Francis Ching goes into detail of describing stairs, he views stairs as a special entity, Stairs don’t always affect the exterior of a building but do affect the internal organization of a building this could be a structural pattern of a layout of a building. Ching goes into detail to show us what a stair is made up of and the required dimension they have to meet. Stairs are made up from Risers and Treads, Riser being how tall the base is and tread being how long a stair is. Ching provides a formula for stairs: Tread(in) + 2x Riser(in) = 24-25 this formula can be used to calculate if the stairs that are being made meet building code in terms of dimension this is used mostly for interior stairs because exterior stairs are not as steep because they can propose a danger in certain weather conditions.
Stair should be a minimum of 36/44in for 49 people or less.
Handrails should be 4-1/2 inches from the wall and should be on both sides of the stair and should be 34-38 inches of height and should have guard rails.
Landings should be the width of the stairs and have a minimum length of the width of the stairs.
Treads/Risers/Nosings- there should be a minimum of 3 risers per flight in order to help prevent people from tripping.
Doors in stairwells should be facing the way of egress for emergency purposes.
The purpose of a stair is to provide a way of transportation from one level to the next they also help organize a circulation.
Stairs also take up a good amount of space, there are different varieties of stairs: Straight run, Quarter Turn, Half turn, Winding stair, Circular stair, and Spiral stair.
Quarter turn stairs make a right-angle L shape, Half turn stairs make a 180 degree turn, Winding stairs are any stairs that are constructed with winders, circular stairs are circular and spiral stairs are made of wedge shaped treads (these are the smallest type o stair but can only be used in private individual dwellings due to code.