403A Stair Construction

Question 1

What is the maximum unit rise permitted for interior stairs under the National Building Code of Canada?

Accepted Answer

200mm

Answer

The NBC limits interior stair risers to a maximum of 200mm to ensure safe and comfortable climbing.

Question 2

A staircase has a total rise of 2,800mm and requires 14 risers. What is the unit rise?

Accepted Answer

200mm

Answer

Unit rise = total rise ÷ number of risers = 2,800 ÷ 14 = 200mm.

Question 3

Which stair component directly supports the treads and risers along the sides of the staircase?

Accepted Answer

Stringer

Answer

The stringer (also called a carriage) is the structural inclined board that supports the treads and risers.

Question 4

What is the minimum unit run (tread depth) required for residential stairs under the NBC?

Accepted Answer

235mm

Answer

The NBC requires a minimum tread depth (unit run) of 235mm for residential stairs to ensure safe foot placement.

Question 5

What is the minimum required headroom clearance for a staircase under the National Building Code of Canada?

Accepted Answer

1950mm

Answer

The NBC mandates a minimum of 1950mm of headroom measured vertically from the nosing line to the ceiling above.

Red Seal Carpenter 403A Practice Test