403A Stair Construction 2

Question 1

What characterizes a 'housed stringer' (closed stringer) in stair construction?

Accepted Answer

Treads and risers fit into routed grooves on the inside face of the stringer

Answer

A housed stringer has dadoes (routed grooves) machined into its inner face so the treads and risers slot in, creating a clean finished appearance on both sides.

Question 2

What is the maximum allowable variation in riser height within a single flight of stairs according to the NBC?

Accepted Answer

5mm

Answer

The NBC limits the variation between the tallest and shortest riser in any one flight to 5mm to prevent tripping hazards.

Question 3

What is the maximum permitted opening between balusters on a stair guard?

Accepted Answer

100mm

Answer

The NBC requires that no opening in a guard allow passage of a 100mm sphere, preventing a child's head from becoming trapped.

Question 4

Under the NBC, a guard must be provided when the stair or surface is adjacent to a drop of more than:

Accepted Answer

600mm

Answer

The NBC requires guards wherever a walking surface or stair is adjacent to a difference in elevation exceeding 600mm.

Question 5

What is the minimum clear width required for a residential staircase under the NBC?

Accepted Answer

860mm

Answer

The NBC requires a minimum clear stair width of 860mm for residential stairs to allow safe passage and furniture movement.

Red Seal Carpenter 403A Practice Test

Red Seal Carpenter 403A Practice Test

403A Stair Construction 2