Precast concrete units with reinforced concrete topping. Precast units include hollow-core slabs, solid slabs, a system of precast concrete joists with timber or hollow masonry infill, double-tee units. Sometimes overlaid with light-weight roofing. This system is similar to Precast Concrete Floor with Reinforced Concrete Topping.

Precast roof system, Algeria (S. Brzev)

Roof/floor system consisting of cast-in-place reinforced concrete joists and precast concrete masonry units, Algeria (S. Brzev)


Roof/floor system consisting of concrete masonry units and cast-in-situ reinforced concrete joists (known as "Tralix" system), Chile (S. Brzev)


A double-tee beam lifted by the crane at the construction site, Denver, USA (K. Porter)


Wall corbels ready to support double-tees, Denver, USA (K. Porter)