Broaden a foundation

Again and again it can happen that the foundation in its existing design is no longer sufficient. Then, under certain circumstances, a broadening of the foundation can be made. What a widening of a foundation looks like and what to pay attention to, can be read here.

Guidelines for widening a foundation

First of all, it must be said that the widening of foundations (at least for building projects subject to building permits) can not be carried out haphazardly or according to one's own ideas. On the contrary, the broadening of foundations can be so complex that even structural engineers or architects struggle to find a suitable solution.

In addition, an executive craftsman should not be given any tips or guidelines for widening a foundation. Rather, it should only be agreed that this is done properly according to DIN. This is especially true if it is a recognized Baumangel.

If, for example, the client comes up with suggestions as to how the widening of the foundations should be carried out, this may eventually lead to a complicity in the court. The possibilities presented below for expanding the foundations are therefore more illustrative.

Procedures for spreading a foundation

The undertaking of a foundation with a strip foundation

One possible approach is to underbuild or undertake an existing foundation. In this case, a ring foundation, which extends under the existing foundation, created. How deep the new ring foundations have to reach under the existing foundation has to be determined by the structural engineer.

Tighten strip foundation with existing foundation

In other cases, a foundation is literally widened. As a strip foundation or as a cast-on strike. Also, a ring foundation is laid around the existing foundation. But not under the foundation. Rather, clamping anchors are used in the old foundation (injection adhesive) and then clamped to the new foundation. For this purpose, however, a correspondingly high voltage must be achieved.

In a contract with a craftsman to decide this

If you have signed a contract with a construction tradesman, he must professionally carry out the foundation widening. Since you as a layman can not weigh what would be statically competent, that is up to the executive craftsman. The subsequent technical acceptance then shows whether the measure on the one hand sufficient and on the other hand was also professional in the execution. Sometimes it can even happen that a foundation has to be completely redesigned.

Tips & Tricks

For smaller foundations that need to be widened, you'll need to consider making sure the foundation is cast deep enough when making the foundation. Because the frost resistance of the foundation is to produce. In addition, a gravel layer (compacted) can be recommended. Depending on the project, the structure of the foundation may differ significantly.

Artikelbild: I AM NIKOM / Shutterstock

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