Check local building codes and permit requirements
Measure the total vertical rise between floors
Decide the stair location and available horizontal run
Calculate the number of risers
Divide total rise by desired riser height
Adjust riser height to match code limits
Calculate tread depth and total stair run
Choose stair width
Select materials for stringers, treads, risers, and handrails
Mark and cut stair stringers
Test-fit the stringers
Install the stringers securely
Attach risers to the stringers
Attach treads to the stringers
Install landing platforms if required
Add handrails and guardrails
Secure all fasteners
Check for level, plumb, and consistent rise and run
Sand and finish exposed surfaces
Inspect the staircase for safety and code compliance