Faucets

Formwork pouring: which design is better. How to make a formwork for the foundation of the boards with your own hands? What is the best formwork for the foundation

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

Removable and non-removable

According to the principle of use, the formwork can be removable (collapsible) and fixed. 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 multiple times. Depending on the material, the same kit can withstand from 3 to 8 pours, industrial options can be used several dozen, and some hundreds of times.

Removable formwork is dismantled after the concrete has gained 50% strength

Fixed formwork becomes an inseparable part of the foundation. Such systems began to be used relatively recently. They are made mainly from extruded polystyrene foam. Blocks of different configurations are produced, which are interconnected using locks and metal studs. From the blocks, as from the constructor, the necessary form is typed.

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

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

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

formwork requirements

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

Removable construction materials

In construction organizations, there are metal structures assembled on studs and bolts. In private construction, formwork panels are made of boards, moisture-resistant plywood and OSB. Wooden blocks are used as stops and spacers. Nobody bothers to make a metal structure, but it is very expensive and unprofitable for a single use.

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

What does the formwork for strip foundation look like in section

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 with bars of section 60 * 40 mm or 80 * 40 mm. If the height of the foundation is large - it is deep - 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 or 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 from plywood. There is even a special formwork, laminated with paper with synthetic impregnations. 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 40 * 40 mm, fasteners need to be used shorter - 50-55 mm. When using plywood, it will be easier to work with self-tapping screws: nails are hard to hammer.

Construction of formwork panels made of plywood and OSB

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

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

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

Do-it-yourself formwork for a 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 cost of foundation formwork materials will be very significant. Especially with deep foundations.

Shield design and 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. Height - 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 optimal length about 2 m. The total length of the entire formwork should be such that they become exactly along the markings of the foundation (do not forget to take into account the thickness of the shield).

How can formwork for a strip foundation be installed: in a trench dug according to the dimensions of the tape and in a pit in braces

When making formwork from boards, cut several pieces of the same length, fasten with bars and nails or self-tapping screws. When using nails, hammer them with inside shield, bent on a bar. It is easier to work with self-tapping screws: they do not need to be bent, because 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 be facing the foundation wall).

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

Approximate dimensions of formwork boards from edged boards

Plywood or OSB boards are assembled on a bar frame. When assembling, it is important to strengthen the corners well. In this design, they are the most weakness. 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 stretched marking cords. The difficulty lies in the fact that at the same time you need to expose in a vertical plane. For fixing, you can use bars clogged at the mark and set vertically. When installing, set the plane of the shields close to these bars. They will be both support and guides.

Shields with extended transverse bars are easier to install

Since the bottom of the trench or pit must be flat (compact it and level it to the level), it should be easy to set the shields horizontally. Try not to hammer them too much: it will be easier to level them 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 the building level, apply along the shield and hammer the second edge with a hammer until the upper edge is set horizontally. You are already setting up the next shield relative to the installed one: they must be at the same level and in the same plane.

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

Strengthening - 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. Supports should be at least a meter apart. Particular attention should be paid to the corners: they put stops in both directions. If the height of the shield is more than 2 meters, then one belt of stops is not enough. In this case, at least two tiers of spacers are made: upper and lower.

Outside the formwork put stops and braces. With a high height, they are made in several tiers. Pay attention to the thickness of the support beam

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 appropriate diameter. Studs are installed in two tiers: above and below, at a distance of 15-20 cm from the edge.

The length of the studs is approximately 10-15 cm longer than the width of the tape. There are two options:

Both ends of the reinforcement are threaded. Then each stud will require two metal sealing plates and nuts.
On the one hand, 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 shields, equal to the design width of the tape, is fixed using segments plastic pipes. Their inner clearance should be slightly larger than the thickness of the studs.

How to make spacer studs in formwork

The assembly goes like this:

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

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

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

How to spend less

A lot of material is spent on the manufacture of formwork for a strip foundation: the boards form the entire strip on both sides. At great depths, the flow rate is very high. Let's say right away: there is an opportunity to save money. To make only part of the formwork and pour not everything in one day, but in parts. Despite popular belief, this will hardly affect the strength of the foundation (if you know the secrets), and you can save decently. You can divide the foundation either horizontally or vertically.

Filling with layers

With a large depth of laying, it is more profitable to fill in parts horizontally (in layers). For example, the required depth is 1.4 m. You can break the pour into two or three stages. With two stages, it will be necessary to make shields 0.8-0.85 m high, with three - 50-55 cm.

If the foundation has a great depth, it can be poured in two or three parts, divided vertically into approximately equal shares

The order of work is as follows:

The formwork is set up from the short panels made, the reinforcement is knitted for the entire required volume.
Concrete is poured according to the height of the formwork.
After 7-8 hours after pouring, it will be necessary to remove the top layer from the entire surface of the tape with a trowel. When vibrating concrete, cement milk rises. As it hardens, it becomes brittle and brittle. It is this layer that will need to be removed. As a result, the surface will be uneven and rough, and this will improve adhesion (adhesion) with the next layer of concrete.
At a temperature of +20°C, after three days the formwork can be removed, the boards cleaned and fixed higher. When removing the shields, take out the studs. Tubes can be left in concrete. They have already become part of the monolith. Sometimes they are taken out, and the holes are filled with mortar.
Raise the formwork higher and pour it again.

The shield is simply installed on the already "grabbed" concrete, and rests against the edges of the trench, but at a different level

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

The fittings are already connected, the internal studs are cut. It remains only to put the other tubes, put the studs back in place and put the outer stops and braces. It does not take much 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 in the calculation. She goes to reserve. In addition, the load in strip foundations is distributed along the long side. And there are no gaps in length. So the foundation will stand for a long time.

vertical division

The second way is to split 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 space the joints a certain distance.

In the part of the building selected for installation, install the formwork with "plugs" in those places where the part to be installed ends. Inside the installed part, knit a reinforcing cage. In this case, the bars of 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 outlet 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 to these 60 cm.

One important detail: when breaking down the plan of the house into parts, make sure 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 (they are marked in different colors in the figure)

Fill the assembled area with concrete. As in the previous method, after 7 * 8 hours it will be necessary to beat the solution, but already on vertical surfaces. Take a hammer and remove the side plug, beat cement-sand mortar to gravel (near the formwork there will most likely be a layer of mortar without aggregate). As a result, the surface will be chipped, which is good for adhesion with 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 workloads on concrete walls and the foundation is incomparably larger.

There is another trick. Everyone says that boards or plywood can then be used in auxiliary work. In practice, it turns out differently: it is impossible to cut wood or plywood soaked with cement. In addition, it becomes dirty and rough, and it is also unrealistic to clean and polish it: it does not “take” any grain. So, in order for the wood (and plywood, if not laminated) to remain usable, the front of the shields is covered with a dense film. It is fixed with a construction stapler and staples. If it is damaged, replacement takes very little time. Formwork improved in this way gives almost perfect flat surface foundation, which facilitates subsequent work on hydro- and thermal insulation.

Do-it-yourself formwork for a strip foundation: fixed and removable, how and from what to make, establish ways to save

One of the stages in the construction of a strip foundation is the manufacture of formwork - a system of shields that give shape to concrete. At self construction it can also be made by hand.

Creating a strip foundation for a house is almost never complete without formwork. It gives shape to the concrete structure, prevents the outflow of water from the concrete, makes the surface of the tape smooth so that waterproofing and thermal insulation can be easily done. How to do the formwork for the strip foundation with your own hands?

Requirements

The formwork should create an optimal temperature and humidity regime at which the concrete hardens well and gains maximum strength. An important requirement is the chemical neutrality of the materials used. They must not react with concrete.

If the formwork is removable, it should be easy to remove without damaging the concrete structure.

Formwork types

Formwork for a strip foundation can be

removable,
fixed,
combined.

It is also sometimes allowed to pour concrete directly into the trench without a mold.

Removable

Removable formwork is made of boards or plywood and other panel materials: chipboard or fiberboard. Most cheap material- wood. You can also use a slab, but it must be edged (edged) so that the boards fit snugly together. You can also buy or rent a ready-made set of prefabricated metal, plastic or wooden shields. Whether plastic metal shields allow you to make the concrete surface very smooth or, conversely, textured.

Fixed

Fixed formwork is most often made from extruded polystyrene foam (EPS). She looks like in the photo.

For a stronger connection, the sheets are fastened with plastic ties. At the same time, this form acts as a heater.

Important! EPPS is afraid of ultraviolet radiation, so the foundation needs to be shaded while the concrete is curing.

You can assemble it yourself from polystyrene foam sheets, or you can buy a ready-made kit. It can be standard or collapsible for non-standard buildings. The advantages of the non-removable option are precise observance of the geometry and high speed of work. Minus - it is difficult to evenly concrete the foundation

Removable-non-removable (combined)

This is a combination of removable and fixed formwork. This design is used on loose soils. It consists of two layers: an inner layer of extruded polystyrene foam and an outer layer of a conventional removable board deck.

EPPS is attached to the ground on nails 20 cm long, to a tree - on self-tapping screws. This option has its advantages:

immediately there is thermal insulation from the sides and from the base of the foundation,
a smooth surface is obtained on which the soil will slide when moving.

Such formwork can be made with insulation only in the underground part or to the full depth.

If the XPS blocks are installed to the full depth, they are placed directly in the trench, before that dowels are inserted into them so that the XPS is securely attached to the concrete. In the upper part protruding from the trench, a formwork of plywood panels is installed, which are fixed with braces and stakes. Before installing the XPS blocks, the trench is lined with a film. XPS is attached to the walls of the trench and wooden shields with nails 20 cm long.

If EPS is installed only in the underground part, a wooden formwork is made in the upper part, into which metal or plastic sheets are inserted to obtain a smooth plinth surface.

Concrete preparation

Concrete preparation (podbetonka) is a thin layer of concrete that forms the bottom of the formwork. It has a waterproofing function, does not allow cement milk to go into the ground. However, a footing device is optional. They also make formwork without concrete preparation, especially in private construction. In this case, it is necessary to pour a sand cushion and compact it well. Polyethylene or roofing material is laid inside the formwork. At the bottom, waterproofing must be laid in several layers, it is attached to the wall with a stapler.

To make formwork with concrete preparation, the trench is expanded, and its walls are made in the form of slopes. In this case, boards or plywood boards are installed to the entire depth of the trench and attached to the timber frame.

The shields are pulled together with a metal pin inserted into the tube so that it can be removed. At the ends of the studs, wooden bars and nuts are installed. Such screeds are made at a distance of 0.5 m. Also, the formwork is strengthened with struts and stakes. If the formwork is placed on concrete preparation, then anchors are made in the latter. Also, such formwork can be done without concrete preparation, for example, on loose soil.

Preparatory work

Before you make the formwork for the strip foundation, you need to prepare the site. To do this, it is cleaned of debris, trees, the fertile layer is removed, leveled. After that, the dimensions of the future building are transferred to the site. Careful marking is very important.

Further, trenches are dug for the strip foundation, the depth of which depends on the type of foundation: 50-70 cm for shallow and below the freezing depth for buried. There is also a non-buried type of strip foundation. Usually a trench is dug 10 cm wider than the foundation tape. The bottom of the trench should be flat, this moment is controlled by the level or by the ropes stretched during marking.

A sand or sand and gravel cushion is made in the trench. To do this, a layer of sand is poured onto the bottom, it is moistened and carefully compacted. If the soil is dusty, geotextiles are placed at the bottom of the trench before filling the sand. Also, the pillow is made two-layer: 20 cm of sand and 20 cm of fine gravel. After these preparatory work you can collect the form for the foundation.

Manufacture of removable formwork

The load, i.e. the pressure of the concrete on the formwork, depends primarily on the height of the belt. The larger it is, the greater the load on the formwork and the stronger it should be.

Most often, boards with a thickness of 25-50 mm and a width of 10 cm or more are taken, the wider the board, the easier it is to assemble the structure. The shields assembled from the boards are installed in the trench with the help of pegs, strengthened with struts. The struts are made from a bar with a thickness of at least 5 cm and are placed at a distance of 0.5 m. You can also use panel materials:

plywood.

Connect boards or shields with screws or nails.

Plywood shields are installed on the edges of the trench, reinforced with braces to stakes installed at a distance of 1 m from the edge of the trench. Between the braces should be no more than a meter. In the upper part, the deck is fastened with wooden lintels at a distance of 0.5-1 m. Inside, the form is lined with polyethylene or other waterproofing, which should completely cover the shields and bend outwards. Polyethylene is fixed with a furniture stapler.

You can use both new and used boards. It is important that they are not cracked, it is also necessary to pull out all the nails from them. It is advisable to use boards made of coniferous wood, they must be sufficiently moist (at least 22%).

Important! After assembling the formwork, it is necessary to check its strength. It must withstand pushes, kicks. Don't be afraid to break the boards: it's better if you find a weak spot during the inspection phase than if it reveals itself during the pouring of concrete.

Immediately you need to provide channels for pipes and other communications. To do this, holes of the required diameter are drilled in the shields and pipes are inserted into them.

The formwork should be slightly above the concrete level, which is marked on the boards with a cord. It is possible to make formwork flush with concrete, but it is more difficult for non-professionals.

It is important to control how evenly the shields are installed. This is especially true of the above-ground (basement) part of the foundation. The walls must be strictly vertical, and the upper edges set in the same horizontal plane.

Dismantling

An important question that worries builders is when to remove the formwork? If this is done too early, the foundation may be damaged; if it is done too late, the adhesion of the boards to the concrete will be too strong, in addition, when the wood dries, it will shrink and create tension.

Depending on the air temperature and season, the formwork is removed after 2-15 days, when the concrete hardens. The lower the temperature, the more time you need to wait. The formwork can be removed when gaps appear between it and the concrete. The boards can be reused, for this the formwork is lined with polyethylene or treated with oil or lime milk. Remove the boards from the strip foundation carefully, avoiding blows to it.

Properly made formwork prevents many problems during the pouring and further operation of the strip foundation. Therefore, it is necessary to approach this task responsibly and follow the technology.

The main stage in the construction of a foundation foundation of any type is the arrangement of formwork. Formwork for the foundation is a solid support-panel structure that gives concrete or reinforced concrete products the required shape.

The shield base can be made of plastic, metal, plywood or board. With the right approach, even a private developer can install, fix and dismantle it.

Why formwork is needed and its types

The main task of the design is to ensure the strength of the finished structure. In addition, the foundation formwork meets the following requirements:

distributes the pressure of concrete around the entire perimeter of the base;
retains the required shape when pouring the foundation;
quickly and easily erected, provides reliable sealing of the future foundation structure.

For the construction, practical and reliable materials are used, providing additional strength and durability of the base.

There are two main types of formwork: fixed and collapsible (removable).

Removable formwork used in the construction of the base, requiring decorative cladding. Such a frame is completely dismantled after the concrete mixture has completely solidified. The main advantage of the design is the possibility of its reusable use for the construction of foundations of various types.

Fixed formwork becomes the main part concrete base. In addition, it improves the heat and sound insulation characteristics of the foundation. For the arrangement, slabs of expanded polystyrene and hollow blocks of concrete are used. Such materials allow you to create a foundation of a suitable size and configuration. Such a frame is convenient and easy to install, does not require the use of protective elements - supports and spacers.

Materials for creating fixed formwork

The non-separable formwork is made of the following materials: wood, metal, reinforced concrete and polystyrene foam plates.

from wood

Wooden formwork - the most affordable option, which does not require the involvement of expensive mounting equipment. For its manufacture, plywood sheets and edged boards are used. The only drawback is the need to use auxiliary fixing elements to strengthen the finished structure.

metal

The most durable and reliable option, for the construction of which steel sheets up to 2 mm thick are used. The advantages of the design include the following:

allows you to build a base of varying complexity and configuration due to the flexibility of the metal;
provides reliable waterproofing protection of the foundation;
suitable for the construction of foundations of tape and monolithic type;
allows you to perform decorative trim foundation raised above the ground.

The main disadvantages of the design are the high price and the complexity of the installation work.

From reinforced concrete

An expensive and time-consuming option, for the manufacture of which reinforced concrete slabs are used.

Significant advantages of the design: the possibility of reducing the consumption of concrete mix, increased strength and durability.

The disadvantages include: big weight and dimensions of the plates, the need to use specialized equipment and additional fixing elements for installation.

Styrofoam

The most reliable and popular option for the construction of formwork. Expanded polystyrene has the following advantages:

light weight;
availability of installation;
variety of forms;
high hydro- and thermal insulation characteristics.

But the main drawback of the material is the high price.

Materials for the construction of collapsible formwork

Collapsible formwork is wooden and metal. For the manufacture of a wooden structure, laminated plywood is used and wooden planks. It is preferable to use products from spruce, pine, linden and aspen.

Formwork panels must meet the basic requirements: to be durable, wear-resistant and resistant to the negative effects of moisture. For erection wooden frame no specialized equipment is required, and all work can be done independently.

The metal structure is made of plates with a polished surface. Such a frame is suitable for the construction of foundations for private houses. The metal base provides reliable protection against the flow of concrete mixture at the joints of the plates.

The advantages include: low construction costs, availability and high performance characteristics of the material. The disadvantages are: the complexity of installation and the need to attract specialized equipment.

How to calculate the formwork design

For calculations, the type of material selected for formwork around the house is taken into account. An example is given for the calculation of a wooden structure.

For work, a standard board 600 cm long, 10 to 15 cm wide, and 2.5 cm thick is used.

The perimeter (P) of the future base is divided by the length (D) of one board, the height of the foundation (H) is divided by the width of the board (W), and the obtained values are multiplied together to determine the required amount of material (M).

For example, P - 1500 cm, D - 600 cm, height - 35 cm, width - 10 cm.

M = P / D × H / W = 1500/600 × 35/10 = 8.75 boards.

One cube of lumber includes from 40 to 65 boards. To the cost of the formwork material, you should add the cost of consumable fasteners - nails, staples, spacers and reinforcing bars.

Formwork construction on the example of a strip foundation

To make a formwork for a strip foundation, you need to follow the instructions below.

earthworks

After drawing up a working draft and calculating the required amount of material, an earthen trench is prepared.

Important! To simplify the installation between the walls of the structure and the trench, it is necessary to make a technological gap of 2.5 cm.

A pillow of sand and small gravel is laid at the bottom to reduce the consumption of concrete mix. Next, the base is reinforced with reinforcing bars.

Assembly of structural elements

The next stage is the installation of formwork for the strip foundation from the selected material with additional reinforcement of the structure.

After completion of the preparatory work, the frame is poured with concrete mixture according to the level. And if the pouring technology has been observed, in a month you can start the main construction work.

For pouring the foundation, concrete M 150 and 200 is used, with a high GWL (level ground water) it is recommended to choose concrete M 300 and 350.

To create a wooden frame, boards with a thickness of 25 to 45 mm of arbitrary width are used. The wider the board, the stronger and more reliable the finished formwork.

From the prepared material, a shield is assembled with a height equal to the height of the base.

Separate parts of the shield are fixed to each other with bars on self-tapping screws, while the hats should be located on the inside. Slots and voids are clogged with wooden slats according to the size of the finished shield.

Assembly of formwork for a monolithic slab

Installation of formwork for a monolithic foundation is carried out according to the following scheme:

Installation of vertical supports - telescopic legs made of metal or wooden logs with a diameter of up to 12 cm. The distance between the supports is 100 cm, the distance from the racks to the wall is 22 cm.
Installation of fixing crossbars on supports to provide additional reinforcement of the formwork. To do this, you can use channels, longitudinal bars or I-beams.
Installation of the frame in a horizontal position on the installed crossbars, while its dimensions must correspond to the dimensions of the future foundation.
Height adjustment of supports and installation of vertical structural elements.
Checking the horizontal position of the installed formwork with a level.

In some cases, the surface of the frame is covered with a film to create a waterproofing layer. This will ensure easy dismantling of the formwork and a flat surface of the concrete base.

Violation of the formwork installation technology for strip or monolithic bases may have Negative consequences that the building owner will have to face. A year after commissioning, the first cracks and faults may appear on load-bearing walls, internal partitions and foundations, which will lead to shrinkage and deformation of the entire building structure.

Many experts recommend entrusting the construction of foundation formwork to professional builders who are able to put into practice any technically complex project. But this does not mean that the private developer will not be able to participate in the construction process. The main thing in this matter is compliance with all established rules and recommendations.

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

Materials used

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

Removable formwork can be made from the following building materials:

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

Shield wooden structure removable type

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

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

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

foundation poles with fixed formwork from asbestos-cement pipes

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

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

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

An example of using OSB plywood

Preparation for work

First you need to prepare the following lumber:

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

Non-separable foam fencing

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

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

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

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

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

Removable formwork assembly technology

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

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

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

What tolerances should be observed when assembling the formwork:

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

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

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

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

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

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

In conclusion - the nuances of concreting

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

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

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

Structural engineer with over 8 years experience in construction.
Graduated from East Ukrainian National University. Vladimir Dal with a degree in Electronic Industry Equipment in 2011.

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

Formwork requirements and options for its arrangement

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

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

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

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

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

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

unedged board;
plywood;
chipboard scraps.

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

Frame for strip support structure

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

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

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

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

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

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

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

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

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

In the formwork located above the ground, segments are installed pvc pipes. After pouring the foundation, they will perform the function of ventilation products or serve for laying communications. In the absence of pipes, make technical openings it is possible with the help of wooden boxes, which are subsequently removed from the foundation.

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

The nuances of making formwork for a columnar foundation

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

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

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

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

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

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

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

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

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

Stepped foundation: how to make a frame

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

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

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

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

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

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

Preparing the frame before pouring a monolithic slab

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

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

The formwork for the slab foundation is installed along the perimeter of the future building. Its main task is to maintain the shape of the base until the concrete has completely solidified. You can make a frame from edged boards, but at the same time it is necessary to monitor the absence of cracks at the joints. It is extremely convenient to use inventory shields for these purposes. It is optimal to make formwork from coniferous wood due to the extreme strength of the material. Larch is suitable as spacers and other additional elements.

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

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