Stair Well Floor Opening Size
Calculate the size of the floor opening based on required headroom.
Note: Keep in mind that the required headroom must allow for finished surfaces.
Stair Well Opening
- riser height (unit rise)
- run depth (unit run)
- thickness of floor structure (floor finish material plus joist plus plywood plus ceiling finish)
- required headroom
- nosing, the amount the stair tread projects passed the vertical riser below (if there is any)
- the length of the opening in the upper floor