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