Concrete blind area is an important element of the house. Often this design seems insignificant, but if you look at the issue, it is very important. It is necessary to observe the technology and choose the right type of design. How to properly fill the blind area independently around the house is described below.
What is it for?
Concrete blind area - a must. Its device performs a very important function - the protection of the foundation. This element around the house removes rain and melt moisture from the perimeter of the basement walls, thereby reducing the load on the drainage system and vertical waterproofing.
Before you make a blind area with your own hands, you should decide on its width. To perform a given function, its protrusion of the blind area around the house is taken equal to one meter. This value allows you to reliably protect the basement walls. In some cases, it is allowed to reduce the width, but only if absolutely necessary (for example, the tightness of the conditions on the site). The minimum size is 80 cm. It is important to consider the protrusion of the eaves of the roof. Its projection on the surface of the earth should be at least 20 cm smaller than the protrusion of the concrete shield.
In addition to waterproofing, the blind area takes on several more functions:
- completion of the architectural appearance of the house;
- arrangement of a pedestrian zone around the building (the blind area plays the role of a pedestrian path).
You can use the blind area as a path only for low-rise individual buildings, provided that ice is removed from the eaves and snow from the roof in a timely manner. It is important to remember safety measures in the winter, since there is a danger of snow and ice falling on a person when moving close to the eaves.
To perform the main function - water flow, the blind area should be made with a slope. The decrease in height occurs away from the walls of the house.
The blind area around the building involves a slope of at least 0.015.
This value means that for every meter horizontally there is a vertical change of 1.5 cm. Before pouring the blind area, you should calculate its height at the walls of the house.
Blind construction and materials
Concrete blind area is arranged quite simply. Filling the blind areas around an individual house is beyond the reach of a professional. The device requires the preparation of the following materials:
- Additive that needs to be done before pouring the solution with your own hands. You can make a filling of various materials. The design allows the use of medium or coarse sand, sand and gravel, crushed stone or gravel of a not very large fraction. Do not pour cement mortar over fine sand. Such a base can shrink, which will lead to the fact that the concrete for the blind area will crack. It is best to make a pillow from two types of material. The first layer needs to be done in order to compact the base soil and level it. To do this, use gravel or gravel. Making a second layer is made of sand.
- To increase the strength, filling the blind area involves reinforcement. You can reinforce the element around the house with your own hands using reinforcing mesh. It is recommended to make grids of reinforcement with a diameter of 6-8 mm, depending on the characteristics of the base soil. The blind area device implies mesh sizes of 30x30 or 50x50 mm.
- Before casting, formwork must be done. You need to make wooden boards around the perimeter of the blind area so that the concrete mortar does not spread. To make the formwork, you need wooden boards. The width is selected depending on the thickness of the blind area. To keep the solution, it is enough to purchase a material with a thickness of 22-25 mm.
- The main material for the manufacture is concrete mortar. The most important thing here is to choose the right brand of mix. The concrete class should be at least B15 in strength (old marking M200).
A solution of higher grades can be used, but this is not beneficial from an economic point of view. To make a durable building element, you also need to think about frost resistance. The concrete grade for the blind area for frost resistance should be at least F50. It is best to opt for the F100 brand, such a solution will provide better resistance to temperature changes. When preparing concrete, it is important to observe the proportions of its components.
Composition of concrete for the blind area
To do quality work with your own hands, you will need to correctly select the concrete mix. You can get a solution for pouring in two ways:
- purchase at the factory and transportation with a concrete mixer;
- self-cooking.
It is better to opt for the second option. This is due to the following factors:
- to buy the finished mixture is always more expensive than to cook with your own hands;
- a small amount of concrete is required on the blind area, and factories sell it in sufficiently large volumes;
- No need for transportation costs.
The home master in the manufacture of the mixture should only correctly select its components and observe the proportions. The composition of concrete for the blind area is as follows:
- cement (it is better to use PTs400);
- sand (the best option is medium, fine is allowed);
- coarse aggregate (crushed stone or gravel);
- water.
The proportions of each of these components are set depending on what brand of concrete you need to get. For concrete grade B15 (optimal for the blind area), the proportions you need to do are:
- cement -1 part;
- sand - 2.8 parts;
- coarse aggregate - 4.8 parts.
These proportions of 10 liters of cement provide 54 liters of concrete mix. For every 6 parts of water, 10 parts of cement should be by weight.
If it is necessary to create material of a different brand and it is not possible to familiarize yourself with the information more carefully, it should be remembered that in the general case the proportions look approximately as follows: 1: 3: 4 (cement: sand: crushed stone, respectively).
Work order
A do-it-yourself device involves performing actions in the following sequence:
- first you need to mark the blind area on the ground;
- digging a trench around the perimeter of the building to the depth of the blind area (depends on the thickness of the layers of backfill and concrete);
- compaction of the basis;
- installation of formwork panels and fastening them together;
- laying of bulk materials (sand, gravel) with compaction;
- laying reinforcing mesh;
- installation of boards that will play the role of expansion joints that prevent concrete from cracking in the winter) with a step of 2 meters;
- concrete laying and compaction, leveling;
- surface ironing;
- waiting for time to set strength, care for concrete.
It is important to provide a distance between the blind area and the wall of about 2 cm. This gap will allow structures with different weights to settle independently of each other and prevent the occurrence of cracks.
A set of full strength with concrete occurs in 28 days at an average daily temperature of +20 degrees Celsius. If the air temperature is lower, it will take longer. The formwork can be removed after reaching a set strength of 70%.
Concrete care consists in its periodic wetting. To prevent moisture evaporation, the blind area after pouring is covered with a film or burlap. These measures will prevent the appearance of cracks during solidification.
An additional measure may be the insulation of the element. To do this, use extruded polystyrene foam, which is placed under a layer of concrete on the bedding. Warming is relevant when the depth of the foundation sole is higher than the freezing depth.