Formwork system failures are the cause of many accidents and building failures that occur during concrete construction, usually when freshly poured concrete is being placed. Generally, some unexpected event causes one member to fail, then others become overloaded or misaligned and the entire formwork structure collapses.

The main causes of formwork failure are:

1. Improper stripping and brace removal.

2. Inadequate bracing.

3. Vibration.

4. Lack of maintenance and attention to formwork details.

5. Inadequate control of concrete placement.

6. Unstable soil under basement (A plank, frame, or small footing on the ground used as a base for an acrow steel prop or post in formwork). The acrow steel prop is not plumb.

In designing and building the formwork system, the construction personnel should aim for the maximum economy without sacrificing quality or safety. Size, shape, and alignment of slabs, beams, and other concrete structural elements depend on accurate construction of the forms.

The forms must be:

1. Sufficiently rigid under the construction loads to maintain the designed shape of the concrete;

2. Stable and strong enough to maintain large members in alignment, and substantially constructed to withstand handling and reuse without losing their dimensional integrity;

3. The formwork must remain in place until the concrete is strong enough to carry its own weight, or the finished structure may be damaged.