Laundry room partition with door opening
What's wrong here?
- Nothing. This installation is compliant
- A single flat 2x4 may not be used as a header over a door opening
- Every stud wall must be capped with a double top plate
- Table R602.7.5 requires two full-height king studs at each side of this opening
Show the answer and the code reference
The answer
Nothing is wrong: this is an interior nonbearing partition, so a single flat 2x4 header and a single top plate are both permitted.
Correct choice: 1. Nothing. This installation is compliant
The floor joist above runs parallel to the partition, so no joists, rafters or trusses bear on it; the wall only holds up itself and the drywall. R602.7.4 says load-bearing headers are not required in nonbearing walls and allows a single flat 2x4 header for openings up to 8 ft wide where the vertical distance to the parallel nailing surface above is no more than 24 in., which is easily met here. R602.5 lets interior nonbearing walls be capped with a single top plate (and even framed with 2x3 studs at 24 in. on center). The bottom plate on the basement slab is preservative-treated, the usual way to meet R317.1 for a plate resting on a slab.
How to fix it
No correction needed. Before calling it nonbearing on a real job, confirm what is above: joists running parallel to the wall, or trusses designed to clear-span, with no point loads or posts landing on the plate.
Code references
IRC 2018 R602.7.4 — Nonbearing walls
Load-bearing headers are not required in interior or exterior nonbearing walls. A single flat 2x4 may be used as a header in a nonbearing wall for openings up to 8 ft wide if the vertical distance to the parallel nailing surface above is not more than 24 in.; no cripples or blocking are required above it.
Drills citing R602.7.4IRC 2018 R602.5 — Interior nonbearing walls
Interior nonbearing walls may be framed with 2x3 studs at 24 in. on center (or flat 2x4s at 16 in. where not part of a braced wall line) and must be capped with not less than a single top plate; they must be fireblocked per R602.8.
Drills citing R602.5
2024 IRC:not yet checked Confidence: low
Minnesota
Minnesota adopts the 2018 IRC with Minnesota amendments as the Minnesota Residential Code (Minn. Rules ch. 1309). No Minnesota amendment to R602.7.4 or R602.5 is known. DLI is adopting the 2024 IRC as the next edition; see the 2024 IRC note.
About the Minnesota Residential CodeWhy the other choices are wrong
- A single flat 2x4 may not be used as a header over a door opening. R602.7.4 allows a single flat 2x4 header in a nonbearing wall for openings up to 8 ft wide when the nailing surface above is no more than 24 in. away. The joist above runs parallel to this partition, so nothing bears on it.
- Every stud wall must be capped with a double top plate. R602.3.2's double top plate applies to exterior walls and, through R602.4, to interior bearing walls. R602.5 lets interior nonbearing walls be capped with a single top plate.
- Table R602.7.5 requires two full-height king studs at each side of this opening. Table R602.7.5 sets the number of full-height studs at the ends of headers in exterior walls. This is an interior nonbearing partition, and one king stud each side is normal.