Corridor Clash: Duct, Beam, Conduit, and Sprinkler Main
A general contractor is managing a three-story, 36,000 sq ft office fit-out in Hartford. The schedule shows mechanical rough-in starting in three weeks. The structural drawings show a W18 beam at 10 ft 0 in above the second-floor slab along the main corridor. The mechanical contractor's duct layout calls for a 24-inch by 12-inch supply trunk at 9 ft 6 in to 10 ft 6 in in the same corridor. The electrical contractor has a 4-inch conduit rack at 9 ft 8 in, and the sprinkler contractor has a 2-1/2-inch main at 10 ft 2 in. The ceiling is at 9 ft 0 in. The architect has not provided a reflected ceiling plan. The owner has a fixed tenant move-in date and a $1,500 per day liquidated damages clause. The superintendent proposes field-cutting the beam and rerouting the duct below the ceiling. The mechanical subcontractor says it can downsize the duct to 18 by 10 but needs the engineer's approval, which will take two weeks.
1. Evaluate the superintendent's proposal and identify the coordination failures.
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The superintendent's proposal to field-cut a W18 beam is unacceptable. Cutting a structural beam without an engineer's design violates the building code and the permit, and it could fail. The deeper problem is a coordination failure: no reflected ceiling plan, no combined MEP and structural elevation drawing, and no clash review before release for construction.
The corridor has only about 12 inches between the 9 ft 0 in ceiling and the 10 ft 0 in beam bottom. The proposed duct at 9 ft 6 in to 10 ft 6 in, the conduit rack at 9 ft 8 in, and the sprinkler main at 10 ft 2 in cannot all fit and maintain ceiling height. Each trade designed independently, and the architect omitted the ceiling plan that would have forced the elevations to be resolved.
2. Recommend a resolution and a schedule recovery plan.
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Resolution: hold a coordination meeting within 48 hours and build a combined 3D or elevation drawing of the corridor. Options, in order:
- Route the duct below the beam in a soffit if the architect accepts a lower ceiling in the corridor.
- Resize the duct to 18 by 10 only with the mechanical engineer's written approval, checking friction loss and static pressure.
- Shift the conduit rack and sprinkler main to the side of the beam.
- Reroute the trunk to another corridor.
Do not cut the beam. Schedule recovery: expedite the engineer's review to five business days, issue an RFI immediately, authorize overtime or a second shift for mechanical rough-in, and resequence electrical and sprinkler to follow the duct. The three-week start date is not achievable for the corridor; notify the owner now to limit liquidated damages exposure.
3. Discuss documentation and change-order implications, including who should bear the cost and time.
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Documentation should include an RFI, a formal coordination drawing, the schedule impact, and a change order for the engineer's redesign and any added soffit or rerouting. If the duct downsizing is approved, capture the engineer's sealed response. If the owner or architect caused the delay by not providing a reflected ceiling plan, preserve a time extension claim.
The cost allocation depends on the contract documents. If the design omitted required coordination, the owner may bear the redesign and soffit cost. If the mechanical contractor installed outside the contract documents, that subcontractor may bear the rerouting cost. The $1,500 per day liquidated damages makes early notice critical; the GC should not wait for the two-week turnaround to flag the risk. Silence until the schedule slips will weaken any later claim.