Concrete formwork stable and tight build yourself

If you want to build a concrete formwork yourself, you must connect the appropriate formwork material precisely and resiliently. Indispensable is the exact space calculation of the content taking into account the shrinkage behavior of the concrete. The resulting pressure of the poured concrete must not be underestimated.

The different formwork types

The cost of self-construction of a concrete formwork is low in flat trades. For the casting of a concrete foundation or a concrete floor, a simple lateral board formwork is sufficient. Steel or wooden pegs driven into the ground hold the boards.

Elaborate are concrete formwork for buildings such as a concrete wall or a concrete post. All-round formwork is necessary here, which must be tight and very strong. The supporting structure must not yield and no concrete should escape through joints, cracks or slits.

Building a concrete formwork for a concrete or concrete block resembles the construction of a "box" of wood. Here, a self-existing in the box attachment, for example, with screwed metal bands sufficient, through which the concrete formwork remains mobile.

Materials for formwork

For the self-construction of a concrete formwork, materials are suitable that absorb no water and can be provided with a release agent. These include the classic construction rescue, wood panels with waterproof coatings and acrylic glass for small concrete formwork. Absorbent materials such as MDF and chipboard are not suitable and metals such as aluminum must never be used. They enter into a chemical reaction with the concrete, damaging the formwork and component.

Pressure and tightness

The pressure of fresh concrete develops enormous power. The decisive factor is the height of the concrete formwork. While flat formwork boards for floors and foundations are adequately secured by pegs, in the case of higher structures, in particular the lower areas of the concrete formwork must be reinforced with circumferential metal or tension bands or wooden strips. Basically, a concrete formwork should always be bolted and not nailed to facilitate disassembly and increase durability.

The cut edges of the concrete formwork must be very precise, which is best ensured by a circular saw. Even with minimal scribe formation, these should be sealed with sealing tape or sealing cement.

Tips & Tricks

When you get the formwork material, you buy a material overhang of ten to twenty percent, in order to replace any blends or "crooked" workpieces.

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