Construction of formwork for the foundation. Installation of formwork for strip foundations. Video: installation of reusable formwork

Using monolithic technology, you can build an entire building. The formwork around the house is going to build a blind area. This is a strip of concrete that encircles the building.

It is being built at the last stage of the construction of the building, and if this was not done on time, then it is possible to build a blind area even during the operation of the house. Moreover, the work on its construction is not particularly difficult.

Appointment blind area

Let's figure out how to make formwork around the house, if you plan to do the work yourself. First of all, it is worth clarifying the purpose of this design. In fact, this is just a strip of concrete, it is located close to the walls of the building and encircles it.

The main function of the structure is to protect the foundation. Improper manufacture of the blind area or its complete absence can reduce the life of the building. The blind area around the house is constructed for the following purposes:

• protection of basements from ingress of melt or rain water;
• somewhat reduces the depth of soil freezing in a protected area, which favorably affects heat saving;
• gives the building a finished look, it looks more neat and solid.

It is extremely important to make the formwork around the house correctly, so if you plan to carry out the work yourself, you need to carefully study the technology.

Formwork materials

If you decide to make the formwork yourself, then at the initial stage it is worth choosing the material. Several options are possible, including:

• Concrete solution. The minimum thickness of the concrete layer is 50 mm, but the optimal thickness is from 70 to 100 mm.

Advice! When making a blind area around the house with your own hands from a solution, you can use large pebbles for decoration. The stones are laid close to each other or at a distance so that the individual elements do not touch each other.

• Rubble. This option is allowed if the soil water is deep enough.

Advice! Expanded clay, pebbles or gravel can be used to fill the blind area. Stones can be used in the same fraction or different sizes.

• Paving stones. You can buy concrete pavers ready-made or make your own. Paving stones can have a different shape and color. The gaps between the individual elements are filled with sand.

Most often, blind areas are made of concrete. Construction is carried out quickly, the necessary materials are available, the work is easy to do on your own.

Formwork calculation

As usual, construction begins with calculations and drafting, this element is being built in accordance with the requirements of SNiP. Primary requirements:

• the formwork should go in a continuous tape without gaps and breaks;
• a gap is left between the basement of the building and the concrete tape to compensate for thermal deformations. This gap is filled with an elastic sealant;
• it is important to ensure the drainage of water from the house, so the concrete tape is made with a slope. The slope should be between 1 and 10 percent. As a rule, the slope is two to three centimeters for every meter of track width;

• the width of the formwork is determined depending on the type of soil, but it must be at least 1 meter;
• when determining the width of the tape, the size of the protrusion of the roof should also be taken into account, the blind area must necessarily be wider, at least 20 cm;
• the outer edge must be even, the presence of any curvature is not allowed;
• Do not allow the presence of defects - cracks or depressions. Moisture can seep through these defects or plants can germinate, which will contribute to the destruction of the structure.

Formwork installation

It is better to start the installation of formwork around the house in the warm season. Prior to the start of construction work, it is necessary to prepare the site and carry out marking. Marking is carried out with the help of pegs, they are driven into the corners of the building and twine is pulled between them.

Advice! To prevent the germination of plants, it is recommended to water the prepared area with a special solution.

• chipboard;
• moisture resistant plywood;
• steel sheets;
• fixed formwork options use forms made of expanded polystyrene reinforced with fiber additives.

But most often boards are used, for assembling the frame it is recommended to take a bar with a section of 30 by 60 mm. The rules for mounting formwork are quite simple. It is necessary to drive prepared boards or strips of plywood around the perimeter of the markings made.

Supports are used to strengthen the structure. The same boards are installed across in increments of about 1 meter. These elements will help create expansion joints. Next, you need to lay a layer of waterproofing and pour a layer of sand 5 cm thick.

The poured sand is shed with water and rammed to increase the density of the bedding. The second layer of backfill is crushed stone, this layer also needs to be compacted, but without moisture. When backfilling, it is necessary to form a slope from the walls to ensure the drainage of water.

Formwork dismantling

After the formwork is assembled, the reinforcement is laid inside and the cement mortar is poured. After pouring concrete, you need to give time for it to solidify. The duration of exposure depends on climatic conditions.

At high temperatures, it is necessary to additionally spill the poured concrete and cover it with polyethylene so that the mortar dries evenly. When the concrete hardens, it will be possible to disassemble the assembled formwork, first removing the supports, and then the main boards.

So, concrete formwork is assembled to make a concrete blind area. The purpose of this structure is to protect the foundation. Therefore, it must be done. You can do the work yourself. For the manufacture of formwork forms, boards and bars are most often used, but other materials can also be used.

The construction of the foundation is a labor-intensive and expensive process; in individual construction, the only way to save money is to do all the work (or their individual stages) on your own. In particular, this applies to the formwork device when pouring tape-type bases, with the right approach and studying the video instructions, even a non-specialist will carry out its installation, fixing and removal. The material of shields and supports can be any: plastic, metal, moisture-resistant plywood, boards. Wood is used most often due to reasons of economy, ease of assembly and fitting to the desired dimensions.

At the preparatory stage, the foundation is marked, its perimeter is calculated. The formwork is placed on even and compacted layers of a drainage pad of sand and gravel. Shields and supports are assembled in advance, the gap between digging a trench and installing them should be minimal, otherwise the walls will begin to crumble, and rain moisture will accumulate at the bottom. It is easy to calculate the required number of boards or plywood for formwork under a strip foundation, it is enough to know its area. Up to 90% of supporting structures in private construction are made of wood, their thickness depends on the mass of poured concrete and the purpose of the building. The minimum for timber is 50 × 50 mm, plywood - 10 (subject to its support), boards - from 22.

Construction technology step by step

Consider the standard instructions for building formwork with your own hands in stages (more recommendations can be found in):

1. Drawing up a scheme of the foundation, selection and calculation of the material.

2. Knocking down shields. The boards are sawn into pieces of the same size, fastened to the timber with nails or self-tapping screws, with hats inside. Deviations in level are inevitable (they do not exist except when using plywood), but it is important that they do not exceed 2-3 cm. Gaps and cracks are unacceptable: large ones are clogged with thin slats, small ones - with tow. This step is easy to do by yourself, the help of another person is required only with limited strings.

3. Lowering and fastening the formwork panels to each other. The method of fixation depends on the variety: removable ones are twisted from the outside, non-removable ones (from expanded polystyrene, fiberboard or other DSPs) - as it will be more convenient. Corners require special attention.

4. Installation of spacers (wooden bars or pieces of plastic pipes at reusable formwork between panels with a length equal to the width of the strip foundation) and fixing the structure from the outside with supports sawn at an angle of 45 °, the second end of which is buried in the ground.

5. Checking the strength and deviations from the markup. Final fixation, sanding the lower section. Designation of the line border of the upper edge of the base.

6. Flooring inside the waterproofing film. This stage is optional, but it is recommended to carry out in the presence of gaps between the boards and in order to facilitate the removal of the formwork. When working with boards made of plywood, plastic or metal, the inner surface should be lubricated with oil.

7. Pouring and distribution of concrete inside the foundation formwork: in layers, but without significant interruptions, compacting every 20 cm and leveling the upper edge with a trowel. With properly selected boards and reliable fixation, the structure does not bend under the weight of the solution and remains motionless when air is forced out. It is this condition that allows you to get a stable foundation.

8. Formwork dismantling - depending on the brand and the time of concrete hardening, but not earlier than 3 days. Private developers remove it after 70% hardening - that is, after 2 weeks. The main sign of the admissibility of such an operation is the appearance of a gap between the concrete base and the formwork. You should not do the work yourself, especially when removing large supports.

After that, they proceed to the next stage of erecting a strip foundation with their own hands: waterproofing, if necessary - insulation, backfilling with soil. A slightly different (simpler) scheme of actions is observed step by step during the installation and operation of non-removable forms of formwork recommended for construction in areas with heavily frozen soils in winter. Structures with walls made of expanded polystyrene or DSP reduce the load on the foundation and give it stability. They are easy to assemble on their own, but unlike ordinary wooden ones, they remain in the ground (points 8 and 9 of the above instructions are skipped).

If the height of the strip foundation exceeds 2 m, it is advised to make formwork panels from solid materials, and not knock them down from boards. In this case, square structures are considered the strongest; when installing too long, the requirements for the number and reliability of stops and internal struts increase. With a deep foundation, due to the increase in costs, it is worth considering the option of renting formwork.

Contacting specialists (at least consulting) is required when building on loose soils. In addition to increasing the number of supports (with a standard step of 0.9-1 m), it is recommended to combine materials, for example, upholstering formwork boards from the inside with plywood. The opinion of professionals is also important when organizing vertical and lateral supports with a significant rise of the tape above the zero mark, in some cases the latter type is even screwed to the walls. The standard maximum is 15 cm above the ground level, when it is exceeded, the formwork for the future base is supported from all sides.

When choosing an internal waterproofing, two factors are taken into account: the budget and the size of the aggregate fractions in the concrete. It is not recommended to use roofing felt for these purposes, it is inferior in flexibility to polyethylene (especially in winter). Most often, the choice is made between thick film and moisture-resistant plywood, the second option is optimal when working with heavy coarse-grained concrete.

Rules for uneven ground

The above instruction implies the laying of a standard strip foundation; when working on a slope, the process becomes more complicated. In this case, the base is made stepped, at the lowest point the formwork is made higher, at the top the tape should rise above the ground. The bottom is required to be even under any conditions, by analogy, layers of sand and larger aggregates are gradually filled up and compacted, it is recommended to fill in a layer of lean concrete.

This type of foundation on a slope will be appropriate when building a house made of heavy bricks (but with differences of more than 1 m, the costs increase unreasonably, it is not allowed to exceed the height of the tape at the lower point by more than four times its width), for light buildings, a pile-grillage type is considered a good alternative. The formwork for pouring a hanging grillage is distinguished by the presence of a bottom and additional supports (the weight of the concrete is directed to it, and not to the ground).

Bug Propagation

Violations of technology when installing formwork for a strip foundation include:

• Use of an uncut or oversized board. The correctness of the cement hydration process depends on the evenness of the inner surface and the absence of cracks. Serious deviations or gaps lead to the flow of the solution, the solidification of the tape with uneven walls (more susceptible to groundwater later on).
• Installation of formwork for the foundation of overdried wood (for similar reasons). In this case, raw boards are preferred.
• Errors in choosing thickness and width. It is wrong to use plywood without deck support, as well as knocking down too thin boards.
• Removal of the formwork ahead of time, rough dismantling (tearing off with force).
• Installing formwork on uneven ground.
• No internal spacers at the start of concreting. There is an important rule: all wooden elements are removed as the formwork is filled with concrete. It is permissible to leave only reinforcing screeds made of tin inside the tape.

Ignoring the rules is fraught with bending structures and overconsumption of concrete, leakage, the formation of uneven walls and difficulties in further finishing the strip foundation. The involvement of specialists is required if concreting is necessary in winter, work is carried out on difficult soils, and installation time is limited.

Incorrectly assembled formwork from boards can be strengthened - it is enough to beat it from the inside with moisture-resistant plywood. If you want to reuse the supporting and shield structures, the removed shields are washed, leveled and dried.

Formwork can be done in a variety of ways. The main stages of the process depend on the shape of the supporting structure, the characteristics of the soil, whether it will be removable or fixed. The information provided will help to study the types of formwork for the foundation and correctly make the frame, taking into account the accompanying factors.

Formwork requirements and options for its arrangement

The construction of the foundation is a capacious process that requires a significant investment of finances, effort and time. Therefore, the strength of the frame is of great importance. Violation of its integrity will lead to additional unplanned costs and significantly increase the construction period. To make high-quality formwork under the foundation will allow taking into account the factors affecting the stability of the structure:

• lumber quality. There are no boards with the same characteristics. Knot placement or malformations can reduce the intended strength.
• indicators of concrete. The viscosity of the mortar for the foundation affects the force of action from inside the formwork. The loads on the frame depend on the presence of reinforcement, the speed of pouring the foundation and the options for its tamping.
• Weather. Heat or sub-zero temperatures change the strength of the formwork for the foundation.

Comment! Due to the presence of many objective and subjective reasons that determine the reliability of the formwork for the foundation, it will be right to make a frame with an increased margin of safety.

According to SNiP, the maximum deflection of the boards intended for the frame is:

• for the underground part of the foundation - 1/250 of the length;
• for a foundation above the surface - 1/400 of the length.

The choice of material depends on the frequency of its application. Reuse involves the installation of boards from high quality edged boards or laminated plywood with water-repellent properties. One-time application allows you to make formwork from low quality materials:

• unedged board;
• plywood;
• chipboard scraps.

According to the installation options, there are two types of formwork: removable and fixed. In the first case, the frame is dismantled after the concrete has hardened and can be reused or spent on other construction needs. For a fixed structure, wood material or polystyrene foam is used, which has high thermal insulation performance. When the foundation gains strength, the trench with fixed formwork is covered with earth.

Frame for strip support structure

The construction of heavy buildings requires the arrangement of a reliable supporting structure. For these purposes, the strip foundation is optimal. There is no single algorithm for how to properly make a frame for pouring concrete. Each master makes his own adjustments. Here is one of many possible options. Edged boards of 2 grades with a thickness of 25 mm were used for the manufacture.

Work begins with the preparation of shields, the dimensions of which are oriented to the depth and length of the trench. Avoid bulky dimensions, it is better to make formwork elements that do not exceed 3-4 m in length. The same edged boards or slats are suitable for connecting shields, thin slats are fixed with an edge.

Comment! On the issue of the use of fasteners among the masters, the controversy does not fade away. For some it is more convenient and cheaper to use nails, for others it is more practical and faster to fasten the shields with self-tapping screws.

The next step in the design of the formwork for a monolithic foundation is the installation of shields in a trench. This will require corner supports and pegs for driving into the ground. The supports should be correctly made double-sided with an interval of 0.5-0.7 m. To avoid displacement of the formwork during fastening, the installation of spacers between parallel panels, which subsequently remain in the foundation, will help.

Pegs are located at the corners of the trench, a rope is pulled between them. Its height exceeds part of the future foundation, rising above the ground. Then comes the installation of the remaining pegs. After mounting one row of formwork panels, they are fixed with pegs. Do the same with the second row. Be sure to check all the markings of the foundation.

Plastic tubes, metal rods or wooden slats are used as horizontal spacers between the formwork panels. The gap between the spacers is 1 m, they are not exposed to the bursting force of the poured foundation, but only facilitate the installation process of the formwork.

After determining the required width in the upper part of the frame, the shields are interconnected by rails to prevent deformation of the structure. The maximum gap between the rails is 0.5 m. If the height of the ground part of the foundation exceeds 50 cm, the formwork boards are connected to each other through two. Then the ends of the wire are fixed on the outer vertical posts.

Advice! Correctly do twisting with a little tension. This will provide the basement of the foundation with even walls.

In the process of dismantling the formwork, the wire is cut off and remains in the foundation. To install the supports on the shield, a short block is nailed to stop. The lower part of the formwork support rests against the pegs. The joints of the shields must be supported by a support.

In the formwork located above the ground, segments of PVC pipes are installed. After pouring the foundation, they will perform the function of ventilation products or serve for laying communications. In the absence of pipes, technical holes can be made using wooden boxes, which are subsequently removed from the foundation.

At the final stage, the strength of the formwork installation is thoroughly checked. Even with a significant mechanical impact, it should not stagger. After eliminating all the shortcomings, you can proceed to pouring the foundation.

The nuances of making formwork for a columnar foundation

Light buildings do not need a monolithic structure and can be content with the installation of pillars as a support. The formwork for the columnar foundation can also be removable and non-removable. As a non-removable material used:

• roofing material, the shape of which is preserved due to the reinforcing cage;
• various pipes: asbestos-cement, metal, PVC.

You can make a frame of a columnar foundation with your own hands from various materials. The most popular option is boards up to 40 mm thick (more often 25 mm is enough), the width of which varies from 100 to 150 mm. In addition, suitable:

• dense laminated plywood with water-repellent properties;
• steel sheets, from which a box is formed using bolted corners.

The frame installation algorithm for a columnar support structure is much simpler than the preparatory stage for pouring a strip foundation. Key points of the process:

• Under the pillars, pits of appropriate sizes are prepared.
• A drainage cushion is arranged at the bottom.

Advice! In order for the ground part of the columnar foundation to have a smooth surface, the boards should be sanded. An alternative approach is to fix the oilcloth or polyethylene inside the wooden box with a stapler.

• Initially, bars are driven in from the outside at the corners of the future formwork.
• Shields are prepared for them, the dimensions of which correspond to the calculations of the project documentation.
• The formwork box and the previously driven bars are fixed together with nails or screws.
• If the future pillars are of impressive size, the frame must be further strengthened with supports from the outside or the walls of the box should be pulled together with studs.

Formwork installation is carried out with strict observance of the vertical level of the columnar structure. It is important to avoid gaps greater than 4 mm between the boards. This will provoke a leak of concrete mortar and a deterioration in the strength of the foundation. The height of the formwork must exceed the level of the poured concrete solution.

Stepped foundation: how to make a frame

Periodically, situations arise when the formation of a support structure of a stepped shape is required. The design of the formwork of the stepped foundation depends on the tasks assigned to it:

• The building is being built on a slope. Then the frame is formed by ledges, taking into account the steepness of the slope.
• It is required to make a box for a pole, which has a wide base, and each next level is smaller than the previous one.

Key points of work for arranging the foundation shown in the photo above:

• Soil excavation is carried out from the bottom mark manually and is carried out in tiers. Thus, each ledge will retain the mainland soil under it.
• To avoid shedding of the earth between the steps will allow the strengthening of the vertical wall with formwork panels.
• The trench under the foundation is dug in stages.
• The formwork is installed in accordance with the design drawings. Compliance with the dimensions of each step is mandatory.
• Frames should be made solid. Each of them has spacers, end pieces, struts and reinforcing posts fixed vertically.
• Ledge sections are equipped with non-removable shields, which are cut to the height of the strip foundation.

To make the formwork for the support shown in the photo below, the corner shields and mounting brackets are initially fixed.

The shields are fixed with tension clamps, with the help of spring clips they are interconnected. Then, the contractions of the next tier are hung on the frame of the first level. A glass formwork is installed on the final box. Two people are required to carry out the work.

Preparing the frame before pouring a monolithic slab

Extremely massive buildings or problematic soil forces one to resort to the arrangement of a solid foundation slab. The process is labor intensive and it is not possible to carry it out alone. For the slab, it is also necessary to make a formwork; wooden panels are suitable as a material.

Comment! If it is not possible to deal with the frame, and the walls of the pit will perform its functions, it will be necessary to waterproof the surfaces using polyethylene or roofing material.

The formwork for the slab foundation is installed along the perimeter of the future building. Its main task is to maintain the shape of the base until the concrete has completely solidified. You can make a frame from edged boards, but you should make sure that there are no gaps at the joints. It is extremely convenient to use inventory shields for these purposes. It is optimal to make formwork from coniferous wood due to the extreme strength of the material. Larch is suitable as spacers and other additional elements.

The wood must be damp, otherwise the boards will quickly absorb moisture from the concrete solution, as a result of which the strength of the concrete will deteriorate. To reduce the adhesion of concrete to the inner surface of the formwork, the wood is treated with clay mortar or oil. This contributes to the formation of a smooth surface of the monolithic foundation slab.

Do-it-yourself formwork is easiest for a columnar base, followed by a strip and slab foundation in complexity. It is better to entrust the design of a stepped structure to professionals.

The construction of the strip foundation consists of several stages. Site preparation, excavation, formwork, reinforcement and concrete pouring. The strength and durability of the base depends on the shape. On the creation, which is affected by the correct erection of the formwork structure.

In the article we will tell you how to make a formwork for the foundation with your own hands according to the instructions. How to calculate the amount of material and which one is better to choose for the construction of the frame. We will analyze the types of removable and fixed formwork.

What is formwork?

The formwork is a design from boards, spacers and stops. Used in the construction of foundations. The purpose of the formwork structure is to shape the concrete or reinforced concrete mortar after pouring. To create a concrete tape, two types of formwork are used: removable and fixed type.

With independent construction, preference is given to removable formwork.

The construction of the frame takes 20-25% of all funds spent on the construction of the foundation.

Formwork materials

In the manufacture of formwork for the foundation, the following materials are used:

Metal

Metal formwork is used in the construction of strip and monolithic foundations. The reinforcement is welded to the sheets to increase the rigidity of the base. Sheets of metal are taken with a thickness of not more than 2 mm.

The main advantage of metal formwork is convenience and flexibility (metal is easy to bend and give the desired shape). The disadvantages of the material include a high price.

Reinforced concrete

Reinforced concrete formwork is quite expensive. Consists of concrete slabs of different thicknesses. The use of reinforced concrete slabs will save on concrete mortar, without losing the strength of the foundation.

Plates are not always the right size. Therefore, gaps and voids are covered by installing additional spacers, which is not very convenient.

A crane is used to install heavy concrete blocks.

Styrofoam

Expanded polystyrene blocks lend themselves well to processing and are simply mounted. Difficulties arise when assembling corners and roundings. Despite the practicality and high quality, the price of the material is too high.

improvised materials

In private construction, for example, in the construction of baths or outbuildings, improvised means are used to reduce material costs to a minimum.
The formwork is built from slate, pallets and corrugated board. However, it is difficult to assemble a frame without gaps from such materials. Since there is a risk that the solution will leak through the cracks. The bearing capacity of such a structure is low. This option is only suitable for small buildings.

Wood

The most common material in private construction because it is affordable and inexpensive. For the construction of wooden formwork, sheet plywood and boards are used. During the assembly of the frame, the material does not require the use of complex tools or techniques. With large foundation sizes, they increase the strength of the formwork structure due to additional stops.

Types of formwork for strip foundation

To shape the strip foundation, they use: removable, fixed and combined formwork.

• The removable version, with proper operation, is used several times. Parts of the structure are dismantled after the concrete has completely set. In industrial construction, elements of such structures can withstand dozens or even hundreds of construction projects. In private practice, a removable frame is built from boards or plywood.
• The non-removable option remains with the foundation forever. This practice is widespread in industrial construction. The material for such structures is extruded polystyrene foam. Subsequently, this material performs the function of insulation and sound insulation. Ready-made kits made of polystyrene foam parts simplify the assembly process and reduce construction time.
• Combined formwork is used for construction on loose soil. They combine the internal non-removable and external removable parts, which prevent soil from shedding.

Foundation formwork calculation

There are two ways to calculate how much wood is needed to build formwork.

First way:

1. The length of the foundation is multiplied by 2, since the shields run on both sides of the trench.
2. The resulting value is multiplied by the height of the foundation plus the allowance.
3. The result remains to be multiplied by the thickness of the board (in meters). It will become known how many m³ of boards will be needed.

Second way:

It takes approximately 45 to 65 parts per 1 cubic meter. When calculating the cost of formwork, the cost of fasteners and reinforcement is taken into account. Some people prefer to rent a removable frame, it comes out cheaper than self-build.

Mounting fixed formwork

For the construction of fixed formwork with your own hands, CSP sheets, fiberboard, hollow concrete blocks or pipes and wood are suitable. The construction of the structure consists of the following steps:

1. They dig a pit or trench, based on the size and features of the future foundation. For this, a project is preliminarily drawn up.
2. A gap of 1 to 3 cm wide is left between the formwork and the ground (it facilitates installation). After the structure is fully installed, the gap is covered with earth.
3. The bottom of the trench is covered with sand and gravel, the layers of backfill material are carefully compacted.
4. To give additional strength to the foundation, a mesh of reinforcement is placed on the backfill layer.
5. The formwork device consists in fitting the frame elements. Fasteners are selected depending on the material. If the structure is wooden, the bars are first driven into the ground, and then boards or plywood sheets are nailed to them.
6. It is easier to expose the parts along the fishing line, periodically checking their position with a level. After installing the boards from the boards, they are coupled to each other from above with wooden blocks. This will prevent the boards from buckling or bulging during compaction of the concrete.
7. After fitting the parts and fixing the structure, the pouring of the solution begins.

Video: Fixed formwork for the foundation

Construction of removable formwork: step by step instructions

The pressure of the solution on the walls of the formwork depends on the height of the structure. The higher the foundation, the stronger we make the wooden frame.

After carrying out the preparatory earthworks, the construction of wooden shields begins:

1. The support bars are placed so that they are outside the structure.
2. Installing the assembled shields in the trench, they are strengthened with pegs and struts. In addition to boards, plywood, sheets of chipboard, fiberboard or OSB are used.
3. Parts are connected with screws or nails. To give additional rigidity, studs are used (if a large amount of mortar is poured).
4. All walls are set strictly vertically.
5. Close cracks and gaps exceeding 4 mm. Place the plastic film so that it covers the wooden shields and folds outwards. A furniture stapler will allow fixing polyethylene or other insulating material.
6. All nails are removed from the boards. In addition, the wood must be damp (22% moisture).
7. After installation, the frame is checked for strength, the wall must withstand a kick.
8. The dismantling of the removable structure is carried out in a month and a half. During this time, the foundation is gaining a sufficient level of strength. The gaps left after the removal of the formwork parts are covered with earth or filled with mortar. In hot weather, when the concrete dries quickly, dismantling is possible in two weeks. A sign that it is time to remove the removable parts are the gaps that have appeared between the frozen foundation and the formwork wall.

IMPORTANT! Wooden shields are made higher than the future base. It is difficult to work if the formwork is flush with the concrete mortar. The estimated level of the solution is marked on the boards with a cord or rope.

Video: Do-it-yourself wooden formwork for the foundation

Errors in the construction of formwork

Inexperienced builders often make typical mistakes when constructing a form-building structure.

• Savings on materials. Do not assemble shields from thin boards or other fragile materials. With strong pressure, deflection occurs, and it is very difficult to strengthen a structure filled with concrete mix.
• Incorrect assembly. All parts are linked in such a way that there are no cracks and gaps or liquid concrete leaks. Then the hardening will be uneven. In addition, the height of the shields must exceed the design markings by at least 10 cm.
• Lack of waterproofing material. Protects from moisture: polyethylene or bituminous mastic.
• The absence of additional connections between the parts of the prefabricated structure, props and slopes that prevent tipping over. If this moment is not foreseen, the pressure of the foundation will lead to a visible deformation of the contour.
• Loose wedges that level the side shields may not be able to withstand the vibration from the special equipment used to level the poured mix. As a result, the walls will collapse.

To give the reinforced concrete base of the building under construction the design shape and dimensions, a special fence is used - the formwork for the foundation. Its task is to hold the concrete mixture until it hardens, not allowing it to spread. This article provides a detailed guide on how to properly make a reliable formwork structure with your own hands.

Materials used

When constructing reinforced concrete foundations for a private house, a bathhouse and other capital buildings, 2 types of formwork are used - removable and fixed. The fencing of the first type is reusable, reused at the following construction sites. Disposable formwork structures are not removed from the hardened monolith and remain to serve as the outer shell.

Removable formwork can be made from the following building materials:

• wood - edged board and timber;
• plywood, OSB sheets;
• cement-bonded particle boards (DSP), better known as flat slate;
• improvised materials available on the farm - iron sheets, solid wooden doors, chipboard from old furniture.

Removable type wooden panel structure

Note. Whatever building material is used as a fence, the formwork walls will have to be reinforced with slopes and struts. These elements are made of timber, metal pipes or other rolled products.

The assembly of fixed structures is made from the following materials:

• high density slab foam;
• extruded polystyrene foam;
• the same DSP boards;
• for columnar foundations - steel and asbestos pipes with a diameter of more than 20 cm.

Foundation pillars with fixed formwork made of asbestos-cement pipes

Reference. Sometimes masonry made of bricks or aerated concrete blocks acts as formwork.

In the vast majority of cases, country cottages and adjoining buildings are erected on a reinforced concrete base in the form of a tape or pillars connected by beams. Pile-screw foundations are arranged without concreting and do not need enclosing structures.

We propose to consider the installation of a collapsible wooden formwork of the strip foundation, shown above in the photo. The assembly technology is quite simple and applicable in the case of using other materials - plywood, DSP, and so on.

An example of using OSB plywood

Preparation for work

First you need to prepare the following lumber:

• boards 10-15 cm wide and 25-30 mm thick for assembling fencing panels;
• a beam with a section of 10 x 5 cm will go to the spacers;
• bars or boards 4-5 cm thick will be needed for mowing and stakes;
• knitting wire;
• nails, self-tapping screws (inexpensive black ones will do);
• dense polyethylene film.

Non-separable foam fencing

The number of building materials is considered along the perimeter of the future building, the width of the foundation tape and the height of the base to the top of the basement. When calculating, the following requirements must be taken into account:

Advice. If you want to buy timber for the manufacture of structures, you should consider renting ready-made formwork of a sliding (adjustable) type, used for pouring foundations, columns and ceilings of monolithic buildings. It may turn out that the cost of renting finished fences will be less than the price of a set of materials. What different types of formwork panels are made of, see the video:

Before you make a wooden formwork for the foundation tape, complete a series of preparatory work:

1. Dig a trench to the design depth and width. The first is usually taken along the freezing boundary (on stable soils), the second is made 10 cm wider than the thickness of the future wall.
2. Tamp the bottom of the trench and trim the walls vertically.
3. Arrange a footing or a gravel-sand cushion 100-150 mm high.

A trench in dense soil is dug along the width of the foundation tape, and the formwork is set above ground level. In the process of digging, pay attention to the slope of the site and immediately bring the bottom of the pit to the horizontal. In loose and sandy soils, the trench expands to the desired size so that the walls do not crumble and do not interfere with the installation of fences to full depth.

Removable formwork assembly technology

Installation of a collapsible structure involves the reuse of its elements for various purposes, for example, pouring a blind area, a capital staircase or a porch at the entrance. If the boards can be isolated from the effects of the concrete mixture, the material can be used for any purpose.

What does the order of work look like when installing a removable formwork with your own hands:

Note. If the foundation strip is laid in an arc, then semicircular formwork panels must be assembled from segments or bent from plywood.

What tolerances should be observed when assembling the formwork:

• the panel structure can deviate from the vertical by no more than 5 mm per 1 m of height;
• the upper edge of the last board of the shield should be strictly horizontal, and not repeat the natural slope of the land;
• the maximum allowable displacement of the formwork fence is 15 mm;
• the difference between the boards is no more than 3 mm.

In the process of conducting formwork, the future foundation can be insulated in advance with polystyrene foam or expanded polystyrene. The trench must be expanded by the thickness of the thermal insulation, and the slabs must be attached to the earthen walls and shields with nails, as shown in the diagram. Insert dowels - fungi - into the insulation in advance - they will connect the insulation with concrete. The rest of the technology remains unchanged.

In loose soil, the trench is made wider, additional supports are placed on the sides

The use of polyethylene film provides a number of important advantages, and therefore it is mandatory:

• waterproof gasket serves as waterproofing and does not allow moisture to penetrate into the thickness of the concrete base;
• cement milk does not go into the ground;
• the film protects the wood from the effects of concrete and prevents the latter from seeping through the cracks.

The technology for mounting formwork of a fixed type differs little from the above instructions. Since the material remains the shell of the foundation, it is allowed not to fasten the slopes, but it will be necessary to securely tie the sheets together. For more information on installing a fence, see the video:

In conclusion - the nuances of concreting

Due to a decent mass, the concrete mixture exerts great pressure on the walls of the formwork structures (a cube of reinforced concrete weighs at least 3500 kg). In order for the filling to be successful, follow a few recommendations:

1. The main thing is to assemble a strong and reliable formwork, do not spare materials for supports and stretch marks.
2. Loose earth from a pit cannot be used as a support for a shield - concrete will easily move the embankment and squeeze out the fence.
3. Prepare a repair kit of several boards, beams and nails in advance. If the structure fails and there is a breakthrough of the concrete mass, you can quickly patch up the hole and support the wall.
4. Order the amount of the mixture with a margin of 0.5-2 cubes (depending on the size of the monolith) to ensure that the entire foundation is filled. Find a use for the excess concrete ahead of time, such as making the base of a fence or porch steps.
5. Fill in layers 50 cm thick, compact the mixture with vibrators or manually with metal rods.

After 2-3 weeks after laying the concrete, the formwork can be removed by biting the wire ties from the outside. Start further work after 28 days, when the monolith has completely hardened. To avoid errors when assembling formwork elements, watch the latest video:

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