Abstract: A unitary concrete form installation of the flying deck type, preadjustable to selected dimensions and adapted to produce a horizontal building floor slab, comprises a deck formwork including a pair of deck supporting stringers, and scaffolding supporting the stringers and consequently the formwork, the scaffolding including spaced supporting posts disposed in quadrilateral relationship beneath the stringers, each post including elevator screw means for varying the effective length of the post, a shore head mounted on the upper end of each post and releasably secured to a stringer, pairs of cross braces of selected length extending between longitudinally and transversely spaced pairs of posts, and means for releasably securing the cross braces to the posts, thereby providing a form installation which may be transported as a single unit from one location to another for producing floor slabs in successive locations without dismantling the installation between locations and which may be dismantled following use.