Stair Construction Flashcards

When calculating the number of risers for a staircase, the total rise is divided by the desired unit rise and the result is:

Answer: Rounded up to keep each riser within the maximum height

Rounding up ensures each riser stays at or below the maximum unit rise; rounding down would make at least one riser exceed the code maximum.

What is the required handrail height above the stair nosings according to the NBC?

Answer: 865mm to 965mm

The NBC specifies that handrails must be between 865mm and 965mm above the nosing line of the treads.

An 'open stringer' (cut stringer or sawtooth stringer) is characterized by:

Answer: Notches cut along the top edge create a sawtooth profile to support treads and risers

A cut (open) stringer has triangular notches cut from its top edge to form seats for the treads and risers, creating a visible sawtooth profile.

What is the purpose of a 'kicker plate' (kicker block) at the bottom of a stair stringer?

Answer: To anchor the base of the stringer to the floor and prevent it from kicking out under load

A kicker plate is fastened to the subfloor to resist the horizontal outward thrust at the base of the stringer when weight is applied to the stairs.

When cutting notches in a stair stringer, what is the minimum remaining depth of material at the notch to maintain structural integrity?

Answer: 89mm (3-1/2")

A minimum of 89mm (3-1/2") of net depth must remain below the tread notch in a stringer to ensure adequate structural strength.

Which formula is most commonly used to verify that a stair's rise-and-run combination will be comfortable for users?

Answer: 2 × Rise + Run = 635mm

The formula 2R + T = 635mm (approximately 25 inches) is the standard comfort check, balancing the energy of lifting and the distance of stepping.

A staircase has 13 risers each measuring 191mm. What is the total rise of the staircase?

Answer: 2,483mm

Total rise = number of risers × unit rise = 13 × 191mm = 2,483mm.