- Spiral staircase: a choice to consider well
- Recommended dimensions of steps
- Methods of fixing the spiral staircase
- The central pivot
- The rule of Blondel
- Stairs with screws: elements in kit to assemble
Like endless screws, these flights make you turn your head. They remain the solution saving space par excellence, sometimes to the detriment of comfort.
Spiral staircase: a choice to consider well
The spiral staircases meet a growing success because they are often aesthetic and offer the possibility of being inserted in small hoppers. Because their stride line forms a propeller, they are the ones with the smallest footprint and are satisfied with the smallest spaces. They can be lodged between four walls, but remain mostly apparent to fit the decor. In this case, a standard railing is required, security requires. This type of staircase is usually without risers, a feature that gives it a more contemporary appearance and promotes brightness.
The smallest of them fit in hoppers of 1.20 to 1.30 m with a step of 50 cm. But there is a flip side: if you gain a significant gain of space, the staircase is less comfortable and better not to think of mounting a sommier upstairs. To reserve therefore for secondary uses. When used in main access, the helical must measure 2 m in diameter with a step of 90 cm and more. Conditions that require to have a hopper of 2 x 2 m minimum. When the required space is lacking, you should know that this type of staircase is not necessarily a panacea. For example, with a 1.60 x 1.60 m hopper, walking will be only 18 or 19 cm on the stride line (about the middle third), while it can be raised to 23 cm with a model two rotating districts. From where a better comfort to the rise and especially to the descent.
In fact, spiral staircases (also called screw or spiral staircases) are a variant of balanced stairs. Their design and realization follow the same principles. Only differences: they only have radiant steps and converge towards a central point. Two types are proposed: central core (the steps are connected to a drum) or daylight (also called central light) when they present two silts. In this case, the core may be a solid wall or openwork.
Recommended dimensions of steps
If comfort of use is not preponderant, the steps can be content with a useful width of 80, even 60 cm.
For optimum comfort, the useful width can be increased to 120 cm, a diameter of 270 cm.
Methods of fixing the spiral staircase
The barrel is fixed to the ground, usually by means of a plate, using expansion plugs. The fixing is to be adapted to the case by case according to the nature of the soil.
The central pivot
Spine, the central core is imperatively fixed at the head and foot in accordance with the recommendations of the manufacturer. It is never freestanding except in special cases that are the subject of a study.
The rule of Blondel
For turning marches, the rule of Blondel is to be respected on the line of stride. The outer lap must be less than or equal to 42 cm and the inner lap greater than 9 cm.
Stairs with screws: elements in kit to assemble
Metallic or not, these stairs are usually provided in separate elements (central shaft, steps, guardrails, bearings, screws...), and mounted on site as a kit with reduced tools.