Helical or Spiral Staircase in Saudi Arabia: How to Choose the Right One
Take a floor-to-floor height of 3.0 m and a comfortable 250 mm tread depth at the walking line. A spiral staircase then needs a circle 2.0 m wide, while an open-well helical stair wants 2.4 m and gives you a gentler turn. Those two figures come from the worked example further down, and they show better than any definition what separates a helical or spiral staircase in practice.
The two names get swapped constantly, even by suppliers. That matters, because a quotation for a “spiral staircase” can describe two different structures, one needing a larger footprint and heavier engineering than the other. Choosing between a helical or spiral staircase in Saudi Arabia comes down to the floor area you can spare and how the stair carries its load, then to what your code consultant accepts under the Saudi Building Code.
Helical or spiral staircase: the short answer
A spiral staircase has a central vertical column, and the treads fan out from it. The column carries the weight. A helical staircase has no central column. The treads wind around an open well, usually called the eye, and the load travels through one or two curved stringers instead.
That one structural difference drives almost everything else: how wide the stair must be, how each tread feels underfoot, how long it takes to engineer, and what it looks like from the floor below.
| Feature | Spiral staircase | Helical staircase |
|---|---|---|
| Support | Central column, treads cantilevered from it | Curved stringer or stringers, open center |
| Open eye in the middle | No | Yes |
| Circle needed for a 3.0 m rise (worked example) | 2.0 m, 3.14 m² | 2.4 m, 4.52 m² |
| Rotation to climb 3.0 m at a 250 mm going | 436.5° | 286.5° |
| Walking width (in the example) | 950 mm | 800 mm |
| Engineering and fabrication | Simpler, many repeated parts | Heavier engineering, stringers rolled to an exact radius |
| Sightlines | Column and tread edges interrupt the view | Light and sightlines pass through the eye |
| Where it usually fits | Secondary stair, mezzanine, compact feature | Main feature stair in a lobby, villa or showroom |
Every number in the table comes from the space test below, so you can rerun the helical or spiral staircase comparison with your own dimensions.
Why the two names get mixed up
What the geometry says
Strictly speaking, a spiral is a flat curve and a helix is a curve in three dimensions. The University of Luxembourg’s notes on helices and spirals point out that everyday speech blurs the two, and they use the spiral staircase as their example. A stair climbs, so every curved stair, with a column or without one, follows a helix. “Spiral” is just the name that stuck.
What an 1860 dictionary said
The 1860 edition of the Encyclopaedia Britannica, in its entry for “helix”, records a distinction credited to Daviler. A stair was helical when its steps wound round a cylindrical newel. A spiral one wound round a cone and kept closing in on its axis. That is close to the reverse of the modern workshop habit, where the column stair is called spiral and the open-well stair is called helical. Nobody is wrong. The vocabulary drifted.
What it means for your quotation
Since the words overlap in conversation, a drawing labelled “spiral” can show an open-well stair, and a supplier can price a column stair against it. Arabic specification sheets have the same weakness: a line that only says سلم حلزوني doesn’t tell a fabricator which of the two you want. Add one sentence to every request, either “central column” or “open well, no column”. It takes five seconds and removes the most common reason two quotes can’t be compared.
The space test for a helical or spiral staircase: a worked example for a 3.0 m rise
Most guides stop at “helical stairs need more space”. Here is how much more, with the arithmetic on show.
The assumptions
Floor-to-floor height is 3,000 mm. With a maximum riser of 180 mm, 3,000 ÷ 180 = 16.67, so the stair needs 17 risers of 3,000 ÷ 17 = 176.47 mm each. That gives 16 treads, because the upper floor acts as the last step.
The target going, meaning tread depth at the walking line, is 250 mm, and the walking line sits at mid-width. The spiral stairs have a 100 mm column and outer diameters of 1,600 mm and 2,000 mm. The helical stair has a 2,400 mm outer diameter and an 800 mm eye.
These are illustrative figures for a helical or spiral staircase, not code limits. Codes set their own minimum going and define the walking line in their own way, so your consultant has to rerun the sums with the project’s values.
The calculation
Walking-line radius is the average of the inner and outer radius. Angle per tread is the going divided by that radius, converted from radians to degrees. Total rotation is the angle per tread times 16. Rise per full turn is 360 divided by the angle per tread, times 176.47 mm.
For the 2.0 m spiral: (50 + 1,000) ÷ 2 = 525 mm. Then 250 ÷ 525 = 0.4762 rad, which is 27.28°. Sixteen treads give 436.5° of rotation, and one full turn climbs 13.19 × 176.47 = 2,328 mm. The other two cases follow the same steps.
| Spiral, 1.6 m | Spiral, 2.0 m | Helical, 2.4 m | |
|---|---|---|---|
| Walking-line radius | 425 mm | 525 mm | 800 mm |
| Angle per tread | 33.70° | 27.28° | 17.90° |
| Total rotation | 539.3° | 436.5° | 286.5° |
| Rise per full turn | 1,885 mm | 2,328 mm | 3,548 mm |
| Clearance under a 250 mm slab | 1,635 mm | 2,078 mm | Not applicable |
| Going if the stair made one 360° turn | 167 mm | 206 mm | 314 mm |
| Floor area of the circle | 2.01 m² | 3.14 m² | 4.52 m² |
What the numbers show
The 1.6 m spiral needs 539° of rotation, a turn and a half, to reach the upper floor at a 250 mm going. One full turn climbs only 1,885 mm. Take away a 250 mm slab and 1,635 mm is left where the stair passes beneath its own floor. Nobody’s head clears that. The fixes are a wider circle or a shorter going, and a shorter going means steeper, meaner treads: squeeze the same stair into one turn and the going falls to 167 mm.
The 2.0 m spiral turns 436.5° and leaves 2,078 mm under the same slab, which works if the headroom your consultant requires is lower than that. The helical stair turns 286.5° and never passes under itself, so the headroom problem simply doesn’t arise. You pay for that in floor area: 4.52 m² against 3.14 m², or 44% more.
Run this check before you fall for a render of any helical or spiral staircase. A stair that turns past 360° has to be tested for headroom, and many attractive spiral designs fail on exactly that point.
How each stair carries its load
Spiral: a column and cantilevered treads
Each tread is a small cantilever fixed to the central column. The column takes the bending from every tread and passes it to the base fixing, which is why column diameter, wall thickness and base plate deserve real attention. Rounuq’s spiral staircase design and planning guide goes through those components, the tread materials and the handrail options in detail.
Helical: the stringer becomes a curved beam
With no column, the weight of the treads and everyone on them has to travel along the stringer. That makes it a curved beam in bending and in twist. Helical stairs therefore tend to need a deeper or closed stringer section, careful connections at the top and bottom landings, and steel rolled to the exact radius before it’s welded. It is the main reason an open-well stair usually costs more to engineer than a column stair of the same height.
Where the Saudi Building Code comes in
The Saudi Building Code Center publishes the 2024 code set online, including SBC 201 (the general building code) and SBC 801 (fire protection), alongside SBC 306 for steel structures. Which provisions govern your helical or spiral staircase depends on the building type, the occupancy and whether the stair forms part of an exit route.
International model codes treat a “spiral stairway” as a defined category with its own limits, separate from ordinary curved stairs. Whether SBC 201 draws the same line is a question for the code text and your consultant, and so is the edition in force for your permit. Don’t copy tread or riser dimensions from a guide written for another country, including this one.
Materials and finishes for Saudi conditions
Whichever helical or spiral staircase you pick, the finish decides how it ages. Indoors, powder-coated mild steel is the usual starting point, and Rounuq’s page on architectural powder coating covers how to specify a finish that survives Saudi conditions.
Outdoors, location matters. Riyadh brings high summer heat and fine dust that wear coatings and settle into textured treads. Coastal areas on the Red Sea and the Arabian Gulf add humid, salt-laden air, and there 316 stainless steel is the safer choice. The comparison of 304 and 316 stainless steel lays out the trade-off.
For a feature stair, a PVD finish can color the handrail or stringer. One caution for helical designs: a long continuous stringer shows every weld mark and surface flaw along its whole length, so surface preparation matters more than the color you choose.
Handrails deserve the same thought on any helical or spiral staircase. On a helical stair the rail follows one continuous three-dimensional curve, and stainless steel handrails tend to look cleaner when that curve is formed in as few pieces as possible.
Living with the stair every day
Tread shape is where a helical or spiral staircase differs most underfoot. In the 2.0 m spiral the tread depth runs from 24 mm at the column to 476 mm at the rim, so only the outer part is really walkable. In the 2.4 m helical stair the depth runs from 125 mm at the eye to 375 mm at the rim, a much narrower spread, and the useful part is wider.
Walking width matters for furniture on any helical or spiral staircase. In the example the spiral tread is 950 mm long and the helical tread is 800 mm, and either way a sofa or a wardrobe has to swing round a curve. Plan the delivery of bulky items through a window or by crane before you plan the stair.
Households with elderly relatives or young children should look hard at the tread numbers above. A deeper, more even tread favors a helical stair or a straight one over a tight spiral. If the stair is the only way between floors, settle the code category before the style.
Buying in Saudi Arabia: what to check before you accept a quotation
Saudi VAT is 15% on most goods and services. Check whether each quotation shows prices before or after tax, because a line of SAR 1,000 becomes SAR 1,150 once VAT is added. The ZATCA VAT page links the official regulations and registration details.
Before you commit to a helical or spiral staircase, make sure every supplier is pricing the same thing. Ask each one to state:
- Whether the stair has a central column or an open well.
- The outer diameter and, for a helical stair, the eye diameter.
- The total rotation, or the position of the exit on the upper floor.
- The walking width and the going at the walking line.
- The tread material and its thickness. Stone adds weight and changes the structure.
- The handrail and balustrade type.
- The finish, and whether the stair is indoors or outdoors.
- Whether fabrication drawings, installation and VAT are included.
Rounuq Almsar’s spiral staircase service covers custom stairs adjustable by height, radius, tread style and material, in stainless steel, mild steel or aluminum, and the company says each unit is built in-house. It is based on Al Kharj Road in Riyadh’s New Industrial Area. If your drawings show an open-well helical form instead of a column stair, send them over with the floor-to-floor height and the opening size and ask for a feasibility review before you lock in either type.
The company’s ladders and staircases range also lists straight and emergency stairs. A straight flight is often the better answer when the stair is the main route between floors.
Which one should you choose?
The right helical or spiral staircase depends on the site more than on taste. Choose a spiral staircase when the floor opening is tight, the stair is a secondary route or a mezzanine access, and you’re happy for a central column to be part of the look. Choose a helical staircase when the stair is the centerpiece, you want an open eye and a long handrail curve, and you can spare a wider circle.
Use this three-step test to settle the helical or spiral staircase question:
- Work out the total rotation at your target going, using your site’s floor-to-floor height.
- If the rotation passes 360°, calculate the clearance under the floor above and compare it with the headroom your consultant requires. Enlarge the circle, or move to helical, if it fails.
- If the stair is the main route between floors, or could count as an exit, get the code category confirmed before you choose a style.
Mistakes that cause redesigns
The first mistake on a helical or spiral staircase is measuring height from the wrong datum. A 20 mm error in total height, spread over 17 risers, adds 1.18 mm to each one, or lands as a single odd riser if nobody catches it. Codes restrict how much one riser may differ from the next, so confirm finished floor levels before fabrication starts.
The second is picking a heavy tread material late. Stone and glass change the loads on the column or stringer, so the structural design has to start from the final material.
The third is forgetting delivery. A helical stringer can arrive in long curved sections, and a narrow lift or stairwell can stop them from reaching the floor they’re meant for.
Helical or spiral staircase: frequently asked questions
What is the main difference between a helical and a spiral staircase?
A spiral staircase is carried by a central column. A helical staircase has an open center and is carried by curved stringers. In everyday talk the words are often swapped, so state “central column” or “open well” in any request for a quotation.
How much space does a spiral staircase need?
In the worked example, a 3.0 m rise at a 250 mm going needs a circle 2.0 m wide, and it turns 436.5° to reach the upper floor. A 1.6 m circle needs 539° and leaves only 1,635 mm of clearance under a 250 mm slab. Those are illustrative figures, so rerun them with your consultant’s code values.
Is a helical staircase bigger than a spiral staircase?
For the same rise and tread depth, yes. In the example the 2.4 m helical stair covers 4.52 m² against 3.14 m² for the 2.0 m spiral, which is 44% more floor area. It turns less than a full circle, so it never passes under its own floor.
Which costs more, a helical or a spiral staircase?
A helical stair usually costs more because the stringers carry bending and twist and have to be rolled and welded accurately. Final price also depends on diameter, tread material, handrail, finish, installation and 15% VAT. Ask for a written quotation against a defined specification.
Can a helical or spiral staircase be used as an emergency exit in Saudi Arabia?
Not automatically. It depends on the building type, the occupancy and the provisions of the Saudi Building Code that apply to the project, so ask your code consultant before the design is fixed. Dedicated emergency stairs are a separate product category.
Which material suits a staircase in Saudi Arabia?
For a helical or spiral staircase indoors, powder-coated mild steel is a common choice. Stainless steel suits premium interiors and humid or coastal sites, and 316 grade is the usual choice near the sea. For outdoor stairs inland, the coating system matters more than the color.
Can I fit a helical or spiral staircase in an existing villa?
A helical or spiral staircase can be fitted when the floor opening and the site access allow it. Cutting a new opening in a slab needs structural approval, and the delivery route for the components has to be checked first. Share drawings and site photos with the fabricator early.
What information does a fabricator need to quote a custom staircase?
Floor-to-floor height, the opening size and shape, whether you want a column or an open well, tread and handrail materials, the finish, and whether the stair is indoors or outdoors. Drawings and site photographs speed up the feasibility review.
Getting a quote you can compare
Choosing a helical or spiral staircase is easier once the numbers are on the table: the height, the circle you can spare, the rotation and the clearance. Bring those to a fabricator and the conversation moves from style to engineering, which is where good staircases get decided.
To discuss a helical or spiral staircase project, you can talk to Rounuq Almsar’s team about a custom staircase or send drawings through the contact page.