Stair Glossary
Find out all the important definitions and measurement rules in the staircase construction regulations and DIN 18065:2011-06.
Clear Stair Passage Height
Measured as the vertical finished dimension above an inclined plane formed by the front edges of the steps, or from horizontal landing surfaces to the underside of elements above.
Clear Step Gap
The vertical finished dimension between the tread surface and the underside of the step above, measured in slab steps.
Closed Staircase
Staircase without openings between the treads.
Compensation Step
Step between two levels with a minor height difference.
Essential Staircase
A staircase required by regulations (e.g., building codes) as part of an emergency escape route.
Intermediate Landing
Flat platform between two stair runs or located between floor levels.
Non-Essential Staircase
An additional staircase that may also serve primary usage.
Open Staircase
Staircase with openings between the treads.
Rise-Run Ratio
The ratio of riser height to tread depth (s/a), indicating the stair’s slope, given in millimeters (e.g., 172/280).
Riser
Vertical or nearly vertical component of a step.
Side Clearance
The clear finished dimension between the stair run, landing, or handrail and adjacent structures such as walls, railings, or central supports.
Stair Handrail
Securely graspable component serving as a walking aid, attached to the railing and/or wall, or as an intermediate handrail on wide stairs.
Stair Landing
Flat platform at the beginning or end of a stair run, often part of the floor structure.
Stair Railing
Safety barrier to prevent falling from stair runs and landings.
Stair Railing Height
The vertical finished dimension from the step’s front edge or landing surface to the top edge of the railing.
Stair Rise s
The vertical dimension from the tread surface of one step to the tread surface of the next step along the walking line.
Stair Run
Structural component supporting the steps; also known as a stair beam.
Stair Run Length
The plan dimension measured along the walking line from the front edge of the starting step to the front edge of the last step.
Stair Run Line
Design line indicating the typical walking path on a staircase, located within the walking area.
Stair Run Width
The construction width measured in the plan view, bounded by structural elements such as walls.
Stair Side Stringer
Side structural component supporting the steps and often delimiting the stair run.
Stair Spindle
Central structural element supporting a spiral staircase.
Stair Step
Part of a staircase comprising the riser and tread, typically climbed in one step.
Stair Stringer
Structural component supporting the steps; also known as a stair beam.
Stair Tread Depth a
The horizontal distance from the front edge of one step to the projection of the front edge of the next step along the walking line.
Staircase
A fixed, immovable construction consisting of at least one stair run, used to traverse height differences between at least two levels by stepping.
Staircase Core
Open space enclosed by stair runs, landings, or railings.
Staircase Opening
Recess in the floor structure to accommodate the staircase.
Staircase Start Step
The first (lowest) step of a stair run.
Step Length l
The length of the smallest rectangle enclosing the step’s edge in its installed position.
Step Overhang u
The horizontal dimension by which the front edge of a step projects beyond the tread surface of the step below.
Step Thickness d
The maximum height (thickness) of solid steps, wedge steps, and slab steps, or the maximum thickness of tread surfaces for angle-shaped steps.
Step Width b
The width of the smallest rectangle enclosing the step’s front edge in its installed position.
Story Staircase
Staircase connecting two stories.
Straight Tread
Tread with a front edge parallel to the front edge of the following tread, typically rectangular in top view.
Tread
Horizontal or nearly horizontal component of a step.
Tread Surface
Horizontal or nearly horizontal surface of a step that is walked upon.
Tread Surface Location
The tread surface location in the stair width is determined at the front edge of the step, and in the stair depth, it is measured vertically to the front edge within the walking area.
Usable Stair Landing Depth
The usable depth of a stair landing is the clear finished dimension measured at handrail height between bounding elements (e.g., walls or railings) and the inner edges of handrails or front edges of steps.
Usable Stair Landing Width
The usable width of a stair landing is the clear finished dimension between bounding elements (e.g., walls or railings) and the inner edges of handrails or front edges of steps.
Usable Stair Run Width
The usable width of a stair run is measured as the clear finished dimension between bounding elements (e.g., walls or railings) and the inner edges of handrails or front edges of steps.
Winder Step
Tread, typically used in a spiral, with a front edge not parallel to the following tread.