Spiral staircase design guide: sizes, comfort, and fabrication

A spiral staircase solves two problems at once. It fits where a straight stair will not, and it can become the most striking object in a room. But a spiral that is too tight or badly set out is uncomfortable and unsafe. This guide covers the decisions that make a good one.

Spiral vs helical

A spiral staircase has treads fixed to a central column. It is compact, economical, and relatively simple to install. A helical staircase has no central column. The treads span between curved stringers, or cantilever from a single curved stringer. Helical stairs are more open and dramatic, and need more engineering and specialist rolling.

Choosing the diameter

Diameter is the most important decision. Bigger is more comfortable, because the walking line has deeper treads, but it takes more space.

• Compact diameters suit occasional access to roofs, plant platforms, and storage mezzanines.
• Medium diameters suit regular use in villas and offices.
• Large diameters suit public and retail spaces, and stairs used to carry things.

We recommend you walk a few spirals before deciding. A site visit helps us propose the right size for the opening.

Rotation, treads, and headroom

The number of treads depends on the floor-to-floor height and a comfortable riser. The rotation, how far the stair turns from bottom to top, depends on how many treads there are and how wide each is. Rotation decides where you step off at the top, so it must suit the landing and the door. Headroom is checked where the stair passes under the floor opening above. All of this is set out in shop drawings before fabrication.

Code considerations

Spiral stairs are generally fine for private use and secondary access. They usually cannot serve as the main escape stair in a commercial building, because fire codes set minimum tread depths and widths that compact spirals do not meet. In Dubai, check the Dubai Building Code and UAE Fire and Life Safety Code with your consultant.

Materials and finishes

• Treads: chequered plate, folded plate, grating (outdoor), or pans for timber and stone
• Balustrade: vertical bars, rods, mesh, or glass
• Handrail: rolled steel tube, or timber capping on steel
• Finish: powder coat or paint indoors, and galvanizing plus paint outdoors

Outdoor spirals in Dubai

Roof access spirals are popular on villas and warehouses. Outdoors, sun, sand, and humidity are hard on steel, so galvanize and paint the stair, use grating or perforated treads so sand does not build up, and specify stainless fixings.

How we fabricate a spiral staircase

1. Measure the opening, floor-to-floor height, and landing position on site.
2. Prepare shop drawings with the diameter, treads, rotation, and balustrade.
3. Fabricate the column, treads, and landing, and roll the handrail to radius.
4. Trial-assemble in the workshop, then finish.
5. Install, align, and fix on site.

See our work

We built an external spiral staircase in Sharjah Industrial Area 15 and a curved feature stair at a Dubai Mall site. Looking for a spiral staircase fabrication company in Dubai? Send us the opening size and height.