CSLB General Building (B)Mechanical, Electrical, Plumbing CoordinationHard
During framing, the plumber discovers that a required 4-inch drain vent stack conflicts with a structural engineered floor joist that cannot be cut or notched per the manufacturer's specifications. What is the correct course of action?
- ASubmit a request for information (RFI) to the architect or structural engineer for an approved solution
- BField-cut the joist slightly undersized to fit the vent and continue work
- CSubstitute a smaller diameter vent pipe that fits without modifying the joist
- DReroute the vent path using standard fittings without notifying the design team
Show answer & explanationAnswer & explanation
Correct answer: A. Submit a request for information (RFI) to the architect or structural engineer for an approved solution
Engineered joists have strict manufacturer limitations on cutting and boring; any conflict must be resolved through an RFI to the design professional so a code-compliant, structurally approved solution can be provided rather than improvising in the field.
Why the other options are wrong
- B. Cutting an engineered joist beyond manufacturer allowances can cause structural failure and code violations.
- C. Reducing vent pipe diameter without engineering or plumbing code approval can violate drainage venting requirements.
- D. Rerouting without proper coordination risks other conflicts and does not document an approved resolution.
MEP-Structural Conflict Resolution
When mechanical, electrical, or plumbing systems conflict with structural elements like engineered joists, the proper resolution is to submit an RFI to the design professional rather than field-modifying the structure.
- Engineered joists (I-joists, LVL) have strict manufacturer cutting/boring limits
- Unauthorized field cuts can void warranties and violate code
- RFIs create a documented, approved resolution path
Memory trick: When pipes and joists collide, let the engineer decide.