The fans run throughout construction of the dome. 3 Polyurethane foam is applied to the interior surface of the Airform. Approximately three inches of foam is applied. The foam is also the base for attaching the steel reinforcing rebar. Small domes need small diameter bars with wide spacing.
Large domes require larger bars with closer spacing.
The steel rebar is embedded in the concrete and when about three inches of shotcrete is applied, the Monolithic Dome is finished. The blower fans are shut off after the concrete is set.