Formwork should not be removed until the concrete has sufficiently hardened in order that it can carry safely its own weight and any other live loads it is subjected to.

The supporting period (the period between the placing of concrete in formwork and removal of forms) differ according to the type of cement used and the design of formwork. In general, structures carrying construction loads, side timbers shall not be removed within 7 days and supporting timbers within 28 days of placing of concrete.

In no circumstances shall forms be stuck until the concrete reaches the strength of at least twice the stress to which the concrete may be subjected at the time of striking.

The strength referred to shall be that of concrete using the same cement and aggregates, with the same proportions, and cured under conditions of temperature and moisture similar to those existing on the work. Where possible, the formwork should be left longer, as it would assist the curing.

In normal circumstances (generally where temperatures are above 20-degree centigrade), and where ordinary cement is used, forms may be struck after the expiry of following periods.

For rapid hardening cement, 3/7 of the above period will be sufficient in all cases except vertical sides of slabs, beams, and columns which should be retained for 24 hours.

All formworks should be removed without shock or vibration as this would damage the reinforced concrete. Before the soffit and struts are removed, the concrete surface should be exposed, where necessary in order to ascertain that the concrete has sufficiently hardened. Proper precautions should be taken to allow for the decrease in the rate of hardening that occurs with all elements in the cold weather.