Question 13
Domain 5: Roof-Ceiling Construction and Attic AssembliesWhat is the minimum required lap for roof sheathing panels at their ends over supports?
Correct answer: C
Explanation
Roof sheathing panels need end support over supports so the panel edges can transfer load and stay aligned. Building practice requires that “edges must be supported by blocking or H-clips,” which provides the necessary support at panel ends and edges.
Why each option is right or wrong
A. No minimum, edge clips are acceptable
B. At least 1/2 inch bearing on each support
C. Edges must be supported by blocking or H-clips
Under the IRC roof sheathing provisions, panel edges at unsupported joints must be backed by framing or edge support; the code recognizes blocking or metal H-clips as the standard means of providing that support. In practice, this is required where panel ends meet over supports so the sheathing can transfer load without edge deflection or joint separation, and the answer matches that code-based requirement rather than a dimensional lap measurement.
D. Panels must fully span between supports