Formwork for a plinth made of boards. How to make formwork for the foundation. Material calculation, necessary tools

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

Types of structures

The construction of an auxiliary structure made of wood, metal or other materials involves the use of rigid structures interconnected and capable of supporting the mass of concrete, but some types also provide excellent thermal insulation characteristics Houses. For arranging formworks they are used various types materials, let’s stop and first look at the types of formwork for strip foundation:

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

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

Design elements and material

The formwork consists of several main elements:

1. Wooden boards of rectangular or square shape of any size.
2. Clamps for vertical placement of panels.
3. Horizontal internal bushings, they are used to provide the required internal width of the tape and prevent the expansion of the panels
4. Waterproofing. It prevents liquid from leaking out of the formwork, and also ensures a faster drying speed of the solution.

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

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

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

Installation of wooden formwork

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

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

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

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

How to install formwork for strip foundations on unstable soil

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

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

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

How to arrange a combined formwork for a strip foundation

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

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

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

The role of permanent formwork for strip foundations

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

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

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

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 the type of foundation - the main structural element of the 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 the shape of their 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, removable formwork is used to fill a strip foundation, since this option is more economical. However, non-removable and combined designs have recently begun to enjoy increasing popularity.

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, is an environmentally friendly 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 precise dimensions, which allows for a significant reduction in 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 the installation of boards of walls of the 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 lumber from coniferous trees can be used.

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 staff of the capital construction department of 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, it is advisable to use the services of a qualified specialist who will help you correctly make the 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 thermal engineering calculations of the 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. All other external boundaries of the concrete base are marked in a similar manner.

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.

Earthworks

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 tip: 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 wooden product itself. 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 bars is determined. 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;
• measuring tape;
• building level.

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

1. 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.
2. 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.
3. Installation of panels. We attach the boards to the beams and connect them with nails. The procedure is performed from bottom to top.
4. 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 at the bottom of the trench it is necessary to make a window to remove industrial waste, which in this case can be a lot.
• A layer of waterproofing material is laid on last stage installation of formwork, before reinforcement.
• If a collapsible structure is intended to be reused, 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 of 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. Choice of material preparatory work and installation of a wooden structure.

When constructing monolithic reinforced concrete structures, it is very important to correctly install the formwork. The strength characteristics and appearance future construction.

Therefore, this part of the work needs to be given special attention. You can make formwork yourself from scrap materials (boards, plywood), or you can use factory-made kits.

Basic rules for installing formwork

Prefabricated formwork for creating monolithic reinforced concrete structures consists of panels or blocks connected by fasteners and reinforced with supports. The nuances of assembly depend on the type of formwork and the material of its manufacture.

But there is also general rules installation Therefore, it is worth getting acquainted with the peculiarities of the work. When performing installation work, the following rules must be observed:

• Before starting installation, it is important to thoroughly clean the construction site; it is necessary to remove debris, snow, ice, etc.;
• Leveling the site is carried out by cutting the soil. Adding soil is strictly prohibited;
• elements are installed starting from the corner. Corner elements are a kind of beacons along which the main structure is aligned;
• when installing elements, it is necessary to pay attention to the verticality and horizontality of the elements;
• before pouring the solution, you must ensure that the structure is tight; all joints must be sealed;

Advice! Particular attention must be paid to checking the tightness of formwork forms assembled from boards. In this case, not only the joints, but also the shields themselves may become leaky. Large cracks are filled using slats, and small cracks are filled with tow.

• Before installation, the inside of the panels should be coated with a special compound that will prevent the concrete mixture from sticking to the formwork.

Installation instructions for formwork

Above are general instructions for installing formwork of any type. But when assembling forms for foundations, walls and ceilings, there are special nuances that you definitely need to know about.

Foundation

When installing formwork for strip foundations, panels made of boards or plywood are often used. It is these elements that bear the main load exerted by the concrete solution.

The strength and service life of the entire building depends on how correctly the formwork for the foundation is assembled, since the foundation is its basis. Before starting the construction of the foundation, it is necessary to carry out a number of preparatory measures.

At the initial stage, it is necessary to familiarize yourself with the requirements of the project, in addition, it is necessary to take into account the climate. It is advisable to carry out work at positive temperatures, that is, in late spring or summer, when frosts are unlikely.

If you plan to build the most common version of formwork from boards, then the procedure should be as follows:

• On the prepared site, the corners of the foundation to be poured are marked. The remaining elements will be attached to these bars;
• the distance between the bars is measured and, depending on the results obtained, boards are assembled from the boards;
• they knock together the shields using bars, which should remain on the outside of the forms;

• shields are made in duplicate, since these elements are installed opposite each other;
• The shields are sealed, in addition, they are processed inner surface, it should be as smooth as possible;

• the shields are installed between the corner bars, securely fastening the elements to each other. From the outside they are strengthened by installing slopes. The spacing of these elements depends on the thickness of the foundation and ranges from 0.5 to 1 meter. Inside, the boards are fastened by installing ties.

Advice! Screeds can be permanent or removable. If the second option is used, then the clamping elements are installed inside plastic tubes. During dismantling, the tightening screws are removed, and the tubes remain inside the monolithic structure. Holes on the inside and outside are sealed with mortar.

• The inside of the assembled formwork forms is lined with thick polyethylene film or roofing felt, and the waterproofing material is secured with self-tapping screws. This will help prevent the solution from leaking out through the cracks. It is recommended to pour crushed stone or sand at the bottom of the molds so that the liquid from the solution does not absorb into the soil too quickly;

• Before pouring the solution, you must once again check the horizontality and verticality of the installed elements.

Stan

When assembling formwork for erecting walls, the installation technology differs little from the technology for assembling foundation forms. Two types of wall formwork are used:

• small-panel - assembled from relatively small panels of laminated plywood or plastic. This equipment is suitable for the construction of small objects, for example, low-rise buildings;
• large-panel – characterized by the presence of large-area shields. Used for the construction of large objects, for example, multi-storey buildings.

The distance between the panels depends on the thickness of the walls. When assembling forms, you should take into account the need to leave openings for windows and doors. The panels are dismantled after the concrete solution has completely hardened.

Advice! To make it easier to carry out subsequent wall finishing, it is necessary to use panels with ideal flat surface. For example, from laminated plywood.

Floors

When installing floor formwork, horizontal forms are assembled at height. The installation option depends on the planned ceiling height. Most often, structures on telescopic racks are used; they can be used if the ceiling height does not exceed 4.5 meters.

Tripods are mounted at the bottom of the racks for stability, and universal forks are attached to the top. These forks are used to secure the support beams, on top of which the cross beams are laid.

The horizontal part of the form, the deck, is laid on top of the beams. And along its perimeter, vertical sides are installed, their height depends on the design thickness of the floors.

Fixed

Installation of permanent formwork is simpler than assembling adjustable forms. To assemble permanent formwork, special blocks of foamed polystyrene are produced. Other material options are used much less frequently - reinforced concrete, wood concrete, metal.

Expanded polystyrene blocks are installed on a pre-prepared base. If this is wall formwork, then they are placed on a ready-made foundation, covered with a layer of waterproofing. The blocks are placed on top of reinforcement bars protruding from the foundation. The lateral connection of adjacent blocks occurs due to the fastenings available on them.

So, installation work formwork assembly is an extremely important stage in the construction of a building. Not only the appearance of the cast structure, but also its strength characteristics directly depends on the quality of the work performed. Therefore, installation must be carried out with care special attention and carefully comply with all technological requirements.

The foundation is poured into pre-arranged formwork. This structure must be installed in compliance with a number of established rules and regulations. Check out the features existing varieties formworks, the procedure for their calculation, instructions for the construction of the most common structures and get to work.

Of course, before erecting the formwork, you need to decide on the type of foundation that you will build. We recommend reading the following materials on our portal:

— first of all, we invite you to familiarize yourself with the step-by-step technology for constructing a strip foundation. In which, among other things, it talks about the method of constructing wooden formwork.

Materials for the manufacture of formwork

Foundation formwork can be made from different materials.

Metal

Universal and most expensive formwork option. To assemble the structure, steel sheets with a thickness of 1-2 mm are used.

Metal formwork is perfect for arranging strip and monolithic foundation structures. it will be possible to weld directly to the formwork sheets, which will help increase the rigidity of the foundation.

The main advantage of the metal is the simplicity and convenience of its processing - the sheets can be bent to the required shape of the concrete base without any problems.

The main disadvantage of metal formwork is its very high cost when compared with other existing options.

Reinforced concrete

A relatively expensive type of formwork.

This formwork is constructed from concrete slabs. Depending on the thickness of the slabs used, when pouring the foundation it will be possible to slightly reduce the consumption of concrete mixture, which will save on the construction of the foundation without compromising the strength and other important characteristics of the structure.

Among the disadvantages, it is necessary to note the large weight of the slabs, which requires the use of special equipment for their installation.

Moreover, if the formwork is made from ready-made slabs and the dimensions of one element are not enough, you will have to install additional spacers, which will also not have the best effect on the final cost of the structure.

Expanded polystyrene

A very high quality and practical option. The formwork is assembled from ready-made individual polystyrene foam blocks. The formwork elements are extremely easy to install. They can be processed to the required shape without any problems.

The main disadvantages are difficulties at the stage of selecting certain structural elements (usually roundings and corners) and relatively high cost.

Available materials

During the process of arranging the formwork, make sure that its walls are installed exclusively vertically.

It is important that there are no large gaps in the structure. Seal gaps with suitable materials at hand. In this case, a gap with a width of more than 4-5 mm is considered large - such a gap will be quite enough for the leakage of concrete mortar.

Additionally, to prevent minor leaks of the solution, you can attach plastic film to the inner surface of the formwork walls.

It is recommended to dismantle removable formwork only after the foundation has reached the required strength. On average, this takes 3-5 weeks. The gaps left after dismantling the formwork are usually filled with soil. In some situations they are filled with concrete or cement

Happy work!

Prices for various types of construction boards

Construction boards

Video - DIY foundation formwork

The shape of the future foundation is determined by the formwork. Installation of formwork for strip foundations will be the main topic of this article. From it you will learn:

• how to build a foundation with your own hands;
• how the formwork is constructed;
• how to assemble a reinforcement cage.

The advantage of a strip foundation is that its installation does not require the use of heavy construction equipment. The closed contour of the strip foundation, reinforced with a metal structure, will have to withstand the weight of the heavy material from which your future home will be built. The thrifty owner will be pleased with the price-quality ratio.

Before installing the formwork for a strip foundation, geotechnical surveys should be carried out. To do this, you need to contact your local capital construction department, they will help you find out important information about your soil. Please note that the future foundation

1. cannot be located below the upper groundwater level;
2. 0.3 m should be below the freezing level.

Despite the fact that it is quite simple to make formwork for a strip foundation with your own hands, do not risk designing the foundation yourself. In case of unprofessional actions, you may find cracks in the constructed walls, encounter deformation of the base and other troubles.

When designing a strip foundation, a number of features should be taken into account

• dimensions of the future building;
• number of internal partitions;
• number of load-bearing walls and their sizes.

Keep in mind that the thicker the walls, the more they weigh, and therefore the foundation will be more impressive.

Construction can begin only when the issue regarding the size and geometry of the foundation has been resolved. The first thing to do is to apply markings in the place intended for the foundation.

We mark the area for the strip foundation.

Before you start marking, you should remove vegetation from the entire perimeter of the area allocated for future construction. After this, we will mark the outer edges of one of the outer walls of the foundation with two U-shaped structures, consisting of two pegs driven vertically into the ground and one block nailed on top of the pegs. Stretch a rope between these structures.

Other external sides of the foundation are designated in a similar way.

The perimeter has been marked, it's time to tackle the internal partitions. The ropes should be pulled parallel to the threads marking the edge of the foundation. Observe the angles, they should all be 90 degrees. The distance between the threads should be equal to the width of the walls of the future foundation.

Now it’s time to take up the shovel - we will dig trenches along the lines marked with ropes. The width of the dug trenches must exceed the width of the walls of the future foundation; compliance with this condition will allow us to construct the strip foundation formwork according to the rules.

The trench should go deep to the amount made up of compacted layers of sand and crushed stone, 15 cm each, and the depth of the foundation.

We build formwork

The formwork for the strip foundation is built after the compaction procedure using a vibrating plate of the above-mentioned layers. It is recommended to moisten the sand with water - then it will be possible to achieve more dense shrinkage.

Standard planed boards with a thickness of 25 mm are considered the best material for formwork. It is this thickness that will allow the boards to withstand the pressure of concrete. Give preference to boards made from coniferous trees - they are characterized by natural strength and elasticity.

We will also need:

• wooden blocks 50*50 mm - we will use them for spacers;
• for fixing the shields - pegs.

When assembling the formwork, it is recommended to use edged boards; they will allow you to avoid unnecessary gaps. The width of the boards should be 15 cm. Select raw wood before work. Dry boards take moisture from the concrete, thereby disrupting its hardening process and reducing its strength.

Check the boards for any gaps - a gap of more than 3 mm may allow cement mortar. Small cracks will not cause significant damage - they will disappear on their own after the wood is saturated with moisture.

1. put together from wooden planks panels, the width of which should be equal to the sum of the depth of the trench and the foundation base;
2. drive vertical wedges in 1 m increments;
3. screw the pre-prepared shields to the wedges using self-tapping screws;
4. strengthen the resulting structure with spacers and crossbars;
5. make sure that the shields are strictly level;
6. measure the diagonals - the measurement results should coincide.

If gaps of more than 3 mm have formed between the boards, fill them with slats or caulk them with tow. Pay due attention to fixing the formwork; if you do not pay due attention to this now, in the future you will experience deformation of the foundation, which can lead to the inability to withstand the design loads.

Don’t be lazy to install additional supports; remember that the foundation walls must be perfectly smooth.

If you plan to use the shields multiple times, pay due attention to their cleanliness. Otherwise, they will have to be cleaned for a long time before subsequent use.

If you use nails instead of self-tapping screws, make sure that the caps are on the inside of the formwork, and the points are facing outward, which must subsequently be bent down.

When the installation of formwork for strip foundations is completed, we will begin laying roofing felt at the bottom of the trench. By doing this, you will avoid subsequent absorption of moisture from the concrete. To maintain the proper humidity regime, attach a durable film or, if possible, roofing felt to the knocked together panels.

Reinforcement cage

Now it’s time for reinforcement cages; they are needed to give the foundation reliability. They should be assembled from reinforcement of the diameter specified in the foundation design. It is strictly prohibited to use welding to install the reinforcement cage. All connections must be made directly in the formwork using tying wire.

Make sure that there is about 5 cm on each side from the frame to the walls of the formwork. This way, you will be able to protect the reinforcement from contact with excess moisture that can seep through the soil. Place at least three reinforcements in the longitudinal direction, the laying floor spacing is no more than 250 mm.

It is necessary to lay openings where ventilation and communications will lie. Lay between the shields asbestos cement pipes, they will allow the formation of through holes in the future foundation. The installation of the formwork for the strip foundation can be considered complete; it’s time to pour concrete into our structure.

Pour the mixture into the formwork

The mixture is poured along the entire perimeter of the foundation at once. Pouring in layers will result in insufficient concrete strength. Of course, it would be optimal to order the mixture at the factory - they will bring you the required amount of concrete, prepared in full compliance with the required proportions.

If for some reason you cannot do this, you will have to make do with your own resources and a concrete mixer.

All components must not contain clay or other foreign elements. Of course, the water must also be clean. The optimal grade of cement is considered to be 500; below 400 cannot be taken. The higher the grade of cement, the stronger the concrete will be. In addition, its hardening time is significantly shorter.

Please note that the resulting mixture should be plastic. For orientation, for a cube of concrete you have to spend five bags of cement, ten bags of sand, thirty bags of crushed stone. Next, the mixture poured into the formwork must be compacted. For this manipulation you will have to rent a deep vibrator from a construction company.

Do not remove the boards until the mixture is completely dry. After you have poured the foundation, it should take about two weeks, then you can remove the panels. Concrete gains the required strength after a calendar month.

In hot weather, concrete surface it is necessary to moisten from time to time - this will help you avoid the formation of a crust that prevents the deeper layers of the foundation from hardening. If the weather is rainy, cover the foundation with film, otherwise it may get wet.

Although making formwork for a strip foundation is a rather labor-intensive process, it can be done.