Formwork from osb for a strip foundation. The use of OSB formwork, advantages and disadvantages of the design

When constructing suburban real estate, developers apply formwork for strip foundation from boards, plywood, OSB. The quality and design of non-removable polystyrene foam blocks do not meet the requirements of the SP standards for concrete work.

Construction and materials

used by the owner of a suburban area once. Therefore, the most important condition for reducing the construction budget is the reuse of structural material in the following stages. Shields are made from edged board, OSB, plywood, dismantled after stripping, turn into partitions, draft floors, roof lathing, ceilings.

To save lumber, wood-based boards from contact with concrete mix shields are wrapped from the inside with polymer films. With these waterproofing materials, it will later be possible to make a horizontal layer that cuts off the walls from the foundation. When laying a mixture from a concrete mixer, the formwork experiences loads per unit surface within 400 kg. If the concrete is poured out of the mixer, the load rises to 600 kg, the concrete pumping requires special strength of the decks, since the loads reach 800 kg.

Wheelbarrows are transported over the shields, builders walk, therefore minimum thickness decks from different materials is 2.5 - 5 cm. The thinner the lumber, the more difficult it is to find a use for it in the future, more often you need to put racks with jibs. Depending on the height of the belt, horizontal loads increase significantly. Therefore, the following schemes are recommended:

For a non-recessed tape belt, boards of 2.5 cm can be used. The step of the racks will be 60 - 80 cm for a tape 50 cm or 20 cm high, respectively.

Monolithic tape technology implies the presence of an underlying layer instead of heaving soil, 5 - 7 cm footing on top of it with 2 layers of built-up waterproofing material. Therefore, problems with the installation of shields do not arise in principle. To fix the decks in space, stakes, jib bars, ties, horizontal stops are needed.

Attention: To reduce labor costs at the stage of protecting concrete structures from moisture, freezing, insulation can be placed in the formwork, a penetrating composition is added to the concrete. After that, the foundation becomes waterproof with an external insulation contour, which does not need to be glued, fixed with dowels.

Manufacturing technology

It is better to build formwork panels on a flat area directly on the site. Subject to the construction technology of the strip foundation, it is possible to unify the dimensions of the formwork, apply the in-line method:

The simplest option is the MZLF tape on a flat area. To calculate the number of boards, you must perform the following steps:

• add the length of the outer sides of the foundation
• divide the sum by 6 m ( standard length lumber) to obtain the number of boards in one belt (N 1)
• add 5 cm to the height of the tape (shields are mounted above the design level so that the concrete does not splash out during vibration compaction)
• divide the result by 10 cm or 15 cm (the width of one standard board) to get the number of belts (N 2)
• multiply N 1 and N 2 to get the total consumption of lumber

Attention: The cube contains 44 boards 2.5 x 15 cm, 37 boards 3 cm thick or 27 pieces 4 cm thick. Taking into account the mounting step of the boards on the footing, you can calculate the board / beam consumption for racks, jibs, stops.

If sheet materials are used, it is extremely important to reduce the amount of waste, scraps. The length of the decks should not exceed 3 m, so that it can be moved, mounted in windy weather by two workers.

Board shields

After purchasing the material for the manufacture of shields, the following technology is used:

Then, a polymer film is shot on the inner surface of the shield deck with a stapler. This will prevent the seepage of cement milk through the cracks, save lumber for recycling, and facilitate stripping.

Attention: In the presence of a screwdriver, assembly productivity is increased by fastening lumber with self-tapping screws. However, with serious loads on the formwork panels, it is better to use nails. Hardened screws can be sheared by concrete pressure.

plywood deck

Shields from sheet materials constructed using a different technology:

The inner surface is processed with a film, the decks are laid out with components in the building spot. Diagonal lintels in frames significantly increase the reliability of the structure.

Shields from OSB boards

Experts do not recommend the use of oriented strand board, since this material is inferior to plywood in terms of rigidity with the same thickness. Wetting during precipitation leads to partial delamination, loss of appearance.

However, this option is preferable if RSD is planned to be applied later in solid crate roofs. Decks are built according to the above technology using a frame system. It is allowed to use OSB-4, in extreme cases OSB-3. The decks are pulled together with studs, lintels made of timber are strictly prohibited.

Curved formwork

Classic facades of cottages often do not suit individual developers. Semicircular bay windows, curvilinear walls are used, which require a foundation of a similar configuration. You can assemble such decks according to the following methods:

For a radius, curvilinear wall, it can be bent along a fiberboard contour drawn on the footing (with the front side inward), supported from the outside with board racks located close to each other. So that the fiberboard does not collapse when wet, its surface is sheathed with polyethylene.

Attention: All existing polystyrene fixed formwork is designed for walls. It is forbidden to compact the concrete inside it with a vibrator, the laying of reinforcing cages is impossible in principle (lintels interfere). The binding of frames inside the formwork, the destruction of expanded polystyrene under the pressure of concrete, sharply reduce the productivity of the process.

Mounting Features

The unfolded decks begin to mount from any angle in the following way:

There is an option for fixing the decks with U-shaped clamps, which are put on the shields from above. Clamps are made according to the scheme:

This design allows you to fix outer dimension tape, used only in conjunction with internal stops.

Attention: Shields for deep-laid tape are mounted after installation of reinforcing cages. Due to the large height of the decks, it is not possible to lay the frames inside the assembled formwork in compliance with the protective layers of concrete.

Ribbons require entry holes engineering systems, ventilation products. They are made by installing pipes passing through two shields. These void formers are also mounted after the reinforcement cages have been placed.

External insulation of the strip foundation is often carried out during the construction of the formwork. This option reduces labor costs, but is only recommended when penetrating compounds are added to the concrete. Otherwise, waterproof the outer surface concrete structure impossible, expanded polystyrene is not a full-fledged waterproofing layer.

For insulation of foundations, it is better to use expanded polystyrene grades XPS or high-density EPS. Thermal insulation is carried out according to the scheme:

In this case, the processing of the shields with a film can be omitted, after the concrete has hardened, the dowels will remain embedded in the foundation, thermal insulation material will be held by their hats. Using warm circuit the distance between the shields should be increased by the thickness of the expanded polystyrene. Outer protective layer concrete is measured from the heat-insulating material.

Thus, the construction of the strip foundation formwork from boards, sheet materials is not difficult. Fixed formwork better not to use for foundations. The choice of material depends on the design of the roof, partitions, subfloors, in which they are usually used after stripping.

Formwork is an integral part of the construction site. It is used not only for the construction of a strip foundation, but also for stairs, armored belts, floor slabs, columns, wall structures. Allows you to create products from a concrete solution of a certain shape. Often the main elements for its manufacture are wooden boards or metal plates. One of the most practical options is OSB.

Oriented strand board is a type of engineered lumber that resembles chipboard in its wood structure. It is formed with the help of special adhesives and by pressing several layers of wood chips, oriented in the necessary way. It has a somewhat rough surface, where small chips of wood with dimensions of approximately 2.5x10 or 2.5x15 cm are visible. They are arranged randomly, while their thickness and appearance differ from each other.

To create OSB, three thin layers of chips are used, while the two extreme opposite to each other are laid along, and the middle one is perpendicular. It is this oriented arrangement that provides proper strength. Water-resistant synthetic resins and high temperature pressure molding are also applied to improve performance. Due to the homogeneous structure, they work well for bending and tearing.

OSB formwork has:

• Low hygroscopicity. The material is particularly resistant to swelling or delamination.
• Ease of processing. Easy to saw and drill.
• Reusable. OSB-3 do not lose their qualities, since one of the sides is laminated.
• Light weight. Simplifies installation work, therefore, it is in demand among private developers.
• The possibility of using large-sized slabs, which allows you to create large-panel formwork with a small number of joints.

Advantages and disadvantages of such formwork

The manufacture of OSB is carried out by pressing large chips (50-80 cm) under high temperature. At the same time, waterproof resins and chemical additives are added that exclude damage by fungal microorganisms or mold. Under the influence of moisture, the products are not able to warp and collapse for a long time, due to which they are effectively used in the construction of formwork for the foundation.

Compared with wooden planks plates are not deformed due to impact external factors and atmospheric precipitation, therefore, they are applied several times without loss of operational characteristics. They have perfectly smooth edges, which is not always possible to achieve from ordinary wood.

Since OSB is easy to saw, it is possible to create boards of any size, which makes it easy to pick up necessary elements. The material is sufficiently elastic, therefore it is less prone to destruction under bending loads. Also, this and its low weight makes it possible to easily and quickly create formwork, saving time on construction.

OSB boards have some disadvantages:

• Poor resistance to high concentrated loads.
• Have phenol in adhesive compositions which is harmful to human health.
• Panels 3 and 4 types can only be placed outside the building.

Plywood and OSB formwork is often used in the construction of buildings and structures for various purposes. Thanks to them mechanical properties they are widely used for wall cladding, roofing floors, foundation frames, floor slabs and other reinforced concrete monolithic structures. There are elements with a laminated surface, which greatly simplifies their installation and increases their effectiveness as enclosing products. The panels are also used in the manufacture of furniture products.

Necessary materials

Calculation of the formwork for the strip foundation is carried out only after the installation of trenches. In this case, the height of the basement of the building and the specific density of the concrete solution, which imposes a certain load on the shields, should be taken into account. For its manufacture are used:

1. Wooden blocks as stiffeners.
2. Hardware for connecting the structure (bolts with nuts, washers, studs).
3. Metal corners for reliable fastening of plates.
4. Plastic pipe for fastening opposite shields.
5. Reinforcing rods.
6. Plywood or slats for closing gaps.
7. Self-tapping screws for connecting OSB and glassine.

On preparatory stage cutting of plates of the required dimensions, plastic pipes and fittings is carried out, as well as the calculation of the dimensions of the shields.

Step-by-step installation technology

Assembly of the fence begins after earthworks and styling sand cushion under the strip foundation. by the most practical option is the device removable formwork. Prefabricated shield systems allow you to quickly and easily assemble shields the right sizes with corner correction.

Provide places for laying engineering and plumbing communications that will be located on the construction site.

Installation is carried out in the following sequence:

1. OSB-plates are cut according to the dimensions of the edges of the foundation, while the height is made slightly larger than the net level by 15 cm.

2. Frames for walls are made. Budget option is wooden, however, for repeated use, you will need shields made of metal bent-welded profiles.

3. The OSB blank is attached to the frame with self-tapping screws, the caps of which should be on the inside and slightly recessed.

4. Each side of the formwork is reinforced with transverse bars in increments of 40 cm. This will allow you to observe the geometry of the structure being created.

5. Opposite elements are connected with metal studs that are threaded through the previously drilled holes 16 mm in diameter. Fasteners should extend 3-4 cm outside the shields on each side to ensure secure fastening with washers and nuts. The lateral plane of the fasteners is chosen wide so that under the pressure of the mixture they do not push through the OSB.

6. Threaded plastic pipes, which will allow you to maintain the accuracy of the width on any segment of the strip foundation. After pouring the mortar and its hardening, they remain in the concrete body, while working well as ventilation.

7. If there are no pipes, fastening can be done with nuts. Then there are about 4 pieces with washers per side. When dismantled, they are removed and the ends of the studs are cut off flush.

8. When pouring the concrete mixture, the corner sections perceive the greatest efforts, therefore, reinforcement is carried out with wooden blocks vertically driven into the ground. For additional reinforcement, steel corners are used to connect the shields to the pegs.

To give maximum rigidity, holes are made in the shields into which embedded reinforcement products are inserted in the shape of the letter "T". The long side is welded to the reinforcing cage of the foundation and the mortar is poured. After solidification, the excess parts are cut off with a grinder.

Inclined bars with outer side structures with a step of 1 m allow you to keep it in a vertical position until the very end of construction. Spacers should be attached to the shields at an angle of 30-45 °, then the possibility of their collapse is excluded. At the end of the formwork device, a control check of the parallelism of the side faces is carried out. This will require a piece of timber and a water level.

Concrete work can be carried out in layers, taking small breaks between pouring. Then the solution will set, and the spacer pressure will decrease. However, if the foundation area is small, it is recommended to lay the mixture in full, excluding the appearance of cold joints.

Formwork reduces construction time by combining the laying of the foundation and its insulation. To do this, at the stage of the installation of enclosing structures, between reinforcing cage and shields are laid plates of polystyrene.

The operational period of the foundation and its strength index in most cases are determined not only starting materials for pouring, but also the organization of work. Therefore, it is necessary to approach with full responsibility the installation of the formwork system for pouring the base of the object, so that there are no void areas and other defects in the foundation body that have a negative impact on operational performance. And today, even private developers know that OSB formwork is exactly the option that helps create a reliable foundation for an object under construction.

Areas of use

OSB is widely used in the construction of residential buildings. From this material, crates are mounted and formwork structures are installed.

Often, OSB formwork is installed to fill the foundation. In addition, it is used in the construction of fences and buildings for economic purposes, erected by monolithic casting.

The material is easy to process, which allows you to create structures of various shapes from it.

It should be noted that OSB have found their application in the installation of wall and floor battens, under roofing. The manufacturer produces OSB material with a laminated surface, which greatly facilitates installation work and increases the energy efficiency of the entire structure. Finally, OSB boards are used in furniture production.

Advantages and disadvantages

The formwork for pouring the foundation base must be strong in order to hold the concrete mass until it finally hardens. The use of OSB boards creates good advantages over the well-known method of arranging shuttering boards from boards.

The advantages of the material include:

• low level of hygroscopicity. Boards do not swell under the influence of a humid environment, as happens with ordinary lumber. Such formwork can be used repeatedly, since it does not lose its properties;

• The material is easy to process and cut. The specific gravity of OSB is much less than that of wood, it is more convenient to work with them;
• the time intervals required for the installation of formwork are reduced;
• solid boards are made from OSB panels that do not have docking areas, which minimizes the likelihood of leakage of the concrete mix.

It should be noted that with all the advantages of OSB, there are certain disadvantages:

• there is a weak resistance to loading influences;
• in the adhesive involved in the production of the material, there is phenol, which poses a threat to the body.

Materials used

To prepare OSB formwork for the foundation with your own hands, you need to prepare everything that is needed for work.

The necessary calculations are performed when the foundation ditch is prepared. The height of the plinth and the specific gravity of the concrete solution should be taken into account.

For work you will need:

• OSB boards;
• bars, for the manufacture of stiffeners on boards from OSB;
• fasteners for the assembly of the structure. This will require nuts with washers, studs and bolts;
• tubes from plastic material, with the help of which the connection of opposite formwork panels is performed;
• metal corners. They are installed on the corner sections of the formwork to increase the reliability of the OSB structure;
• reinforcing bars for pegs;
• plywood material or glassine. They lay slotted areas in the formwork;
• self-tapping screws. With their help, plates, plywood and glassine are fixed.

At the preparatory stage board material cut into necessary elements, the dimensions of which correspond to the performed calculations.

Design features

OSB - oriented strand board is considered engineering lumber, with its wood structure resembling chipboard panels. For the manufacture of OSB boards, a special glue is used that connects several layers of pressed wood chips, properly oriented.

The surface of the plates is slightly rough, small chips are visible on it, the dimensions of which are 2.5 by 10 or 2.5 by 15 cm. They are arranged randomly, differing in thickness and appearance.

When forming an OSB plate, three layers of chips are used, the outermost of which are laid lengthwise in relation to each other, and the middle one is laid at an angle of ninety degrees. This arrangement creates the necessary level of strength.

Synthetic resin compounds are involved in the production process, pressing is carried out under strong pressure and high temperature regime which helps to increase performance characteristics plates.

The uniformity of the structure contributes to the good work of OSB boards in tearing and bending.

Installation of OSB formwork

Cooking construction site, we dig a trench under the foundation base, we arrange a sand cushion at its bottom.

When pouring the foundation, do not forget to determine the places for laying pipes along its perimeter, into which we will then pass communications.

The work algorithm is as follows:

• OSB boards are cut required dimensions. At the same time, we take into account that the height should be ten to fifteen centimeters more than the upcoming pour;
• frames are made for shields. If we plan to use the formwork repeatedly, then the wooden bars should be replaced with profile pipes;
• OSB with the help of self-tapping screws is fastened to the frame, leaving caps on the inner surface;
• The sides of the formwork panels are reinforced with bars, which are stuffed in increments of forty centimeters. Thus, the foundation geometry will be better formed, the required parameters will be provided when pouring the concrete solution;
• shields are installed on both sides of the trench, connected by spacer metal studs. For this purpose, holes with a diameter of 1.6 cm are made at the attachment points. The length of the studs should exceed the width of the formwork structure by several centimeters. Fastening is carried out with nuts and washers. These elements must be wide so that from the pressure created by the concrete, the stud does not push through the plates through, pulling out the nuts;
• inserting the studs, we pass them through plastic tubes of the same size. This will help to set the formwork to the same size in width around the entire perimeter. When dismantling the structure, the tubes remain in the concrete monolith. In the future, they can be used for ventilation devices;
• if there are no tubes, the studs are attached to four nuts on both sides;

• dismantling such a formwork, it is necessary to unscrew the nuts and cut off the ends of the studs. After removing the shields, trimming is performed again;
• on the corner sections of the formwork, bars are driven into the ground, reinforced with steel corners for reliability. Formwork assembly requires strength corner connections, as the weakest points of each design. When pouring a concrete mixture in such places, the strongest pressure is formed;
• in order for the formwork of OSB boards to be durable, in some places of the frame base, holes are made with a drill into which reinforcing sections shaped like the letter “T” are inserted, welding them directly to the frame. During the dismantling of the formwork, all fasteners protruding outwards are cut off;
• outside the formwork structure, the bars are set at an angle. The installation step is one meter so that the system can withstand the pressure created by the concrete mixture. The angle of inclination of the strut is thirty - forty-five degrees;
• having fully completed the preparation of the structure, we check the shield edges for parallelism. This will require building level and even wooden beam OK.

If breaks are allowed during concreting, pouring in layers, concrete mortar will set gradually, reducing the pressure on the formwork system.

Conclusion

The use of OSB formwork systems makes it possible not only to pour solid foundation, but also to carry out its warming. For this purpose, polystyrene sheets are laid between the shields and the concrete layer. The construction of formwork from oriented strand boards will reduce the time of work and reduce financial costs.

The choice of material depends largely on the type of construction, since it is necessary to calculate the strength of boards, shields, metal and other elements that participate in this "interactive event". Let's assume we are building cottage or a garage. For formwork, we need OSB sheets with a thickness of 12 mm, 10 mm can be used, but it will be necessary to pour concrete gradually so that the “belly” does not squeeze out anywhere. Instead of OSB sheets, you can use the old wooden doors, metal gate, sheets of iron and everything that is not weaker in strength and has a flat surface.

It doesn't have to be exactly on both sides. Even with inside irregularities of 2-3 centimeters are allowed - this is quite normal and will not affect the process in any way. The main thing is that you can easily pick this material from the concrete later, that is, without any elements that fall into the space intended for pouring concrete. Next, we need a wooden beam 50x50 mm, which we will cut. It is desirable that it be made of hardwood, perfect option- larch. Its cost, of course, is considerable, therefore, if there are not enough funds, you can buy 10 meters of pine timber.

We expose the formwork and the internal screed

In order for the formwork for the foundation to be even, it is necessary to level the sole according to the level, make sure that its angle of inclination is insignificant, and there is a small gap between the OSB sheets and the ground, which can easily be filled with mortar. Next, you need to follow the instructions.

Step 1.

We cut a wooden beam 25 centimeters each (depending on the width of the foundation, if it is 30 cm, then we cut it into 30), and we make sure that the cut is as even as possible. We will need about 4 such pieces per 1 meter of the running foundation, if its height is 150 centimeters (average for a house).

Step 2.

We put 2 sheets of OSB or shields opposite each other, insert a bar 25 centimeters long between them and screw 1 screw with different sides through OSB plate. This procedure is also necessary when installing ordinary boards in the role of formwork, as it significantly increases the strength of the entire structure.

Step 3.

We fasten the next block of OSB or any other material so that there is a minimum gap between them, we screw it with slats. So we expose everything to the very end, so that there are no gaps anywhere. The thickness of the foundation will be the same everywhere, since you can control it with wooden block. Such a strip foundation formwork device can significantly increase its accuracy.

Now we have finished construction, which must be leveled left and right. It still moves easily and can be corrected, but it is better to initially set everything in order to avoid possible “waves”. It is much harder to work with boards, although it will turn out 20% cheaper. The thickness of the board for the foundation formwork does not have to be large - 1.5 cm will be enough, because the main thing is internal reinforcement and external supports.

Outer spacers

Now let's move on to the most important part of our business - external formwork supports. Without them, it will simply fall apart, so you need to take a little time and allocate materials for the construction of such elements. Consider step by step instructions how to do it.

Step 1.

We cut a wooden beam measuring 60, 90 and 120 centimeters. We leave 1 edge cut at an even angle, and make the other 45 degrees.

Step 2.

Every meter we install 3 supports at a height of 60, 90 and 120 centimeters, respectively. We rest against the ground with a right angle and hammer the beam a little, after which we tilt the pointed end to OSB sheet to which it fits perfectly. We screw the screw.

Step 3.

We hammer in the vertical supports. Basically, the entire structure will rest on them. I need to take a stepladder and metal pipes, corners, squares - everything that has a good bearing capacity and hammer them 50-60 centimeters into the ground, and right next to the formwork. This will not allow the bottom to move away.

Making formwork for a strip foundation in this way will make it possible to protect the structure from breakage as much as possible, even when the foundation is quickly poured. But do not rush, it is better to do everything in several stages - the effect will be much better.