Problem
We are putting this pattern in the language because our experiments have shown us that lay people often make mistakes about the volume which a staircase needs and therefore make their plans unbuildable.
Solution
Make a two story volume to contain the stairs. It may be straight, L-shapes, U-shapes, or C-shapes. The stair may be 2 feet wide (for a very steep stair) or 5 feet wide for a generous shallow stair. But, in all cases, the entire stairwell must form one complete structural bay, two stories high. Do not assume that all stairs have to have the “standard” angle of 30 degrees. The steepest stair may almost be a ladder. The most generous stair can be as shallow as a ramp and quite wide. As you work out the exact slope of your stair, bear in mind the relationship: riser + tread = 17 1/2 inches.
Related Patterns
… Staircase as a Stage (133) and Open Stairs (158) will tell you roughly where to place the various stairs, both indoors and outdoors. This pattern gives each stair exact dimensions and treats it like a room so that it becomes realistic in the plan.
Construct the staircase as a vault, within a space defined by columns, just like every other room - Columns at the Corners (212), Stair Vault (228). And make the most of the staircase; underneath it is a place where the children can play and hide - Child Caves (203); and it is a place to sit and talk - Stair Seats (125) …
Alexander, Christopher. A Pattern Language: Towns, Buildings, Construction. Oxford University Press, 1977, p. 900.