Helical stairs generally require more floor space than other types of stairs. They provide a sweeping curve around an open area for maximum aesthetic effect. The footprint of a helical staircase can be circular, elliptical, constant width or tapering. Helical stairs will require a balustrade or barrier to both sides of the flight. Helical stairs create a sculptural aesthetic and particularly in an entrance hall offer the 'wow' factor clients often desire. Due to the stairs structural requirements the build specifications of helical stairs are more complex than other types, but creative design and experience result in stunning installations. Scala stair designs incorporate a steel core structure, particularly advantageous with helical stairs as this allows strength and stability whilst remaining slim in profile. Depending on the stair design concept, this can then be finished with stone, timber, polished stainless steel, glass, polished plaster, etc. to provide stunning and stylish final installations. A helical stair differs from a spiral stair in that a spiral is circular in plan and revolves about a central column. Helical stairs can be circular or elliptical in plan and are offset from the setting out point of origin.