Formwork assembly technology. Filling the formwork: which structure is better

Confirmed by many decades of observation, research and technology refinement.

The construction methodology of this type of foundations has been worked out to the smallest detail, which makes errors unlikely.

All possible problems arise only with the independent construction of the foundation by people who do not have experience and appropriate training.

Most of the mistakes are made at the preparatory stage, when creating belt structural elements.

Consider one of the important stages of construction - the assembly and installation of formwork.

Formwork is a form for pouring concrete. It is a panel structure made of wood, plywood or polymer materials, which forms a container in the form of a concrete strip. It is built directly at the casting site, according to the dimensions indicated in the project or working drawing.

In most cases, the exhibition is made from edged boards, but there are also more specialized designs designed for reusable use. The main requirement for formwork is strength, the ability to withstand the loads that arise when concrete is poured and hardened.

In addition, the tightness of the form is important, which prevents the concrete from flowing out and excludes unproductive losses of material.

Kinds

There are different types of formwork.

They differ in the type of construction and installation:

• Small and large panel... The most common type.
• Blocky. Used to fill wells, columns, etc.
• Volume-adjustable... Used for parallel casting of vertical and horizontal surfaces.
• Sliding... Moves as the concrete sets for further pouring.
• Horizontally movable... A type of sliding formwork for pouring horizontal structures.
• Lifting-adjustable... It is used for tier concreting of vertical structures.
• Non-removable... Concrete or expanded polystyrene blocks are used, from which the wall is assembled, and the inner cavity is filled with concrete. The technology is relatively new and not yet widely adopted.

Of the listed options, panel types are mainly used, since the rest of the structures are intended not so much for a strip foundation, but for general construction work.

There are varieties according to the level of heat saving:

• Insulated.
• Heating.
• Special.
• Uninsulated.

The choice of the type and material for the formwork is made at the design stage and is based on engineering calculations.

Most private house projects only consider timber formwork due to the ability to assemble any size, but there are other solutions.

What material is used

Formwork can be created from various materials:

• Wooden.
• Plywood.
• Made of expanded polystyrene.
• Metallic.

In addition, there are options in synthetic fabrics or rubber. Wooden structures predominate, since they are cheap, they can be used repeatedly and in different sizes.

Reusable molds are designed for mass production of castings of the same size and configuration, so they are made from materials that are stronger and more durable.

The advantage of wooden structures is low cost and versatility, but their assembly time is much longer than that of plywood or metal finished panels.

How to calculate the quantity?

The simplest way to calculate is using an online calculator. You enter your own data in the corresponding windows - the height of the tape, the total perimeter multiplied by 2, and the type of material.

The result is the amount of wood in cubic meters. This is convenient, since the usual calculation is made by area, which is then converted to cubic meters.

For those who do not trust the online calculator, the calculation method is useful:

1. The perimeter of the tape is calculated.
2. Divided by the length of one board, we get the number of shields.
3. The width of the shield is selected according to the height of the tape (usually a multiple of the width of the boards).
4. The number of boards in each board is calculated.
5. Multiplied by the number of shields.
6. The result is multiplied by 2.

In addition, you need to calculate the number of planks required to create crossbars and stops. It is determined by the product of the total number of shields by the number of strips of one shield.

NOTE!

Any calculation method is approximate enough, therefore it is recommended to purchase 10-15% more than it turned out when calculating.

Which board is best to use

For the assembly of formwork, the most common material is usually used - edged pine board. It is recommended to plan the working surface of the boards, but this is not always possible, therefore most often the boards are assembled from unplaned boards.

An important issue is the moisture content of the lumber. In this case, the use of a dry board is not necessary, and sometimes even undesirable. For a long time, the formwork keeps the massif moist, which is periodically watered all this time.

Dry lumber begins to actively absorb moisture, swells and increases in size, which is why individual boards are squeezed out of the plane by the shield a.

The thickness of the boards used for the assembly of panels ranges from 25 to 40 mm. The higher and wider the tape, the thicker the boards must be in order to withstand the loads during pouring and the pressure of liquid concrete on the walls.

Installation procedure

Formwork is created in stages.:

1. Vertical cross bars are cut... Their length is 40-50 cm higher than the calculated width of the shields, since they have to be driven into the ground. For this, one end is sharpened for better entry.
2. Preparing the boards... They are cut to length (if necessary) and stored on a flat surface. Optimally - close to the trench so that you do not have to carry ready-made shields over long distances.
3. The cross members are laid out with a step of 0.8-1.2 m... The upper cut is aligned with the line.
4. Assemble shields... First, attach the top board, then attach the rest as tightly as possible. Nails or self-tapping screws are used.
5. Shields are lowered into the trench, aligned in axes and dimensions... The pointed ends of the vertical planks are driven into the ground until the horizontal planks come into contact with the bottom of the trench.
6. Parallel shields connected by crossbars determining the thickness of the tape. Their role is sometimes performed by U-shaped clamps assembled from wooden blocks.
7. From the outside additional inclined spacers are installed, excluding the extrusion of shields when pouring concrete.

The inner surface of the formwork should be covered with plastic wrap to ensure tightness and prevent concrete leakage. No matter how neatly and tightly the formwork is assembled, the loads during pouring are very high and arise abruptly... The shields diverge slightly, which leads to the appearance of gaps. The film saves material and prevents waste.

Installation of removable plywood formwork

Plywood allows you to get sealed panels with a flat and smooth surface. For one-time you can get by with the cheapest pine plywood, but for reusable formwork, it is recommended to choose a more durable birch plywood, impregnate it with linseed oil or purchase film faced plywood (the best option).

The thickness of the sheets is chosen based on the height of the formwork, but not less than 10-12 mm. Usually 14-18 mm plywood is used.

Assembly order:

1. Plywood boards are cut to size.
2. The frame of the panels is made from wooden blocks (50 to 50 mm). It is an edging located on the outer (non-working) side of the shield. It is not necessary to connect the planks to each other, but they are firmly attached to the plywood sheet. For fastening, nails, screws or metal pins are used (for large shields).
3. Pegs are driven into the trench, intended to abut the shields.
4. The finished shields are placed in the trench, their position is leveled. The distance between the parallel shields is fixed with transverse struts, which are subsequently removed before pouring.
5. The individual panels are interconnected to obtain continuous formwork walls. The joints are sealed as tightly as possible; when gaps appear, they are immediately sealed.
6. U-shaped clamps are installed on top of the shields with a step of about 1 m, which keep the shields from being squeezed out during pouring.
7. It is recommended to cover the inside with polyethylene in order to seal the formwork and improve the concrete hardening regime. The plywood will remain clean and can be reused or reused.

NOTE!

After purchasing the material, you need to inspect it and apply a layer of drying oil to the entire surface and end areas. This will help ease the dismantling of the formwork and save it for reuse.

How to assemble from expanded polystyrene

In this case, the formwork cannot be dismantled, being first a mold for casting, and later - a layer of insulation. Ready-made blocks of extruded polystyrene foam and additional elements for them are used - jumpers, parts for longitudinal connection, etc.

All of them are commercially available and purchased in advance in the required quantity, which greatly facilitates assembly and allows you to obtain a strong and sealed outer cocoon for the concrete tape. The technology was invented a long time ago, but for various reasons it was not used, it is starting to gain popularity only at the present time.

However, the results allow the methodology to predict good prospects.

Assembling the formwork is simple. The blocks are interconnected according to the principle of a constructor, fixation is done using jumpers. The assembly process, in addition to creating a mold for pouring, combines insulation and sound insulation, which reduces the overall work time and simplifies the work in general.

The fewer operations, the less the possibility of errors or technology violations.

The main disadvantage of this technique is the high cost of expanded polystyrene blocks, which increases the cost of.

This is the main obstacle to technology diffusion.

Installation of removable formwork with insulation

Do-it-yourself installation of this type of formwork is carried out according to our own method:

1. The trench has a width equal to the thickness of the tape plus a double layer of insulation. Extruded polystyrene foam is usually used. The insulator sheets are installed vertically on the edge and fastened with 20 cm long nails directly to the walls of the trench.
2. Before installing the heat insulator from the reverse side, facade dowels are installed over the entire area.... Their ends pass through the material and protrude into the trench in order to ensure a high-quality connection of concrete and insulation after pouring.
3. Wooden formwork is installed along the edge of the trench, forming an upward extension of its walls. The heat insulator is attached to it in the same way as to the ground - with nails, only of a shorter length. The technique for creating shields is common, the only difference is the installation not inside the trench, but along its edges.
4. Pouring concrete ensures tight contact of the tape with the insulation, the absence of gaps and the tightness of the insulation layer. After the concrete hardens, the wooden formwork is dismantled, and the heat insulator remains on the concrete surface. Taking into account the specifics of the material, it is necessary to install a protective layer of the plinth plating to exclude mechanical stress on the insulator.

It is necessary to dismantle wooden boards carefully so as not to destroy the expanded polystyrene plates.

Installation of permanent formwork

In addition to expanded polystyrene, concrete is used for the manufacture of permanent formwork. Hollow blocks are made from it, which are assembled like parts of a designer, forming a hollow wall of the desired size.

After that, concrete is poured inside, filling the voids and forming a solid solid wall. This technology appeared earlier than polymer permanent formwork, but, for various reasons, did not become widespread.

The creation of such an external frame allows solving a number of problems with stiffness, tightness of connection with concrete filling and finishing works. and can be produced without waiting for the final hardening of the concrete.

There is a saving of building materials, since there is no need for conventional formwork.

The formwork assembly technique is simple and does not raise any questions. Blocks are installed in the prepared trench on the waterproofing layer, a layer of waterproofing is applied to the side surfaces, after which concrete is installed and poured.

The procedure is simple and allows you to significantly speed up the creation of a solid foundation.

How to further strengthen this device?

The weight of the concrete is very high, and the loads on the formwork during pouring can destroy it or create cracks through which the concrete will flow out. For strengthening, additional elements are used that reinforce the walls and take on the load from the weight of the concrete.

Usually, at a distance of about 50 cm from the outer surface, stakes are driven into the ground, to which inclined stops are attached. In addition, horizontal stops are laid from below, tightly inserted between the stakes and the lower edge of the shields.

As a result, a number of additional fastenings are formed, which increase the stability of the formwork and protect it from destruction.

When to remove the formwork from the strip foundation?

Dismantling of the formwork is traditionally carried out 10 days after pouring. R Various technological options allow earlier or later dismantling within 5-15 days, which is due to the size and thickness of the tape - the larger it is, the longer the holding time in the formwork.

When dismantling at an earlier date, the utmost care must be taken as corners or edges of the tape can be easily beaten off.

Useful video

In this video, you will learn how to make the right formwork for a strip foundation:

Conclusion

Formwork is an important and crucial element in creating a strip foundation. It is necessary to treat its assembly with the utmost care and accuracy, without neglecting any stages or elements of technology.

The quality of the fill and the entire foundation to a large extent depends on how reliably and firmly the form is assembled. It is better to spend a little extra time and get the best result, since the fate of the entire building depends on it.

In contact with

The formwork serves as an element of the fence when pouring concrete, preventing it from flowing out of the future structure and thus giving it the required shape. This device is used for the manufacture of different types of foundations. The most common application is to form strip foundations. With the help of formwork, reinforced belts are made for floor slabs or the roof frame of a building, as well as many other structures in which it is assumed that the form is filled with concrete or cement mortar. The material for the foundation formwork can be used in different ways, and in our article we will consider several options.

Wooden formwork with waterproofing coating Source demidovo52.ru

Types and materials for the manufacture of formwork

Depending on the desired quality of the concrete structure, the speed of its construction and the possibility of reusing the enclosing material, the following types of formwork are distinguished:

• Removable (collapsible)... Implies the reuse of functional parts of the fixture. It is dismantled after the reinforced concrete has hardened.
• Non-removable... Remains in the foundation, while serving as an additional protective or decorative element of the structure.
• Wooden... It is used in collapsible structures. Edged wooden boards of different sections, plywood, OSB boards, and in rare cases chipboard are used as the main enclosing material.
• Metal... The enclosing elements in such a formwork are made of sheet metal. Nodes that provide rigidity and prevent deformation of the planes can be made of wood or a metal profile.
• Polymer... It can be both removable and non-removable. In the first case, it means the use of special plastic sheets as a fence. In the second, concrete is poured into expanded polystyrene molds, assembled by means of locks into an integral structure.

Reusable formwork - often rented out Source stroiecoplast.ru

Overview of typical formwork: types and conditions of use of formwork structures

Depending on the requirements for the reinforced concrete structure, a type of formwork is selected. The dimensions of the foundation, namely its height and width, are of paramount importance. The higher the structure, the stronger the enclosing material must be.

Demountable formwork

This is the most common formwork device for strip foundations and more. Its popularity is due to its ease of manufacture, availability of material and low cost compared to other options.

Most often, such a formwork is built from OSB, boards from wooden boards, plywood, sometimes chipboard. A wooden beam of a suitable section or a metal profile is used as a material for the frame. After dismantling the formwork, all material can be used in further construction work. Naturally, this is possible with a careful attitude towards him.

Even a single-use formwork can be collapsible, and the boards are quite suitable for a sub-floor or similar work. Source readmehouse.ru

From planks

For the construction of the formwork, you will need a board with a thickness of 25 mm, if the width of the foundation is up to 300 mm. A more overall design with a tape width of 400 mm and more will require the use of a 40-50 mm board. Lumber of any species, both deciduous and coniferous, is suitable. It is most economically feasible to use spruce or pine. In addition, these rocks have sufficient strength and resistance to moisture changes.

Flaws: long-term assembly of panels and subsequent assembly / disassembly of construction elements; the structure requires additional reinforcement.

Dignity: low cost.

Plywood, chipboard, OSB

In order for the OSB formwork for the foundation, or of plywood and chipboard, to be strong, one cannot do without a wooden beam, which will be necessary when assembling the frame and stops with braces. The recommended thickness of the slabs is 18 mm or more. The thicker the slab, the less stiffening timber you will have to add. Sheet size:

• waterproof plywood - 1200 * 2400;
• construction plywood - 1500 * 1500;
• OSB: 2500 * 1250;
• Chipboard - 3750 * 1750.

For a single use, you can use ordinary plywood, OSB boards or even chipboard (then you will have to throw it out). If many pouring cycles are planned, you should pay attention to the laminated waterproof plywood.

On our website you can find contacts of construction companies that offer repair and design services for the foundation. You can communicate directly with representatives by visiting the Low-Rise Country exhibition of houses.

Positive traits: simplicity and speed of assembly in comparison with all other collapsible options. When using cheap types of slabs, the cost of such a formwork for a foundation will be lower than that of a wooden one.

Flaws: high cost of waterproof film faced plywood; one-time use of inexpensive board materials.

Metal formwork

An expensive but practical option that can provide a high surface quality, which reduces the cost of subsequent sanding (if any). Such structures are more often factory-made, therefore, they are maximally adapted for quick assembly. They have significant rigidity and the same significant weight, which implies the involvement of a team of builders for installation and, possibly, lifting equipment. There are lightweight options made of aluminum or its alloys, but using them to save on workers' wages and cranes is impractical.

The metal formwork for the foundation (photo below) is designed for reusable use and has significant potential in this regard, which partly justifies its high cost.

Reusable metal formwork Source stroyday.ru

The quality of the foundation, made using iron formwork, is an order of magnitude higher than the wooden options. This is due to the properties of metal, which, unlike wood, does not absorb moisture and thus provides favorable conditions for concrete ripening.

Polymer boards

The meaning is the same as with plywood, OSB or chipboard, with the only difference that a polymer plate is used as the material for the fence, the size and thickness of which depends on the required rigidity. To ensure the proper rigidity of the structure, a frame made of a bar or a metal profile is required.

Polymer formwork is an expensive pleasure, but they are indispensable in the construction of standard structures. Source stroykarecept.ru

Fixed construction

When choosing a material for non-demountable formwork, one should choose one that will give the monolithic structure the necessary properties. For example, if insulation is subsequently required, it is better to use expanded polystyrene than concrete blocks or metal sheets.

Expanded polystyrene blocks

A very simple and quick option, moreover, the finished concrete structure is already insulated. The production of formwork for a strip foundation from blocks evokes an association with the designer: lightweight blocks of high density polystyrene are assembled by means of locks located on the contacting sides of the product. The technology provides for the presence of linear, angular, radius and other elements for the implementation of any geometric shapes and solutions.

There is also an option where sheets of dense polystyrene are used as the limiting material. Joining of sheets to each other is realized using a simple tongue / groove connection. Opposite walls are connected with special metal brackets, which in parallel determine the width of the foundation strip.

The material has a small mass and is easy to handle, therefore, structures made of it are assembled quickly, do not require special equipment and skills.

Permanent formwork also works as insulation Source gmk.spb.ru

Reinforced concrete foundation blocks

The name speaks for itself. Structurally, it resembles expanded polystyrene formwork. The difference is the lack of insulation, significant mass and greater rigidity of the finished monolithic structure. In the case of work with large-sized blocks, a team of builders and lifting equipment will be needed for installation.

Auxiliary materials and necessary tools

In the process of installing the formwork for the strip foundation, you have to use various devices. Most often they are needed in the case of the manufacture of wooden structures, especially when an improvised sheet material is used. Factory products are usually equipped with everything you need.

Metal studs

Required for tall buildings. It is not possible to provide high-quality fixation of the tape thickness over the entire area of ​​the fence by other methods. Studs are not needed for structures less than half a meter high, especially if sufficiently rigid sheet materials or boards are used.

The purpose of this element is to prevent the expansion of the formwork walls. For proper functioning, the stud is installed in a plastic pipe. This is done in such a way that when tightening, the walls of the fence from the inside rest against the pipe. From the outside, it is recommended to put washers on the stud.

Braces

Designed to prevent the walls of the fence from bending outward. They are made of wooden blocks of different lengths. Entrance goes to all suitable material, including trim.

Polyethylene film

Prevents the concrete mix from flowing out of the formwork. It is mainly used for board structures, including unedged ones. Helps prevent excessive contamination of wood with cement mortar, which gives wider possibilities for their subsequent use.

Manufacturing of removable formwork for a strip foundation

There are a lot of options for the construction of such structures, and the choice of the most suitable one depends on the situation and the preferences of specialists. Consider how the formwork is made for a strip foundation using wooden panels and timber.

Manufacturing technology of wood shields

The thickness of the board is selected depending on the width of the tape and the height of the structure. With a width of up to 300 mm and a height of up to 1 m, a board of 25-30 mm can be used. The length of the shields also depends on the dimensions of the fence and the geometry of the structure. Considering the standard length of the board (4.5 - 6 m), the optimal length of the board is 2 - 2.5 m.

When manufacturing, it is better to use nails as fasteners. This will greatly facilitate dismantling, save money and speed up the process.

For shields up to 1 meter in height, the assembly represents the following sequence of actions:

• It is necessary to prepare boards for a set of one shield, for example, 10 boards 2 m long, 100 mm wide;
• To ensure rigidity and bundling of boards, you can use a bar with a section of 50 * 50, - for one shield 4 pcs;
• The board is nailed to a beam, which is located at regular intervals, while at the edges of the ends there should be a distance of about 200 mm (to tie the boards together during installation). The bars should be made slightly longer so that they can be driven into the ground, if this is provided for by the design.
• For tall structures with a tape width of 400 mm or more, a board with a thickness of 40 - 50 mm must be used, a bar for the frame - at least 100 * 50 mm.

Installation work

You must first make the markup. After that, the shields are located along the foundation tape. Outside, the tapes are fixed with braces, and stops or pins are installed from the inside. During work, it is necessary to control the level in all planes and the geometric accuracy of the structure.

Video description

You can clearly see the formwork for the foundation in the video:

Assembly of permanent formwork

The construction of polystyrene blocks is assembled gradually - as the height of the foundation or walls increases. The first row is laid out on a prepared base - a pillow, after having laid the waterproofing with an approach to the walls of the trench (in the case of a trench version). The assembly is carried out into locks on the edges of the blocks.

The height is gained at which it is possible to tie the reinforcement without significant difficulty. In the case of using polymer sheets, the walls are fixed to each other with brackets that come with the kit. Having typed several rows and untied the reinforcement, they are poured with concrete, after which the next rows are assembled and so on until the structure is fully ready.

The process is the same for non-separable concrete block formwork. The difference in the design of the material and the method of decoupling the reinforcement, which fits into specially provided recesses on the upper and lower surfaces of the blocks. The installation process also takes place gradually - after pouring one or two rows, the following are mounted.

Video description

For more information on non-removable formwork, see the video:

Outcomes

The use of one or another formwork largely depends on the costs that the developer is ready to go to, as well as the requirements for the quality of the foundation. For budget options, timber formwork using improvised means is quite suitable (there are examples using cardboard boxes). If speed is important, and quality will have to consider other options that will be expensive.

Formwork is a structure of panels, spacers and stops, which serves to shape concrete and reinforced concrete products. If we talk about construction, then this system is necessary when pouring any type of foundation, but the largest structures are needed when constructing a l and a. Formwork is also used when creating reinforcing belts in the masonry of walls from building blocks. In the same buildings, a reinforced belt is often needed at the top to create a solid foundation for attaching the roofing system. It is also formed using formwork. This design will also be needed when pouring concrete paths or concreting, for some other types of work.

Removable and non-removable

According to the principle of use, the formwork can be removable (collapsible) and non-removable. As the name implies, the removable one is disassembled after the concrete gains strength above the critical one (about 50%). Therefore, it can be used several times. Depending on the material, one and the same set can withstand from 3 to 8 fillings, industrial versions can be used several dozen, and some hundreds of times.

Permanent formwork becomes an integral part of the foundation. Such systems began to be used relatively recently. They are made mainly of extruded polystyrene foam. Blocks of different configurations are produced, which are interconnected with locks and metal pins. From blocks, as from a constructor, the required form is typed.

Fixed formwork becomes part of the foundation - it is also a heat insulator

Fixed formwork made of expanded polystyrene not only gives shape, but also at the same time is heat and hydro insulation, also has soundproofing properties. It costs a lot, but it immediately solves many problems, and the time spent on the foundation is significantly reduced.

There is another type of permanent formwork - hollow concrete blocks. They also have different configurations - wall, corner, radius, etc. They consist of two or three walls and several bridges that hold the walls in a certain position. They are connected to each other with locks, reinforced with rods.

Formwork requirements

Since this entire system is created in order to shape concrete and reinforced concrete products, it must be strong and resilient enough to withstand the pressure of a mass of liquid concrete. Therefore, quite serious requirements are imposed on the materials for the formwork in terms of strength. In addition, the assembled panels should have a smooth and even inner surface: it forms the walls of the foundation, and then hydro- and / or heat-insulating materials are fixed on them. It is easier to attach them to even (at least relatively) surfaces.

Removable materials

In construction organizations, there are metal structures assembled on pins and bolts. In private construction, formwork panels are made from boards, moisture-resistant plywood and OSB. Wooden blocks are used as stops and spacers. No one bothers to make a metal structure, but it is very expensive and unprofitable for a one-time use.

When building a cottage or a country house, boards from boards are most often used. You can use any species, both coniferous and deciduous. It is better to take an edged one: the solution should not ooze through the formwork, and it is unrealistic to achieve this with an unedged board.

With a foundation height of up to 1.5 meters, the formwork board must have a thickness of at least 40 mm. Shields are fastened using bars with a section of 60 * 40 mm or 80 * 40 mm. If the height of the foundation is large - it - such bars will not be enough to hold the mass of concrete. At a height of more than a meter, you need to use a bar of 50 * 100 mm and more. For assembly, use nails or screws. Their length is 3/4 of the total thickness of the board and bar (for the above dimensions 60-70 mm).

Formwork is also made of plywood. There is even a special formwork laminated with synthetic paper. The coating has increased resistance to aggressive environments, which is liquid concrete. This material is marked with FSF (using formaldehyde glue).

The thickness of plywood for formwork is 18-21 mm. Shields are assembled on a metal or wooden frame. The wooden frame is made from a bar of 40 * 40 mm, you need to use a shorter fastener - 50-55 mm. When using plywood, it will be easier to work with self-tapping screws: nails are hard to hammer.

OSB is rarely used for this purpose, but this option also takes place. The thickness is about the same: 18-21 mm. Structurally, it is no different from plywood boards.

Select the dimensions of the sheets of these sheet materials based on the dimensions of the required formwork panels - so that there is as little waste as possible. A special surface quality is not required, so you can take low-grade materials, which are usually called "building".

From what to make the formwork for the foundation, decide for yourself: it depends on the prices of these materials in your region. The usual approach is economic: what is cheaper is used.

Diy formwork for strip foundation

The most voluminous is the formwork for the strip foundation. It follows the contours of the house and all load-bearing walls on both sides of the tape. When constructing a more or less large building with a large number of partitions, the consumption of materials for the foundation formwork will be very significant. Especially with deep foundation.

The design of the panels and their connection

When assembling the formwork with your own hands, it is important to make the shields strong: they will need to hold the mass of concrete until hardening occurs.

The dimensions of the formwork panels vary and depend on the geometry of the foundation. The height is slightly higher than the height of the foundation, you determine the length of each shield yourself, but usually it is from 1.2 to 3 m.It is inconvenient to work with very long structures, so the optimal length is about 2 m.The total length of the entire formwork should be such that they became exactly according to the marking of the foundation (do not forget to take into account the thickness of the shield).

When making formwork from boards, cut several pieces of the same length, fasten them with bars and nails or self-tapping screws. When using nails, they are hammered from the inside of the shield, bent over on a bar. It is easier to work with self-tapping screws: they do not need to be bent, since due to the thread they provide a snug fit of the elements. They are twisted from the inside of the shield (the one that will face the foundation wall).

The first and last bar are fixed from the edge at a distance of 15-20 cm. Between them, at a distance of 80-100 cm, additional ones are placed. To install formwork panels it was convenient, two or three bars (at the edges and in the middle) are made 20-30 cm longer. They are sharpened and driven into the ground during installation.

Plywood or OSB boards are assembled on a bar frame. When assembling, it is important to reinforce the corners well. In this design, they are the weakest point. You can strengthen them with metal corners.

Do-it-yourself formwork installation

If the shields were made with several elongated bars, they must be placed along the cords of the stretched markings. The difficulty lies in the fact that at the same time it is necessary to exhibit in the vertical plane. For fixing, you can use bars hammered along the mark and set vertically. When installing, the plane of the shields should be set close to these bars. They will be both support and guides.

Since the bottom of the trench or foundation pit must be flat (they are compacted and leveled under the level), it should be easy to place the shields horizontally. Try not to hammer them too much: it will be easier to align later. Lower one of the corners to the level of the bedding. There should not be a gap, the solution should not flow out. Having achieved a snug fit, take a building level, apply it along the shield and hammer in the second edge with a hammer until the upper edge is set horizontally. You are already exposing the next shield relative to the established one: they must be on the same level and in the same plane.

If the shields are made without long bars, a bar is fixed at the bottom of the pit, along the line marking the tape, which will serve as an emphasis. The shields are placed close to it, then they are fixed with the help of slopes and spacers.

Reinforcement - braces and stops

In order for the formwork not to fall apart under the mass of concrete, it must be fixed from the outside and from the inside.

Braces are installed outside. The supports should be at least every meter. Particular attention should be paid to the corners: here they put stops on both sides. If the height of the backboard is more than 2 meters, then one stop belt is not enough. In this case, at least two tiers of spacers are made: an upper and a lower one.

It is also necessary to stabilize the distance between two opposite shields. To do this, use studs made of reinforcement with a diameter of 8-12 mm, metal gaskets and nuts of the corresponding diameter. Hairpins are installed in two tiers: above and below, at a distance of 15-20 cm from the edge.

The length of the pins is about 10-15 cm larger than the width of the tape. There are two options:

• Threads are cut at both ends of the reinforcement. Then for each stud you will need two metal sealing plates and nuts.
• On one side, the hairpin is bent and flattened, a thread is cut with an arc. In this case, one nut is needed (there are still two plates).

The internal distance between the panels, equal to the design width of the tape, is fixed using pieces of plastic pipes. Their internal clearance should be slightly more than the thickness of the studs.

The assembly takes place as follows:

• Holes are drilled in both shields with a long drill.
• A piece of pipe is installed between them.
• A hairpin is threaded.
• Metal plates are installed (they will not allow the hairpin to break the shield material).
• The nuts are tightened and tightened.

You need to work together, or better - three. One installs tubes inside between the shields, and one person for installing studs and tightening nuts.

When removing the formwork, first unscrew the nuts and remove the pins, then dismantle the slopes and stops. The released shields are removed. They can be used further.

How to spend less

It takes a lot of material to make the formwork for the strip foundation: the shields form the entire strip on both sides. At great depths, the consumption is very high. Let's say right away: there is an opportunity to save money. Make only a part of the formwork and fill not all in one day, but in parts. Despite the popular belief, this will hardly affect the strength of the foundation (if you know the secrets), and you can save a lot. You can divide the foundation either horizontally or vertically.

Fill with layers

If the depth is large, it is more profitable to fill in parts horizontally (in layers). For example, the required depth is 1.4 m. You can split the fill into two or three stages. At two stages, it will be necessary to make shields 0.8-0.85 m high, at three - 50-55 cm.

The order of work is as follows:

When installing the second (and third, if necessary) tier, the shields are slightly found on the already filled area, covering the tape from the sides. In this case, the lower row of pins usually serves as a stopper and an emphasis. Therefore, when installing them, put them all at the same level from the lower edge of the shields.

The armature is already tied, the inner studs are cut. It remains only to put other tubes back into place the pins and put the outer stops and braces. It takes less time to install the next layer of formwork.

Why does this method not affect the strength of the foundation? Because the strength of concrete is not taken into account when calculating. She goes to the "reserve". In addition, the load in strip foundations is distributed along the long side. And we have no gaps in length. So the foundation will last for a long time.

Vertical division

The second way is to break the plan vertically. The foundation can be divided into two or three parts. Only you need to divide not exactly "along the line", but to spread the joints to some distance.

In the part of the building chosen for installation, install the formwork with "plugs" in those places where the part to be installed ends. Knit a reinforcing cage inside the installed part. In this case, the rods of the longitudinal reinforcement must extend beyond the formwork by at least 50 diameters of the reinforcement used. For example, a 12 mm bar is used. Then the minimum release outside the formwork will be 12 mm * 50 = 600 mm. The next rod is tied to this release, and one by one they will go on these 60 cm.

One important detail: breaking down the plan of the house in parts, make it so that the "pieces" poured during this period end at different levels (see the picture).

The second way is to divide the plan into several sections (in the figure they are marked with different colors)

Fill the assembled area with concrete. As in the previous method, after 7 * 8 hours it will be necessary to beat off the solution, but already on vertical surfaces. Take a hammer and, having removed the cover-sidewall, beat the cement-sand mortar to gravel (there will most likely be a layer of mortar without filler near the formwork). As a result, the surface will be chipped, which is good for adhesion to the next portion of the mortar.

These methods can be safely used in private construction: they are practiced in the construction of monolithic multi-storey buildings, and there the workloads on concrete walls and foundations are incomparably greater.

There is one more trick. Everyone says that boards or plywood can then be used in auxiliary work. In practice, it turns out differently: it is impossible to saw wood or plywood soaked in cement. In addition, it becomes dirty and rough, and it is also unrealistic to clean and polish it: no grain "takes". So, in order for the wood (and plywood, if unlaminated) to remain usable, the front part of the shields is covered with a dense film. It is secured with a construction stapler and staples. If it gets damaged, it takes very little time to replace it. The formwork improved in this way gives an almost perfectly flat foundation surface, which facilitates subsequent work on hydro and thermal insulation.

There are several ways to level the formwork. The rules for carrying out work are reflected in the specialized documentation: SNiP 3.01.03-84 "Geodetic works in construction" and SNiP 2.03.01-84 "Concrete and reinforced concrete structures".

In most cases, individual developers have no time to learn the rules and regulations. Therefore, the most useful are the recommendations of builders, based on the requirements of SNiP and optimized for different conditions for performing concrete pouring work.

The choice of material for formwork

Formwork is a frame, the cavity of which is poured with concrete. After it has set, the auxiliary structure is dismantled (removable formwork) or it remains in the same place and will be an integral part of the structure being erected (non-removable).

In the first version, new sheet materials are used for other purposes. But in this case, the inner walls of the frame are covered with overlapping canvases of dense polyethylene film, which is fixed to the boards with staples and a construction stapler. This precaution will protect the materials from grout contamination.

For the device of the formwork, you can use:

• Edged or unedged boards;
• Plywood or OSB sheets;
• Cement particle boards (DSP);
• Styrofoam with a thickness of at least 5 cm;
• Chip cement slabs (fiberboard);
• Metal sheets from 2 mm thick;
• High strength plastic sheets.

How to make shields

When pouring the foundation, you can face such a problem as the expansion of the formwork. This nuisance arises for two reasons:

• Wrong material selected;
• Incorrectly assembled and installed frame shields for concreting.

In order to make a solid formwork from edged boards, lumber with a cross section of 100 × 25 mm and 150 × 30 mm is used. The shields will need to be supported by bars with a cross section of 100 × 50 mm. It is also used to install vertical formwork struts, located with a step of 80-100 cm. Installation of panels consists of several stages.

Install vertical racks from a bar of 100 × 50 mm.

Sew up the inner walls with boards with a thickness of 2.5 cm, using wood screws.

The mounted panels are supported with bars installed on the outside of the formwork. The step between the supports is 60-70 cm. Such a structure will withstand the pressure of concrete. After the foundation is poured and gains brand strength, the wooden frame is dismantled, and the lumber is used for other purposes. For example, for the device of the roof rafter system or for the device of a ventilated facade.

With a shield height of 90 cm and pouring concrete in a mechanized way (from a concrete pump), the pressure per 1 running meter of the frame will be at least 2300 kgf / p. m. The formwork may not withstand and deform. Therefore, its walls must be pulled together with metal studs fixed on the outer sides of the frame with nuts.

Site preparation

The formwork can only be positioned exactly on the preliminary basis. This stage of work is called "planning" and is carried out manually using shovels and improvised devices. It consists in leveling the site by moving the soil from higher places and filling it with depressions in the marking area.

Installation begins with the installation of vertical supports. The frame is erected inside a trench for a strip foundation or a foundation pit for a slab foundation.

The bottom of the grooves must be leveled and compacted. It is necessary to pre-form a shock-absorbing "cushion" on it, consisting of two layers: sand and gravel. Each layer also needs to be leveled and tamped. After that, proceed to the installation of the frame as described above.

Alignment

An important point in the construction of formwork is its leveling. A recommendation from the builders: no need to strive to align the upper planes of the frame "to zero". On the contrary, it is better to make the walls of the formwork higher than the planned foundation height by several centimeters. And on the inside of the boards, apply marks with a marker, drawing horizontal lines corresponding to the required plane of the foundation to be poured.

The main difficulty lies in drawing these lines correctly. Pouring and leveling concrete on them is not difficult. To accomplish the task, you can use the water level.

First, find the desired foundation height at the lowest point of the marking. A flask of a water level is applied to it, the water level is memorized or marked with a risk. Then, with the help of the second flask, the corresponding marks are set on the remaining pegs. Lines are drawn and, if necessary, duplicated with thin wire.

There is another point of view on alignment: the walls of the frame must be aligned "to zero". For these purposes, at the stage of marking, the height of the foundation is determined in the above way and at this level the ropes or fishing line are pulled. Shields are mounted, focusing on these devices.

The second way to level the formwork walls is to cut the boards along the lines drawn along the fishing line or rope. When pouring, concrete is compacted with a reinforcement bar and leveled with a rule, which in this case must rest on the walls of the formwork.

How to use the laser level

This tool will come in handy for most of the marking, installation and finishing work.

The principle of operation of the level is simple: it shows a perfectly flat horizontal line due to the self-leveling mechanism located inside the device.

Watch additional video:

The correct use of the level is to follow a few simple recommendations:

• Preliminarily remove all obstacles in the path of the laser line;
• It is not recommended to exceed the optimal distance from the level to the object specified in the instructions for the device;
• The device must be installed on a flat surface or on a tripod;
• If there is no self-leveling function, before starting work, adjust the level using the built-in bubble level.

When erecting walls using monolithic construction technology, several types of formwork can be used. In the construction of large civil and industrial facilities, removable panel formwork is relevant, allowing you to quickly erect long and high walls. In the private sector, a non-removable type of formwork systems is used, which makes it possible to fill an entire building along a finished contour. Each of the varieties has its own pros and cons, as well as device features.

Removable panel wall formwork

The first stage in the assembly of removable formwork is the drawing up of a detailed project, which should take into account all the typical and geometric features of the structure being erected. Also, before installing and fixing the molding complex, the corresponding calculations are made, which determine:

• optimal wall thickness, taking into account climatic features and bearing capacity of architectural elements and formwork;
• brand of concrete and reinforcing elements.

Installation diagrams of removable panel formwork for various wall options

After drawing up the technological plan, they proceed to the process of arranging the formwork system, which includes:

• connection of formwork panels with each other using locking mechanisms and ties;
• installation of a deck sheet made of waterproof plywood;
• fastening the formwork with struts;
• installation of reinforcing elements;
• connection of ready-made blocks (boards), standing in parallel using clamping screws.

Wall formwork panels are connected in successive segments using locks of various types, which provide reliable fixation and a sufficient level of strength. Wedge and universal locks can be used in straight segments. Pivots or special ties are used to fasten the corner shields. After the formation of a block of the required dimensions, it is necessary to fix it in a vertical position and create conditions for 100% stability.

Wall formwork panels are connected in successive segments using locks of various types

The deck can be installed in a horizontal or vertical position, depending on the dimensions of the formwork frame. Fixation of the contact surface to the frame ribs is carried out by means of special fastening devices, the type of which also depends on the type of formwork system.

The struts will help to fix the complex of formwork panels in a vertical position, as well as to carry out the adjustment. There are two types of these devices: two-level and single-level. They are distinguished by their bearing capacity and load distribution mechanism. A two-level strut is used for larger structures with a high load index.

Reinforcement of the casting mold is carried out in accordance with the technological requirements for the structure. Based on the functionality of the wall (load-bearing or not), the type of reinforcement (type, thickness, etc.) is selected. When placing a reinforcing element between the formwork panels, there must be sufficient space for the concrete to form the outer edges of the slab. To ensure a stationary position of the reinforcement inside the formwork, special clamps are used.

To ensure a stationary position of the reinforcement inside the formwork, special clamps are used

After placing the formwork segments in a vertical position (parallel) and laying the reinforcing elements, they are fastened with a tightening screw, which ensures reliable coupling between the parallel walls of the formwork. After completing this stage and carrying out all the necessary engineering and technical checks, the concrete mix can begin to be pumped.

Permanent wall formwork

Fixed formwork for the construction of monolithic structures can have various shapes. In addition to the main functions, the material used to create the molding space plays the role of insulation, therefore, the use of this type of formwork is advisable in low-rise private construction. As a rule, in this case, polystyrene foam blocks are used.

The device of this type of formwork for monolithic walls consists in forming a molding contour by connecting polymer blocks by means of profiles already installed on each of the elements. The wall thickness depends on the type of block used. Pouring the wall can be started after the blocks have been bonded, the form has been reinforced and all checks have been carried out.

Wall reinforcement in permanent formwork