Pouring formwork: which design is better. Installation of formwork for different types of foundations Installation of wooden formwork

Advantages and disadvantages of the design. Types of formwork. Permanent formwork for foundations, walls and ceilings.

Many experts advise using this particular type of plywood when assembling formwork with your own hands. For walls, a slightly different technology is used, but for the foundation this option is the most acceptable. Another advantage of FSF is that it can be used several times. It is not recommended to cover the interior parts of the room with such plywood.

Before the beginning installation work standard calculations are required. These include determining the amount of material needed and finding its final cost. It is important to consider the type of raw material that will be used to make the formwork. OSB boards, plywood, chipboard, boards - all these materials have different prices.

OSB formwork is most often used in private construction, since this material is not suitable for large projects due to its poor resistance to moisture. Calculating the number of boards is very simple. To do this, first of all, it is necessary to divide the perimeter of the planned foundation by the length wooden part. Next, you need to divide the height of the base by the width of the wooden board.

Expanded polystyrene blocks for formwork are very quickly installed

The last thing to do is to multiply the two values obtained earlier. The result will correspond to the number of boards that will need to be purchased. Experts recommend adding a small margin (about 10%) to the calculated data.

Note! One cubic meter of boards can hold an average of 40 to 65 products.

In order to determine the cost, you need to multiply the price by the number of cubic meters of lumber required to install the formwork for the foundation.

Other expenses should be added to the resulting figure. For example, to assemble a forming structure, a certain amount of timber will be required. Wooden spacers are also used to strengthen the formwork. Procurement costs additional materials can in some cases amount to 40–50% of the total price of plywood sheets and boards. The final cost calculation also includes the costs of purchasing tools and elements that will be used to fix the individual components of the formwork.

Before starting the assembly of a removable forming structure, it is necessary to purchase the appropriate tools and materials, and it is also worth preparing the area that has been designated for installation of the foundation. The most common is the strip base. To make removable formwork you will need the following materials:

Before starting the construction of formwork, it is necessary to purchase the appropriate tools and materials

Counting materials for organizing formwork strip foundation is carried out based on the dimensions of the future foundation. It is necessary to take into account several requirements to correctly implement the forming design. The height of the formwork assembled from plywood must exceed the level of the base by 50 mm. Spacers are installed at a strictly defined distance from each other (700-1000 mm).

It is important to remember that there should be as many stakes as there are side supports. The shields in the corners are fixed together. For this purpose, side jumpers are used. When organizing formwork, a dense film made of polyethylene material is used. It should cover the entire inside of the fence. Before you begin, it is recommended to watch training videos on how to properly make a foundation.

Preparing the place where the base will be cast includes several types of work. First of all, you need to dig a ditch in the ground. The trench must correspond to the designed depth. In this case, it is required that the width of the ditch have a margin of 10 cm greater than that of the future strip base.

Next, you need to level and compact the soil at the bottom of the trench. Then the walls are leveled. One of the most important conditions When pouring the foundation, it is necessary to organize a special cushion of gravel and sand at the bottom of the ditch. Standard width this layer is 10-15 cm.

The most commonly used material for formwork construction is boards

Note! Not all buildings require the organization of the foundation using a forming structure. In some cases, it is possible to pour the foundation without formwork. This foundation is suitable for various types of temporary buildings. The technology of such construction takes into account digging a trench, laying polyethylene and reinforcement.

In soil that has a high density coefficient, a trench is made corresponding to the width of the concrete strip. Moreover, the formwork in this case should be located above the soil level.

Installation of a removable structure most often takes into account its reuse. If this is not necessary, then you can purchase a non-separable polystyrene foam form. Doing this work on your own is quite difficult. To do this, you need to draw up a competent project and strictly follow the instructions for organizing the base formwork. Let's look at each stage of the work in more detail.

First of all, it is necessary to make shields, which are the main forming elements. Nails are used for fastening. The height of the shields should be slightly higher than that of the base (about 10 cm). In order to understand the features of assembling the forming structure, it is recommended to study the corresponding photos and videos. The formwork for the foundation is strengthened with your own hands using wooden stakes. As mentioned above, their pitch is approximately 70-100 cm. The distance from the foundation to the stakes should be approximately 1 meter.

Next, you need to place the shields along the edges of the ditch and connect them to the stakes, using special jumpers. Then the fence is leveled in a vertical plane, for which you will need to use a building level. After this, the structure is fixed to the mow.

In some cases, it is possible to pour the foundation without formwork

On next stage The internal cavity of the formwork is covered with dense polyethylene film. The edges of the canvas are fixed using a construction stapler. Next, you will need to place a reinforcing grid in the intermediate space. When installing formwork for a strip foundation with your own hands, you may need to add reinforcement under wooden supports, the height of which is 5 cm.

Note! Before starting pouring, it is necessary to organize passages for communications. Round sleeves are used for this.

After laying the reinforcing grid, the plywood panels should be tightened using wire. It is worth noting that if the foundation has rounded areas, then in this case you will need to bend the plywood to achieve the desired shape.

During the assembly of the forming structure, it is necessary to comply with certain dimensional requirements. All possible deviations from the norms should be taken into account. Otherwise, an unstable shape may result, which will subsequently negatively affect the technical characteristics of the base. So, there are special requirements for the manufacture of formwork.

How to make a foundation correctly? It is important to remember that the deviation of the panel structure in the vertical plane should not exceed 5 mm per 1 meter of height. Quite often, inexperienced craftsmen make the mistake of placing boards in areas that have a natural slope of the ground. The top formwork board in this case should be positioned strictly horizontally. Repeating the tilt is strictly prohibited.

Wall formwork is not yet widely used in construction

There are also clear restrictions on the displacement of the forming structure from its original position. The maximum permissible displacement is 15 mm. When installing boards, you need to take into account that the differences between them should not exceed 3 mm.

How to install formwork on an area with loose soil? In this case, it is necessary to make a wider ditch, on the sides of which additional spacers need to be arranged.

If desired, at the stage of assembling the formwork, you can insulate the future foundation. To do this, use any suitable, inexpensive material (for example, foam). In this case, the trench expands in accordance with the thickness of the insulating material.

In the case of organizing a foundation without formwork, suitable reinforcement is selected in the ground from which the lattice is constructed. It is not recommended to use this technology if the soil on the site does not have sufficient density.

When installing permanent formwork, it must be remembered that the most important criterion is its tightness. If we neglect this, then the thermal insulation qualities of the non-demountable structure will be greatly reduced.

The forming structure is used not only for pouring the foundation of residential and commercial buildings. The need for formwork is also present when installing some protective structures. Solid base The fence guarantees the protection of the site from entry by unauthorized persons.

The construction of a fence is not complete without pouring the foundation.

In this case, before installing the formwork, you will also need to carry out some preparation. The first step is to mark the perimeter of the future structure. Then the soil is prepared, which involves removing vegetation, stones, debris and other obstacles that may interfere with the installation of formwork under the fence.
Next, you can start digging a trench. It is worth considering several rules. At the points corresponding to the installation of supporting elements (pillars), the depth should reach 80 cm. The same figure for spans is 50 cm.

Note! After organizing the trench, you need to pour sand and gravel into it to prepare a special cushion .

How to build the formwork for the foundation of the fence yourself? It is not so difficult to make this device at home. Even a person who does not have relevant experience can cope with such work. To organize the forming structure under the base of the fence, you should follow a step-by-step algorithm of actions.

The first step is to strengthen the waterproofing qualities of the wood from which the formwork will be made. For this purpose, used machine oil is most often used. Next, vertical stakes are installed. The distance between them should be at least 50 cm, but not more than 1 meter.

A foundation is needed even for a fence made of corrugated sheets

Then the support posts are installed from timber and the panels are fixed to them. For fastening in this case, use ordinary nails or self-tapping screws. At the next stage, it is necessary to tighten the shield fence with wire and install the reinforcing mesh.

After installing the reinforcement, the upper part of the frame is fixed. For this purpose they use wooden blocks. In the corners there are brackets that perform a fastening function. At the final stage, you will need to seal the cracks in the structure. This completes the installation of the formwork for the base of the fence.

Independent installation of formwork for the foundation of a residential or commercial building requires serious preparation. In addition to drawing up a plan, you should calculate the quantity necessary materials. Before assembling this structure, it is recommended to study all possible video materials on this topic.

Any construction of buildings requires the mandatory installation of floor slabs, which can either be purchased ready-made or manufactured directly on site. construction site. However, the latter option is very popular because it is considered less expensive. To do monolithic slabs independently, it requires the creation of a special structure - floor formwork.

Device

The monolithic ceiling is one of the main elements of the structure, which increases performance characteristics building and makes it durable. Its installation begins with the assembly of formwork, which allows the concrete to maintain its shape and immobility until it hardens. Floor formwork is considered difficult building structure, which usually consists of such elements.

Support nodes. These are wooden beams that look like telescopic posts. In order to evenly and correctly distribute the dynamic load on this element, the distance between them must be accurately calculated. With the help of such supports, formwork is assembled for pouring monolithic slabs no higher than 4 m in height. Often, additional or starting posts are used during the construction of structures. They are made of metal profiles and are fixed together with special fasteners (cup or wedge). Thanks to such supports, it is possible to construct formworks up to 18 m high.

Racks, which are usually used when installing formwork in high-rise buildings, consist of three elements: a unifork, a vertical support and a tripod. The unifork is the upper part and serves, as a rule, to fix the working surface. It is often also called the “support fork”. This element is produced from four tubes (square cross-section), which are welded at the corners, and metal plates with a thickness of at least 5 mm. The tripod (skirt) is designed to provide stability to the stand and allow it to be held securely horizontally. In addition, the tripod also takes on part of the main load when pouring concrete.

According to the standards, during the construction of ordinary residential buildings, it is allowed to use racks of the following sizes to install an auxiliary structure: 170-310 cm, 200-370 cm. If you plan to build a private house outside the city, you can get by with supports standard size 170-310 cm, they are placed in increments of 150 cm.

Base. It is made from sheet material, for which sheets of plywood, metal profiles and boards are most often used. To increase the strength of the structure, it is recommended to use a material with high moisture resistance.

Metal or wooden beams. These elements are placed perpendicular to each other. For the construction of formwork, you need to choose beams with increased rigidity, since the retention of the mass of concrete and the strength of the formwork itself depend on this.

Formwork for floors can be made in various types, it all depends on the type of support, the thickness of the concrete poured and the height of the structure.

Advantages and disadvantages

Floor formwork is considered indispensable building element. However, they have both advantages and disadvantages. Therefore, before building them, it is important to take into account all the characteristics. The main advantages of formwork include such moments.

Providing high strength to monolithic slabs. Unlike conventional prefabricated structures, they do not have joint areas or seams.
The ability to implement non-standard projects, since such formworks allow the production of floors of various shapes.
Elimination of displacement of floors in the transverse and longitudinal direction. Monolithic slabs acquire additional rigidity.
Easy installation. It is possible to create formwork on your own without the use of special equipment, which significantly saves construction costs.
Possibility of reusable use. Adjustable formwork is used to pour hundreds or more monolithic slabs. It's financially beneficial.

. As for the shortcomings, there are few of them.

Compared to the use of ready-made slabs, the time costs are greater, since additional construction and dismantling of structures is required. Besides, construction process takes a little longer because you have to wait for concrete pouring will gain strength.
The need for strict adherence to all technology for manufacturing and pouring concrete mortar. This is difficult to do because concrete is poured in huge quantities.

Kinds

Floor formwork, intended for concreting monolithic slabs, comes in several types, each of which differs in assembly technology and technical characteristics. The following type of structures is most often used in construction.

Stationary (non-removable)

Her main feature It is believed that after the solution hardens it is not removed. Stationary formwork consists of thermal insulation sheets and layers of waterproofing material, so they provide the building with additional warmth and protection from moisture. Upon completion of concreting, the permanent structures are transformed into one of the elements of the reinforced concrete structure. These structures have a number of advantages: they simplify installation work, reducing labor costs, and give the structure decorative look, as they are made from modern materials.

Removable

Unlike the previous type, these structures can be dismantled after the concrete has completely hardened. They are in greater demand than stationary ones because they are characterized by low price and easy installation. Many builders rent removable formwork, as this allows them to reduce the cost of assembling the structure and quickly complete the concreting process.

Collapsible

This type formwork is divided into several classes and differs in level of complexity. So, for example, when constructing horizontal planes, simple (frame) formwork is recommended, but if you plan to erect buildings of complex shapes, then a volumetric (large panel) structure is suitable. The assembly of such elements is carried out from moisture-resistant plywood, corrugated sheets, penoplex, polystyrene foam and expanded polystyrene.

In addition, slip formwork is sometimes used for the construction of small and large modules. It is installed vertically. The type of structure is chosen in construction depending on the complexity of the project.

Technical requirements

Since formwork for floors is responsible for the further strength of monolithic blocks, it must be erected in accordance with established construction standards, taking into account all technologies and rules. The following requirements apply to this design.

High safety margin. Each component element of the structure must withstand not only reinforcement cage, but also the weight of liquid and hardened concrete.
Safety and reliability. During reinforcement and pouring of mortar, workers move along the base, so it must be rigid and prevent any vibration. Otherwise, monolithic slabs may develop defects, which can further lead to emergency situations. Construction tables, which can also be moved during construction work, also help prevent damage to the integrity of the structure.
Long service life. This primarily concerns collapsible and removable formworks, which are used repeatedly in construction. To create a monolithic floor, it is recommended to install formwork made of durable material that will withstand subsequent use after dismantling.
Resistance to loads. Since concrete is poured superficially and with a recess, its mass creates increased dynamic loads on the formwork. In order for the structure to reliably withstand them, it is necessary to select the correct material for its manufacture in advance and prepare a plan for the foundation slab, which complements the formwork drawing and slinging diagram.
Have accelerated installation. Today there are many support parts and ready-made sections available for sale that allow quick assembly designs.
Possibility of disassembly. After the solution has hardened, the formwork, consisting of several elements, can be dismantled for further use. This process should be quick and easy.

DIY installation

Installing formwork for floors is considered a responsible and complex process, so if you plan to assemble it yourself, you must have some experience and comply with all technology conditions. Many builders prefer to purchase ready-made monolithic slabs; their installation requires only jacks and workers. The only thing is that construction equipment is not always available in use and in hard to reach places she won't be able to work. Therefore in such cases monolithic blocks It's best to do it yourself. To do this, you will need to strengthen the formwork, after which concrete is poured. The construction process in more detail is as follows.

At the first stage of work, accurate calculations should be made. For this purpose, design is carried out and an estimate is drawn up. In the project, it is important to take into account the strength of the formwork so that it does not crack under the weight of the concrete solution. In addition, a diagram of the placement of slabs is made, taking into account the configuration features of the future building, the grade of concrete and the type of reinforcement. So, for example, to build an ordinary residential building, the span width of which will not exceed 7 m, you will need to make a durable floor with a thickness of at least 20 cm.
At the second stage, all necessary materials are purchased. This is the base for the formwork, supporting and fastening elements.
The next step is to assemble the formwork itself. Its installation should begin after the walls are erected, when their height has already been set. For horizontal pouring, you can use two types of formwork: ready-made (purchase or rent, it only requires assembly) and permanent. In the first case, it is recommended to choose a structure made of durable plastic or metal; after completion of the work, it can be reused many times. Such formworks usually include sliding supports that allow you to hold the floor at a certain level. They are installed very simply and quickly.

In the second case, you will have to assemble the formwork yourself from plywood and edged boards. It is recommended to take plywood with increased moisture resistance, and it is best to select edged boards of the same size, this will save you from adjusting them in height in the future. First of all, the foundation for monolithic slabs is prepared. If during assembly of the formwork there are gaps between the elements, then additional waterproofing material. You can also make a structure from corrugated sheets. It is much easier to work with and this material eliminates the formation of gaps.

Great attention should be paid to the choice of plywood. It is advisable to purchase laminated or glued sheets that have increased moisture resistance and a thickness of 18 to 21 mm. This material is made from several layers of wood veneer, each of which is laid across the grain. Therefore, this type of plywood is durable. The installation of plywood sheets must be carried out in such a way that their joints fall on the crossbars; in addition, after assembling the formwork, not a single seam should be visible.

The installation process should begin with the installation of supports that will support the future monolithic block. Both sliding metal elements and homemade ones made from logs are suitable as racks (they must have the same thickness and height). The supports must be placed in such a way that there is a distance of 1 m between them, and the distance between the nearest supports and the wall should not exceed 20 cm. Then the beams responsible for holding the structure are attached to the supports. Horizontal formwork is additionally installed on them.

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

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

All possible problems arise only when self-construction foundation by people who do not have experience and appropriate training.

Most mistakes are made at the preparation stage, when creating the design elements of the tape.

Let's consider one of the important stages of construction - assembly and installation of formwork.

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

In most cases, the exhibition is made from edged boards, but there are also more specialized structures 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, preventing the leakage of concrete and eliminating wasteful loss of material.

Kinds

Exist different kinds formwork.

They vary in type of design and installation.:

Small and large shield. The most common type.
Block. Used for filling wells, columns, etc.
Volume-adjustable. Used for parallel casting of vertical and horizontal surfaces.
sliding. It moves as the concrete sets for further pouring.
Horizontally movable. A type of sliding formwork for pouring horizontal structures.
Lifting and adjustable. Used for tiered concreting of vertical structures.
Fixed. Concrete or polystyrene foam blocks are used, from which the wall is assembled, and the internal cavity is filled with concrete. The technology is relatively new and not yet widely used.

Of the listed options, predominantly panel types are used, since the remaining structures are intended not so much for strip foundations, but for general construction work.

There are varieties according to the level of heat saving:

Insulated.
Warming.
Special.
Not insulated.

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

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

What material is used

Formwork can be created from various materials:

Wooden.
Plywood.
Made from polystyrene foam.
Metal.

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

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

Advantage wooden structures is low cost and versatile, but their assembly time is much longer than that of plywood or metal ready-made panels.

How to calculate the quantity?

The simplest way to calculate is to use an online calculator. You enter your own data into the appropriate boxes - 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 will be useful:

The perimeter of the tape is calculated.
Divided by the length of one board, we get the number of shields.
The width of the shield is selected based on the height of the tape (usually a multiple of the width of the boards).
The number of boards in each shield is calculated.
Multiplied by the number of shields.
The result obtained is multiplied by 2.

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

NOTE!

Any method of calculation is quite approximate, so it is recommended to purchase 10-15% more than what was calculated.

Which board is best to use?

To assemble the formwork, the most common material is usually used - edged pine boards. It is recommended to plan the working surface of the boards, but this is not always possible, so most often the assembly of panels is made from unplaned boards.

An important issue is the degree of moisture content of the lumber. In this case, the use of a dry board is not necessary, and sometimes even undesirable. Formwork for a long time keeps the array moist, which is periodically watered with water all this time.

Dry lumber begins to actively absorb moisture, swells and increases in size, causing individual boards to be squeezed out of the plane by the board.

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

Installation procedure

The creation of formwork is carried out in stages:

Vertical cross bars are cut. Their length is 40-50 cm greater than the estimated width of the shields, since they will have to be driven into the ground. To do this, one end is sharpened for better fit.
Preparing the boards. They are cut to length (if necessary) and stored on a flat surface. Optimally - close to the trench, so that you don’t have to carry ready-made shields over long distances.
Lay out the crossbars in increments of 0.8-1.2 m. The top cut is aligned along the line.
Assembling shields. First attach the top board, then attach the rest as tightly as possible. Nails or screws are used.
The shields are lowered into the trench, aligned along their 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.
Parallel installed panels connected to each other by crossbars, which determine the thickness of the tape. Their role is sometimes played by U-shaped clamps assembled from wooden blocks.
WITH outside additional inclined struts are installed, eliminating the extrusion of panels when pouring concrete.

The inner surface of the formwork should be covered with plastic film 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 cracks. The film allows you to preserve material and prevent wasteful losses.

Installation of removable plywood formwork

Plywood makes it possible to obtain sealed panels with a flat and smooth surface. For a one-time you can get by with the cheapest pine plywood, but for reusable formwork it is recommended to choose more durable birch plywood, impregnate it with drying oil or purchase laminated 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:

Plywood panels are cut to size.
The frame of the panels is made from wooden blocks (50 by 50 mm). It is a edging located on the outer (non-working) side of the shield. There is no need to connect the planks together, but they are firmly attached to the plywood sheet. Nails, self-tapping screws or metal pins (for large panels) are used for fastening.
Pegs are driven into the trench to support the shields.
The finished shields are placed in the trench and their position is leveled. The distance between the parallel panels is fixed with transverse struts, which are subsequently removed before pouring.
Individual panels are connected to each other to form continuous formwork walls. The joints are sealed as tightly as possible; if cracks appear, they are sealed immediately.
U-shaped clamps are installed on top of the shields at intervals of about 1 m, holding the shields from being squeezed out during pouring.
It is recommended to cover the inside with polyethylene to seal the formwork and improve the curing behavior of the concrete. The plywood will remain clean and can be used again or for other purposes.

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 make it easier to dismantle the formwork and preserve it for reuse.

How to assemble from polystyrene foam

In this case, the formwork cannot be dismantled, being first a mold for casting, and subsequently a layer of insulation. Ready-made blocks of extruded polystyrene foam and additional elements to them - jumpers, parts for longitudinal connections, 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 durable and airtight outer cocoon for the concrete strip. The technology was invented quite a long time ago, but for various reasons it was not used; it is only beginning to gain popularity at the present time.

Nevertheless, the results allow us to predict good prospects for the technique.

Assembly of the formwork is simple. The blocks are connected to each other according to the principle of the designer, fixation is carried out 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 there are, the less possibility of errors or technology violations.

The main disadvantage of the method is the high cost of polystyrene foam blocks, which increases costs.

This is the main factor hindering the spread of technology.

Installation of removable formwork with insulation

Do-it-yourself installation of this type of formwork is carried out using our own methods:

The trench has a width equal to the thickness of the tape plus a double layer of insulation. Typically extruded polystyrene foam is used. The insulator sheets are installed vertically on the edge and fastened with nails 20 cm long directly to the walls of the trench.
Before installing the heat insulator, facade dowels are installed on the back side over the entire area. Their ends pass through the material and protrude into the trench in order to ensure a high-quality connection between concrete and insulation after pouring.
Wooden formwork is installed along the edge of the trench, forming an upward continuation of its walls. The heat insulator is attached to it in the same way as to the ground - with nails, only of shorter length. The technique for creating shields is common, the only difference is that they are installed not inside the trench, but along its edges.
Pouring concrete ensures tight contact of the tape with the insulation, absence of gaps and tightness of the insulation layer. After the concrete hardens, the wooden formwork is dismantled, and the heat insulator remains on the surface of the concrete.

Taking into account the specifics of the material, it is necessary to install a protective layer of the base sheathing to prevent mechanical impacts on the insulator.

Wooden panels must be dismantled carefully so as not to destroy the polystyrene foam boards.

Installation of permanent formwork

After this, concrete is poured inside, filling the voids and forming a solid solid wall. This technology appeared earlier than polymer permanent formwork, but, due to various reasons, has not received wide distribution.

Creating such an external frame allows you to solve a number of problems with rigidity, density of connection with concrete filling and finishing work. and can be produced without waiting for the final hardening of concrete.

Savings appear building materials, since there is no need for conventional formwork.

The formwork assembly method 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 side surfaces, after which the concrete is installed and poured.

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

How can I further strengthen this device?

The weight of concrete is very large, and the loads on the formwork during pouring can destroy it or create cracks through which concrete will flow out. For strengthening, additional elements are used to strengthen 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 placed below, tightly inserted between the stakes and the lower edge of the shields.

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

When to remove formwork from a strip foundation?

Formwork is traditionally dismantled 10 days after pouring. R Different technological options allow earlier or later dismantling within 5-15 days, which is determined by the size and thickness of the tape - the larger it is, the longer the curing period in the formwork.

When dismantling more early dates Extreme care must be taken as corners or edges of the tape can easily be knocked off.

Useful video

In this video you will learn how to properly make formwork for a strip foundation:

Conclusion

Formwork is an important and critical element in creating a strip foundation. Its assembly must be handled with the utmost care and precision, without neglecting any stages or elements of technology.

The quality of the pour and the entire foundation largely depends on how securely and firmly the form is assembled. It’s better to spend a little extra time and get the optimal result, since the fate of the entire building depends on it.

In contact with

With my own hands, I will devote several articles to installing formwork for the foundation. The correct choice of formwork and adherence to its installation technology are extremely important for obtaining a high-quality result, because in many respects the service life of the entire structure depends on the strength and quality of the foundation. summer cottage. Today we will talk about the types and methods of installing formwork for the foundation.

Formwork materials

Formwork is a pre-prepared frame for pouring the foundation. The main task of the formwork is to hold the foundation in the desired place of the stated shape until it hardens. Installation of formwork is a mandatory step in installing the foundation of a house or any other building that requires a foundation. Before we begin to study the technology of installing formwork, we will consider the types of materials used to construct the frame. The most common formwork materials are:

Metal formwork. Metal formwork is mounted from steel sheets up to 2 mm thick. Advantage metal formwork in the ease of working with it, as well as in flexibility and plasticity. The steel sheet bends easily, which allows you to get the formwork (and, consequently, the foundation) of the desired shape. This feature is especially important if you want to round the corners of the foundation. The disadvantage of metal formwork is its price; despite the overall savings in the construction budget, metal formwork will not suit you.

Reinforced concrete formwork. Reinforced concrete formwork is convenient, practical and popular. But, in addition to the high price, it has one significant drawback: the large weight of the slabs obliges the owner of the building to hire a team of workers with special lifting equipment. However, using reinforced concrete as formwork saves the amount of concrete that will be required at the foundation pouring stage. It turns out that at one stage the financial losses are greater, at another - less.
Formwork made of polystyrene foam. Expanded polystyrene blocks for formwork are produced industrially, and this is their main difference and advantage. Assembling formwork from expanded polystyrene is simple and quick; the blocks are attached to each other using a special locking groove. The only disadvantage of block formwork is the high cost of materials.

Wood formwork. Wooden formwork is possible from various types of wood: sheets of wooden plywood, OSB boards, and even regular boards. The advantage of wood formwork is its low cost when comparing this type of materials with those listed above. In addition, installation wooden formwork It’s not complicated and intuitive; any man with carpentry experience can handle it. However, wooden formwork also has a drawback: it must be properly strengthened, especially in places where the thickness of the concrete being poured increases.

Types of formwork

In addition to the material used, foundation formwork differs in type of construction. There are three main types of formwork, which have functional and structural differences.

Permanent formwork for the foundation. As the name suggests, permanent formwork is installed at the foundation installation stage and left in place for the entire life of the building. Most often, they are used as permanent formwork reinforced concrete blocks, but polystyrene foam structures often remain in place. Permanent formwork has two significant advantages: you do not waste time dismantling it, and in addition, the formwork performs not only a fixing role, but also an additional technical, sound or heat insulation role.

Removable formwork for the foundation. After the foundation has completely dried, the removable formwork is dismantled. The advantage of removable formwork is the possibility of using elements at another construction site. Removable formwork is made of wooden beams, polystyrene foam blocks, metal sheets. The elements are fastened using special groove locks, pins or nails. Despite the need for dismantling, work with removable formwork is considered easier and more accessible.
Sliding formwork for foundations. Sliding formwork is a foundation that smoothly transitions into the walls of the future building. The construction of walls begins with pouring the foundation, and layer by layer rises to the ceiling of the building. The main disadvantage of sliding formwork is the difficulty of installing it yourself; to implement this type of formwork you will have to seek help from a team of professionals.

Installation of formwork

Regardless of the chosen material, installation of formwork begins with theoretical and drawing work. The drawing is necessary for the correct calculation of the formwork for the foundation. To calculate, you will need the length of the perimeter of the building, multiply it by two, since the formwork is installed on both sides of the foundation. Add here the length of the partitions, the width of the foundation, and set aside 5-10% for possible mistakes and corrections in calculations. Further step-by-step instructions depend on the selected formwork material.

Plywood formwork

Do-it-yourself plywood formwork begins with the right choice of material. The thicker the future foundation, the greater the load the formwork must withstand, therefore plywood sheets It is better not to choose less than 3 cm thick.
Saw the sheets until required sizes, after which the creation of plywood panels will follow: connect the sheets together to obtain the desired formwork height. Use a wooden beam for fixation. It’s easier and faster to use nails as accessories.
Install the plywood panels in the prepared ditch in the ground, make sure that no gaps form between the panels (if any appear, remove them before pouring the formwork). Check that the smooth side of the boards is facing inward and the connecting bars are on the outside.
Install the reinforcement inside the frame and tie the reinforcing bars together.
Using wooden beams, install pegs on both sides of the formwork and dig them into the ground. They are necessary to maintain the pressure of the concrete during pouring.
The formwork is ready, you can pour the solution. Do-it-yourself wood formwork is popular for pouring, as the most common among the possible types.

Expanded polystyrene formwork

Do-it-yourself polystyrene foam formwork is easier and faster; blocks of material are already ready for use at the time of purchase.
Prepare a trench for the foundation, pour a sand cushion at the bottom and lay the selected waterproofing material. Install polystyrene foam blocks in the trench and secure with special locks.
During the installation of the blocks, do not forget to install blanks for communication holes, and also at this stage the reinforcement for reinforcing the foundation is laid.
After completing the installation of the formwork, check the evenness of the frame using a building level.

Reinforced concrete formwork

Do-it-yourself reinforced concrete formwork is a relative concept; without special equipment it will not be possible to install reinforced concrete blocks.
Dig a trench, taking into account the thickness of the reinforced concrete blocks. Place a layer of sand and a layer of small pebbles at the bottom.
Place the blocks in place, having previously made holes in the inside for installing the fittings. Put the reinforcement in place, tie it together to obtain a reliable fixation.
The blocks are installed in several rows, connecting them together using a mounting layer. Make sure that the blocks overlap each other and overlap.
Cover the final row of blocks with reinforcing screed; after drying, the formwork is ready for pouring the foundation.

Finally, I will bring to your attention a few secrets of installing strong and reliable formwork:

After fixing the formwork, it is important to check the horizontal and vertical position of the structure. To do this, use plumb lines or a building level.
Do not allow gaps in the formwork. Gaps larger than 5 mm are considered large and require sealing before pouring concrete.
The strongest angle is obtained when the reinforcement is bent in the right place. If it is not possible to bend the rod, use a special connector, or complete the reinforcement by tying the joint with ties.

Dismantling the formwork is permitted only after the concrete solution has completely dried. This rule applies to any formwork material.
Before starting work, study maximum amount materials for the chosen formwork installation method, listen to the advice of specialists, and if you don’t feel strong enough or don’t fully understand the whole process, contact the company to call a team of professionals who will carry out the work quickly, efficiently and with a guarantee.

Properly executed formwork is a guarantee of a reliable foundation; approach this stage of construction with all responsibility so that the structure can serve you without problems for many years.

Almost all existing types of strip foundations can be poured using only formwork - an auxiliary structure, which is often made from scrap material. It serves not only to ensure constant dimensions of the base, but also gives the foundation even, regular shapes and reduces the consumption of concrete mortar. Plus, it can be removed, moved to another construction site and used more than once.

Types of structures

The construction of an auxiliary structure made of wood, metal or other materials involves the use of rigid structures interconnected and capable of supporting the mass of concrete, but some types also provide excellent thermal insulation characteristics of the house. Various types of materials are used to construct formworks; let’s stop and first look at the types of formworks for strip foundations:

Removable (collapsible). These are wooden, less often plastic and metal panels, which are assembled in the form of a constructor, ensuring reliable connection of elements and tightness of seams. In most cases, the calculation of the amount of required materials is done on site when necessary. After use, you can remove and reapply. You can make it yourself from wood.
Fixed. This is a disposable design, made from polystyrene foam, and serves as the main thermal insulation layer. Needed when the building area is limited. Thanks to reinforcement with special supports and spacers, the foam plastic can withstand heavy loads, does not deform, and do-it-yourself assembly is done like a construction set from factory elements. It cannot be removed; it is necessary to calculate the panels for each specific construction. Various materials can be used, but most often polymer products.
Combined. Here, wood is simultaneously used as the outer layer of formwork, and polystyrene foam is used as insulation. After pouring the foundation, the outer part of the structure can be removed, while the insulation remains embedded in the concrete.

Several years ago, builders preferred to use removable formwork for strip foundations, since it is reusable and can be rented at affordable price. Moreover, many companies and small firms produce such formwork with their own hands and then rent it out at an affordable price. It is worth noting that it is difficult to erect formwork correctly, according to all standards, given specifications materials used, as well as the possibility of expanding the sole if necessary.

Design elements and material

The formwork consists of several main elements:

Wooden boards of rectangular or square shape of any size.
Fasteners vertical arrangement shields
Horizontal internal bushings, they are used to ensure the required internal width of the tape and prevent the expansion of the panels
Waterproofing. It prevents liquid from leaking out of the formwork, and also ensures a faster drying speed of the solution.

Formwork for strip foundations can be made from wood. The most accessible and cheapest material, the device is simple and anyone can make a frame with their own hands using available tools. For the production of formwork in private conditions, plywood up to 15 mm thick or edged board 40 mm thick. In this case, it is easier not only to construct a strip foundation, but also to correctly calculate the required amount of materials.

Metal factory structures are strong and reliable. They are durable and reusable, but due to their large mass they are difficult to transport. Only experienced builders can install such shields correctly. Tape extension is not allowed.

Plastic formwork or polypropylene foam is lightweight, compact, expensive and versatile. Great for construction load-bearing walls and floors, as well as when pouring strip foundations. Plastic and polystyrene foam are artificial thermal insulation, calculations are made right on the spot, and the panels can be cut to your size. It is also easy to construct a plinth on such a ready-made, flat surface.

Installation of wooden formwork

To produce wooden formwork, it is better to use edged board or wide plywood. Ready-made shields of fixed sizes are made from these materials, then grooves are made on the external contours to connect the shields to each other. All joints are treated with waterproof sealant or polyurethane foam. The moisture content of the wood should not be high, the thickness of the cracks should be up to 2 mm. The height of the shields should not exceed 5-7 cm above the level of the foundation strip. Installing the formwork is quite simple, you can do it yourself:

First, the construction site is prepared.
The dimensions of the formwork are calculated, the appropriate materials are selected and the structures are assembled.
Then the shields are installed on the outside and reinforced with braces, where the main fixation will be the soil or reinforced pillars. The braces are nailed to the boards and installed at intervals of at least 1 m from one another, the minimum permissible distance is 30 cm for thick bases.
Jumpers of a fixed length are secured with nails or corners - this is the maximum allowable width of the foundation strip.
The inner part of the formwork is installed in the same way and tightened with clamps, nails or other fasteners.
The vertical and horizontal position of all shields is checked, the permissible slope angle is no more than 3 degrees, and they must not have deflections or bends. The condition of the surface of the boards should be regulated by slats, a level or a construction hydraulic level. Local deviations for plywood should not be 2 mm, and for boards - up to 3 mm.
After pouring the concrete solution, the formwork can be removed and reused, and the base can be constructed on a flat outer surface.

The correct positioning of the formwork panels can also be controlled using casting threads and wires, as well as fixed type fasteners. In the case of using permanent formwork, it is advisable to fix it on the inside of the polystyrene foam wooden planks, install strong hooks in them and connect the fittings flexibly. Then the hooks will tension both surfaces of the formwork and fix them within the specified parameters.

After installation, the inside of the formwork must be covered with roofing felt in several layers so that the concrete does not leak out, as well as to ensure waterproofing of the tape. Waterproofing must be laid from downward slopes, closer to the sand cushion, so as not to tear the layer during concreting. Upper part It is better to bend the ball of roofing material over the top edge of the formwork, secure it with clamps or screws, and secure it with a stapler. Then the sheet will withstand the load that will occur when pouring concrete from a concrete mixer.

How to install formwork for strip foundations on unstable soil

Even just digging a trench or pit in loose soil is fraught with some danger due to its possible shift. Therefore, first they make the outer formwork of the trench in order to prevent soil shifts, and only then they equip the inside of the trench.

To protect the labor of workers, a trench is dug at a certain slope of the walls and of sufficient width for convenient installation of shields. Then the formwork is installed, which is often made in several layers, where the intermediate zone is the clamps of the outer edge from the ground and the inner edge from the concrete mortar zone.

To ensure that the formwork stands securely, you can pour a layer of medium-density concrete on top of the sand-gravel mixture so that it inside fixed the shields. When formwork is installed on a concrete base, it is better to use special threaded ties. They fix the slabs together, prevent them from spreading under the mass of concrete, and steel bushings are provided inside the formwork.

How to arrange a combined formwork for a strip foundation

Combined formwork justifies itself when you need to erect a high-rise building and install thermal insulation on a limited area of the construction site. The design involves a combination of removable and permanent formwork, which can be made with your own hands, while its design remains quite simple. On the outside there are ordinary removable plastic or wooden panels, and on the inside there is a layer of polystyrene foam.

This design carries the advantages and disadvantages of two types of formwork. Some developers spend money and time on thermal insulation, especially when it is necessary to build a foundation without calculations in a short time. The disadvantage of such formwork is that when it comes to waterproofing, it can only be placed on the outer surface, and the inner part of the insulation cannot be removed.

If the strip base is erected on strong soils that are not prone to heaving, then the trench is dug taking into account the thickness of the insulation, as well as the removable formwork panels. In the underground part, the insulation is attached to the walls of the trench, and in the above-ground part - using self-tapping screws. You can also use special mounting dowels and umbrellas, but then removing the insulation during restoration or repair is problematic. If the tape is installed in loose soils, then the insulation is installed completely immersed in the ground, provided that the level of frost heaving in the region is insignificant.

The role of permanent formwork for strip foundations

These are panels made of polystyrene foam, connected to each other by grooves in the shape of a construction set, so they are often made with their own hands according to ready-made drawings. A reinforcement frame is installed inside and then filled with concrete. Due to the presence of expanded polystyrene, a thermal insulation and waterproofing layer is simultaneously formed on the surfaces of the tape. This type is used when the building area is limited or high level occurrence groundwater. The advantages are obvious:

it can be quickly assembled directly at the construction site and does not take up much space;
it is supplied in a factory configuration, there is no need to calculate the parameters of the panels, they can simply be cut, which cannot be done with wooden formwork;
all external and internal surfaces the tapes remain insulated;
the result is the smoothest outer surface, ready for construction and resistant to frost heaving.

The key disadvantage is the cost of permanent formwork, since it is produced in a factory from expensive materials and it cannot be removed. At every individual construction you have to re-calculate the dimensions of the slabs.