Any house must be built on a solid foundation. There are several types of foundations poured under buildings. At the same time, the most inexpensive type of such structures is columnar. These foundations are quite reliable and durable. At the same time, they are poured using a relatively simple technology. Even a person who does not have construction skills can build such a foundation for a house.
Definition and purpose
The column foundation is a solid structure, which is a series of supports under the building. Foundations of this type are usually erected during the construction of lightweight houses. That is, buildings with shield walls assembled from timber or foam blocks. In some cases, various small brick structures can also be built on columnar foundations. For example, such structures are often installed under gazebos. Depending on the material used, the supports of such foundations may have a round or square section.
The main load in suchstructures carry pillars buried in the ground. In some cases, in addition to the construction of foundations of this type, a grillage can also be poured. Sometimes the pillars of such foundations are made of brick or wood. But most often, the supporting structures of this variety are still poured from concrete.
Pits under the pillars of such foundations are made using a drill. Roofing material or asbestos pipes are most often used as formwork. Of course, to increase the bearing capacity, the pillars of such a foundation are always additionally reinforced.
In addition to the grillage, one of the elements of such a base can be a pick-up. This is the name of the structure that closes the gaps between the pillars. The fence is arranged in order to give the building a finished look and prevent cold air from entering the premises through the floor in winter.
Material selection
The columnar foundation is a structure, during the construction of which only high-quality materials should be used. Cement for pouring such a base is chosen by brands not lower than M400. In this case, sand for the preparation of the solution is used exclusively coarse, preferably river. In addition to these materials, columnar foundations are being erected using:
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reinforcing bars with a diameter of 8 mm;
- roofing material (for formwork).
If it is necessary to build a grillage, the following materials are also used:
- formwork boards;
- film for laying formwork.
For connecting reinforcing cage elementscolumn foundation, a special knitting wire is used. Pits under the pillars themselves during the construction of small suburban buildings are usually made using a garden drill with a diameter of 25 cm.
Regulations
The column foundation device is not too complicated. However, during the construction of such structures, it is necessary, of course, to follow certain rules. Base supports of this type are usually installed at a distance of 1.5-2 m, but not more than 3 m from each other.
Pits for such foundations are supposed to be drilled below the freezing depth of the soil. Otherwise, due to spring heaving, the entire structure may warp, resulting in cracks in the grillage and walls of the house.
The foundation pillars of this type are supposed to be located:
- on the corners of the building box;
- under all interior walls;
- at the intersection of walls.
Before pouring foundations of this type, you should also calculate the section of the pillars. The finished structure, of course, should easily support the weight of the buildings built on it.
Principle of column foundation calculation
In order to determine the size of the cross-section of this type of base supports, you must first calculate the load that the house will subsequently exert on the bearing soil. To do this, add up the weight of all the materials used to build the building. The columnar foundation for a frame house, of course, will not be so powerful. Unlike the grounds forbuildings with walls made of timber or foam blocks.
The mass of the columnar foundation itself should be added to the amount received. Also, when calculating the load, it is necessary to take into account the weight of those items that will subsequently be in the house, as well as the people living in it.
Based on the obtained load indicator, the total cross section of the columns is then calculated. In this case, the following formula is used:
S=1.4 x P/Ro, where P is the weight of the building, Ro is the soil resistance
When building a low-rise private building, the resulting figure is usually subsequently divided by 20-25. After all, this is the diameter of the holes dug with a garden drill. As a result, the required number of supports is obtained.
DIY columnar foundation: step by step instructions
The construction of such a base usually includes the following steps:
- markup execution;
- drilling holes for poles;
- filling the sand cushion;
- installation of roofing material formwork;
- installation of fittings;
- pouring the pillars with concrete.
When erecting frame and block houses, the grillage on the supports of such a base is usually not poured. Its role in this case is most often performed by the lower strapping or crown.
When using foam blocks or bricks for the construction of walls, a concrete grillage is poured on the pillars of the columnar foundation. At the same time, such a tape is necessarily reinforced with metal rods.
In some cases, to distribute the load from the walls on the foundation supports, a metal grillage can also be laid. Most often, the pillars are connected with a channel or an I-beam.
Marking and drilling holes
First of all, before pouring the columnar foundation for the house, all debris is removed at the construction site. Next, markup is made using an inelastic cord, pegs and a level. In order to make the corners of the building as even as possible, when performing this operation, the methods of the Egyptian triangle or two curves are used. Of course, the location of all the pillars is also marked with pegs.
At the next stage, the top sod layer of soil is cut off at the construction site. Next, proceed to the actual drilling of holes for supports. When choosing their depth, the height of the sand cushion is taken into account. At the final stage of drilling, they compact and level the bottom of each hole.
Pillow device
Under the supports of the columnar foundation, sand must first be applied. The cushion formed by this material is intended for shock absorption of pillars during spring heaving and building movements during shrinkage. The thickness of such a layer under the supports, according to the regulations, should not be less than 15 cm.
The pillow is arranged under the columnar concrete foundation as follows:
- pour a 5 cm layer of sand onto the compacted and leveled bottom of the pit;
- carefully spill it with water to seal;
- pour the following5 cm of sand and tamper again;
- pour another 5 cm of sand and water it.
At the final stage, the sand cushion is covered with a piece of roofing material. This prevents water from being drawn out of the underlying concrete layers of the support.
Installation of formwork and installation of reinforcement
The metal frame of the pillars of such a foundation usually consists of 4 rods. With the help of a knitting wire and ring-shaped clamps, they are connected into a frame. Next, bars (or special plastic coasters) 5 cm thick are placed in the pits. A frame is installed on them. This is necessary so that the metal reinforcement subsequently becomes completely embedded in the thickness of the concrete and subsequently does not rust.
When erecting a columnar foundation for a wooden building, the length of the frame is chosen equal to the length of the supports themselves (minus 5 + 5 cm at the top and bottom). If it is supposed to arrange a grillage, the rods are brought out over the last ones by 20 cm. In the future, this will make it possible to connect the reinforcement of the pillars and the grillage.
Pouring concrete
A columnar foundation is a structure, during the construction of which, of course, it is necessary to follow all the required technologies exactly. Sand for the foundation pillars of a lightly loaded house must be carefully sieved before preparing the solution. Under no circumstances should this operation be ignored. Cement for kneading should be used exclusively fresh.
In the prepared pits with reinforcement installed in them, formwork from roofing material is placed. Fortheir manufacturing material is simply rolled up.
The mortar is prepared in the proportion of cement / sand as 1/3. Lime is not added to the mixture. This material can reduce the ability of the posts to resist soil moisture. To make the pillars strong, they are poured in one go. At the final stage, the mixture is pierced with rods to remove air bubbles.
How to make a columnar foundation: pouring grillage
This element is built approximately on the same principle as the strip foundations of houses. That is, the concrete mixture is poured into the formwork with a metal frame pre-installed in it. The reinforcement of the grillage is connected to the rods of the pillars with the help of wire.
The bottom of the formwork under the tape is usually not stuffed. Instead, earth is poured under the walls of the mold from below. Filling is carried out with a solution, also prepared in a ratio of 1/3.
Arrangement of the pick-up
Such a structure when erecting columnar foundations is often laid out of brick. In this case, the usual technology with ligation of sutures is used. To save money, masonry is done according to the “half-brick” or “brick” method. To ventilate the poles in such a fence, small "air vents" are left in several places.
Also, sometimes the supports of such a foundation are closed at home with simple shields made of boards. Of course, the wood is subsequently painted to extend its service life. In addition to boards and bricks, a house pick-up can also be equipped with sheet materials, for example:
- slate;
- moisture resistant plywood;
- siding;
- corrugated board;
- basement siding.
Under small structures, such as gazebos, the collection is usually not collected.
