An integral part of a cottage, country house or summer cottage is a reliable fence. It protects private property from unauthorized access by unauthorized persons, and also prevents the possibility of neighboring animals from entering the territory. When planning to build a high-quality and original fence, it is necessary not only to purchase the necessary materials. You should also consider what kind of foundation to build for the fence. A solid base affects the lifespan of the fence and its stability. Let's consider the features of various base options.
When planning to lay the foundation for a fence with your own hands, it is important to choose the best base design option.
It must meet the following criteria:
The strength characteristics of the base are directly proportional to the weight of the enclosing structure.
The service life of the fence and its main characteristics largely depend on the quality of the foundation.
When thinking about how to make a foundation for a fence, you should choose the best base design option by analyzing the following factors:
When performing the analysis, you should also pay attention to the proximity to the fence of busy roads and railways. The design must painlessly absorb vibration loads that are created when vehicles move.
Various types of foundations are used for the construction of fences:
Currently, several main types of foundations are successfully used for installing fences Depending on the design features of the fences, different types of foundations are used. One of the most common options is ribbon-column. Thanks to its design features, it is able to withstand significant loads that are created by most erected fences. Let us dwell on the features and technology of construction of each type of foundation.
The most optimal design option for self-construction is a strip-column base Main features:
It is necessary to note the shortened construction cycle, with a total duration of no more than ten days. At the preparatory stage of work, it is important to perform the following work:
The foundation for the fence is poured according to the following algorithm:
To achieve maximum reliability and the required stability of the structure, the tape and columnar supports are necessarily reinforced The tape-column base will be used for a long time, maintaining its integrity under the influence of significant loads.
This design has its own characteristics:
For the construction, it is necessary to prepare the required number of pits, install vertical columnar supports in them and then pour the concrete mixture. Wooden planks can then be nailed to the posts, wire mesh attached, or corrugated sheets secured.
Let us consider in detail the construction mechanism:
When performing work, pay attention to the following points:
When performing work, you should focus on the mass of the future fence and soil characteristics.
Non-buried reinforced concrete foundation Features of the strip base:
The following materials are used for production:
The construction process is similar to the arrangement of a strip-column base. Procedure:
A month after concreting, the cement hydration processes will be completed and further work can be carried out.
Strip foundation for a fence The main features of a gravel foundation:
The sequence of technological operations resembles the execution of work on the formation of other types of foundations:
If it is necessary to install support columns, they can be placed in the trench before pouring concrete.
Peculiarities:
This type of foundation is ideal for installing heavy and large fences Construction procedure:
For normal aesthetic perception, you can stop laying when the foundation is raised above the zero mark by 50 cm.
Various types of foundations can be used to build a fence. The choice of the optimal option is made individually, depending on the characteristics of the soil, calculation results and personal preferences. When performing work, you should be guided by the requirements of technology and use high-quality materials. If you do not have the skills to perform construction work, you should turn to professional builders. They will make the necessary calculations and quickly build a solid foundation for the future fence.
Before starting the construction of strip foundations, it is necessary to understand their features so as not to make mistakes that cannot be corrected later.
When building foundations, you must adhere to the following sequence:
Before you start calculating the volume and cost of building materials for the construction of strip foundations, familiarize yourself with the basic requirements for them. Strip foundations are built for capital structures with a large load on the base. In order to correctly pour a rubble or concrete strip foundation for a fence with your own hands, you must first check the bearing capacity of the soil, calculate the materials, and find out the laying depth.
In order to draw up a working plan, it is necessary to measure the length of the proposed fence with a tape measure with an accuracy of 1 centimeter. Such accuracy is needed in order to be able to calculate not only the amount of building materials, but also to correctly place the pillars on the plan.
What do you need to know before starting construction? The main questions that will have to be resolved are:
Vertical load is the weight of building structures and materials located on the foundation. The calculation is made in tons/m2 based on the volumetric weight of the materials. For a brick fence, the weight of one brick (approximately 4.5 kg) is taken into account and multiplied by their number. Vertical load is directly related to the bearing capacity of the soil and is measured in kg/cm2. Having the total load on the foundation, in tons per square meter, it is not difficult to find out how many kg/cm2 falls in each specific case. To do this, you need to divide the load by area in cm2.
Horizontal loads can arise from strong cross winds or from hanging heavy metal gates.
To determine the type of soil, you need to dig a hole to the freezing depth and look at its structure. The pit will give a general idea of the presence of aquifers on the site and the level of underground groundwater.
Find out the amount of soil freezing from any construction organization conducting construction work in your area. How to calculate the freezing depth, see SNiP 23-01-99*.
If groundwater comes high to the surface, a drainage layer of crushed stone or gravel 200 mm thick must be made at the bottom of the trench.
Solid strip foundations are built if some part of the foundation rises above the ground. The upper part is lined with:
Solid fences made of corrugated sheets, bricks, and rubble stones can be built on strip foundations. For these types of fences, you need to make a solid concrete base. This is especially true for fences with brick pillars. For them, the geometric dimensions of the brick are taken into account. Brick pillars are laid in 1.5 bricks or 380 mm. This size will be the width for the entire strip foundation. In order to save material, the gap between the pillars is reduced in width to 200 mm. A fence body with a width of 0.5 bricks or 125 mm is laid on it.
In order to reduce the width of the foundation to 125 mm, it is necessary to use concrete reinforcement. Such measures lead to higher construction costs. However, modern industry has found a way out. For reinforcement, use fiberglass reinforcement. It is several times cheaper than metal fittings.
For the installation of strip foundations for fences, it is recommended to use the M200 grade of concrete. Concrete with a grade below M200 is used for lightweight structures or preparation for foundations. To calculate the grade of concrete, you don’t need to reinvent the wheel. This issue has been studied for a long time and it is necessary to adhere to the recommendations of cement manufacturers.
When preparing the mixture yourself, you must pay attention to the water-cement ratio and strictly adhere to it. If desired, you can make a rubble concrete strip foundation in the ground using river or quarry stone. The use of rubble stone significantly reduces cement consumption and generally reduces the cost of construction while maintaining the specified strength characteristics. Rubble concrete foundations will last hundreds of years.
Try to sink the stones into the solution so that they do not touch each other. There must be a layer of concrete of at least 20 mm between the stones.
When making your own concrete mixture, you must strictly follow the established rules:
During preparation, the solution may be either too thick or too thin. Add to it some sand and cement in the required proportion.
Very often, cement manufacturers give recommendations for preparing mortar in kilograms, as if everyone has a scale at home capable of weighing materials in tons. Therefore, convert the weight ratios to volume ratios. And pour the materials into the concrete mixer in buckets. This is the most convenient way to keep track of ingredient consumption.
When building a foundation, consider some nuances. If the soil is clayey and the walls of the trench hold well and do not crumble, you can use concrete in the ground without formwork. After pouring concrete in the ground, formwork is built on it to the required dimensions. But it should be remembered that a freshly dug trench may crumble over time or under the influence of precipitation. Therefore, it is necessary to pour the concrete mixture quickly, without waiting for the walls of the trench to collapse.
If the soil is sandy or sandy loam, then you will have to make formwork both in the ground and above the ground. The width of the trench should be such that a worker can stand freely in it on at least one side. To ensure the strength and rigidity of the formwork, wooden stakes are driven into the ground. The shields are tied together with metal wire ties. To ensure that the foundation is of the same thickness, wooden spacers of the same size are installed between the panels. While pouring the mixture, they are pulled out.
If there is a need to reinforce the base, the mixture must be compacted with vibrators. If there is no vibrator, replace them with steel peaks made from reinforcement. During pouring, the concrete mixture is “bayoneted” in layers of approximately 200 mm.
The formwork can be removed on the third day. And laying should be done no earlier than after 2-3 weeks. The concrete mixture hardens completely after 30 days, and gains maximum strength after 21 days.
Step-by-step instructions for building a strip foundation in 14 steps:
Video: Foundation for a fence with brick pillars
Video: Technology for building foundations for heavy fences
Four sensible tips:
The construction of a fence begins with solving a difficult problem: it is necessary to choose a foundation for the fence. On the one hand, it is necessary that it does not get mowed down in the spring, during heaving, on the other hand, there is no desire to bury extra money. So we have to solve the puzzle, choosing which of the foundations is needed - just put up pillars, cast a strip tape, or settle on an intermediate option - a columnar one with a grillage.
No matter how many fence designs there are, they all stand on several types of foundations. The depth, diameter or cross-section of pipes, width and depth of the base may differ. These parameters depend on the climate zone and the material from which the fence spans are made. But there are not very many designs and ways to implement them:
The designs are arranged in order of increasing cost: the least expensive is the first method, the most expensive is the fourth. The choice of foundation for the fence depends primarily on the type of soil and the level of groundwater. If the soil drains water well and the groundwater level is low - below the freezing depth - it can be installed on any structure. If the groundwater is located high, you want a “serious fence” made of brick or rubble, for example, and the soil is clay or loam - you will have to make a more serious foundation, which costs a lot.
If you don’t know how deep the water is in an area, dig a pit near the planned fence. Its depth is 50-70 cm below the freezing depth for the region. If you have dug to this level and there is no water, then you are lucky and you can make a fence with the base of any structure.
A lightweight fence is one whose spans are covered with relatively low-weight materials: chain-link mesh, wood of any design, corrugated board, metal picket fence, welded or forged metal mesh. Pillars without plinths are most often placed under them.
The cheapest and most universal way is in a wide hole and filling the gap with crushed stone. It works great on heaving soils with a high groundwater level, and costs many times better than poured concrete. A light fence installed correctly using this method will never be pushed out in the spring.
The cheapest, and yet most reliable way to install a fence is with pillars in a compacted backfill.
Holes for posts of this type are obviously drilled much wider than the diameter of the pipe. They poured crushed stone or sand onto the bottom, compacted it (with a long pole or crowbar), set up a post, covered it with crushed stone around it, set the post up vertically and secured it with temporary spacers. Pour crushed stone around in layers - 10 cm each, carefully compact it to the maximum possible density. That's it, installation is complete.
It is worth explaining why it is more stable and how such a pillar works on soils with normal drainage ability. Water in any quantity goes deep through the crushed stone, where it disperses naturally. When freezing, the amount around the pillar is not enough to have a noticeable effect. The soil freezing around the pillar puts pressure on the crushed stone, which, due to its mobility, compensates for it almost completely.
It is better to make a foundation for a fence made of corrugated sheets by pouring the upper part with concrete, otherwise wind loads will cause the posts to loosen over time (see the next paragraph)
On such soils, crushed stone can be replaced with coarse sand. The coarser the grain, the better, but dusty or fine-grained sands are not suitable. Lay the sand in layers, pour it thoroughly. Otherwise the whole system works the same.
The key point here is the depth to which the post must be buried. If the windage is small and the soil drains well, it is enough to bury it to 1/3 of its height or a little more. In this case, the hole needs to be made a little deeper: so that there is a cushion under the pipe of about 10-15 cm. Water will go into it and the column will remain almost dry. This is good for both its durability and stability.
If the soils are clayey, it is necessary to dig 10-15 cm below the freezing depth. Water will collect in this crushed stone cushion, since they do not always have time to drain on clayey soils. If the pillow is located below the freezing depth of the soil, there will be no problems with heaving: there is still no water around the column, it has accumulated below and is in a liquid state.
If the freezing depth is very large - 2 meters or more, even this “economy” option will be very expensive. Then you can make a drainage system around the fence to lower the groundwater level. The decision is correct, but implementation is even more expensive.
Another option is to use screw piles. They can be drilled 2 meters much faster. But the piles themselves, and the services for their installation, are not the cheapest. You can, of course, try it manually first; if that doesn’t work, call the technician.
The most budget-friendly option in such a situation is to bury the pillars to a depth that is more or less acceptable, make the hole wider - about 50 cm in diameter or a square with the same side, that is, increase the damping layer. In winters with average temperatures, the fence will stand normally, but in abnormally cold or little snow some pillars may fail. But in most cases, light fences react to this normally, and in the spring everything “sits” into place. It is necessary to correct the position only if the pole is skewed.
If the spans have a continuous or almost continuous surface, the wind creates a decent load on the foundation pillars of the fence. But if the weight of the filling is still small - corrugated sheets, wooden panels - you can still get by at low cost. In this case, to compensate for the wind load, the upper part of the backfill must be concreted. The depth of the concrete block is about 30 cm.
To prevent the concrete block from being destroyed by gusts of wind, a reinforcing mesh is laid. You can use a ready-made mesh with a pitch of 5 cm, you can make it from a 6-8 mm rod. If the mesh is galvanized, it is placed so that it is buried in the concrete by at least 30 mm (monitor the distance from the sides). When using ferrous metal, the layer of concrete along the edges of the rods increases: at least 70 mm. In total, the dimensions of the concreted area with a ferrous metal mesh are: depth 30 cm, sides - at least 34 cm, with a galvanized mesh, the side of the square around the column is 30 cm.
If the bearing capacity of the soil is very low - these are peat bogs, dusty, loose sand - in addition to backfilling with crushed stone, the hole must be concreted to the full depth. In this case, the measure is necessary. Concrete creates a significantly larger supporting surface, and this is important for these soils: the load from the fence is distributed over the entire surface and it stands normally.
Cheaper in this case are bored-rammed piles: a hole is drilled, a sleeve of roofing material rolled into a tube of suitable diameter is inserted into it, preferably 2 or 3 layers. A pole is inserted inside this formwork, set up, and around it is filled with concrete grade M 300 and no lower.
If the groundwater level is high, but the inflow rate is low, you can try to pump it out of the hole and then fill it with concrete. If the water arrives quickly, take a plastic bag of suitable length. It is lowered inside the formwork, the edges are secured around the protruding sleeve. A pole is carefully placed in the bag and concrete is poured. Concrete gradually displaces water and fills the entire form.
The second method is suitable if below, under peat or sand, there is a layer of soil with normal bearing capacity. In this case, you can make a foundation for the fence on screw piles. They are twisted to the required depth - going 20-25 cm into the supporting layer. Fence posts are attached to the protruding heads, or the remaining length of the pile is used.
If you want to make a fence on brick pillars, the work and costs will be more significant. Even if at the same time the weight of the span remains small - corrugated sheets, wood, forging with some kind of material, going in pairs or without it - it doesn’t matter. You will have to make a serious foundation for the pillars themselves, because they themselves create a serious load.
Such fences do not respond well to uneven shrinkage. A mortgage is usually placed in brick pillars, which is then connected to the crossbars of the entire fence. The connection turns out to be rigid, and with uneven shrinkage, cracks appear in the places where the mortgage is attached, and the destruction of the masonry begins. Therefore, the minimum permissible level of foundation for a fence with brick pillars is below the depth of soil freezing. This approach will ensure stability.
Even if the water drains well, in order for the fence to stand for a long time, you have to dig below the freezing depth. But still, significant forces act on that part of the pile body that falls into the freezing zone. When freezing, the soil and concrete freeze into a single mass, and then heaving forces are able to break the pile and squeeze out a piece of the fence.
To avoid such a situation, the foundation for the fence is made in permanent formwork. In this case, the soil cannot freeze with the concrete and “works” on its own. As formwork, you can use several layers of rolled roofing felt, polystyrene foam or polystyrene foam (even packaging from household appliances will do), plastic or asbestos-cement pipes of a suitable diameter.
In any case, there must be reinforcement inside the pile. This is a structure of 4 bars of 8 mm reinforcement, connected by crossbars of 4-6 mm bars. It goes to the entire depth of the pile, with an outlet into the pillar. Then, if desired, you can increase the reinforcement and fill the gap between the bricks in the column with concrete. The second option is to attach a pipe to the fittings, around which a column is placed. Recently, this has been a more common method of constructing a brick pillar.
TISE piles are more reliable in such a situation. They have a cylindrical flare at the end, which significantly increases the resistance to buoyant force. Such foundations for a fence can be made on slightly and moderately heaving soils.
To make this type of piles, a drill with a folding blade is used, which folds back after reaching the required depth. In order for such a foundation to work normally, it is advisable to make the expansion below the freezing depth.
But it is not always possible to drill with a hand drill. On very dense clays and soils with crushed stone, drilling a hole can be unrealistic. And if the freezing depth is about 2 meters or more, then it may be impossible to cope with such a task. In such cases, there are several solutions:
After pouring, piles on normal soils are backfilled with “native” soil; on those prone to heaving, it is better to fill them with crushed stone. In this way, a damper backfill will be created around the pile, compensating for the lateral soil pressure on the pile. And the vertical pushing will be resisted by the pillow.
If the freezing depth is too great or the soil is very heaving, another solution is required. It is necessary to tie the foundation pillars to distribute the resulting loads. For fences with stone pillars, but light filling, this is done using a grillage - a reinforced concrete strip. To prevent it from being bent by heaving forces, an air cushion about 10 cm thick is placed underneath it.
Such a foundation for a fence is built like this: after pouring the piles, a trench is dug, which is larger in size than the required grillage: formwork will need to be installed. Low-density foam plastic, 10 cm thick, is laid at the bottom of the trench and around the piles. A reinforcing frame is made: four rods of 10 mm in diameter, connected with a 4-6 mm rod. The pile outlets are combined with grillage reinforcement. Everything is filled with concrete. After setting, the formwork is removed, the foam remains under the grillage. It provides the required air gap: with a low density, it consists of 90% air. After winter, of course, it will shrink, but that’s not a big deal: the air will remain. But to prevent sand or debris from falling into the cracks, it is necessary to bury flat slate on both sides, which will block this crack, preventing it from silting.
The same grillage can be made on screw piles. If they suit you better, everything remains in effect - their cutting parts are buried below the freezing level, and then everything is the same as with a grillage, ditch, formwork, polystyrene foam, reinforcement, filling.
Why shouldn't you put sand or crushed stone under the grillage? Because in this case it will be wet and most likely will not help much when it freezes. As a result, the grillage will burst.
In principle, the same foundation as for a medium-weight fence will do. You just need thicker reinforcement: 12 mm. When reinforcing, it is necessary to place the rods so that they are at least 70 mm deep in the concrete. Based on this, and the requirement that the minimum distance between the reinforcement bars must be at least 2 infill diameters, we obtain a minimum grillage width of 250 mm. This is if the concrete is filled with crushed stone of a fraction of 20-40 mm.
In addition to the usual grillage reinforcement, it is advisable to lay a layer of metal mesh on the upper longitudinal bars in increments of 5 cm. It will give the upper zone of the tape greater strength. And you can start laying the infill 2 weeks after pouring, rather than 4.
The grillage is made in exactly the same way: with the formation of a damper layer of foam underneath it. After the concrete has gained most of its strength, it is advisable to coat it with bitumen mastic. This is necessary not so much for waterproofing, but to reduce adhesion to the soil. Since the grillage under a heavy fence is most often located in the ground, it is also affected by the tangential forces of heaving. To reduce them, coating is necessary.
Don't forget also about the sheet blocking access to the damping zone under the grillage. Without it, after some time the gap will silt up, which will lead to heaving under the tape, and this will lead to the appearance of cracks in the fence.
Is it possible to make a strip foundation for a stone or brick fence? Can. If you make it below freezing level, it will stand great, but it costs a lot more.
Almost all owners of personal plots sooner or later face the problem of installing a fence. But no matter what it is - light or heavy, in any case, in order for the structure to be reliable and serve properly for a long time, it is necessary to construct a foundation.
The foundation is the main load-bearing part of the fence. The service life of the entire enclosing structure depends on how correctly its type is chosen and how well it is made. If the foundation is weak or does not exist at all, then the fence may sway, it may move during soil heaving during the spring thawing of the soil, or it may even fall.
The foundation for a fence performs several important functions:
Despite the important functions listed above that the foundation performs, when building a fence, many owners of personal plots, calculating their costs, still think about whether it is worth making a foundation for the fence. It all depends on what type of fence you decide to install on the site.
If this is a lightweight, ventilated structure made from a chain-link mesh or a wooden picket fence, then it is quite possible to get by with concreting only the supports themselves. But at the same time, you need to remember that even for light fences this is not the most reliable foundation, and such a fence will last at most 5-7 years.
If you decide to make a fence that is more solid and durable, then you cannot do without a foundation that matches its weight.
The most common option for constructing a foundation for a fence is a strip foundation. It is most suitable for constructing stone fences or fences with stone pillars, between which a fence made of corrugated sheet metal, forging, wood and other materials is fixed. The concrete base of such a foundation allows the load to be evenly distributed. A strip foundation is suitable for installing metal supports in it followed by attaching fencing structures to them.
To construct this type of foundation, a trench is first dug to the calculated depth and width, at the bottom of which a cushion of crushed stone and sand is placed. Formwork up to 30 cm high is placed above the trench. Pillars are installed inside the trench and reinforcement is laid. Next, the foundation is poured with concrete.
The concrete pouring process is sometimes replaced by laying precast concrete blocks. They are installed close to each other and only the seams between them are filled with concrete.
The most budget-friendly option for constructing a foundation for fence supports is a columnar foundation. This type of base is most suitable for heaving soils. Metal or asbestos pillars, brickwork on a concrete base or screw piles can be used as supports. The distance between supports is usually 1.5-2 m.
Depending on the type of soil and climatic conditions, a hole for the supports is dug to a depth of 1-1.5 m. A cushion of crushed stone and sand is placed at the bottom and compacted. Next, install the pillars, fix them vertically and fill the hole with concrete.
A universal option is a combined foundation, which is a combination of the two previous types of concrete foundations.
This type of foundation is used for constructing fences made of concrete slabs, forging, and corrugated sheets, especially in the presence of brick pillars. To install a columnar strip foundation, first dig a trench about 0.5 m deep.
In it, holes are drilled in marked places with a depth exceeding the freezing depth of the soil. Next, formwork is installed in the trench, a mixture of sand and crushed stone is poured, and reinforcement is installed. After this, the foundation is poured with concrete.
The type of fencing is one of the main factors that determines what the foundation should be.
For fences made of corrugated sheets, forged elements, mesh, and wooden picket fences, two types of foundations are used. The first option is when the foundation is made for each support (columnar). To do this, a hole is dug in the soil. A pillar is buried in it, and the space around it is filled with concrete.
The second option is a strip foundation, which is a trench dug in the ground into which supports are installed at a certain step and filled with concrete mixture. This foundation design is used when the pillars are located at a fairly short distance from each other.
The strip type of foundation is also arranged when stone or brickwork is supposed to be installed in the lower part of the fence. In this case, the concrete foundation serves as a kind of foundation separating the masonry from the soil surface.
Separately, it should be noted that if you plan to install a fence made of corrugated board with a height of up to 1.2 m, then you can completely get by with pouring a columnar foundation. If the height of the profiled sheet is over 1.2 m, a strip foundation will have to be poured. Since this material is characterized by increased windage, in a strong wind the columnar foundation may simply not withstand the load, and the supports may tilt or even fall.
If you plan to make a fence with brick pillars, then the foundation for it should be quite serious. Such fences are very sensitive to uneven shrinkage. In pillars made of brick, stone or blocks, a mortgage is usually installed, connected to the crossbars of the entire enclosing structure.
If uneven shrinkage occurs, cracks may appear at the junction of the crossbars and the mortgage. To minimize such phenomena, the foundation for such fences is built quite deep, always below the soil freezing level.
Another important factor that determines the reliability and durability of a fence structure is the depth of the foundation.
For lightweight fences, the most optimal depth is considered to be 50-60 cm. With this depth of foundation laying, the required reliability of the structure is ensured, as well as economical consumption of building materials. But if a light fence is installed on stone pillars and there is above-ground masonry between them, then the foundation can be raised slightly.
With heavier structures the situation is more complicated. When building a foundation for them, one cannot fail to take into account, in addition to weight, the structure of the soil and the depth of its freezing in a given area.
The lower level of the foundation should be located 40 cm below the freezing depth. To clarify this mark, you can use construction reference books.
If a massive fence structure is being built on soft soils in which groundwater runs quite high, it is better to play it safe and lay the foundation deeper to prevent deformation of the structure due to severe subsidence of the soil. A higher foundation location is possible on hard soils. The foundation on shale soils can be constructed at a depth of no more than 25 cm.
Making a foundation for a fence with your own hands is not difficult. You just need to make all the necessary calculations in advance and strictly follow the step-by-step instructions when performing the work.
To calculate at what depth it is necessary to lay the foundation for medium-heavy and heavy fences, it is necessary to take into account the following factors: the design features of the fence, the depth of soil freezing, the slope of the terrain, the structure of the soil and the height of the groundwater.
In order for the calculation to be correct, it is necessary to calculate the area of the foundation. So, if we have a foundation 50 meters long and an estimated width of 30 cm, then we can easily determine its area (15 m2), which will later become the basis for calculating the depth of the foundation.
In addition, it is necessary to determine the reliable area of the foundation, which is determined by dividing the pressure of the above-ground part of the foundation, adjusted by the safety factor, by the soil resistance and the operating conditions factor.
The resulting value must be compared with the estimated area of the foundation. The latter must be no less than the calculated value, otherwise it must be adjusted.
On heaving clay soils, it is best to use a combined type of foundation. Before pouring a columnar strip foundation under the fence, you must first dig a trench corresponding to the calculated depth and width. In the places where the pillars are installed, drill holes for installing the pillars.
Next, wooden formwork is installed along the entire perimeter of the future base of the fence. At the bottom of each hole under the pillars, roofing material folded in two layers is placed. Next, the pillars are installed and the foundation strip is reinforced with a mesh of reinforcement.
Now you can start pouring concrete. The correct way to fill it is in horizontal layers. If it is not possible to fill the entire strip at one time, then you should not allow the formwork to be filled to the top in one place, and not be there at all in another. The concrete will take 3-5 days to dry.
If it is hot outside, the foundation must be watered. The formwork is removed from the tape after 2-3 weeks.
A strip shallow foundation is even easier to make. It is laid above the freezing level of the soil. Therefore, such a foundation is susceptible to seasonal ground movements. Such a base is more suitable for installation in areas where the soil has a uniform structure over the entire area of the fence.
To construct such a foundation, dig a shallow trench (0.5-0.7 m), at the bottom of which sand (0.15 m) is placed and compacted. A layer of crushed stone (0.15 m) is poured on top. Crushed stone and sand are a kind of drainage base, thanks to which water will be drained from the foundation. Next, holes for pillars with a depth of 0.3-0.4 m are drilled in the trench.
Sand (0.1 m) is poured into each hole for drainage. Supports are inserted into the holes and aligned in all planes.
Next, the pillars are connected with reinforcement using welding. Install the formwork. After this, they begin pouring concrete, adhering to the general rules described above. After the concrete is poured, be sure to once again make sure that the pillars are level.
There is another alternative option for constructing a foundation - from old car tires. But it is quite controversial and is not widely used in constructing foundations for fence structures.
In order for the foundation under the fence to last for a long time, it is necessary not only to fill it correctly, but also to protect it from precipitation. And for this it is necessary to make a blind area or ebb, which is a threshold running along the entire perimeter of the foundation with a slope in the direction opposite to the foundation base.
Casting can be done either simultaneously with pouring the foundation or after. To do this, a trench is dug along the entire fence line to a width of about 0.5 m and a depth of 0.15 m, which is filled with crushed stone and compacted. When the casting is carried out simultaneously with the foundation, reinforcement bars are released from it towards the blind area. If the casting is done after installing the base of the fence, then holes are made in it and reinforcement rods are inserted into them.
Film roofing felt is placed under the reinforcement and formwork is made. After this, concrete is poured, and always with a slope.
If it is necessary to build fence structures on a site with a large slope, then the foundation under it should not be inclined. In such cases, a stepped base is built, each section of which is strictly horizontal. In the lowest place, the foundation is made level with the soil. The transition from level to level is made by ledges. The length of the ledges should be no less than 2 times their height. The height must be at least 0.6 m.
If the site has a slight slope, then, as a rule, the soil is leveled along the entire perimeter of the fence structure or a concrete base is installed.
To improve the appearance of a concrete foundation, you can apply decorative plaster on it by spraying it with a special textured plaster or colored mortar using a regular broom.
The base under the fence can also be painted with special paints for concrete. You can also find colorful edging or border coverings at hardware stores. Acrylic, latex, epoxy, polyurethane, and alkyd compounds can be used to paint concrete bases.
Acrylic paint is made on a water basis with the addition of acrylic dyes. Due to the presence of copolymers in their composition, it creates a polymer layer on concrete surfaces that protects the foundation from the effects of environmental factors. This paint is easy to apply, dries quickly and is economical in consumption.
Latex paint is made up of water, pigments and polymers. Sometimes it may contain silicone or acrylic resins. This paint can be applied to the concrete base immediately after it has hardened.
The advantage of latex paints is increased resistance to temperature changes, the ability to fill even small cracks, moisture resistance, and economical consumption.
Epoxy compounds are considered the most durable foundation paints. They can protect a concrete base for almost a quarter of a century. The paint consists of two components - epoxy resin and a special hardener, which are mixed immediately before application. The composition is applied in two layers. Epoxy coatings are vapor permeable, which is very important for concrete bases, and are resistant to exposure to the sun, acids and alkalis.
Polyurethane paint also consists of two components that must be combined immediately before applying the paint composition. The paint is applied in two layers. The advantage of polyurethane paints is that they improve the properties of concrete, are frost-resistant, form a protective coating, and close microscopic cracks and pores in concrete.
Alkyd paints are made from alkyd resin. They have a rich palette, dry quickly, are resistant to sunlight, frost-resistant, and are economical in consumption.
But before choosing one or another product, you need to pay attention to whether it is suitable for a given climate. Paint should only be applied to a dry and free of dirt concrete base.
There are two ways to waterproof the foundation:
Experienced builders advise adhering to certain rules when laying a foundation for a fence:
If there is a desire to protect your site from neighbors, passersby and to ensure the safety of private property, fences are used. But in order for the fence to be reliable and durable, it is necessary to create a strong foundation. This raises the question - how to pour a foundation for a fence and what are the basic rules for performing this operation. The requirements for the fencing base are the same as for residential premises, resistance to destruction and the ability to withstand the weight of the structure.
The most reliable fences are made from brick, iron rods or concrete slabs, due to which the weight becomes quite large. This does not allow the use of non-buried or shallow foundations, due to the unsafe possibility of collapses.
When choosing the type of foundation, it is worth taking into account the bearing capacity of the soil and the level of groundwater. It is important what buildings or roads are nearby. Without high-quality geological exploration, calculations and drawing up a construction plan, a heavy fence poses a danger not only to the owners, but also to passers-by.
There are 4 types of foundations for a fence:
The tape evenly distributes the loads from the fence onto the soil and is used for heavy fences. With a foundation height of 50 cm or more, its above-ground part is only 10 cm, and the rest is located in the ground. To create a strip foundation, bricks, monolithic blocks or pouring concrete are used.
Rock foundations use large stones of varying sizes and cement. This is a fairly durable method for fencing. It is little susceptible to destruction and does not require special care.
A columnar foundation is used for lightweight fences due to the fact that the load on the soil is transferred pointwise. It is built from stones, bricks, piles or filled with concrete, and is easy to prepare and construct.
Columnar-ribbon. With this type of foundation, the main load goes on the pillars, and thanks to the strip base poured on top, it is distributed evenly. In this foundation, the strip base is deepened to a maximum of 20 cm. It is built from reinforced concrete or metal piles, which are strengthened on top with cement mortar.
Any foundation, except the pile type, can be strengthened by digging special supports into the ground. Such supports can be made of special wood, pipes and other materials that add rigidity to the base. This method is very popular for creating a strip base. After special treatment, the supports are buried up to 2 m into the ground, in increments of 2–3 m.
If the fence is planned from corrugated sheets, then strengthening the foundation is necessary. The pipes will not only hold the foundation together, but will also support the fence sheets.
Before applying an anti-corrosion compound to metal amplifiers, they must be cleaned of rust or any other contaminants. If metal pipes are used, they must be coated not only on the outside with moisture-resistant compounds, but also on the inside. Another option for protecting against moisture contained in binding solutions is to install plugs at the ends of the pipes.
To pour a foundation for a fence, you need to purchase materials and tools, as well as prepare the area depending on the chosen foundation. The main thing is to have a construction plan with accurate calculations, which will make construction work easier and save money on purchasing and redoing mistakes.
Tools and materials:
The construction of the foundation begins with markings. For this purpose, pegs are installed along the perimeter of the future foundation, four on each wall, and a rope is pulled between them. You should end up with a rectangle of rope. To prevent the rope from sagging, additional pegs are installed. For a columnar foundation, mark the position of the pillars by placing stakes at their corners and fastening ropes across the previous one to create a square the size of the future pillar.
For a strip foundation, an indentation of 30 cm is made on each side of the border for mounting the formwork. If the foundation is of a mixed type, then the trench between the pits for future pillars is 30-40 cm deep.
If a brick foundation is used, then at least 2 m of free space must be provided. This is also necessary for a columnar brick foundation.
If the fence is being built on a slope, then it must be taken into account that the bottom of the trench must be stepped, and the base will consist of several sections. The bottom of each fragment must be absolutely flat, and to prevent slipping, the edges of adjacent sections are connected with pillars.
Crushed stone from 10 cm is laid at the bottom of the trench, after which it must be leveled. 5 cm of sand is poured on top of the crushed stone and compacted. After this, you can begin installing the formwork. The best option for concreting a fence is removable formwork made from boards. They are strong enough and cheap for private construction. First, you need to mount the boards into panels that will be the walls of the formwork, then lower them into the trench and install lintels so that the foundation is the same width. Creating stops in the trench walls along the entire length of the formwork.
Before pouring concrete, reinforcement must be created. The reinforcement can be welded or tied with wire, this does not particularly affect the result. The finished reinforcement should contain 4 horizontal rods, 2 at the bottom and at the top, as well as vertical rods, in increments of 20 cm. The reinforcement should be 1.5-2 cm smaller than the future foundation so that the concrete completely covers it, to prevent contact with moisture . At the site of the future gate or wicket, a grillage is welded on top of the reinforcement to enhance the load-bearing capacity.
You can watch the video on how to properly pour a strip foundation under a fence.
To prevent the “concrete milk” from seeping into the ground, a thick film or waterproofing is placed on the bottom of the formwork, depending on the funds allocated for construction. If this is not done, the base may become brittle and prone to cracks. If the budget is small and it is impossible to use insulation, the trench is moistened with water so that the earth does not pull it out of the foundation. However, due to the length of time it takes for the concrete mixture to dry, this method is still less reliable.
The mixture for the foundation is created in proportions of 4:2:1, sand, crushed stone and cement, respectively. For a uniform consistency, you need to start mixing with cement and water, after obtaining a homogeneous composition, sand is gradually added, and then crushed stone. If the foundation is not sectional, then it is advisable to fill the mixture within 1 day. Concrete is poured into the formwork to a depth of 5–10 cm, after which reinforcement is installed and pouring continues. It is better to secure the reinforcement at the top until the concrete mixture reaches its top; this will prevent possible distortions that may occur due to the heterogeneity of the concrete during pouring.
With a stepped foundation, the same thing is done only in sections, and the reinforcement at the edge of the bottom protrudes so as to be a continuation of the reinforcement at the top. After the lower reinforcement hardens, install the formwork of the upper section and the connecting column and repeat the pouring. Thanks to this design, a homogeneous foundation is achieved, which prevents possible landslides of the fence.
Before you continue building a fence, just like in the foundation of a house, you need to lay insulating material. The most affordable is roofing felt.
The difference between filling a columnar base and a strip base is only in the final result. In a mixed base, a grillage is welded onto the pillar reinforcement, and then the strip part of the base is poured.
When pouring the foundation, you must remember that it must perform its functions for at least 10 years. A properly constructed foundation will not require repairs for a long time and will allow the installation of a heavy fence and gates that protect privacy from prying eyes.
