Types of stairs

[edit] Introduction

Stairs are used to create a pedestrian route between different vertical levels by dividing the height between the levels into manageable steps. Very generally, the word 'stairs' refers to a staircase, whereas the word 'step' refers to the steps that make up the staircase.

The type of stairs suitable for different situations will depend on:

• The supporting structure.
• The amount and type of usage it is likely to receive.
• The space available and its geometry.
• The difference in height between the top and bottom.
• Materials selection

Stairs may be:

• Open tread or closed tread.
• Provided with handrails on one or both sides, or in the middle on wide stairs.
• Enclosed by walls or open on one or both side.
• Different widths and lengths and may have a range of step dimensions.
• Different geometries.

[edit] Geometries

Some of the most common types of stair geometry include:

[edit] Straight

Generally the most prevalent type of stairs, straight stairs comprise a single linear flight which does not change direction.

Where there are more than 36 risers in consecutive flights of stairs, Approved Document K requires that there is at least one change of direction, with a landing that has a minimum length equal to the width of the stairs.

[edit] Quarter-turn

Quarter-turn, or L-shaped, stairs comprise a straight flight of stairs that makes a 90-degree turn after a landing. This type can be considered safer than a straight staircase since the landing reduces the number of treads in one flight and provides a place to rest.

[edit] Winder

This type of stairs is similar to a quarter-turn staircase, but consists of winders which are wedge-shaped treads, wider on one side than the other. Winders allow a turn by 90-degrees (single winder) or 180-degrees (double winder).

For more information see: Winder.

[edit] Half-turn

Half-turn, or U-shaped, stairs comprise two straight flights of stairs that make a 180-degree turn having been separated by a landing.

[edit] Spiral

This type of stair is a compact design with flights resembling a circle (or part of a circle), and centred around a single vertical column. Similar to winder stairs, the treads are wedge-shaped but differ in that they are all uniformly sized (except the final one).

Although spiral stairs are often considered to be aesthetically pleasing and effective in terms of space, they may not be the most convenient in terms of frequent use as the treads can often be less easy or safe to traverse than other types of stairs.

[edit] Helical

A helical stair similar to a spiral stair, but the helix wraps around a central void rather than a column.

[edit] Curved

Also known as arched stairs, this type of stair comprises a continuous flight that is shaped like an arch, with no landings. The treads are wedge-shaped similar to winder stairs. Although achieving an elegant aesthetic, curved stairs are difficult to construct since all basic details, banisters, and so on, need to be curved.

[edit] Bifurcated

Bifurcated stairs comprise a grand and sweeping set of stairs that divides into two smaller flights that split off into opposite directions.

[edit] Compact

This type of stairs, also known as narrow stairs, are often designed as a solution to confined space within a building. They comprise distinctive treads that are designed to take one foot only.

[edit] Alternating tread

A stair with paddle-shaped treads where the wide portion is on alternate sides on consecutive treads. On older stairs, they tread may sometimes just alternate from one side to the other. This is sometimes referred to as a 'witches stair' because of the belief that witches were unable to climb them.

[edit] Uses

Different types of stair use include:

[edit] Utility stair

Approved document K defines a 'utility stair' as '...a stair used for escape, access for maintenance, or purposes other than as the usual route for moving between levels on a day-to-day basis.'

[edit] General access stair

Approved document K defines a 'general access stair' as '...a stair intended for all users of a building on a day-to-day basis, as a normal route between levels.'

[edit] Private stair

Approved document K defines a 'private stair' as '...a stair intended to be used for only one dwelling'

[edit] Protected stair

Approved document B defines a ‘protected stair’ as ‘…a stair discharging through a final exit to a place of safety (including any exit passageway between the foot of the stair and the final exit) that is adequately enclosed with fire resisting construction’.

See: Protected stairway for more information.

[edit] Firefighting stair

Approved document B defines a ‘firefighting stair’ as ‘… a protected stairway communicating with the accommodation area through a firefighting lobby’.

[edit] Common stair

Approved document B defines a ‘common stair’ as ‘… an escape stair serving more than one flat’.

[edit] Related articles on Designing Buildings

• Alternating tread stairs.
• Banister.
• Landings in buildings.
• Maximum length of a flight of stairs.
• Spiral stairs and helical stairs.
• Stair design.
• Stairs going.
• Stairs nosing.
• Stairs riser.
• Stairs string.
• Stairs tread.
• Winder.