A one-way retractable building formwork apparatus for mounting on a mounting surface of a substrate module includes a first side bar disposed on one end of the mounting surface that extends along a lateral direction, a second side bar disposed on another end of the mounting surface and opposite to the first side bar along an extending direction transverse to the lateral direction, and a retractable unit that is disposed on the mounting surface, that is connected to the first side bar, and that is extendable along the extending direction to fixedly connect to the second side bar.

A two-way retractable building formwork apparatus includes a substrate module having a mounting surface, a first side bar mounted on one end of the mounting surface that extends along a first direction, a second side bar mounted on another end of the mounting surface that extends along a second direction transverse to the first direction and fixed to one end of the first side bar, a first retractable unit mounted on the mounting surface opposite to the first side bar and extendable along the first direction to fixedly connect to the second side bar, and a second retractable unit mounted on the mounting surface opposite to the second side bar, extendable along the second direction to fixedly connect to the first side bar, and further connected to the first retractable unit.

The disclosure relates to formwork for producing a concrete element, in particular a wall element or ceiling element, having an opening, in particular a window opening or door opening, the formwork comprising: a formwork panel; opening formwork, which has a frame element for delimiting a portion of the opening, a support bracket for supporting the frame element, and a mounting element for mounting the support bracket; a formwork-stripping device for transferring the opening formwork from a formwork position for the formation of the opening into a formwork-stripping position for the release of the concrete element, wherein the formwork-stripping device has a sliding and tilting mechanism for sliding the frame element in a direction parallel to the formwork panel and for tilting the frame element about a pivot axis running substantially parallel to the formwork panel.