How do you fit a straight flight of stairs?
Very simple to explain, very dificult to get right. Here is my
best shot. The 2006 International Building Code states the
following: R311.5.3 Stair treads and risers.
R3126.96.36.199 Riser height.
The maximum riser height shall be 7¾ inches (196 mm). The riser
shall be measured vertically between leading edges of the adjacent
treads. The greatest riser height within any flight of stairs shall
not exceed the smallest by more than 3/8 inch (9.5 mm).
R3188.8.131.52 Tread depth.
The minimum tread depth shall be 10 inches (254 mm). The tread
depth shall be measured horizontally between the vertical planes of
the foremost projection of adjacent treads and at a right angle to
the tread's leading edge. The greatest tread depth within any
flight of stairs shall not exceed the smallest by more than 3/8
inch (9.5 mm). Winder treads shall have a minimum tread depth of 10
inches (254 mm) measured as above at a point 12 inches (305 mm)
from the side where the treads are narrower. Winder treads shall
have a minimum tread depth of 6 inches (152 mm) at any point.
Within any flight of stairs, the largest winder tread depth at the
12 inch (305 mm) walk line shall not exceed the smallest by more
than 3/8 inch (9.5 mm). So taken that a flight of stairs is the
measurement of floor to floor, or approximately 9ft use the
following to find the rise and run: Floor to Floor Dimention
divided by number of risers that will give you an answer somewhere
between 4 inches and 7 3/4 inches. Some trial and error is needed
here to get an even number that you can work with. 9ft/15 = 7.2
inches for riser height. Run is equal to the depth of each tread
plus any landings. 15*10 = 150 inches or 12.5ft long. The with is
described in the IRC as follows: R311.5.1 Width.
Stairways shall not be less than 36 inches (914 mm) in clear
width at all points above the permitted handrail height and below
the required headroom height. Handrails shall not project more than
4.5 inches (114 mm) on either side of the stairway and the minimum
clear width of the stairway at and below the handrail height,
including treads and landings, shall not be less than 31.5 inches
(787 mm) where a handrail is installed on one side and 27 inches
(698 mm) where handrails are provided on both sides. Hope this