Question 18
Domain 4: Wall Construction, Framing, and Exterior CoveringsPer the IRC, what is the minimum size of a header required over a window or door opening in a load-bearing wall?
Correct answer: A
Explanation
The IRC does not give one fixed header size for every window or door in a load-bearing wall. Header sizing depends on the opening span and the loads carried, because the code requires the header to support the wall above based on those conditions.
Why each option is right or wrong
A. It depends on the span of the opening and loads supported
IRC Section R602.7.1 requires headers in load-bearing exterior walls to be sized from the span of the opening and the tributary loads they carry, using the span tables in the code rather than a single universal dimension. The minimum member therefore varies with opening width, roof/floor loads, snow load, and the number of stories supported; the code’s prescriptive tables are what determine whether a 2x6, 2x8, or larger built-up header is required for that specific opening.
B. Always a doubled 2x6
C. Always a doubled 2x8
D. Always a doubled 2x10