SPIRAL STAIRCASES, PLANNING AND DESIGN
Our drawing office is at your service for questions on the dimensioning, drawing and design of floor gratings.
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Staircase radius | Rise | Curved staircases | Headroom | Steps per revolution | Stair treads | Childproof | Handrail | Height, railing | Load, railing | Railing infills | Load on tread | Distance to wall | Stays | Attachment of landings | Attachment base plate | Fire resistance
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 |
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.
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.
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.
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.