When building a private house, it is very important to choose the type of foundation. The cost of work below the floor level of the first floor can reach 30% of the cost of the entire building, therefore, in order to reduce the cost of construction, it is necessary to carefully consider the selection and installation of foundations. When building a house with a basement, the most rational solution will be the installation of a strip foundation from FBS blocks. Step-by-step instructions and recommendations for this type of design are discussed below.
Advantages of FBS blocks
The foundation of FBS blocks is a concrete wall. For the construction, factory-made products are used. Reinforcement is not provided, since the blocks work only on compression, which concrete does very well.
The advantages of this technology include:
- ease of installation;
- high strength and frost resistance of products;
- low cost;
- a wide range of product sizes.
Application area
The foundation of concrete blocks can be made in the form of the following structures:
- Pillars
- tape.
Most often this material is used for strip foundations. Such a foundation can be arranged both for small individual buildings, and for multi-storey buildings. The choice of concrete wall thickness depends on the thickness of the elevated walls, the loads on the foundations, and the characteristics of the foundation soil.
The columnar foundation of FBS blocks can be provided for small light structures with high acidity of the soil and a significant depth of freezing.
Foundations made of FBS are used with fairly good soil characteristics. For marshy and unstable bases, it is recommended to use plate or pile supports.
Item Sizes
Reinforced concrete plants produce products in standard sizes. The thickness of the blocks is selected so that it would be possible to lean on them brick walls of any thickness. Below are the size options in all dimensions.
Height:
- 600 mm;
- 300 mm
- Length:
- 900 mm;
- 1200 mm;
- 2400 mm.
Thickness:
- 300 mm (under walls 250 mm thick);
- 400 mm (under the walls 380 mm);
- 500 mm (under the walls 510 mm;
- 600 mm (under the walls 640 mm);
- 700 mm (for walls 770 mm).
When leaning the walls on the blocks, it is important to remember that the overhang of the brick on each side should not exceed 40 mm. Otherwise, you will have to provide additional ways to enhance the departure of the wall beyond the foundation.
Mounting technology
The foundation from the FBS is mounted in the following order:
- plot marking;
- excavation (excerpt of a pit or trench);
- device pillows for blocks;
- installation of concrete elements;
- verification of verticality and basic dimensions in the plan;
- waterproofing;
- backfilling.
Depth
The height of the underground walls is determined by two factors:
- basement availability;
- soil freezing depth.
Support of foundations should occur below the depth of freezing of the soil by about 30 cm. Otherwise, a phenomenon such as frosty swelling will lead to the formation of cracks and distortions. In the presence of a basement, the depth of the blocks is selected so that it is 20-30 cm below the floor level.
Pillow for blocks
Building from concrete blocks is a fairly simple job. The most difficult thing is to prepare the base for laying. Before you make a foundation of blocks, you need to determine the type of pillow for it. There are several options:
- prefabricated reinforced concrete slabs;
- sandy;
- gravel
- crushed stone.
The construction of a heavy stone house on strip foundations involves the use of reliable reinforced concrete pillows. To mount them correctly, you must:
- level the base;
- lay a sand preparation 30-50 cm thick, depending on the type of soil;
- install FL plates;
- to make a reinforced seam in the places of support of the blocks.
As a preparation for the foundation of the FBS blocks with your own hands, you need to choose sand of medium size or large. The same rule applies for the installation of a sand cushion for a strip foundation of blocks. Fine sand during construction will cause severe shrinkage and lead to malfunctioning of the structure.
The advantages of a sand cushion include:
- ease of manufacture;
- low cost;
- leveling the bottom of the pit and preventing contact of concrete with the ground;
- effective removal of moisture from the structure;
- correctly distributes the load from the building to the base.
The disadvantages include a limited scope. Such a base is suitable only for small light buildings. It is impossible to lay blocks on it under a stone house (brick, concrete).
A higher bearing capacity boasts a sand and gravel pillow. The main material in this case is gravel with the addition of medium-sized sand.
The disadvantage of such a foundation will be a higher cost compared to sand.
But still, the price is much lower than when using reinforced concrete slabs. On such a pillow, it is possible to build a small house with several floors.
Stacking blocks
To simplify installation, it is recommended that you first draw a precast foundation from blocks on paper. This will allow you to properly decompose the elements.
Blocks must be laid with dressing, which will ensure high reliability of the design. During the construction of strip foundations, the dressing should be at least 250 mm. This means that each subsequent row of blocks must be displaced relative to the previous one by at least 25 cm. To ensure dressing and the most rational laying of blocks during the construction of one house, blocks of different lengths are used.
It is preferable to use products with a length of 240 cm, since this reduces the number of vertical joints.
But in individual construction, such blocks are often economically disadvantageous due to the high costs of lifting equipment. In addition, in buildings with small dimensions, it is difficult to lay out walls of large elements in terms of plan.
If reinforced concrete foundation pillows are used as the base for the blocks, it is necessary to ensure dressing with them. Areas for which typical products are not suitable, close up using concrete mix. Brick-ups are possible only for the interior walls of the house. Horizontal and vertical joints are sealed with cement-sand mortar. The solution gains full strength in 4 weeks.
For ventilation of the basement, it is necessary to provide for small openings - vents. The total area of these holes should be at least one four hundredth of the basement area.
The construction of a massive building or structure on soft soils requires the execution of a monolithic reinforced concrete belt along the upper row of blocks. It ensures the joint work of all products and gives the structure additional rigidity.
Waterproofing
An important stage of work is the protection of the concrete wall from moisture. Waterproofing foundations can be of several types, which are used simultaneously:
- vertical
- horizontal
- blind area around the perimeter of the house.
The blind area prevents rainwater from entering the underground walls. Horizontal waterproofing is carried out along the edge of the foundation (the end of the concrete wall and the beginning of the walls of the house) and below the level of the basement floor, if any. In this case, as a waterproofing material, you can stack:
- roofing material;
- hydroisol;
- linocrom.
Vertical waterproofing is carried out to the planning level of the earth. For its device apply:
- surfaced materials (roofing material, linocrom, hydroisol);
- coating materials (bituminous mastic, liquid rubber).
Construction in compliance with all stages will allow to build a reliable and durable foundation from FBS, which is not afraid of anything.