403A Stair Construction 3

Question 1

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

Accepted Answer

Rounded up to keep each riser within the maximum height

Answer

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.

Question 2

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

Accepted Answer

865mm to 965mm

Answer

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

Question 3

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

Accepted Answer

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

Answer

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.

Question 4

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

Accepted Answer

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

Answer

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.

Question 5

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

Accepted Answer

89mm (3-1/2")

Answer

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

Red Seal Carpenter 403A Practice Test