Tunnel forms--either full tunnel forms or half tunnel forms--can be used to cast the walls and ceiling slab of a room at the same time.
THE FORMING PROCEDURE
Step 1: Cast foundation and starter walls. Before tunnel forms can be used, the foundation, first floor slab and starter walls for the first floor level must be cast.
Step 2: Install tunnel forms. After the starter walls have been stripped, room-length sheets of welded wire fabric are tied to rebar embedded two feet apart in the top of the starter walls. The rebar provides continuity of reinforcement at each floor level from the wall below to the wall above. Tunnel forms are then placed by crane between the two lines of wall fabric, butted against the starter walls for alignment and leveled by screw jacks.
Step 3: Form starter walls for next level. Starter walls for the second floor level are formed at the same time the second floor slab and first floor walls are cast.
Step 4: Place concrete.
Step 5: Cure and strip. Propane gas heaters are placed in the bays between wall forms to accelerate curing.