Spiral staircase

Set the diameter, floor-to-floor height, number of rises and total rotation. Treads are curved sectors, not rectangular blocks. The number of rises includes the upper floor; there is one fewer tread below it.

Choose natural wood, dark metal or laminated-glass treads. Column and balusters have a separate finish from the continuous handrail. The railing uses vertical metal balusters; the glass option applies to treads and the landing.

The optional upper landing is an open sector with an outer guard, not a disk blocking the stairwell. Turning it off removes the landing, its mounting plate and guard from both the scene and materials list.

The handrail is one continuous helical tube. Balusters end on its centreline and follow every size change. Import the template to edit the sector, helix, formulas and specification in the standard editor.

Design and estimating demonstration only. Sample prices are illustrative. Before manufacture, have a qualified designer verify rise, going, headroom, openings, loads, glass, guards, supports and connections for the actual installation. This is not a certified staircase design.