Staircase radius Rise Right or left curved staircases Headroom Number of steps per revolution Childproof Handrail Height, railing Load, railing Load on tread Distance to wall Stays Attachment of landings Attachment base plate
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.
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).
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.
Fields marked (green) in the table are the staircase dimensions that should be aimed for during the planning stage.
|Radius steps/revolution||Tread depth along path*||Suitable riser|
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.
As standard handrails are made of stainless steel tube, Ø 42 mm. For wood handrails, the handrail is ø 50 mm as standard.
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 on tread
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.
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
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.
Generally, the distance to the base plate from the wall must be at least the stair’s radius plus 50 mm.