The correct formwork for a strip foundation. Making formwork for the foundation with your own hands

Before you start constructing the formwork for strip foundation, let's look at how many types of formwork structures there are.

The quality of the entire construction largely depends on the quality of the work performed on installing the formwork and on the base of the house, that is, on the foundation.

Types of formwork

The design of the formwork, depending on the type, is divided into two groups:

Formwork with removable structure;
Formwork that has a non-removable structure.

In construction without forming monolithic, concrete and iron concrete structure not enough. It doesn’t matter whether it’s a house or a pre-built frame called formwork.

When self-construction, the formwork for the strip foundation is made by hand. The main thing is to choose the type of formwork and correctly carry out all its step-by-step construction.

Let's take a closer look at each of them.

So, the formwork design, as already mentioned, can be removable or not.

The most famous and widely used type of construction. Removable formwork means that after pouring the strip foundation, this type of formwork must be dismantled.

Moreover, in this case it is removed immediately after the poured concrete has set.

Thanks to this type of formwork it is possible to form a foundation with any shape. This applies not only to strip foundations, but also to flights of stairs, monolithic walls and so on.

A removable structure is made using:

Sliced board;
Sheets of plywood, which differs from ordinary plywood in increased moisture resistance;
Steel sheets, which can be made of any material, that is, both steel and aluminum.

But, for the construction of a strip foundation, it is better to use cut boards, moisture-resistant plywood and wooden beams. You can also simplify the formwork construction process by using a special metal frame for attaching cut boards.

At the same time, remember that it is not worth installing formwork using only plywood. It can only be used if the foundation is small in size.

It is better to opt for beams and wooden boards.

It doesn’t matter what material the formwork structure is made of. The main thing is to follow the basic installation rules during construction.

Permanent formwork is considered an advantageous type and is easy to install; moreover, the construction speed in this case is much higher than with a permanent structure.

For its construction, improvised materials are most often used. It can be chipboard, fibreboard, metal carcass or even metal or asbestos pipes having a diameter of 150 to 200 mm. Therefore this is a huge plus.

This formwork is easy to install and does not require large earthworks. No spacers or supports are needed during construction.

Fixed

Types of permanent formwork

Metal

This type is considered the most expensive. It is made from steel sheets thickness from 1 to 2 mm.

Advantages of this type:

good
She takes it easy the required form foundation
A strip or monolithic foundation will fit perfectly on metal formwork
The outer side is easy and simple to process

high price.

Reinforced concrete

This species is considered a relative variant.

Advantages:

Depending on thickness concrete slabs, you can significantly reduce the consumption of concrete itself. At the same time, its strength will not decrease in any way.

The slabs are very heavy
If the slabs are not monolithic and one height is not enough, you will have to make spacers

Expanded polystyrene

This option is considered the most practical. In this case, the formwork is assembled from separate blocks, which are fixed together.

Advantages:

Easy installation
It is possible to give a certain shape
Insulation

Not very low price
Difficulty selecting some elements

Wooden

The material you can use is plywood sheets or boards.

Advantages:

Good price
Availability of material
Easy installation
No need to purchase optional equipment for installation

Due to the different dimensions of the material, it may be necessary to use additional funds for strengthening and connecting formwork

Available materials

What available materials can be used in the construction of formwork?

Pipes
Corrugated sheet
Slate
Any other suitable material, which can provide the desired shape and at the same time prevent cement leakage

Advantages:

Cheap construction

Assembly complexity
Concrete leakage during pouring
Possibly low load carrying capacity
Additional supports may be needed

How to properly make permanent formwork for a foundation with your own hands?

Do-it-yourself permanent formwork for the foundation

It is being built in several stages.

The first stage - excavation work

After calculation required power future formwork, a trench is being dug.

Advice: leave a margin of 1 to 2.5 cm between the soil and the future formwork. This method will simplify installation.

If you decide to use reinforcement, then it must be installed at this stage.

The second stage is the construction of formwork elements

At this stage, the formation of the reinforcement frame occurs, if one is used. In addition, a structure with the selected material is erected.

After these steps, the concrete is poured. In about 25 - 30 days, construction can begin. During this time, the concrete will set and harden and it will be possible to proceed to the next steps.

How to assemble formwork for a strip foundation

The frame of the structure is only rigid, with strong fixation of all elements;
The formwork elements should not have any gaps, all parts of the formwork must fit exactly together;
The formwork must withstand the pressure created concrete mortar.

Material is being prepared. These should be cut boards, 20-45 mm in thickness. Width doesn't matter. But the wider the board, the easier and faster it is to construct the formwork.

A board is knocked down from the prepared board with a height in accordance with the height of the foundation.

The shields are fastened together wooden beams using self-tapping screws, and only the screws are screwed in with their caps from the inside. The slots are additionally lined with slats in accordance with the dimensions of the shield.

The instructions for constructing the formwork themselves look like this:

Preparation of the workplace, that is, digging a trench, preparing building material and tools;
Cut the boards to size according to the size of the foundation;
Manufacturing of shields;
Fastening the formwork, fixing the strength from the outside of the structure;
Test of strength.

Properly completed formwork construction means there is a complete absence of problems during the manufacture of the strip foundation.

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

Removable and non-removable

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

Permanent 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 connected to each other using locks and metal pins. From the blocks, like from a construction set, the required shape is assembled.

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

Fixed polystyrene foam formwork not only gives shape, but also acts as thermal and hydro insulation and also has sound insulating properties. It costs a lot, but it immediately solves many problems, and the time spent on building the foundation is significantly reduced.

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

Requirements for formwork

Since this entire 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, quite serious demands are placed on formwork materials in terms of strength. Besides, collected shields must have a smooth and even inner surface: it forms the walls of the foundation, and then hydraulic and/or thermal insulation materials. It is easier to attach them to flat (at least relatively) surfaces.

Materials for removable structure

Construction organizations have metal structures assembled with studs and bolts. In private construction, formwork panels are made from boards, moisture-resistant plywood and OSB. Used as stops and spacers wooden blocks. No one bothers to make a structure from metal, but it is very expensive and unprofitable for one-time use.

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

With a foundation height of up to 1.5 meters, the formwork board must have a thickness of at least 40 mm. The panels are fastened using bars with a section of 60*40 mm or 80*40 mm. If the height of the foundation is large - it - such bars will not be enough to hold the mass of concrete. At height more than a meter You need to use a block 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 sizes 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 labeled FSF (using formaldehyde glue).

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

OSB is not often used for this purpose, but this option also exists. The thickness is about the same: 18-21 mm. Structurally, it is no different from plywood panels.

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. No special surface quality is required, so you can use low-grade materials, which are usually called “construction materials”.

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

Do-it-yourself formwork for strip foundations

The most voluminous is the formwork for strip foundations. 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 materials for foundation formwork will be very significant. Especially when laying a deep foundation.

Construction of shields and their connection

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

The dimensions of the formwork panels vary and depend on the geometry of the foundation. The height is slightly higher than the height of the foundation; you determine the length of each panel 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 fit exactly according to the markings of the foundation (do not forget to take into account the thickness of the panel).

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

The first and last bars are attached 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 the formwork panels, two or three bars (at the edges and in the middle) are made 20-30 cm longer. They are sharpened and driven into the ground during installation.

Panels made of plywood or OSB are assembled on a frame made of bars. When assembling, it is important to strengthen the corners well. In this design they are the most weakness. They can be strengthened using metal corners.

Do-it-yourself formwork installation

If the shields are made with several elongated bars, they need to be aligned along the cords of stretched markings. The difficulty is that you need to set it in the vertical plane at the same time. For fixation, you can use bars hammered to the mark and aligned vertically. When installing, align the plane of the shields close to these bars. They will be both support and guides.

Since the bottom of the trench or pit must be flat (it is compacted and leveled), it should be easy to position the panels 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 be no gaps, the solution should not leak out. Having achieved a tight fit, take a building level, place it along the shield and hammer in the second edge until the top edge is installed horizontally. You already set the next shield relative to the installed one: they should be on the same level and in the same plane.

If the shields are made without long bars, at the bottom of the pit, along the line marking the tape, a block is fixed that will serve as a stop. The shields are placed close to it, then fixed with the help of bevels and spacers.

Strengthening - braces and stops

In order to prevent the formwork from falling apart under the mass of concrete, it must be secured from the outside and from the inside.

Braces are installed outside. Supports should be placed at least every meter. Special attention you need to pay attention to the corners: here they put stops in both directions. If the height of the shield is more than 2 meters, then one stop belt is not enough. In this case, at least two tiers of spacers are made: upper and lower.

It is also necessary to stabilize the distance between two opposing shields. To do this, use reinforcement studs with a diameter of 8-12 mm, metal gaskets and nuts of the appropriate diameter. The studs are installed in two tiers: at the top and bottom, at a distance of 15-20 cm from the edge.

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

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

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

The assembly proceeds as follows:

Both shields are drilled long drill holes.
A piece of pipe is installed between them.
The pin is threaded through.
Metal plates are installed (they will prevent the pin from tearing the shield material).
The nuts are tightened and tightened.

You need to work together, or better yet, three. One person installs tubes inside between the shields, and one person each to install the studs and tighten the nuts.

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

How to spend less

It takes a lot of material to make formwork for a strip foundation: the panels form the entire strip on both sides. At great depth the consumption is very high. Let's say right away: there is an opportunity to save money. Make only part of the formwork and fill it not all in one day, but in parts. Despite popular belief, this will have almost no effect on the strength of the foundation (if you know the secrets), and you can save a lot. The foundation can be divided either horizontally or vertically.

Filling in layers

For large depths, it is more profitable to fill in parts horizontally (in layers). For example, the required depth is 1.4 m. You can divide the pouring into two or three stages. With two stages, you will need to make shields 0.8-0.85 m high, with three - 50-55 cm.

The order of work is as follows:

When installing the second (and third, if necessary) tier, the shields are slightly placed on the already filled area, covering the tape from the sides. The bottom row of studs usually serves as a stopper and stop. Therefore, when installing them, place them all at the same level from the bottom edge of the boards.

The reinforcement is already tied, the internal studs are cut. All that remains is to install the other tubes, return the studs and install the outer stops and braces. It doesn’t take much time to install the next layer of formwork.

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

Vertical division

The second way is to split the plan vertically. The foundation can be divided into two or three parts. You just need to divide not exactly “along the line”, but space the joints some distance apart.

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

One important detail: when breaking down the house plan into parts, make sure that the “pieces” poured during this period end up at different levels (see in the picture).

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

Fill the collected area with concrete. As in the previous method, after 7 * 8 hours you will need to beat the solution, but on vertical surfaces. Take a hammer and remove the side panel, beat it cement-sand mortar to crushed stone (near the formwork there will most likely be a layer of mortar without filler). As a result, the surface will be chipped, which is good for adhesion to the next portion of the solution.

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

There is one more trick. Everyone says that boards or plywood can then be used in auxiliary work. In practice, it turns out differently: it is impossible to saw wood or plywood soaked in cement. In addition, it becomes dirty and rough, and cleaning and polishing it is also unrealistic: no grain “takes”. So, in order for the wood (and plywood, if not laminated) to remain suitable, front part The shields are covered with thick film. It is secured with a construction stapler and staples. If it gets damaged, replacing it takes very little time. Formwork improved in this way gives an almost perfectly flat foundation surface, which facilitates subsequent work on hydro- and thermal insulation.

A blind area must be built around any building, or rather along its perimeter. This coating protects the building from the destructive effects of melt and sediment waters, which can wash away the soil under the foundation of the house and lead to its subsidence, as well as destroy the foundation structures. This important protective element around the house is made of concrete or asphalt concrete. In order to complete the blind area, you need to build formwork. At first glance, this is not difficult to do, but there are some nuances that must be observed so that the blind area has the correct slope from the walls of the building. In our article we will tell you how to make formwork around the house.

Features and functions of the blind area

Externally, the blind area looks like an ordinary concrete or asphalt path, which is tightly adjacent to the walls of the building and encircles its perimeter. The width of this covering is standardized by SNiP and can be at least 1 m. It is worth remembering that the outer edge of the blind area must protrude beyond the roof overhang by at least 200-300 mm.

Important: the installation of this protective coating is carried out after the façade finishing work has been completed on the house.

The blind area performs several functions at once:

When snow melts or rain falls, precipitation can soak into the soil near the house and cause the destruction of foundation structures or flooding of the basement. Much more precipitation collects around the house, as it actively drains from the roof of the building and its walls.
Thanks to the blind area, the soil around the building does not freeze to such a great depth as in places open soil. Thanks to this, the basement or basement room It gets warmer, which affects the temperature throughout the house.
In addition, frozen soil can also negatively impact foundation structures. This path near the building protects building construction from the forces of frost heaving, which can lead to movement of the foundation and cracking of the walls of the building.
The presence of a neat blind area around the house improves its aesthetic qualities.

The following materials can be used to make this coating:

Concrete is most often used because it is the most available material, which you can prepare yourself. To pour concrete, you need to properly arrange the formwork. That is why in our article we will look at the intricacies of this process.
You can also make a blind area from paving slabs.
Around large public, multi-apartment residential buildings and shopping centers the blind area is made of asphalt.

Rules for formwork and blind areas

Before you get down to work and start making formwork near your house with your own hands, you should remember a few simple rules that will allow you to complete everything at the highest level:

If work will be carried out in hot weather, then the surface of the formwork and concrete (after pouring it) must be periodically moistened with water. Thanks to this, dried wood will not absorb moisture from the concrete, thereby reducing its strength. Wetting and covering the concrete surface in the first few days after pouring will prevent moisture from evaporating too quickly and unevenly, which can lead to cracking of the surface.
In order to correctly determine the width of the blind area, slope, depth and design, it is important to take into account the geological and climatic features of the construction area. By following this rule, you will make a high-quality and durable blind area.
It is better to install this covering around the building before the onset of cold weather.
This protective concrete product should surround the entire house with a continuous strip. That is, there should be no gaps or areas of unprotected soil in the coating. Otherwise, through such uncoated gaps, water will easily seep into the ground and cause destruction of the foundation structures.
An expansion joint must be made between the blind area and the basement of the house, since these structural parts cannot be connected to each other. The width of the temperature gap is 2 cm. The seam must be sealed with sealant to prevent water from leaking into it.
The slope of the coating must be at least 10 ppm from the walls of the house, that is, 1 cm of slope per meter of width.

Necessary materials

unedged or edged board;
panel formwork can be made of particle boards (chipboards);
also suitable for these purposes moisture resistant plywood or oriented strand board (OSB);
some types of formwork that can withstand heavy loads are made of steel and aluminum alloys;
permanent formwork is made of expanded polystyrene reinforced with fiber additives.

To form the blind area, unedged boards or plywood sawn in strips are suitable. Since poured concrete can slightly expand the formwork structures, bars with a cross-section of 30x30 are used as supports and a supporting frame, from which a durable structure is made.

Important: to make a protective coating around the house, removable formwork is usually used, which is dismantled after the concrete has hardened.

It is equally important to correctly determine the material for making the blind area. The covering can be made from compacted crushed stone, but in this case it is necessary to arrange a good drainage from the roof so that the flowing precipitation does not erode the fragile crushed stone covering.

A little better and more durable than crushed stone coverings will be a blind area made of cement mortar, laid on top of compacted crushed stone. This option provides better protection for the foundation of the house from destruction by melt and sediment waters. And it is this option for arranging the blind area that involves the implementation of formwork.

A more expensive and high-quality option for constructing a blind area is laying monolithic concrete slabs or reinforced slab products. But such materials cannot be used on heaving and clay soils, as well as at high groundwater level, since the structure can quickly deform.

In case of execution concrete blind area you will need the following tools and materials for work:

crushed stone, sand and cement;
polyurethane sealant for insulation expansion joints between the covering and the house;
reinforcing mesh;
nails, screws;
roofing felt or plastic film;
edged (unedged) boards or strips of plywood according to the height of the coating being poured;
level, rule;
spatula, bayonet shovel;
container for mixing concrete.

Formwork technology

After you have decided on the material for making the blind area, calculated its width and the required slope, you can start working:

First of all, it is necessary to mark the future covering around the house. To do this, set the calculated distance away from the walls, hammer pegs in the corners and pull on a fishing line or cord.
After this, within the markings along the perimeter of the building, a fertile layer of soil 20 cm thick is removed. The soil at the bottom of the resulting depression is carefully leveled and compacted.
Now we begin to assemble the formwork. First, a frame is made from timber. To do this, bars are fixed at the corners of the depression in the soil with a height slightly higher than the thickness of the coating being made. Next, along the stretched fishing line, the same bars are installed in increments of 50-100 cm. For greater rigidity, the bars are fastened together with longitudinal bars. Wooden elements connected using nails or self-tapping screws.
After this, we attach an unedged or edged board to the timber frame so that the timber is outside structure, that is, on the concrete pouring side there was a continuous, flat surface of the boards. We fasten the boards to the frame with nails.

Attention: to prevent concrete from leaking between the boards, the gaps between adjacent elements should not be more than 0.3 cm.

To prevent the formwork structure from bursting and deforming after pouring the concrete, oblique struts are attached to the frame from the outside. The installation step of such spacers is 50 cm. We attach the spacers to the frame bars using self-tapping screws or nails.
To make it easier to remove the formwork after pouring and hardening of concrete, its inner surface can be covered with dense plastic film or one layer of roofing material. This material will also perform other additional functions:
- will not allow moisture from the concrete to be absorbed into the formwork boards, thereby reducing the strength of the concrete coating;
- if there are significant gaps between the formwork boards (especially when using unedged boards) the coating will prevent concrete from flowing into the cracks.

Along the walls of the house it is necessary to install an edged board with a thickness of 2 cm and a height slightly higher than the height of the covering in this place. There is no need to firmly fix the board, since after the concrete hardens it will be removed. Using this board we will create the necessary temperature gap between the coating and the walls of the house.

Execution of coverage

After the formwork has been assembled, you can begin to make a concrete covering around the house. In this case, adhere to the following sequence of actions:

First, a sand cushion 10 cm high is made. The sand layer is leveled, moistened with water and compacted.
After this, a layer of crushed stone 10-15 cm high is made. It is also carefully compacted. At the same time, you should not forget about the necessary slope of the blind area from the walls of the building, so already at the stage of making the crushed stone cushion, you can take care of creating a slope.
A reinforcing mesh is laid on top of the crushed stone.
Now you can start pouring the concrete solution. You can use a factory mixture or prepare the composition yourself.

Important: in order for the coating to have sufficiently high strength and not crack over time, concrete must be poured at a time, without long breaks in work.

The solution being poured must be thick enough so that it can be laid in a thicker layer against the walls of the house, thereby creating the necessary slope. Correct filling is checked using a level. The surface is leveled according to the rule.
During the hardening process in the first days, the concrete surface is wetted with water and covered with plastic film.
After removing the formwork and removing the boards that are laid along the walls of the house, the resulting temperature gap is filled with polyurethane sealant.

The construction of a building begins with the creation of a foundation. To implement this design, you need to pour concrete into a pre-constructed frame called formwork. It must be as rigid and strong as possible to prevent changes in the shape and size of the foundation strip. We will tell you what types of formwork exist for strip foundations, what material the structure is assembled from, and how to install it correctly.

What is a strip foundation

The most important point when planning the construction of a house is the correct choice of foundation type - the main one structural element building. An incorrectly designed foundation often causes irreparable consequences during the operation of the building.

A strip foundation is a reinforced concrete strip laid around the perimeter of the building. In this case, the tape is laid under the external and interior walls, which helps maintain their shape cross section. The technology for constructing a strip foundation is not particularly complicated. However, compared to the columnar type, the construction of this structure requires more time and building material.

The scope of application of strip foundations is quite extensive. It is often used:

during the construction of buildings with concrete and brick walls with a high density (more than 1300 kg/cub.m.);
for buildings with heavy floors (monolithic or precast reinforced concrete);
when building houses on areas with heterogeneous soil (to evenly distribute the load on the walls);
if the building is planned to have a basement.

Design requirements

Formwork is a supporting structure that is poured with concrete to form the foundation. Therefore, its material and installation diagram must meet the following requirements:

Strength. The walls of the formwork must withstand the pressure of concrete. In this case, a slight uniform deformation is allowed along the entire perimeter of the building.
The ability to withstand temperature and humidity conditions, which is necessary for thorough hardening of the solution. The formwork should be made of chemically neutral material.
No gaps between formwork elements, chips or cracks in the material. If the solution leaks, unwanted voids are formed in the foundation.
Compliance of the dimensions of the structure with the calculated data.

Types of formwork

When pouring a strip foundation, use different types formwork They differ in design, as well as in the material from which they are made.

According to the design, the formwork for a strip foundation can be:

Removable. Before pouring the concrete mixture, the panels are assembled and installed, and after the solution has hardened, they are dismantled;
Fixed. Such formwork remains in the foundation structure, while serving as insulation;
Combined, which is a combination of the two previous types. It is a removable structure with insulation placed inside, which, unlike external formwork, cannot be dismantled.

Often used to fill a strip foundation removable formwork, since this option is more economical. However, non-removable and combined designs Lately are beginning to become increasingly popular.

Material for production

If you decide to make formwork yourself, the right choice will be the manufacture of a frame from lumber. In this case, the structure will be removable. Wood has sufficient strength, is easy to process, and is environmentally friendly pure material and is inexpensive. Using metal or plastic does not make much sense, especially considering that the former is susceptible to corrosion, and the latter does not tolerate low temperatures.

The most popular lumber for assembling formwork for strip foundations is edged board. The product is preferred due to its exact dimensions, which allows you to significantly reduce the volume finishing works for finishing the concrete base. As a result, the foundation is as smooth as possible. Accordingly, the costs of its construction are also reduced. In addition, due to the linear dimensions of the lumber, it is much easier to assemble the formwork with your own hands, including a set of wall boards required height. In addition, the material can be used repeatedly, which makes it as convenient and cost-effective as possible.

Helpful advice: Use boards that are unsuitable for formwork assembly to create sheathing for the roof or for lining subfloors.

As for the type of wood for making the frame for the foundation, it all depends on the expected load of the concrete solution being poured. The strongest lumber is made from hardwood. Such boards are used to make formwork for foundations in both civil and industrial construction. If extremely heavy loads are not expected, then you can use lumber from coniferous species trees.

Preparing the area

Before proceeding to the construction of the foundation, geotechnical surveys should be carried out in order to determine the type of soil, as well as the depth of the future foundation. In this matter, it is better to consult with the department staff capital construction your region. Be sure to find out the depth of soil freezing in your area and the depth of groundwater. Thus, the foundation should lie 0.3 m below the freezing depth and should not reach the groundwater level.

In order for the foundation and the building itself to last for many years, the concrete base must be designed in accordance with all rules and regulations. Therefore, here it is advisable to use the services of a qualified specialist who will help to competently carry out necessary calculations. Do not attempt to design a foundation yourself without having basic knowledge in the field. This can cause unpleasant consequences, such as the formation of cracks in the walls, deformation of the base, etc.

Before designing the foundation, you need to determine the size of the building, the location and thickness of the internal and load-bearing walls using thermotechnical calculation enclosing structures. The fact is that the wider and heavier the walls, the more powerful the foundation itself should be. Having decided on these parameters, you can move on to laying out the foundation, which begins with marking the territory.

Site marking

First you need to clear the area of debris, remove the plant layer and level the surface. Afterwards, two U-shaped structures are installed on the site, which consist of two pegs driven into the ground with a horizontal rail attached to them. These structures, together with the rope stretched over them, mark the outer edge of one of the foundation walls. Next, a second rope with the same U-shaped structure is pulled perpendicular to the first. The marking of all other external boundaries is carried out in a similar way. concrete base.

The next stage involves marking the inner sides of the walls. The ropes should be pulled parallel to those that define the outer edges of the foundation. In this case, the distance between them should correspond to the width of the walls of the future foundation. After this, it is necessary to take measurements of all angles - they must be straight. If initially it was not possible to make a perfect rectangle, then pull the ropes diagonally and achieve their equality. This way you will get all angles at 90 degrees.

Following the designation of the location of the main contour, the internal walls of the foundation are marked, which will become the basis for the internal partitions of the building.

Excavation

The markings are ready and now you can begin to develop the soil. Trenches should be dug strictly along taut ropes. As noted earlier, the depth of laying the foundation is selected depending on the depth of soil freezing. At the same time, the height of the trenches under the internal walls of a heated house does not depend on this parameter and is often 0.5 m.

It is worth noting several nuances about the cross-sectional shape of the trench for a strip foundation. If the depth of laying the concrete base is less than 1 m, then the walls can be made vertical. In the case of deeper excavation of the soil, the walls must be made with a slight slope.

If it is planned to build a cellar, then a foundation pit is dug for it at the same stage. To reduce the volume of excavation work, it can be placed in any of the corners of the future building, along two walls of the foundation.

Helpful advice: The best place The south side of the house will be used for the cellar.

Material calculation, necessary tools

When purchasing lumber for formwork, you need to remember that the boards will be located on both sides of the trench. In addition, the number of required planks also depends on the depth of the foundation and the width of the foundation itself. wooden product. After all, the boards are knocked together with beams into shields, the height of which should be slightly greater than the depth of the trench. Therefore, to determine the number of boards, it is necessary to measure the total length of the trench, multiply it by two, divide by the length of one wooden product and multiply by the ratio of the height of the trench to the width of the board. As for the bars, their spacing should be no more than 40 cm. Depending on this, the number of necessary beams. So, for work you will need the following materials:

board (humidity – no more than 22%; thickness – 25–50 mm; width – 200–300 mm);
beams (section 40*40 mm; length equal to the depth of the trench);
sand;
nails, screws;
tow;
thin slats.

To install formwork for a strip foundation, you will need the following tools:

wood saw, jigsaw or grinder;
drill, hammer;
yardstick;
building level.

After execution preparatory work and procurement of materials, we proceed to installing formwork for the strip foundation. The procedure is as follows:

Laying a sand cushion. Considering that the weight of the concrete structure is very large, a layer of sand must be laid on the ground to distribute it evenly. The height of the compacted and water-moistened cushion is 150 mm. On a flat and solid base, you can begin installing the formwork.
Installation of guide boards. This procedure must be carried out strictly along the line, so stretch the fishing line along the entire length of the trench in advance. Then install the guide boards according to the markings, securing them with pegs and vertical bars on the inside. On the outside, in addition to the pegs, install additional stops. After this, check the correct installation of the guide elements using a tape measure and a building level.
Installation of panels. We attach the boards to the beams and connect them with nails. The procedure is performed from bottom to top.
After assembling the shields, we install spacers. As the latter, you can also use bars. As a result of installing the spacers, the panels should take their final position, that is, the formwork will take the shape of the walls of the future foundation.

Properly executed formwork for a strip foundation is the key to the strength and durability of the building

Important: To seal the resulting cracks, use tow or thin slats.

This concludes the procedure for installing formwork under a strip foundation. But there are a few more nuances that should be performed if necessary.

Nuances of work

If the height of the formwork exceeds one and a half meters, then a window must be made at the bottom of the trench to remove industrial waste, which in this case can be very large.
Layer waterproofing material fits on last stage installation of formwork, before reinforcement.
If it is expected reuse collapsible structure, then an oily substance must be applied to its inner surface to minimize adhesion to concrete.

The right strip foundation for a house

Remember, well-executed formwork is a guarantee of ensuring the correct shape of the concrete base of the building. Therefore, take this work very seriously and follow the technology for constructing a frame for a strip foundation.

We make formwork for strip foundations with our own hands - required material, calculation, device, etc. with video

Types of formwork for strip foundations. Selection of material, preparatory work and device wooden structure.

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

The panel base can be made of plastic, metal, plywood or boards. At the right approach Even a private developer can install, fix and dismantle it.

Why do we need formwork and its types?

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

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

Practical and reliable materials are used for construction, providing additional strength and durability of the base.

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

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

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

Materials for creating permanent formwork

The installation of permanent formwork is made from the following materials: wood, metal, reinforced concrete and polystyrene foam boards.

Made of wood

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

Made of 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 the construction of foundations of varying complexity and configuration due to the flexibility of the metal;
provides reliable waterproofing protection of the foundation;
suitable for the construction of strip and monolithic foundations;
allows you to perform decorative finishing a foundation raised above the ground.

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

Made of reinforced concrete

Expensive and labor-intensive option, for the manufacture of which reinforced concrete slabs are used.

Significant advantages of the design: the ability to reduce concrete mix consumption, increased strength and durability.

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

Made from polystyrene foam

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

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

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

Materials for the construction of collapsible formwork

Collapsible formwork can be wooden or metal. For the manufacture of wooden structures, laminated plywood and wooden boards. It is preferable to use products made from spruce, pine, linden and aspen.

Formwork panels must meet basic requirements: be strong, wear-resistant and resistant to negative impact moisture. For construction wooden frame No specialized equipment is required, and all work can be done independently.

The metal structure is made from plates with a polished surface. A similar frame is suitable for constructing the foundations of private houses. Metal base provides reliable protection from leakage of concrete mixture at the joints of the plates.

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

How to calculate the formwork design

To carry out calculations, the type of material chosen for the formwork around the house is taken into account. An example is given for calculating a wooden structure.

Used for work standard board 600 cm long, 10 to 15 cm wide, 2.5 cm thick.

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

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

M = L/L × 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 rods.

Construction of formwork using the example of a strip foundation

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

Carrying out excavation work

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

Important! To simplify installation, a technological gap of 2.5 cm must be made between the walls of the structure and the trench.

A cushion of sand and small crushed stone is placed at the bottom to reduce the consumption of concrete mixture. 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 completing the preparatory work, the frame is filled with concrete mixture to the level. And if the filling technology has been followed, after a month you can begin the main construction work.

To fill the foundation, concrete M 150 and 200 is used; if the groundwater level is high, 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.

A shield with a height equal to the height of the base is assembled from the prepared material.

The individual parts of the shield are fixed together with bars on self-tapping screws, the caps should be located on the inside. The cracks and voids become clogged wooden slats according to the size of the finished shield.

Assembling 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 strengthening of the formwork. To do this, you can use channels, longitudinal beams or I-beams.
Installation of the frame in a horizontal position on installed crossbars, and its dimensions must correspond to the dimensions of the future foundation.
Adjustment of supports in height 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 film to create a waterproofing layer. This will ensure easy dismantling of the formwork and a smooth surface of the concrete base.

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

Many experts recommend entrusting the construction of formwork for the foundation professional builders who are able to practically implement any technically complex project. But this does not mean that a 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.