Do-it-yourself formwork from boards. Do-it-yourself installation of removable formwork. Video: applying lubricant with a spray machine
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. With 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 concrete base. In addition, it improves the thermal and sound insulation characteristics of the foundation. Expanded polystyrene slabs and hollow concrete blocks are used for the arrangement. Such materials allow you to create a foundation suitable size and configurations. 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 expensive installation equipment. For its manufacture, plywood is used in sheets and edged board. 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 the high price and complexity of installation work.
Made of reinforced concrete
An 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 not required specialized equipment, and all the 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, availability 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.
For the work, a standard board is used, 600 cm long, 10 to 15 cm wide, and 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 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 reinforcing bars.
Assembly of structural elements
The next stage is the installation of formwork for the strip foundation from the selected material with additional reinforcement of the structure.
After completion of the preparatory work, the frame is poured concrete mixture by 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, at high groundwater level (level groundwater) 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 with 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 monolithic foundation is performed 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. For 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 technology for installing formwork 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 breaks may appear on the load-bearing walls, internal partitions and foundation, which will lead to shrinkage and deformation of the entire building structure.
Many experts recommend entrusting the construction of foundation formwork to professional builders who are able to 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.
Formwork often becomes a key part of the foundation and it is worth thinking about its construction even before the construction of the base of the structure. Some people believe that making formwork for the foundation is difficult and it is necessary to contact specialists.
In fact, the installation process is quite simple, but it has its own characteristics. If you do not take into account the nuances during the work process, you can make a lot of mistakes. It is best to read the instructions for installing the formwork before starting work. There are quite a few of these, and they will significantly reduce your work time.
Due to the fact that the strip foundation has a number of features and differs from the classic options, formwork for it will also not be easy. In this situation, it is necessary to stock up on boards with a thickness of at least 50 mm. At the same time, you must understand that the height of the entire structure can be 2 meters or more.
At the same time, at the beginning of installation, it is always the guide boards that are taken. In fact, they will become the frame for the formwork and will help you start this work correctly. By the way, if you decide to build formwork more than 2 meters high, then instead regular boards It’s better to take shield materials. Take the highest quality ones and if you want the formwork to last as long as possible, then the width of the shield should be equal to the height.
Photo illustration: how to make formwork for a strip foundation
Every builder knows that there should be no gaps in the formwork. Nevertheless, such unpleasant errors regularly arise during the formwork construction process. That is why they should be sealed in advance. For this, ordinary tow is used, and if we are talking about really large cracks, then it is better to take slats for masking and put them on top.
During the construction process, various problems can arise and are often associated with the wrong choice of formwork type. Most people choose the removable option, but if your area has very cold winters, then this may not be the best option. good decision. Also, before starting construction, pay attention to the foundation; the choice of materials for formwork will depend on it. And do not forget that it must be removed on time, because the strength of the structure directly depends on this.
Video instructions on how to make formwork for a strip foundation
How to make round formwork for a foundation
Round option formwork in Lately became very popular even despite some difficulties in the process of its construction.
If you decide to take on this matter yourself, then you should immediately mark the place with special pegs. Then boards will be laid close to the stakes and the sides of the structure will be secured using ordinary nails. If the height is quite large, then you will also have to do installation work at the highest point.
To strengthen the structure, cladding boards are used. This is relevant in situations where the round formwork is filled with concrete on top. In principle, you can do without it, in this situation it all depends on you. Installation takes on average 2-3 days. During this time, it is quite possible to even make a plank covering and seal all the seams that spoil the appearance.
Making removable formwork for the foundation
Making the classic version of formwork is quite simple, you just need to put in a little effort and be patient.
Initially, guide boards are taken and stakes are driven into the ground. Next we work with the foundation, it is necessary to place shields on one side. They must be placed vertically and done with braces, which will help achieve increased reliability. It is very important to observe the dimensions of the foundation, because then the shields will be installed on the other side of it.
The final stage of installation will be fastening the shields using special clamps. The interval between fasteners should be strictly 0.5-1 meter. This is the only way the formwork will not open during the pouring of concrete and will retain its strength. You can also install pegs or some kind of spacers outside for additional fastening. In the end, you will have removable formwork.
How to make formwork from boards
On this moment Wood is the most popular choice for formwork construction. Quality boards cannot replace any other materials. We have already described above how to do it wooden formwork and key aspects of working with boards.
Now it’s worth noting why it’s worth choosing such natural material:
But against the backdrop of quite loud advantages, there are also minor disadvantages:
- It is difficult to make round formwork from wood;
- If you pour a lot of mortar inside the structure, you will have to think about supports;
- In the process of leveling the structure, you may encounter the problem that the board is nailed incorrectly and this flaw is very difficult to correct.
In principle, one could also say that wooden formwork will cost you more than any other, but the cost of the material is completely justified. This is exactly the case when it is better to overpay in advance so as not to encounter problems in the future.
Video: DIY wooden formwork
How to make formwork for the foundation of a bathhouse
The procedure is similar to installing formwork under the foundation. However, it is worth considering that you will have to work with a bathhouse and this has its own characteristics.
First, stakes are driven in outside the structure. It must be remembered that this is done strictly vertically and best along the cords. Your task is to maintain maximum accuracy, otherwise you will have to redo absolutely everything. In situations where builders are not careful about this task, the originally planned size of the structure often changes. That's why be precise from the very beginning.
Formwork for the foundation of a bathhouse: start of work Once the stakes have appeared in the ground, you can attach boards to them. You should start from top to bottom. Installing at the top of the board is quite easy and won't pose much of a problem. When it comes to the lower ones, which are located right next to the foundation, you will have to take a pry bar and press the boards tightly against each other.
If all the boards are securely installed, then you can do whatever you want with them. Often at this stage the boards are trimmed to achieve aesthetic appeal.
Finally, you will need to think about the strength of the entire structure. First, special supports are placed under each stake, then under the upper planks. You need to understand that the next step will be pouring concrete and you need to do everything possible to ensure that the structure does not simply fall apart. Nevertheless, the upper strips should be fastened as carefully as possible.
Video: Homemade formwork for the foundation of a bathhouse
Next, you will have to install a reinforcing frame that will affect them. While pouring the concrete itself, inspect the places where the cushion comes into contact with the boards. There may be small gaps between the ground and the structure. It is necessary to get rid of them and suitable option will be the use of soil. Fill the cracks and do your best to ensure that there are no gaps at all. At this point, the construction of the formwork for the bathhouse can be considered complete.
Formwork for the foundation of a bathhouse - the result Design and manufacturing technology of formwork for columnar foundations
This formwork is usually made from boards, so you need to take them first. You can install it in any place you need.
The design will be a rectangle with a fixed internal size and height, which you can choose yourself. Fastening the boards can be easily done using ordinary self-tapping screws. They must be driven directly into the end of the board. As soon as this stage is completed, it would be a good idea to check the verticals and horizontals of the structure.
Next, a columnar support is made, where each column is lined up with cords that you will have to tighten in advance. Now you can dig a hole and install the finished rectangle in it. Outwardly, it very much resembles a box, which is why most builders call it that. When the structure is in the place you want, you will have to lightly fill it with soil from the outside. In fact, this procedure is identical to that described for the construction of a strip foundation. The installation technologies for both formwork options are almost identical.
Once the installation is complete, you can remove all castoffs. Now you will only need them to check zero level in the bath. In principle, 1-2 cast-offs will be enough to solve this problem. As you can see, there is nothing complicated in constructing formwork of various types, so you can try it even at home!
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 correct forms and reduces the consumption of concrete solution. Plus, it can be removed, moved to another construction site and used more than once.
Types of structures
The construction of an auxiliary structure made of wood, metal or other materials involves the use of rigid structures interconnected and capable of supporting the mass of concrete, but some types also provide excellent thermal insulation characteristics of the house. For arranging formworks they are used different kinds materials, let’s stop and first look at the types of formwork for strip foundations:
- 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 quantity necessary materials done on the spot when necessary. After use, you can remove and reapply. You can make it yourself from wood.
- Fixed. This is a disposable design, made from polystyrene foam, and serves as the main thermal insulation layer. Needed when the building area is limited. Thanks to reinforcement with special supports and spacers, the foam plastic can withstand heavy loads, does not deform, and do-it-yourself assembly is done like a construction set from factory elements. It cannot be removed; it is necessary to calculate the panels for each specific construction. Various materials can be used, but most often polymer products.
- Combined. Here, wood is simultaneously used as the outer layer of formwork, and polystyrene foam is used as insulation. After pouring the foundation, the outer part of the structure can be removed, while the insulation remains embedded in the concrete.
Several years ago, builders preferred to use removable formwork for strip foundations, since it is reusable and can be rented at affordable price. Moreover, many companies and small firms produce such formwork with their own hands and then rent it out at an affordable price. It is worth noting that it is difficult to erect formwork correctly, according to all standards, given specifications materials used, as well as the possibility of expanding the sole if necessary.
Design elements and material
The formwork consists of several main elements:
- Wooden boards of rectangular or square shape of any size.
- Clamps for vertical placement of panels.
- Horizontal internal bushings, they are used to ensure the required internal width of the tape and prevent the expansion of the panels
- Waterproofing. It prevents liquid from leaking out of the formwork, and also ensures a faster drying speed of the solution.
Formwork for strip foundations can be made from wood. The most 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 foam are artificial thermal insulation, the calculation is done right on the spot, and the panels can be cut to your size. It is also easy to construct a plinth on such a ready-made, flat surface.
Installation of wooden formwork
To produce wooden formwork, it is better to use edged board or wide plywood. Ready-made shields of fixed sizes are made from these materials, then grooves are made on the external contours to connect the shields to each other. All joints are treated with waterproof sealant or polyurethane foam. The moisture content of the wood should not be high, the thickness of the cracks should be up to 2 mm. The height of the shields should not exceed 5-7 cm above the level of the foundation strip. Installing the formwork is quite simple, you can do it yourself:
- First, the construction site is prepared.
- The dimensions of the formwork are calculated, the appropriate materials are selected and the structures are assembled.
- Then the shields are installed on the outside and reinforced with braces, where the main fixation will be the soil or reinforced pillars. The braces are nailed to the boards and installed at intervals of at least 1 m from one another, the minimum permissible distance is 30 cm for thick bases.
- Jumpers of a fixed length are secured with nails or corners - this is the maximum allowable width of the foundation strip.
- The inner part of the formwork is installed in the same way and tightened with clamps, nails or other fasteners.
- The vertical and horizontal position of all shields is checked, the permissible slope angle is no more than 3 degrees, and they must not have deflections or bends. The condition of the surface of the boards should be regulated by slats, a level or a construction hydraulic level. Local deviations for plywood should not be 2 mm, and for boards - up to 3 mm.
- After pouring the concrete solution, the formwork can be removed and reused, and the base can be constructed on a flat outer surface.
The correct positioning of the formwork panels can also be controlled using casting threads and wires, as well as fixed type fasteners. In the case of using permanent formwork, it is advisable to fix wooden planks on the inside of the polystyrene foam, install strong hooks in them and flexibly connect the reinforcement. Then the hooks will tension both surfaces of the formwork and fix them within the specified parameters.
After installation, the inside of the formwork must be covered with roofing felt in several layers so that the concrete does not leak out, as well as to ensure waterproofing of the tape. Waterproofing must be laid from downward slopes, closer to the sand cushion, so as not to tear the layer during concreting. Upper part It is better to bend the ball of roofing material over the top edge of the formwork, secure it with clamps or screws, and secure it with a stapler. Then the sheet will withstand the load that will occur when pouring concrete from a concrete mixer.
How to install formwork for strip foundations on unstable soil
Even just digging a trench or pit in loose soil is fraught with some danger due to its possible shift. Therefore, first they make the external formwork of the trench in order to prevent soil shifts, and only then equip inner part trenches
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 top sand and gravel mixture pour a layer of medium-density concrete so that it fixes the shields 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 pays off when you need to build high building and install thermal insulation on a limited area of the construction site. The design involves a combination of removable and permanent formwork, which can be made with your own hands, while its design remains quite simple. From the outside - these are ordinary removable plastic or wooden boards, and inside there is a layer of polystyrene foam.
This design carries the advantages and disadvantages of two types of formwork. Some developers spend money and time on thermal insulation, especially when it is necessary to build a foundation without calculations in a short time. The disadvantage of such formwork is that when it comes to waterproofing, it can only be placed on the outer surface, and the inner part of the insulation cannot be removed.
If the strip base is erected on strong soils that are not prone to heaving, then the trench is dug taking into account the thickness of the insulation, as well as the removable formwork panels. In the underground part, the insulation is attached to the walls of the trench, and in the above-ground part - using self-tapping screws. You can also use special mounting dowels and umbrellas, but then removing the insulation during restoration or repair is problematic. If the tape is installed in loose soils, then the insulation is installed completely immersed in the ground, provided that the level of frost heaving in the region is insignificant.
The role of permanent formwork for strip foundations
These are panels made of polystyrene foam, connected to each other by grooves in the shape of a construction set, so they are often made with their own hands according to ready-made drawings. A reinforcement frame is installed inside and then filled with concrete. Due to the presence of expanded polystyrene, a thermal insulation and waterproofing layer is simultaneously formed on the surfaces of the tape. This type used when the building area is limited or high level occurrence of groundwater. The advantages are obvious:
- it can be quickly assembled directly on construction site, does not take up much space;
- it is supplied in a factory configuration, there is no need to calculate the parameters of the panels, they can simply be cut, which cannot be done with wooden formwork;
- all external and internal surfaces the tapes remain insulated;
- the result is the smoothest outer surface, ready for construction and resistant to frost heaving.
The key disadvantage is the cost of permanent formwork, since it is produced in a factory from expensive materials and cannot be removed. For each individual construction, it is necessary to re-calculate the dimensions of the slabs.
Formwork is a form for laying concrete. When installing it, a system of load-bearing and form-building structures is used, which should provide the characteristics concrete structure, according to the design documentation. The installation of formwork for pouring a strip foundation requires compliance with special building codes, the most important of which are the requirements for tightness, strength, rigidity and compliance with the calculated geometric shape. There are a number of standard technological methods that can provide all the necessary technical characteristics of the formwork and optimize the costs of its construction.
The choice of formwork design depends on the shape and design parameters of the strip foundation, soil characteristics, characteristics of the material used and factors external environment. According to terminology and definitions, for a strip foundation you can use the following types formwork:
- Removable formwork, the design of which allows for its disassembly constituent elements after the concrete has hardened.
- Permanent formwork, the elements of which are integral part strip foundation and may have additional functions thermal insulation, waterproofing, decorative and protective purpose. A set of modular elements reduces installation time and does not need to be removed after the concrete has hardened.
If the soil does not crumble and has sufficient hardness and viscosity, then formwork is allowed, which involves concrete casting directly into the strip foundation trench, which can reduce the consumption of material for the construction of form-building and load-bearing structures.
Expanded polystyrene, foam and foam concrete blocks can be used as permanent elements and taken into account when determining the design cross-section of a strip foundation. Plastic or metal panels are used to obtain a smooth or textured surface of the plinth walls, which can reduce finishing costs. The most available material wood is used for formwork.
Wooden formwork
Wood, waterproof plywood, fiberboard and chipboard are the most accessible and least expensive materials that allow you to make formwork yourself. Small panel formwork made from boards can withstand up to 15 cycles, subject to technology requirements. The thickness of the boards from which the boards for the foundation (deck) are made should be 4-5 cm, and their width should be at least 15 cm. The most suitable varieties wood for these purposes are conifers with a humidity of at least 22%. Gaps between deck boards should not exceed 2 mm. Before pouring concrete, it is possible to treat the installed panels with water to swell the wood and reduce gap gaps. Panels made of plywood, chipboard, or fiberboard can withstand up to 30 pouring cycles.
Construction of wooden formwork for a strip foundation using the trench walls as a form for pouring concrete.
A small-panel collapsible structure made of boards or plywood, installed along the edges of the trench, is the simplest type of wooden formwork that you can make with your own hands. Concrete is poured directly into a trench dug in clay soil. Depending on the material and the presence of non-removable elements, this design may have the following options:
Plywood formwork
Deck made of plywood panels. Installed on the edge of the trench plywood panels(3), which are strengthened using braces (8) to stakes (4), located at a distance of at least 1 m from the edge of the trench. The pitch of the braces should be no more than 1 m. The upper sections of the boards are fastened with wooden jumpers (6) in increments of 0.5-1 m. Permissible deviations in the geometry of plywood boards should not exceed 2 mm per 1 m of the formwork length. The edge threads (7) are installed along the upper edge concrete pouring (5). Waterproofing material made of PVC or EPDM (2) is laid on a sand bed (1) compacted at the bottom of the trench. Its edges should completely cover the ground walls and panels, with a bend along their upper edge and securely fixed using a furniture stapler.
Board formwork
The deck, made of boards (3), is fixed on the edge of the trench. To strengthen it, braces (8) and stakes (4) are used, according to the diagram (Fig. 2). The gap between the boards should not exceed 2 mm. Installation of this structure is similar to installing a deck made of plywood panels.
Formwork with insulation throughout the entire depth
The use of non-removable EPS blocks for the entire depth of the strip foundation formwork, and a plywood panel deck. In expanded polystyrene blocks (12), before installation in the trench, façade dowels (10) are installed. After the concrete has hardened, the dowels securely fasten the EPS panels to the foundation walls. Plywood panels (3) are installed on the edge of the trench and secured using slopes (8) and stakes (4). The upper edges of the shields are fastened with wooden jumpers (6), installed 0.5-1 m from each other.
EPS blocks are joined together using special locks that ensure tightness. The correct height of pouring the strip foundation is determined by the edge strings of the cast-off (7). The height of the plywood panels must be made 5-7 cm above the foundation pouring level (5). Waterproofing film(2) is laid along the entire depth of the trench with a slight overlap and secured with a bend to the upper edge of the boards using a furniture stapler. At the bottom of the trench, a sand cushion (1) with a height of 20 cm is compacted. EPS blocks are attached to plywood panels and the ground walls of the trench using nails 20 cm long (9). The upper ends of the EPS blocks are fixed to the transverse lintels using self-tapping screws (11), which can be easily dismantled when it is time to remove the formwork.
Formwork with insulation in the underground part
Using EPS blocks as non-removable underground elements formwork and smooth (textured) metal, or plastic sheets for legend necessary qualities surface of the plinth. EPS sheets (12) are installed under the cut of the trench, and the deck (3) is covered with ugly sheets (11) to give the surface of the plinth walls the desired texture.
When using permanent EPS blocks (URSA, Penoplex, Dow, BASF) with a thickness of 5 cm or more, a lightweight version of the lattice deck is allowed, which saves building materials.
Installation of wooden formwork for trenches with slopes, or for strip foundations with concrete preparation
If the soil does not allow concrete to be poured directly into the trench, or concrete preparation is required to install the foundation, then wooden formwork is installed to the entire depth of the trench, the width of which increases by 2 times the foundation cut, and the walls of the trench are made in the form of slopes.
It is best to install waterproof grades of plywood (9) as the material for the deck, but it is also possible to use boards 4-5 cm thick and 15 cm wide. Plywood sheets are attached to a frame made of wooden beam(10). Used to tighten shields special device, consisting of a metal tube (5) installed between the shields. Inserted into the tube threaded rod, at the ends of which bars for support, nuts, or threaded plates (4) are installed, with the help of which the shields are tied together. Threaded ties are installed at a distance of 0.5 m from each other. Edge strings (7) are used as guides when installing shields. Using spacers (3) and braces (11) the vertical stability of the structure is ensured. The stakes (12) for supporting the braces are driven at a distance of at least 1 m from the edges of the trench.
The formwork can be installed either on sand cushion(1), or on concrete preparation, in which anchors (2) are installed. According to Table 1 of formwork quality indicators (), the vertical design error should not exceed 5 mm for each meter of height. Unevenness per meter of length should not exceed 3 mm for a deck made of boards, and 2 mm for a deck made of plywood panels. Remove load-bearing and form-building materials wooden structures necessary without the use of shock loads.
Errors that occur during formwork installation
If the developer is faced with the task of correctly making a strip foundation with his own hands, then it is necessary to take into account typical mistakes that builders can do without relevant experience:
- Lack of sufficient distance between the support stakes and the edges of the trench can lead to the collapse of its walls during pouring concrete into the formwork and loss of structural integrity.
- The use of loose wedges to level the side panels with the help of braces and stops creates a risk of their collapse when performing work on vibration impact on concrete poured into the formwork.
- The use of materials whose strength and elasticity characteristics are insufficient to resist the pressure of poured concrete, or errors in the design of supporting elements can lead to unacceptable displacement of the foundation axes in relation to the design position.
Reducing costs for formwork production
To reduce the amount of material required for the installation of formwork, you can use the method of gradually pouring the foundation. The formwork is assembled on a separate section of the belt and reused when pouring in the next section. At positive temperatures and average air humidity, a break between pouring stages is allowed for a period of 3-4 days, necessary for partial hardening of the concrete.
Depending on the availability of material, the pouring process can be divided both by the length of the tape and by height. To ensure a sufficient level of adhesion between sections of the foundation located one above the other, it is necessary to remove the layer of cement laitance that accumulates on the upper edge before starting the next pouring cycle lower tier. To ensure reuse of the material, plywood panels, or the surface of a deck assembled from individual boards, can be wrapped in plastic film, or pre-treated wooden elements, adjacent to concrete, with lime milk.
To do it right yourself good formwork for pouring a strip foundation, it is necessary to strictly observe building regulations and use proven technologies correctly.
Advice! If you need contractors, there are very convenient service by their selection. Just submit in the form below detailed description work that needs to be done and you will receive offers with prices from construction teams and companies by email. You can see reviews about each of them and photographs with examples of work. It's FREE and there's no obligation.
The first stage of construction is pouring the foundation. The strength and durability of the entire structure ultimately depends on its quality and reliability. There are several types of foundations, but the most popular, especially in “private” construction, is the strip foundation. During its construction, you can do without the use of special equipment; it costs less building materials than on a slab foundation, but at the same time a strip foundation is used both for light (garages, bathhouses, etc.) structures and for “capital” buildings. To fill a strip foundation, a number of preparatory work is carried out, the main one of which is the installation of formwork. Formwork is a structure that gives concrete the desired shape and is dismantled after hardening. So, we build the formwork for the strip foundation with our own hands.
Types of structures
Several types of formwork can be used to fill a strip foundation. Let's look at each of them in more detail.
This type of formwork is used in cases where concrete mortar Not only the foundation is poured, but also the walls of the future building. This type of construction is called “monolithic” and is actively used by modern builders. Sliding formwork consists of plastic or metal panels. After pouring concrete, they rise (slide) up the walls, thereby forming the formwork for a new pour.
Such formwork is also made from plastic or metal elements, which, when connected to each other, special fastenings, form a kind of constructor from which formwork of almost any shape can be made. Collapsible formwork is most often used by professional construction teams who need to frequently pour foundations at different sites.
The cost of elements of sliding and dismountable formwork is quite high. But such designs can significantly save time, effort and money during the construction of the foundation. Naturally, this saving will be noticeable only with large volumes of work performed, so it makes no sense to purchase such formwork for “small” construction.
Fixed option
Permanent formwork
The simplest type of formwork, which is installed for the construction of one specific object. Considering the “disposable” nature of this design, materials are used during installation that you won’t mind throwing away later.
This does not mean that all materials will become unusable. Most of them can be used in further construction.
Since the first two types of formwork are used mainly by professional construction teams, let’s take a closer look permanent formwork for strip foundations, as the most popular in private construction.
Required tools and materials
Permanent formwork can be made from almost any sheet material: plastic, wood or metal. The main thing is that it is durable, since it will have to withstand a fairly large amount of concrete (weight 1 cubic meter is approximately 2.5 tons).
In private construction, wood is most often used for formwork - sheet plywood or boards. Moreover, the latter do not necessarily have to be High Quality, even the use of a “croaker” is allowed.
Board for formwork construction
It is important that the ends of the boards are processed and fit tightly to each other. Otherwise, the liquid solution will pour out through the cracks, which will complicate the pouring of the formwork.
- To determine the required cubic capacity of lumber. V = 2PHn, where P is the length of the perimeter of the formwork, H is its height (height of the foundation + 20 centimeters) and n is the thickness of the boards.
- To determine the required number of sheets (for plywood, metal or plastic). 2PH/s, where s is the area of one sheet.
In addition to the material from which the formwork walls will be made, you will need reinforcement to strengthen the foundation and plastic film. It is used to line the bottom and walls of the formwork to prevent the solution from leaking.
From the tools you will need a hacksaw, an axe, a nail puller and a hammer (for wooden formwork) or a set of keys, screwdrivers, a hammer and pliers for metal or plastic formwork.
Video: requirements for boards for formwork installation
You can learn more about the requirements for formwork boards from the following video:
Preparatory work
Site clearing
The area where the foundation will be poured must be cleared of trees and bushes, the remaining roots must be uprooted, and the top fertile layer soil removed.
Marking
To mark the future foundation, it is best to use pegs with a cord or strong thread stretched between them. Pegs are driven into the ground at the corners of each future wall. A cord is stretched between them. It must be tightened strictly horizontally, so when working, be sure to use a rack level.
Please note that the width of the trench for the formwork should be 10 centimeters greater than the width of the future foundation.
Digging a trench
The trench for the foundation should be at least 50 centimeters deep. Its bottom should be smooth and horizontal. You can check the “horizon” using a level or measurements taken from a marking cord.
Foundation trench
The soil removed from the trench can be placed inside the perimeter of the foundation or used to level the area.
Pillow filling
It is necessary to pour a layer of sand at the bottom of the trench, which will protect the foundation from groundwater and freezing, and will also help to evenly distribute the load on the soil.
Sand is poured in layers of 10 centimeters, with the obligatory “spill” of each layer with water. A minimum of three such layers must be laid.
A geotextile fabric is spread over the sand, onto which a layer of fine crushed stone 10-15 centimeters thick is poured. The crushed stone is carefully compacted and leveled.
Foundation pillow
On this preparatory work Based on the construction of the formwork, it can be considered complete.
Installation
Shield assembly
If you are using prefabricated metal or plastic shields, this step, of course, can be skipped. But if you are making wooden formwork, then you will have to make the panels yourself.
The first step is to prepare the support stakes on which the shields will be installed. They are made from timber, one end of which is pointed for ease of driving it into the ground.
The length of the support stakes should be at least 40-50 centimeters greater than the height of the formwork.
The boards are cut into pieces of equal length and stuffed onto stakes laid on a flat surface. The distance between stakes should not exceed 1 meter. The boards should be carefully adjusted to each other, since even small gaps can create problems when pouring the formwork.
When filling boards, make sure that the head of the nails or screws is on the inside of the board. Protruding nail ends can seriously complicate the process of removing formwork after the concrete has dried.
Installation of shields
The boards are installed along the marking threads. When installing, be sure to use a plumb line and level so that the panels are placed clearly vertically. It is also important to ensure that they are all on the same line.
To ensure stability of the formwork, additional spacers are placed on the stakes at an angle, and the upper corners of the boards are fastened with jumpers.
If the formwork is higher than 20 centimeters, then in order to avoid the divergence of the panels under the weight of concrete, they are additionally fastened with jumpers. To do this, holes are made in the opposite panels through which the plastic pipe with a metal pin installed in it. Fixing nuts are screwed onto the ends of the studs. After the foundation hardens, the stud is removed, and the plastic pipe remains in the concrete.
When the panels are installed, it is recommended to cover the walls and bottom of the formwork with plastic film. This will prevent the solution from spilling through the cracks and will simplify the removal of the formwork after the concrete has hardened.
After installing the formwork, you can begin installing the reinforcement.
Video: installing metal formwork screed
In the next video you will learn in more detail about how to install a metal formwork screed in a plastic pipe.
A few common mistakes
In conclusion, let's look at some of the most common mistakes that occur during formwork installation. Despite their apparent “insignificance,” they can have a very negative impact on the final result.
- Poor quality material. It is not necessary to use boards or premium plywood for formwork, but you should not skimp too much on quality. Even one rotten board that bursts after pouring the foundation will lead to the fact that the entire work will need to be redone, and this is much more expensive than the initial purchase of high-quality material;
- Large gaps between boards. The distance between the boards in the formwork cannot exceed 3 millimeters, although ideally it should not exist at all;
- Weak fastening of formwork panels. By saving on installing additional supports or metal braces, you risk encountering divergence of the panels after pouring, and this will make the foundation unsuitable for further construction;
- Damage to waterproofing. Significant damage polyethylene film, which protects the walls and bottom of the formwork, will lead not only to problems during the removal of the panels, but also to a decrease in the quality of the entire structure.
In conclusion, I would like to say once again that the installation of formwork is a very important matter, on which the result of the entire construction largely depends. We hope that our tips will help you avoid mistakes and install formwork efficiently and reliably. Good luck with your construction!
