Question 6
Domain 2: Building Planning, Means of Egress, and Safety ProvisionsWhat is the maximum riser height for residential stairs as specified by the IRC?
Correct answer: B
Explanation
The IRC limits residential stair risers to a maximum of 7-3/4 inches. This means each riser cannot exceed that height, so "7-3/4 inches" matches the code requirement.
Why each option is right or wrong
A. 7 inches
B. 7-3/4 inches
IRC Section R311.7.5.1 sets the maximum riser height for stairs in one- and two-family dwellings at 7-3/4 inches (196 mm). The code also requires the greatest riser height within any flight to be no more than 3/8 inch greater than the smallest riser height, so a value above 7-3/4 inches would fail the prescriptive limit.
C. 8 inches
D. 8-1/4 inches