CLC Stair Layout & Construction

Question 1

A stair has a total rise of 108 inches. What is the most appropriate number of risers if each riser must be no more than 7 3/4 inches?

Accepted Answer

14

Answer

108 ÷ 7.75 ≈ 13.9, so round up to 14 risers. Each riser is then 108 ÷ 14 ≈ 7.71 inches, which is within the limit.

Question 2

A stair has 14 risers and a 10-inch tread depth. What is the total run?

Accepted Answer

130 in

Answer

There is always one fewer tread than risers (the floor above acts as the last tread). So 13 treads × 10 in = 130 in.

Question 3

What is the minimum tread depth generally required for residential stairs under the IRC?

Accepted Answer

10 inches

Answer

The IRC sets a minimum tread depth of 10 inches (and a maximum riser height of 7 3/4 inches) for residential stairs.

Question 4

Within a single flight, how much may the tallest and shortest risers vary under typical code?

Accepted Answer

No more than 3/8 inch

Answer

Code limits the variation between the largest and smallest riser in a flight to 3/8 inch to prevent trips caused by uneven steps.

Question 5

When laying out a stringer with a framing square, what is stepped off along the stringer board?

Accepted Answer

The unit rise and unit run of each step

Answer

The carpenter sets the square to the unit rise on one leg and the unit run on the other and steps along the stringer board. The first and last steps are then adjusted for tread thickness.

(CLC) Certified Lead Carpenter Practice Test

(CLC) Certified Lead Carpenter Practice Test

CLC Stair Layout & Construction