Fire Escapes / Fire Exit Stairs Spiral staircases
The spiral staircase represents a special case among all the forms of circular stairs and requires the least space. Its main characteristic is the load-bearing column in the centre. Spiral staircases are often only mentioned as an aside in standard literature as there are no concrete provisions that regulate them.
Because of the special form of the steps we need to differentiate in principle between the clear tread width (distance between the central column and the inside edge of the banister hand rail) and the usable tread width (from 100 mm run, see DIN 18065) in spiral staircases.
Another special characteristic of spiral staircases is the shifting of the walking area from the centre to the outside at approx. 0.5 – 0.7 of the staircase radius. The smallest outer diameter of a staircase should not be less than 1,300 mm as this only allows severely limited use. A usable tread width of 1,000 mm can be achieved with an external diameter or approx. 2,900 mm.
The standard spiral staircase currently produced by MEISER has a central column with a corresponding step sleeve column. This means that we are in a position to realise a wide range of versions and customer requirements. In the basic form, four column pairs are used which can be selected according to the diameter and height of the staircase and in line with static requirements.
In order to avoid sleeve movement between the individual sleeves in our ‘push-fit system’ we also offer steel spacer rings as turned parts. Another possibility is a column that is split by storey with welded plates to screw on the individual steps. Step connections are achieved using a pipe sleeve and a special screw. Banister shafts are mounted to every second step using a screw connector.
One critical issue is the positioning of access landings above one another with a height between floors of approx. 4,000 mm. It is not possible to select a safe ratio of rise to run for every diameter in order to guarantee a minimum passage height of 2,000 mm.
The handrail on the central column and access security are supplementary measures that ensure safe use and protection from unauthorised access.
It is our job to propose the optimum solution to you. You can place your trust in our ability and our expertise.
Special requests from architects always present us with the challenge of realising the request in accordance with valid regulations. We are also a strong partner in the manufacture of complex welded structures.
MEISER holds the manufacturing qualification in the welding of steel structures in accordance with DIN 18800 Part 7; 2002-09 Class C.
Taking into account experience gained from accidents, the step measurement formula is applicable from a safety perspective if it leads to rises of between 140 and 190 mm and runs between 320 and 260 mm. The relative size of the rise and run take into account
the average persons step measurement.
The following is valid for a staircase that is easy to walk on:
2x (s) rise + (a) run = 630 ± 30 mm
The angle of climb should be between 30° and 45°.
A rest landing should be included after a maximum of 18 steps (per flight of stairs).
Grating flooring on spiral staircases is fitted with anti-skid protection as standard without a non-slip front edge, and welded in a surrounding frame in flat-rolled steel (outer edges are straight and of uniform height). An additional welded, non-slip front edge forms the connection to the straight grating step in accordance with DIN 24531. It improves
safety during the use of spiral staircases, but is not officially required.
Not every building is suited to the mounting of a staircase system at all points. Our design engineers and structural engineers will, however, always provide you with a special solution to connect the staircase to the building safely.
The connection to the building is an important element in the overall structural concept. We always work with our customers to find the best solution; a solution that fulfils all requirements so that it is simultaneously architecturally justifiable and statically verifiable.