Describe what stair construction is. Define terms associated with stair construction. Calculate the unit rise, unit run, angle of incline, and number of treads for a stairway given the total run and rise.
STAIR – a series of steps, each elevated a measured distance, leading from one level of a structure to another. “Flight of Stairs” – a continuous series of steps without breaks formed by landings or other constructions
Types of Stairs ◦ Main Stairs Straight Run, Platform, and Winding ◦ Service Stairs Stairways are usually not built or installed until after interior wall surfaces are complete and finish flooring has been laid.
Stairwell – the rough opening in the floor above to provide headroom for stairs Stringer – one of the inclined sides of a stair that supports the risers and treads Riser – the vertical surface between two treads Tread – the horizontal face of one step
Nosing – the part of the tread that extends over the riser beneath it Newel – the post that supports the railing Handrail – an angled piece supported by a wall or railing intended to be grasped by persons Balusters – vertical members supporting the handrail on open stairs
Platform – a horizontal area placed between to flights of stairs Landing – the floor at the top or bottom of each story where a flight of stairs begins or ends Winders – Wedge-shaped treads installed where stairs turn Unit Run – the width of a tread minus the nosing
Unit Rise – the height or a riser; vertical distance between two treads Total Run – the sum of all unit runs Total Rise – the sum of all unit rises Headroom – the vertical distance from a step to a ceiling above
The rough opening for the stairwell must be carefully laid out and constructed Trimmers and headers should be doubled for support
Stair Angle should fall between 30 and 35 degrees The sum of two risers and one tread should be 24 to 25” G+2R =550 – 700mm The sum of one riser and on tread should equal 17 to 18” An 11” run and a 7” rise follows all three rules.