Types of slab formwork

It is obvious that it is almost impossible to create a monolithic floor outside the factory conditions. Therefore, slab formwork is an important construction tool, which is difficult to do without in the construction of many buildings. At the same time, the requirements for this type of form are very, very high, because, unlike wall formwork, an element that is manufactured in this way has special technical requirements, since it will be operated under load and constantly be under its own weight.

Slab formwork device: types of structures

For different purposes, slab heights and thicknesses, different types of formwork are required. They are divided into:

• frame structures (installed on special scaffolding);
• forms on voluminous racks (for small overlaps);
• formwork on telescopic props (you can conveniently change the length).

All these types of construction are used to create ceilings up to 4-5 meters and more in height. In some cases, they can be combined into one system to achieve the desired result.

Most often, slab formwork is made of wood. This is an excellent choice, as such designs have a number of advantages:

• you can use cheap, even old lumber that is no longer suitable for construction and is only recycled, or used beams;
• the ability to create truss systems;
• Installation is simple and has almost no limit on the number of materials available (finding additional boards is always very easy).

Wooden formwork is used not only in home construction, but also in industrial construction, when it is necessary to pour concrete into small ceilings in hard-to-reach places.

The slab formwork structure, in turn, consists of the following elements:

• racks on which the structure is installed;
• beams that distribute the pressure on the struts;
• braces, even more, distributing pressure between the beams;
• shields into which concrete is poured directly.

Most typically, shields are made from a sheet of plywood, the inside of which is lubricated with a special water-repellent solution. However, it can also be a special metal, plastic or wooden laminated sheet or slate.

Slab formwork requirements

Since a slab can include not only the roof, but also other parts of the building that can be subjected to serious and, importantly, regular loads, the slab formwork should be created by professionals and using formwork accessories of proper quality. Before installing them, you should make sure that the technology for creating a particular floor corresponds to:

• the level of stress to which it will be subject;
• the ability to assemble and disassemble the formwork without compromising the construction process;
• safety and does not pose a threat to people working at the facility.

A certain type of formwork should also be used for economic reasons. Sometimes it makes sense to use a one-time design.

Reinforced construction of bulk struts

The types of structures on bulk racks have a number of advantages. A fairly large number of them can be used, combining them with connecting elements in the form of beams and crossbars, and thus obtaining the ability to hold huge masses of concrete up to one meter thick, which is about 2.5 tons of pressure per square meter of area.

Of course, the requirements for the most reinforced formwork in this case are also quite high, and it is difficult to manually assemble them, and even impossible to place them. The same, by the way, applies to the telescopic racks, which were mentioned earlier. Additional equipment is also required to adjust them.

Advantages and disadvantages of slab formwork

Slab formwork has both advantages and disadvantages. Of course, taking into account the fact that the only alternative to this technology is the installation of finished slabs, which is not always possible due to a number of factors, it is rather conditional to talk about the shortcomings.

Among the pluses, we highlight:

• high strength due to the solidity of the product, the absence of seams and joints with other building elements;
• stability of the structure relative to its position (plate displacement excluded);
• the ability to mount the formwork manually (lifting equipment is needed to transport solid slabs);
• the cheapness of tools and the possibility of their reusable use, or inexpensive rental of construction equipment for a while.

Disadvantages include:

• longer construction time for floors than installation of finished slabs;
• if we are talking about large volumes, then the need for pouring concrete with special equipment.

In any case, the use of formwork for floors should be carried out situationally and in compliance with all building codes.

Installation and dismantling of slab formwork

The formwork of the slabs begins with the calculation of the load on the forms. When building industrial facilities, this is rarely necessary, since the dimensions of the plates are already indicated in the technical documentation, however, for home use, this is usually done independently. In this case, the fullness of the plate has a thickness equal to at least one-thirtieth of the future length of the product. Based on this, it is easy to calculate that, for example, for a slab 5 meters long, the normal thickness will be approximately 170 millimeters. For reliability, this figure can be rounded up to 200 mm, but so that the proportion is no more than 1 to 20 of the length of the plate.

The most difficult stage in the construction of the floor is the collection of formworks for it. If we are talking about a ready-made factory kit, then everything is a little simpler, however, for small ceilings, home-made formwork is typically required, which are assembled from improvised materials.

In any of the above cases, special skills and knowledge are required, because the strength of the future structure depends on this. The main points to consider when assembling the formwork yourself are:

• careful marking of rack mounting;
• reliable installation of supports and jacks under them;
• installation of uniforms for attaching load-bearing beams to the top of the uprights;
• laying perpendicular beams on them;
• setting the support corners on which the shields will be placed;
• observance of the necessary distance between the supports (about 50-100 centimeters);
• use shields made of water-repellent materials.

When installing formwork, remember not only the requirements for the future product, but also safety, especially when it comes to high racks and volumetric ceilings. An error in the calculations in the process of concrete hardening or dismantling of the structure can lead to very sad consequences, which will be difficult to eliminate. It is best to use special equipment. Although it is more expensive, it is more reliable.