Formwork of concrete

Formwork 
The materials employed to construct formwork for in situ concrete are generally softwood boards, plywood and sheet steel for working faces, supported on a softwood or steel framework, often in conjunction with proprietary props. Timber is still widely used in the making of formwork because of the variety of forms that it will allow. Plywood has generally superseded timber boards for forming the faces of members.

Sheets or boards must be of sufficient thickness to lake the weight of wet concrete. For plywood the thickness ranges from 25 to 50mm depending on the structures to be formed and the spans involved.

Timber forms for in situ work are usually unfit for further use after four to six uses. In the production of precast units in a factory, timber formwork will have up to twenty uses.

In accordance with the Working Rules, a carpenter required to reuse materials for concrete work is entitled to an extra payment.