When in private construction it comes to choosing the type of foundation, preference is often given to the columnar with grillage. Why? Mainly because of the cheapness of such a basis. Concrete on it goes several times less than on the tape, and an order of magnitude less than the fill of the foundation slab. But we should not forget about reliability and durability, therefore we will choose reinforced concrete poles.
An important stage of the work is the calculation of the columnar foundation, when it is determined how many poles will be needed and how they will be located.
It is worth starting to carry out geological surveys to calculate the bearing capacity of the soil: will it be able to withstand the weight of the structure. Next, we determine this weight, depending on the material used, as well as on what will be the wind and snow load.
Column foundation
The area of the foundation is the result of dividing the resulting figure by the weight, which is able to withstand 1 square centimeter of soil. To eliminate possible miscalculations, the figure 20-30 should be added to the resulting figure.
To calculate the number of columns, we divide the reference area by the area of the base of the column.
In order to properly mark a columnar foundation with a grillage, it is important to take into account three factors. First, the support must necessarily be under each of the four corners of the building. Secondly, the pillars must be installed at the intersection of the walls. Thirdly, on straight sections the bars are recommended to be located at a distance of 2.5-3.5 meters.
Land works
First you need to remove the vegetative layer along the perimeter of the basement. Then dig the pits under the bollards to a depth equal to the freezing point of the soil, with the addition of 20 centimeters necessary to lay the pillow.
The width of the hole should be the thickness of the wall plus 20 centimeters on both sides for the installation of formwork and struts.
The process of removing the ground layer for the foundation
We lay on the bottom of each pit a cushion of rubble with sand so that it protrudes 10-20 cm behind the base of the column. We shed copiously with water, we compact it. We lay polyethylene or roofing material on top, so that during the pouring of concrete, the moisture from it does not go to the ground, read about the foundation pouring with your own hands.
Formwork device for foundation pillars
For formwork, it is advisable to use boards with a thickness of at least 20 millimeters. They are convenient to install, because they are easy. In addition, it is much cheaper than metal and wood-shaving materials. Iron, ceramic or iron pipes are also used. If the walls of the holes are dry and do not tend to collapse, it is permissible to do without formwork at all - just pour the pit with polyethylene.
If you choose a variant with boards, we shoot them in shields, and then into the boxes. We install into the holes. Wet to prevent the formwork from soaking up moisture from the concrete and simplifying further extraction from the ground after pouring.
Reinforcement of pillar foundation
The reinforcement of diameter 10-14 mm is used.
Scheme of foundation reinforcement
Longitudinal rods of reinforcement are chosen so long that after setting the concrete, they rise above the ground by 30-40 centimeters. Surplus after installation of the reinforced frame grillage can be cut.
The rods are welded or bonded( which is better) with round or rectangular horizontal bridges, which are located at a distance of 30-40 cm from each other. The reinforced frame is collected on the ground and lowered into a pit.
Concrete pouring and backfilling
Concrete is poured in layers of 20-30 centimeters, pierced or leveled with a vibrator to prevent air pockets from forming.
Sample of embedded foundation
To avoid the appearance of seams, which weaken the load-bearing capacity of the structure, the concrete should be laid entirely, without breaks.
Day after three or four you can remove the removable formwork. It is necessary to treat the surface of the column with a waterproofing material( bitumen resin, hydroglass) and fill the soil back. If it turned out to be puchynist, fill it with sand. It is possible before this to warm the foundation with the help of plates of extruded polystyrene foam.
Device for grating the column foundation
For its production, prefabricated or monolithic reinforced concrete is usually used. Builders argue whether the grill should be laid on the ground or lifted above its surface. The main argument in favor of the hanging is that the punching forces do not act on it.
Sample device for grating the column foundation
Set solid formwork along the perimeter of the foundation. At its bottom, pour a layer of sand and cover with cellophane. From the rods d 12-14 mm tie the frame, install it. Calculation of the amount of the required reinforcement is made in the same way as the ribbon foundation. The frame can be tied or welded to the reinforcement bars sticking out of the ground. It is necessary that the rods are at least 5 centimeters from the walls of the formwork.
It is also necessary to fill the grillage at the same time so that no seams are formed. Remove air with a vibrator or a piece of fittings. After grasping the concrete, remove the formwork and sand from under the grillage.
Instead of sand, a plank formwork is suitable in the form of an overturned letter P. It is installed between supports on several brick posts, the reinforcement frame is piled into it and poured with concrete. After three or four days they are removed together with the bricks.
Video - Column Fixed Lint with
