What is a cantilevered staircase?
A cantilevered staircase, often called a floating staircase (in Dutch zwevende trap), is a staircase whose treads are fixed to a wall on one side only. On the other side there is no stringer or support, so the treads appear to float.
Originally the term referred to a staircase without risers: separate treads, each fixed into the wall individually. Today it is also used for stairs where treads and risers are joined into one folded unit, as long as they are fixed to the wall on one side only.
Structure
Each tread acts as a cantilever beam: the entire load must be carried through the fixing in the wall. Someone standing at the free end creates the largest bending moment at the fixing. Therefore:
- The wall must be suitable: a solid, load-bearing wall or a purpose-built steel structure. An ordinary stud partition is not suitable without additional measures.
- Fixing: often a steel stringer or steel brackets anchored in or against the wall, onto which the treads are slid. Treads cast or built into the wall also occur.
- Stiffness: the structure must be designed so that the stair does not feel bouncy or wobbly.
Always have a cantilevered staircase designed by a structural engineer. Building regulations also set requirements for stairs, handrails and guarding.
Pros and cons
Pros
– Light, open and an architectural eye-catcher.
– Lets light and views pass through the space.
Cons
– Without a handrail on the free side there is nothing to hold: less suitable for children, older people and anyone with poor balance.
– Some people feel the stair is not sturdy enough, even when it is.
– More expensive and complex than a standard staircase, and hard to alter afterwards.
Related terms
- Stair tread
- Stair riser
- Stair stringer
- Stair handrail
- Open riser staircase
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