With grillage is a fairly popular building solution. It is great for building relatively light structures. Its construction is relatively economical - it will take less effort, funds and building materials than the construction of the classical ribbon foundation. The only drawback of the columnar foundation with grillage is the impossibility of creating a full-fledged basement or basement without additional work.
The pillars-supports of the grill foundation can be made of various building materials. One of the most popular methods is the construction of poles made of steel-reinforced concrete. This option, perhaps, will be the most reliable and durable.
We expect a columnar foundation with rocithic
The reliability of the structure depends on how well the calculation of the foundation is performed.
At the preliminary stage, the bearing capacity of the soil in your area is determined. This will allow you to calculate what the area of support should be, that is, the sum of the areas of all pillars. When calculating, not only the weight of the foundation itself is taken into account, but also the weight of the structure erected on it, including the weight of construction materials, loads, both domestic and natural.
To compensate for possible errors, the obtained value (the weight divided by the area of the support) should be increased by approximately 30%. After that, we calculate the required number of pillars. The maximum length of the side of the support post does not usually exceed 60 centimeters. Support pillars are compulsorily placed at the corners of the house and at the junction of bearing inner walls. In other respects, the frequency of placement of poles is calculated individually, but in this case, on one section of the foundation, the step between the poles can not exceed 3.5 meters.
We carry out earthworks
At the initial stage we are marking the future foundation, especially carefully verifying the right angles. To do this, we measure the diagonals of the rectangle. Marking is done from a tight cord. We remove the vegetative layer and transfer the fertile soil layer.
In the locations of the pillars, we dig or drill pits to a depth of at least half a meter, exceeding the freezing level of the soil in your locality.
The cross-section of the pit when using wooden formwork should be increased by 20 cm in each direction.
The bottom of the pit under the pillar is covered with a sand cushion about 10 cm thick. It is watered and thoroughly rammed. The sand pillow should extend beyond the edges of the future pillar. On top of the sand lay a sheet ruberoid, preventing the absorption of moisture from the concrete mortar by the soil.
Building formwork for foundation pillars
Usually, wooden formwork is made of a board 2 cm thick. You can also use sheets and cuttings of particleboard.
From the boards are formed shields, and then boxes, which are lowered into the prepared pit. The wooden surface of the formwork can be poured from inside with polyethylene or abundantly moistened with water.
In addition to the wooden formwork - the concrete solution can be poured into other structures. For example, it is possible to use pipes from any material of large diameter, or in general to form a formwork in the form of a cylinder made of roofing material.
In some cases the formwork can not be built at all, for example, with a hole in a dense dry ground. In this case, you can limit yourself to polyethylene.
Arm pillars-pillars of the foundation
The thickness of the reinforcing bar is usually selected no more than 14 mm. The reinforcing mesh should be constructed from all edges of the concrete casting by 50 mm, except for the upper cut, in which the reinforcing bars must be pulled out to further connect them to the reinforcing grid of the grillage.
You can weld the mesh points if the armature has the letter "C" in the marking. Otherwise, the armature is either knitted with wire, or fixed with plastic clips.
We collect the frame on the ground, its configuration is selected depending on the section of the column and we lower it into the formwork.
Fill the concrete mortar and fill the ground
The grade of concrete for pouring is chosen depending on the planned load on the pillars of the support. Each layer of poured concrete, 30 cm thick, after placement in the formwork is processed by a vibrator or bayonet shovel. The air must escape from the concrete mass.
After treatment with a vibrator, the next layer is poured and so to the top of the formwork. Large breaks in the pouring of layers in the column do not be recommended - so the strength of the structure will decrease.
Concrete seizes a day after four, then the removable formwork can be removed. The concrete solution will ripen only after a month, but its upper surface can already be waterproofed, treated with bituminous mastic or put ruberoid on it.
If you are installing the foundation in the abyssal soil, it is recommended to create a sand pillow around the pillars to compensate for soil movements. Poured sand around the pillars must be carefully rammed.
Arrange grillage columnar foundation
Grillage is a horizontal element that connects the foundation foundation into a single rigid structure. Usually monolithic reinforced concrete or ready-made foundation blocks are used for manufacturing.
In case of foundation construction on soils with strong punching, it is advisable to lift the grillage above the ground, so as to exclude the influence of the raised ground.
Installation of grillage - photo To create a hanging grillage between the manufactured poles, a continuous formwork is installed. In order not to create a bottom of such formwork made of wood - you can create its walls from the ground itself, and space for a gap is simply covered with sand.
Inside the formwork, a load-bearing metal frame of rods is formed about 14 mm in diameter. Calculation of the required amount of reinforcement is made as well as in the case of a concrete strip foundation. Since we left the bars of the inner frame of the pillars sticking out, we connect the grill frame to the reinforcement of the already cast poles.
Also, as in the case of poles - the inner metal frame should not touch the walls of the casting and is 50 mm away from them. At a bay from a concrete solution the air which has got there with mixing is obligatory removed. For this, a vibrator is used. After the maturation of concrete, the formwork and sand cushion are simply removed.
The formwork under grillage can be installed in a hanging form. For this, a U-shaped structure is built from the boards.
Video - Cylindrical foundation with grillage
What is the foundation know everything, but about grillage, perhaps, many hear for the first time. When installing a foundation of piles or reinforced concrete poles, a grillage device is mandatory. The columnar foundation is today the most popular in individual construction, mainly due to the rapid installation and inexpensive cost. It is worth noting that this type of foundation is not inferior to concrete in strength.
Feasibility of application
Before considering the question of when and where it is better to use a base of this type, it would not hurt to understand what a columnar-rostvernek foundation is, what it represents and when it is still more profitable to use it.
At the base of this type of foundation are opera poles (piles or reinforced concrete structures), in order to evenly distribute the load from the future construction, all the supports are connected to one structure with a grill that fits in the upper part of the base.
If weak soils predominate at the site of construction: sandy, sandy clayey, then here it is most effective to use the columnar-rostruk foundation. Thanks to it, the piles or poles can be immersed to the maximum depth, which will prevent the bedding of the support in unreliable and loose soils.
In conditions where the soils have a great depth of freezing, the installation of a concrete foundation is too expensive, therefore, in such areas it is also preferable to use pillars with grillage as support.
As supports, piles, pillars of reinforced concrete, wood and metal can be used. The last two options are used extremely rarely and only for light household installations. The most common for pillars of the pillar-grillage base are reinforced concrete.
How to make calculations
Before engaging in the construction of any foundation, it is necessary to carry out soil surveys and perform foundation calculations. This stage is the most important. So, the device of the columnar-grating foundation begins:
- every corner of the future building must rest on a pillar;
- the sections on which the walls intersect should be supported by additional pillars;
- as for the straight sections, 2.5 m is quite a sufficient distance between the supports, which meets all the requirements, but it is not worth choosing more than 3,5 m, since such a distance is already insufficient.
The initial stage of all the preparatory work begins with the removal of the turf throughout the area of the future foundation. Further in places where pegs are hammered, dig pits under supports. The depth of the wells should be greater than the freezing level of the soil plus 20 cm for the middle band. Additional centimeters are necessary in order to arrange a pillow, which in the future will contribute to the correct distribution of loads. The width of the trench will be equal to the width of the wall of the future building. From this size, on each side of the pillar, lay another plus 20 cm and install the formwork.
The construction of columnar-grout foundation begins with the device of a cushion of slag or crushed stone, which must be carefully compacted. The material must be laid across the entire width of the pit. Over the tamped slag lining ruberoid. This requirement is due to the fact that moisture from the concrete solution is not absorbed into the ground, while it will gain strength.
How to make formwork
For these purposes, conventional boards, 2 cm thick, will suffice. A small weight facilitates installation, and they are inexpensive. Of them, the shields are built, then the boxes. Then they are installed in the prepared trenches. Be sure to carefully moisten the surface of each shield with water. This will prevent the moisture from drawing out of the concrete, and in the future will facilitate the disassembly of the formwork.
Instead of planks, you can use pipes made of asbestos or ceramics. After pouring and solidifying the solution, they are left in the ground. It is also possible to avoid the assembly of the formwork, if in the prepared trench the strong walls do not crumble, and the size fully corresponds to the calculations made. To ensure that moisture from the concrete solution is not absorbed into the ground, it is sufficient to insulate the walls with a simple polyethylene film. But to secure the formwork it is still better to use.
How to reinforce the pillars of the base
The columnar-grill foundation for gas silicate should be carried out with the obligatory reinforcement of supports under it. For the skeleton use reinforcing bars. The diameter is suitable for both 10 and 14 mm. Stepping away from the edge of the trench 5 cm, the reinforcement is located in the pit and welded to horizontal rods.
The distance between the horizontal bars is about 40 cm. It is important to remember that the longitudinal rods along the length should be such that after filling the entire amount of solution, the bars have free ends equal to at least 30 cm. (Normally leave 30-40 cm). It is better to leave more than less, because excess centimeters can always be cut off. To these ends will further be welded the frame of grillage from the armature. The reinforcing skeleton should be collected directly on the ground, and only then, in the finished assembled form, lowered into the excavated trench.
Pouring of concrete solution
When the formwork is exposed and the metal skeleton is lowered into the trench, it is possible to start pouring concrete. It is poured in layers. The thickness of each approximately 30 cm. Each poured layer must be pierced to remove excess air and make the concrete dense and durable.
Filling technology is as follows. The first layer is poured, carefully pierced by hand or with the help of a tool, then the next one is poured. It is highly advisable not to pour half of the solution today, but the other tomorrow, as a joint will appear at the junction at the junction point, reducing its bearing capacity.
Formwork can be removed after 4 days. The surface of each support must be covered with waterproofing or treated with a special material. Only after this, the support can be covered with earth. If the site is mostly loose clay soil, then it is better not to return it to the pit, but fill it with sand with a careful ramming.
Installation of grillage
The application of the columnar-grating foundation allows the grillage to be mounted both from monolithic and prefabricated reinforced concrete. You can often hear a variety of opinions about the distance from the ground the grillage should be directly located. But the depth of its laying is determined by several parameters. For example, it is unacceptable to mount the grillage back to ground level, when loose and puffy soils prevail in the areas.
A laid grillage in the prepared formwork in advance, which connects all the pillars together. At the bottom of the formwork, a layer of sand is poured (it is desirable to use fractions more) and carefully compacted.
The second stage is made of a metal frame, which is laid in a mold and welded to the ends of the abandoned reinforcement of the supports themselves. Then pour the solution, removing the air from it. When the solution is completely hardened, the formwork is removed, together with a layer of sand. As a result, the columnar-foundation foundation, which can last for many decades completely ready. The most important thing is to comply with all calculations and requirements, especially when prospecting for soils on the site for construction.
In the process of building private houses, a columnar foundation with grillage is often used. It is much cheaper than the ribbon or slab base for the house.
And this is his main advantage. It is explained simply. Two other above-named species require the application of times more concrete. Therefore, the columnar design with grillage and cost less.
Stages of work
In this article we will consider the process of creating such a product.
It consists of the following stages:
- planning and marking;
- carrying out of earth works;
- preparation of formwork;
- the creation of reinforcing cage pillars;
- pouring of concrete solution and backfill;
- the creation of grillage.
Planning and Layout
This stage is the first and decisive. It depends on him how many pillars will be installed and how they will be located.
First of all, we will be engaged in planning.
The procedure for doing this will be as follows:
- we carry out geological surveys - they will help in establishing the bearing capacity of the soil. To do this, you need to establish the type of soil. Then, using the table below, you can find out how much a kilogram will sustain 1 cm² of soil.
The value of this parameter is very important for us. Knowing it, we will be able to establish the base area of the basement. This is the name of the parameter that determines what area the base should have so that it can support the weight of the house;
- determine the approximate weight of the house - it largely depends on what materials were used in the construction. Also, the wind and snow loads are important here;
- the resulting figure we will divide by the mass, which is able to withstand 1 cm² of soil - in the end, we get the required area of the basement;
- to eliminate the consequences of possible inaccuracies, we will increase this value by 20-30% - this will be the final figure that we will use;
- determine the number of pillars that we need to build. For this purpose, we divide the total reference area by the area of the support of one column.
Having finished the calculations, proceed to the markup. Note the places where the bars will be installed.
In this case, it is worth considering the following:
- the presence of support at every angle is mandatory;
- in the places where the walls intersect, there must also be pillars;
- the distance between them should be set at least 2.5 and not more than 3.5 meters - a shorter distance will not bring any benefit, but will only increase the costs. A larger interval is dangerous. It can lead to damage to the grillage and the formation of numerous cracks in the walls.
Carrying out of earth works
The next stage, which sets our instructions - is the conduct of land works. They begin by removing the entire plant layer in the place where the foundation will be located.
Then dig holes in the points where the poles will be located. Their depth should be equal to the freezing level of the ground plus another 20 cm.
These additional centimeters will be needed for laying the pillow. Depending on the thickness of the future wall, set the width of the excavated pit.
After that, we put a pillow on the bottom of the excavated holes, consisting of sand with rubble. It must be poured with water and carefully dumped. At the same time, we take into account that it must occupy the entire bottom of the pit.
Advice!
Above the pillow is to lay a layer of ruberoid or polyethylene.
With the subsequent pouring of concrete, this will keep moisture in it.
If water goes into the ground, this will lead to a decrease in the strength of the column.
Preparation of formwork
It is made of boards, with a thickness of 20 mm. They are easy and convenient to install. In addition, their cost is lower than for metal or chip analogs.
From the boards are knocked down the shields, which are then used to assemble boxes installed in previously prepared holes. After that, the surface of the formwork is abundantly wetted with water.
Due to this, the material will not absorb moisture from the concrete solution. In addition, this little trick will facilitate the subsequent dismantling of the formwork.
Creation of reinforcing cage pillars
The frame is created by hand from reinforcement with a cross section of 10-14 mm. These bars must be placed inside the formwork so that the distance from them to the boards is not less than 5 cm.
Between themselves longitudinal and transverse rods are welded or bonded. The transverse elements are located every 30 - 40 cm.
Longitudinal reinforcement should be 30 - 40 cm above the post. In the future, it must be connected with the reinforcement cage of the grillage. The excessive length can later be cut off.
All this construction must be collected in advance on the ground. After the assembly, we lower it into the pit.
Pouring of concrete slurry and backfill
Having prepared the formwork and the reinforcing cage, let's move on to pouring concrete. You need to stack it in layers of 20 - 30 cm. Each of them must be pierced or leveled with a vibrator.
This will eliminate the possibility of air pockets. They are very harmful to the design, as they reduce its strength.
Advice!
Fill the concrete solution at a time.
This means that the bay is one layer and having stuck it, you need to immediately cast the next one.
If you do this after a while, then at the joints of the layers a seam is formed.
And this worsens the load-bearing capacity of the product.
After 3-4 days you can remove the formwork. In this case, the concrete will not yet dry completely. The final strength columnar grillage foundation will pick up only a month later. But, nevertheless, the work can be continued.
The surface of the column is treated with a waterproofing material. To do this, you can use bituminous resin or waterglass.
Creating grillage
Grillage may be of the following varieties:
- monolithic or prefabricated reinforced concrete - a monolithic version is more common, as it is cheaper and does not require the use of special equipment. Therefore, we will consider it;
- at the ground level or "hanging" - the second option is more preferable. It avoids the influence of the bundle forces on the grillage. Below we will consider the process of its manufacture.
Between all the posts is a continuous formwork. Further, its bottom is covered with sand. This layer should have a height equal to the distance between the ground and the future grillage.
The sand is covered with cellophane from above. Next, a reinforced frame is manufactured and installed. It is made of bars with a cross section of 12-14 mm. Their number and location will be the same as in the case of the ribbon foundation.
In the photo - reinforced frame grillage
The finished frame is welded to the bars of the reinforcement coming out of the concrete pillars. Then the grout is poured with a concrete solution.
After curing of concrete, the formwork is removed. Along with it, remove a layer of sand. After that, there is empty space between the grillage and the ground.
If you want, you can do without sand. Instead, you can make the formwork in the form of the letter "P", which will be turned upside down. Thus, it turns out a semblance of a box.
It is installed on temporary posts-posts made of bricks. In the box set the reinforcement and pour concrete. (see also the article). After 3-4 days formwork must be removed and the bricks removed.
Conclusion
A foundation with grillage requires the use of less concrete than a plate or belt structure. Due to this, its price is lower than those of the two species.
To make such a foundation is entirely within the power of the home master. To successfully perform this work, you just need to make efforts and follow the instructions clearly.
On our site there is a video clip dedicated to such constructions. In the video in this article you will find additional information on this topic.
Almost every person understands that the foundation is the foundation of a strong and durable building, and therefore the quality of the work performed will depend on the life and operation of the building. Today, during their construction, a number of advanced technologies are used that allow the creation of a full-fledged design as quickly as possible without loss of quality. These include the creation of a columnar foundation with a grillage.
What is grillage and foundation with grillage?
Grillage is a part of the columnar foundation that is on its top and distributes the load between all the pillars, and also serves as a support for all the elements of the structure. The grillage has the appearance of beams, the construction of which unites the heads of the pillars. Usually grillage is made of wood, less often of metal, but modern construction uses reinforced concrete or concrete.
The foundation with grillage is already a design with a reinforced upper part that joins the heads of the pillars. It can be of two types:
- tape;
- solid.
The type of foundation used depends on such indicators:
- soil;
- material;
- method of the device.
Advantages and disadvantages
The main advantages of the columnar foundation with grillage are:
- The field of application is unlimited. Can be erected on clayey, rocky, hard and unstable soils. The relief of the plot also does not matter, which saves the architect from standard solutions and large construction costs;
- A competent installation will provide the building with a durability (more than 70 years);
- Relatively small price;
- There is the possibility of selecting the type and type of foundation and its grillage, which makes it possible to save on the price and timing of the work;
- The simplicity of technology makes it possible to build the foundation yourself.
But, in addition to the above advantages, there are several disadvantages:
- lack of the possibility of building a basement or cellar;
- a small resistance to deformation of the soil during the process of heaving.
Calculations of columnar foundation with grillage
Undoubtedly, it would be better to entrust the execution of the first design stage for the construction of the foundation to specialists, but if the budget is limited, you can try to figure it out yourself with technical literature and the Internet.
The calculation stage includes the following steps:
- geological survey. Are required to determine the load per unit of ground area, which, therefore, will determine the area of support of the future columnar foundation, which must withstand the entire weight of the constructed building. Existing load of 1 square. cm of soil can be found in the technical literature;
- calculation of the weight of the building. This indicator depends on the material used in the construction, as well as the existing load from wind and snow;
- calculation of the base area of the columnar foundation. This figure can be obtained by dividing the approximate weight of a building by its weight, which can withstand 1 sq. Km. cm of soil. To equalize the calculations, we increase the score by 25-30%;
- number of poles. This figure is obtained by dividing the base area of the basement by the base area of one column.
After the calculations, the stage of marking the foundation with a grill is in progress, where the important point is the marking of the place where the holes under the piles will be located. There are recommendations for installing supports:
- the presence of a support under each corner of the building;
- the presence of support in the intersection of walls;
- if there are no corners and intersected walls along the foundation line, the distance between the supports makes 2.5-3.5 meters. If the supports are installed more often, this will increase the cost of the building material, if less than every 3.5 meters, the building may become deformed, which will lead to the appearance of cracks.
How is the columnar grill foundation structured?
The device columnar grillage foundation is not so complicated. The main elements of the foundation are bearing supports (pillars), which can be made of different materials: concrete, rubble stone, brick, metal pipes.
As already mentioned above, the poles are installed at the corners and at the intersections of walls, and the step of their installation depends on the design and the expected load of the building.
Calculations of the diameter of each support are made for each building individually. Depth should be below the freezing level of the soil, and the lower point of the support is placed in a stable layer of soil. A prerequisite is the presence of grillages for a bundle of poles to distribute the load to all existing building structure elements.
Erection of columnar grillage foundation
If you want to do without specialists (engineers, architects) and begin construction of a house or structure on your own, several key aspects should be considered:
- type grillage. It depends on the type of soil and the properties of its movement;
- the construction of the future structure. Area, number of floors, building material affect the level of pressure;
- location relative to the soil.
Stages of erecting a columnar foundation with grillage:
- Calculated. The theoretical part was presented above.
- Preparatory. Includes clearing the site of all irregularities, as well as site planning according to its design. To check the accuracy of the staking, you need to measure the diagonals and angles. Vertical pits for pole mounting can be dug manually or with a drilling rig. It is important not to miss the moment and arrange a form at a depth of one meter to prevent soil shedding. The width of the excavated pit must include the dimensions of the pole, the formwork and the spacer.
- Installation of formwork. Usually use wooden boards, less often plywood with moisture-resistant properties, wood plates, sheets of metal.
- Reinforcement. It is carried out with the help of a metal rod up to 1.5 cm thick, which are connected in a horizontal position to each other by a wire. In order to connect the pole to the grillage, it is necessary to provide the installation of the reinforcement in the vertical position above the support at a distance of 1.5 cm.
- Filling with a concrete mixture. It is produced in several layers, each of which is 2 cm. Each layer is sealed with a hand-held vibrator.
- Waterproofing. It is carried out by laying any waterproofing material inside the formwork.
- Mounting the tube. A vial is a wall that closes an empty space under a columnar foundation. It is needed to conduct communications, as well as to avoid the entry of cold air and various precipitation. The best option is to pre-think the vial before the foundation, because then it will make it more difficult and inconvenient. The material for the tube can serve as a brick. The vial assembly includes ventilation and communication openings. The only drawback of the vial is its possible sediment under the action of soil movement.
The final stage is the removal of the formwork and the grouting of the ends.
The erection of columnar foundation with grillage is an advantageous variant of a low-rise building on complex, marshy and sandy soils, which are distinguished by mobility. And the ease and speed of installation does not require the help of special equipment, in contrast to the slab foundation.
The main reason for the growing popularity of the columnar foundation is the simplicity of the foundation construction. If the soil is relatively stable, and there is no special need for equipping the basement or basement rooms, you can set your house on a columnar foundation. The cost of such a system is relatively small, so it is resorted to in those cases where it is necessary to raise a small building or extension to the house at a small height above the ground.
What is the peculiarity of the columnar foundation device
Despite the external visual similarity with the device of pile systems, columnar foundations have their own specific features, reflecting on the construction of the basement:
- Columnal supports often perform a square cross-section, much less often - a round one. This is determined by the method of manufacture. Support in the form of a pillar can be laid with masonry, a stone - a sheath, collected from the buta, cast from concrete or folded from the buta in the formwork;
- The ratio of the length of the columnar foundation support element to the cross section is much smaller than that of the piles. The stability of a building raised to a significant height when using a columnar foundation is higher than that of a piling scheme, even when using a reinforced grill;
- Due to the high rigidity and strength, the number of supporting elements of the columnar foundation can be made much less than if classic screw or bored piles were used.
Important! One of the most remarkable properties of this scheme is that it is much easier and cheaper to build a columnar foundation with grillage with your own hands than a belt or pile version.
Which column foundation options are most popular
The choice of a specific solution depends largely on the specific design of the house, its weight and the rigidity of the building's frame. To the pillars do not heel and do not fall like candles, the pylons are tied with a special horizontal belt of reinforced concrete, rolled metal, or even just a wooden beam.
There are several basic schemes for using the columnar foundation:
- The classic option - buried in the ground columnar support elements with a hanging grillage, according to this scheme, 90% of all columnar foundations are constructed;
- Pillars without penetration into the ground, supported by a pillow of gravel, most often a monolithic columnar foundation with grillage. In this case, it is possible to obtain a high rigidity of the foundation, which minimizes the risk of heeling or slipping the building;
- Column foundation without grillage. A very popular option, which is used to equip small compact buildings.
For your information! Supports under the columnar foundation with grillage can have a variety of devices, for example, brickwork can be combined with concrete casting or with a basement base. In fact, the foundation properties do not change from this, but such solutions make it possible to greatly simplify and reduce the cost of construction.
Scheme of columnar foundation with buried supports
In fact, such a system is not much different from a pile foundation on very thick and short support elements. Visually, the difference is manifested in a much smaller number of support elements, located at a greater distance from each other. For the pile, the optimal step is equal to one and a half meters, and for the columnar variant, the distance between the supports can be 2.5-3 m, with the same thickness of the grillage.
Conditionally, the structures of such a foundation are divided into shallow and deepening to the freezing level of the soil. The first of these schemes is used on weakly patchy soils. The latter option is very expensive, but it is resorted to in cases where it is necessary to limit the number of piles on the site. In both cases, a brick or cast of reinforced concrete frame is installed on a sand and gravel cushion, making drainage and waterproofing of the columnar foundation.
Immersion in the ground, even at a small depth of a very heavy and massive support, increases the stiffness of the columnar foundation so much that in some cases it is possible to do without a rigid cross-skeleton - grillage.
Columny foundations without the use of grillage
The classic execution of grillage is a reinforced concrete beam, laid on vertical supports or pile heads. In addition to reinforced concrete, a metal profile can be used to equip the grillage, for example, a channel or a Taurus, or even a large oak bar. The main function of grillage is the transfer and distribution of the weight of the building between all the supporting elements of the columnar foundation. The second function grillage - fixing and holding the support in a strictly vertical position.
Heavy and rigid stone supports have tremendous transverse stiffness, so a tipping point can occur only when puncturing the soil, when the frozen ground squeezes one support stronger than the others. In this case, grillage helps to compensate for the uneven load and stop the roll.
On "quiet" soils of coarse-grained sand or with a large inclusion of limestone grillage loses some of its functions, and for a house with a small size of walls - 4x4, 4x6 m from it can be generally abandoned. Most often this is done when building lumber or log cabins, dachas, fishing and hunting lodges. To avoid lateral roll, the support elements of the columnar system are deepened into the ground by half a meter, and the first row of the bar plays the role of the grillage.
To fix the walls to the supports in the masonry or casting at the molding stage, anchor the bolts and lay a double layer of waterproofing from the roofing material and foamed polyethylene. The device and casting of a girder beam made of reinforced concrete requires a considerable amount of time and effort. Therefore, the owners of small houses try to abandon unnecessary in their view the details in the construction of the building.
One of the tasks that need to be addressed in the case of refusal to use grillage is the problem of ensuring equal height of all support elements. Otherwise, the beams of the first row will lie on the columnar system with a slope, and this can lead to the roll of the entire building structure.
In some cases, the grillage is replaced with ordinary thick beams, which are laid on a solid pillow of gravel and sand, leveled in a horizontal plane, fixed with staples and stakes. Further from logs or a beam the basic skeleton of a building with a bandaging of rows of supports under the standard scheme gathers.
Column foundation with grillage without deepening into the ground
The merits of the columnar scheme include the possibility of installing a building box generally without penetration into the ground. Most often, a similar method is realized in the form of a monolithic structure, in which grillage and supports are cast as a single unit of reinforced reinforced concrete. Such a frame has increased stiffness and strength, which is especially important for frame aerocrete walls of houses.
Before casting, it is necessary to concrete pavement areas, which are subsequently installed formwork to form the body of poles and grillage.
A simpler version of the surface foundation is the "shoe" type of supporting elements. Each of the pillars of the foundation is cast in the form of a cube or a truncated pyramid with a height and a base of 30-40 cm. Such a configuration makes the supports extremely durable and stable, enough to level the platform in a horizontal plane and pour pillows under the support blocks of a three-layer sand-gravel mixture.
Conclusion
With all its advantages, the columnar foundation with grillage is not very convenient for complex terrain relief, especially if it is a clayey slope on the shore of a lake or pond. In this case, even a small building will require a powerful grillage and the penetration of the pillars, at least a meter into the ground. Perfectly suitable for hut in the forest, on sandy soil you can confine yourself to a small one, at 20-30 cm deep, and in case of using "shoes" you do not even need this, just tamp the soil and pour the pillow out of the gravel.