the soil to a depth calculated in the first paragraph.
- The base soil is carefully compacted. If possible, a castle is made of clay, which will provide additional protection against moisture.
- The next layer is a sand cushion. Sand has three functions: replacing heaving soil, which is very widespread in the country, with conditionally non-porous, leveling the base, and arranging a drainage layer. The sand cushion is made only of large or medium sand. If the blind area is being built with the use of a small fraction, then large shrinkages, cracking and waterproofing are possible. The thickness of the layer is selected depending on the characteristics of the soil. It is important to consider strength and water saturation. If the soil on the site is strong, it will be enough to lay about 200 mm of sand. Unstable substrates may require 500 mm of sand.
- Filling from crushed stone performs approximately the same functions as sand. Here you can use not only gravel, but also gravel or sand-gravel mixture. The blind area on such a base increases the strength of the soil and increases the reliability of the entire structure. At this stage, the preparatory work is completed. Up to this point, there are no fundamental differences in how to make a blind area for the foundation of different materials.
- The next stage is the exposure of the formwork. Formwork is needed so that the liquid concrete mixture does not leak beyond the marking. For manufacturing, you can buy boards with a thickness of 22-25mm. You can use old materials in order to save. Walls are put together from the boards, which are installed around the perimeter of the foundation. It is important to install the board directly to the wall of the building, the thickness of the formwork element will ensure the necessary expansion joint, the thickness of which is in the range of 20-40 mm. A seam is needed to prevent cracking and deformation of the structure with different shrinkage of the foundation and the blind area.
- After the formwork is installed, reinforcing mesh is laid. They will increase the concrete's flexural strength. The diameter of the reinforcement in the mesh is recommended to appoint about 10 mm. This technology of the blind area will ensure its strength and reliability.
- Further, the blind area device requires the installation of transverse boards around the entire perimeter of the foundation. The boards will provide expansion joints that cut the strip into separate sections. The step of the boards is assigned 2 meters.
- The next stage is concrete pouring. For this, a concrete mixture of classes B20 - B22.5 (grade M300) is made. It is such a solution that can ensure the durability of the structure and the necessary strength. It is possible to use concrete of smaller classes, B15 and B17.5 are suitable, but it is worth remembering that the service life will decrease. When using a mixture of B22.5, the standard service life will be approximately 25 years. Filling in each compartment between the boards of expansion joints is performed in one go. After that, a seal is required. There are several ways, but the most common vibration dampers. In the absence of the necessary equipment, you can use the bayonet.
- After the solution is poured, the surface is iron-plated, this is done to increase the strength characteristics.
- The penultimate stage of manufacturing a concrete blind area of the foundation is the set of structural strength and maintenance. At a temperature of +20 degrees Celsius and normal humidity for curing takes 4 weeks. If the temperature is lower, the process slows down significantly. It is necessary to wait at least 70% of the brand strength of concrete. A week or two after pouring, the surface is moistened every 2-3 hours (and at night 2-3 times a night). This is to prevent cracking.
- When the concrete has gained 70% strength, it is possible to remove the formwork. After that, the blind area is completed.
The paving of the foundation of paving slabs
The blind area around the house with your own hands in this case has only one drawback - the cost. But in terms of appearance, maintainability and ease of use, it surpasses the previous type.
The preparatory phase of work is carried out according to paragraphs 1-7 for the manufacture of concrete paving of the foundation.
Further, the technology is different:
- An additional layer of sand of 70-100 mm is laid on crushed stone, while providing the necessary slope.
- The next step is the installation of tiles.
- Close up joints of piece elements with cement-sand mortar.
More details about this type of construction can be found in the article "Blind from paving slabs." Using the same technology, a cobblestone or ceramic brick structure is mounted.
Clay blind area
Arrangement of this type to protect the foundation requires actions in the following order:
- Preparation according to points 1-7 for concrete paving.
- Laying a layer of clay with a thickness of 100-150 mm and its compaction. For the manufacture of clay, you can use the clay that remained after the fragments of the foundation pit, but only if it is of good quality and high strength.
- The arrangement ends with the creation of a decorative layer. To do this, stones are embedded in the clay layer or laid on top of pebbles. This will create a convenient footpath and strengthen the structure.
Clay blind area is an inexpensive and not time-consuming option for creating a drainage system along the perimeter of the foundation.
Membranes
Before making a blind area around the house, it is recommended to consider the option of PVP membranes.
This material provides the highest degree of protection of supporting structures from atmospheric moisture.
The technology differs from the usual types of protective blind areas:
- Perform steps 1-5 for concrete paving.
- Lay a layer of sand, and in it a membrane.
- They fall asleep all this with a layer of rubble.
- Perform backfill.
- Planted grass.
The blind area from the membrane does not extend to the surface and cannot be used as a sidewalk. Its only function is reliable waterproofing.INThe choice of material depends on the capabilities and wishes of the future owner of the house.