BCT 121 Wall Framing
STAIR CALCULATIONS
STAIR FRAMING
Important Residential Stair Codes
• 1. The maximum stair rise is 8". The minimum is 4".
• 2. The minimum tread depth is 9".
• 3. There is a 3/8" inch allowable tolerance between the largest and smallest distance for the rise, treads and nosing projections in a flight of stairs.
• 4. Nosings are required on treads less than 10". Nosings may project 3/4" to 1 1/4" .
• 5. 6' – 8" minimum headroom clearance is required measured vertically from a sloping plane along the stair nosings.
Calculate Rise• Establish finish floor to finish floor height.
• Height ÷ 7 = number of risers range.
• Select the number of risers and divide it into the FF height = unit rise
• Select the tread length that will work for the horizontal space available.horizontal space available.
• Determine if the landing will be the last rise.
• Lay-out a stringer with the framing square. Cut and test for proper fit. If OK make it the template.
• Rise and Tread must meet code!
The Lay-out• Each student is to lay-out and cut a practice
stringer from an 11 ½” rip of particle board. Any one of a groups that fit can become the template for the 2 x 12 stringers.
• The bottom of the first rise must be shortened by the height of the finish tread.
• If the stringer is resting on the sub-floor, the height to the finish floor must be subtracted from the amount cut off for the tread height.
Practice particle board stringer
Test stringer cut ½” particle board
Don’t over cut stringers
Landing Ledger
Fire blocking ?
Landing is a finish tread height
Tread nosing must not extend past the wall
2 x 4 Skirt & Drywall Spacer
Fire blocking ?
Rake Knee Wall
Fire Blocking