Stair Design Guide
Original design - File:Stairs.fcstd
Stairway for SeedHome v2
Step Size
The steps are 42.125" wide and 11.25" deep with a 1.125" nosing
Rise
The top of the 2nd story sub-flooring is 121.125" from the top of the sill. We also need to add 1.5" from the basement slab to the sill plus 1/4" for the 2nd story flooring (121.125" + 1.5" + .25" = 122.875" total rise)
The actual stairway rise will depend on the height of the landing:
With 2x6s and 3/4" planks (6.25" total) it will need to be 116.625"
With 2x8s and 3/4" planks (8" total) it will need to be 114.875"
15 steps of 7-3/4" (the maximum allowed by code) is 116.25"
15 steps of 7-5/8" provides 114.375"
The landing or the top step can be adjusted to make up the difference
CAD for Stairway with 7 3/4" rise
File:Stairs detail.fcstd - Detailed design file - 7.75" rise
File:Stairs simple.fcstd - Simple object for merge
CAD for Stairway with a 7 5/8" rise
File:7 625 stairs detail.fcstd - Detailed design file - 7.625" rise
File:7 625 stairs simple.fcstd - Simple object for merge
File:7 625 stairs example.fcstd - First floor example