SPIRAL STAIRCASES, PLANNING AND DESIGN

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Staircase radius

The staircase radius is the dimension from the staircase’s centre to the outer edge of the handrail. Weland manufactures spiral staircases with a radius of 600 to 1500 mm. Within this range, there are standard radiuses on even decimeters.

Rise

The rise should be chosen based on the given height between the landings. A suitable radius and the number of steps per revolution then determine the step rise.

The step rise should be between 160 and 220 mm. The lower the rise you choose, the deeper the step needs to be. The normal rise is about 170 to 180 mm.

The formula for the rise is 2 x h + W = 580-640.

Right or left curved staircases

Weland spiral staircases are manufactured curved to the right or the left. Right curved staircase means that it curves to the right while ascending (centre tube to the right while ascending).

Headroom

The headroom on the stairs must not be less than 2000 mm. The height is measured between two points located directly below each other.

Measure from the top edge of the lower step’s nose to the lower edge of the level’s (step) rear edge.

Number of steps per revolution

The step template on the right helps you plan the staircase solution and to determine the number of steps per revolution. The table below shows the tread depth along the path line for each radius and suitable riser heights.

Number of steps per revolution

Radius steps/revolution	Tread depth along path*	Suitable riser
600/14	157	200-220
600/15	147	200-220
600/16	137	200-220
700/15	188	200-220
700/16	177	200-220
700/17	166	200-220
700/18	157	200-220
800/16	216	180-210
800/17	203	180-210
800/18	192	190-220
800/19	182	190-220
800/20	173	190-220
900/16	255	175-200
900/17	240	175-200
900/18	227	175-200
900/19	215	180-210
900/20	204	180-210
900/21	194	180-210
1000/16	294	165-185
1000/17	277	165-185
1000/18	262	165-185
1000/19	248	175-200
1000/20	236	175-200
1000/21	224	180-210
1000/22	214	180-210
1000/23	205	180-210
1100/18	297	165-180
1100/19	281	165-180
1100/20	267	165-190
1100/21	254	170-200
1100/22	243	170-200
1100/24	232	170-200
1100/25	222	170-200
1200/17	351	155-190
1200/18	331	155-190
1200/19	314	155-190
1200/20	298	155-190
1200/21	284	155-190
1200/22	271	160-200
1200/23	259	170-200
1200/24	249	170-200
1300/18	366	155-180
1300/19	347	155-180
1300/20	330	155-180
1300/21	314	155-180
1300/22	300	155-190
1300/23	287	155-190
1300/24	275	155-190
1400/20	361	155-180
1400/21	344	155-180
1400/22	328	155-190
1400/23	314	155-190
1400/24	301	155-190
1400/25	289	155-190
1400/26	278	155-190
1500/22	357	150-180
1500/23	341	150-180
1500/24	327	150-180
1500/25	314	155-180
1500/26	302	155-180
1500/27	291	155-180
1500/28	280	155-180

Stair treads

Additional information about our range of treads.

Grating

Grating stair treads with 33×50 mm mesh width. Hot-dip galvanized finish.
We recommend 17×75 mm if a closer mesh width is required.

Tear plate

Tear plate treads with a hot-dip galvanized finish.

Perforated grip plate

Perforated grip plate treads with a hot-dip galvanized finish. Hole pattern ø 10 mm with 30 mm triangular pitch. Half of the holes have a raised edge for best scraping performance.

Grey concrete

Grey concrete stair treads. Thickness 50 mm. The tread surface is finely brushed. The other sides are smooth cast. If the staircase is outdoors, the tread surface is coarsely brushed. The concrete rests on a support frame of sheet metal profiles.

Terrazzo concrete

Terrazzo concrete stair treads. Thickness 50 mm. The tread surface is finely brushed. The other sides are smooth cast. The concrete rests on a support frame of sheet metal profiles. This type of tread is suitable for outdoor use.

Sheet metal for floor tiles

Stair treads shaped like a metal box for laying tiles. The standard depth of the metal box is 27 mm.

Sheet metal for carpet

Stair treads that are to be carpeted come with a sheet metal tread designed for carpets. Stair nosing should be used if it is not possible to fold the carpet over the front edge.

Ash

Ash wood stair treads of solid, glued laminated timber, 30 mm. Coated with hardened lacquer as standard.

Birch

Ash wood stair treads of solid, glued laminated timber, 30 mm. Coated with hardened lacquer as standard.

Beech

Beech wood stair treads of solid, glued laminated timber, 30 mm. Coated with hardened lacquer as standard.

Oak

Oak wood stair treads of solid, glued laminated timber, 30 mm. Coated with hardened lacquer as standard.

Childproof

Childproof means that none of the openings in the staircase are permitted to be larger than 100 mm up to a railing height of 800 mm.

Handrail

As standard handrails are made of stainless steel tube, Ø 42 mm. For wood handrails, the handrail is ø 50 mm as standard.

Since 2003, we have used stainless steel handrails in our spiral staircases.
We see a number of customer benefits in this, such as a more beautiful product with an even higher sense of quality. Combined with our modern production park, the stainless steel handrail also contributes to very fast delivery times.
Many years of experience with a proven method and a good relationship between anode and cathode where the results do not show any rust, make us very confident that the relationship between hot-dip galvanized and stainless does not cause any corrosion.

Height, railing

The height of the railing is 1100 mm at the nose of the step. Extra handrails are placed at an optional height inside the balusters, for example, 900 mm. The railing height of the landing is 1100 mm as standard.

Load, railing

The railing is dimensioned to withstand a load of 1.0 kN/m handrail.

Railing infills

Additional information about our range of railing infills.

Standard

One U-baluster per step, mounted on the outside of the stair tread’s end.

Hoop

A simpler form of child-proof railing with a hoop welded to a U-baluster. No opening in the railing is wider than 100 mm.

Round bar

The railing infill comprises 25×8 mm flat-steel top and bottom rails. Round bars ø11 mm. Max. opening 100 mm.

Intermediate rail

1-4 intermediate rails made of 50×3 mm flat steel. An intermediate rail can be used on high industrial staircases.

Sheet metal

We offer perforated sheet metal with a choice of hole patterns as standard.
Our most common patterns:

ø15, square pattern c/c 40
15×15, square pattern c/c 40
ø20, square pattern c/c 50
20×20, square pattern c/c 50
ø15, triangular pattern c/c 50
ø20, triangular pattern c/c 60

Other options are available.

Woven wire mesh

Woven wire mesh with standard 40×40 mm apertures. 30×30 mm apertures also available.

Glass

8 mm tempered laminated glass set in layers.

Load on tread

The stair treads are dimensioned for a distributed load of 5.0 kN/m² or a point load of 5.0 kN.

Distance to wall

The spiral staircase’s external radius must be at least 50 mm from walls. The tread depth is calculated along an imaginary path 250 mm from the radius.

Stays

The spiral staircase must be fitted with stays every revolution (2.5 to 3 metres in height). This can be done using the square landing fixing. If the stairs have no square landing on each revolution, bracing must be fitted between the step and wall using custom stays.

When the spiral staircase cannot be braced to an adjacent wall, it needs to be stabilised using a vertical stay. These are attached at the bottom against the completed floor or foundation.

Attachment of landings

Use suitable type of screw taking into consideration the materials at the attachment points.

Attachment base plate

Use suitable type of screw taking into consideration the material at the attachment point.

A base must be cast to fasten spiral staircases when there is no existing platform. Wind strengths, etc. must be taken into consideration when designing this.
Note that attachment at the first step must also be done.

Generally, the distance to the base plate from the wall must be at least the stair’s radius plus 50 mm.

Fire resistance rating R30

We also offer spiral staircases with fire resistance rating R30. Requests for specific sizing should be stated in the contract documents.