Staircase Terminology

Spiral stairs rotate around a central pole. They have a handrail on the outer side only, and on the inner side just the central pole. A spiral stair assumes a circular stairwell and the steps and handrail are equal and spaced screw-symmetrically. A small diameter spiral stair is very space efficient in the use of floor area.

Helical or circular stairs do not have a central pole and there is a handrail on both sides. These have the advantage of a more uniform tread width when compared to the spiral staircase.

Often used interchangeably with "stairs" the stairwell refers to the total space required to fit a stair in including the step, handrail and finger clearance.

At enzie all our stair sizes i.e 1300 1500mm actual refer to the size of the stair therefore clearly showing the amount of space required to fit a spiral stair in.

The part of the stairway that is stepped on. The tread "depth" is measured from the outer edge of the step to the vertical "riser" between steps. On a spiral stair the tread depth should be measure on the walking line (7/10 of the effecitve eidth of the stair)

The vertical portion between each tread on the stair, i.e the "step height. The number of risers on a spiral stair is always one more than the number of treads to allow for the landing

An edge part of the tread that protrudes over the riser beneath. If it is present, this means that horizontally, the total "run" length of the stairs is not simply the sum of the tread lengths, the treads actually overlap each other slightly

where stairs are open on one or both sides, the first step above the lower floor may be wider than the other steps and rounded. The balusters typically form a semi-circle around the circumference of the rounded portion and the handrail has a horizontal spiral called a "volute" that supports the top of the balusters. Besides the cosmetic appeal, starting steps allow the balusters to form a wider, more stable base for the end of the handrail. Handrails that simply end at a post at the foot of the stairs can be less sturdy, even with a thick post. A double bullnose can be used when both sides of the stairs are open.

Often refeered to as a "platform" the Landing is the connection between the top stair and the floor above, This landing can be finished in the same fashion as the rest of the stair or stepped down to allow for existing floor coverings to run over the top.

An intermediate landing is a small platform that is built as part of the stair between main floor levels and is typically used to allow stairs to change directions, or to allow the user a rest.

The balustrade is the system of railings and balusters that prevents people from falling over the edge.

The angled member for handholding, as distinguished from the vertical balusters which hold it up for stairs. The term "banister" is sometimes used to mean just the handrail, or sometimes the handrail and the balusters or sometimes just the balusters

The rise height of each step is measured from the top of one tread to the next. It is not the physical height of the riser; the latter excludes the thickness of the tread.

The going is measured from the edge of the nosing to the vertical riser. It is sometimes called the tread depth. On a Spiral Stair this measure is taken at 7/10th of the clear width from the centre (BCA).

The balustrade is the system of railings and balusters that prevents people from falling over the edge.

For curved stairs, the inner radius of the curve may result in very narrow treads. The "walkline" is the imaginary line some 7/10 from inner edge on which people are expected to walk.