A Minor Detail Affected Another Discipline
Initial State & New Revision
Initial State
The design team finalized the structural drawings with 450mm reinforced concrete columns. At this size, the architectural and mechanical coordination plans showed a 150mm gap between the column surface and the dry-wall partition, allowing for a vertical drainage riser.
New Revision
During a late shop drawing review, the structural contractor requested an increase in column size to 500mm to accommodate higher rebar density. This modification was updated only in the structural model and issued as Revision 2. The change was not communicated to the mechanical or architectural teams, who continued using Revision 1.
Conflicting Requirements & Unresolved Issue
Conflicting Requirements
The mechanical design required a minimum clearance of 150mm for the drainage riser, while the structural design demanded a 500mm column width. This left only a 100mm physical gap, meaning the riser could not fit in the designated wall cavity without protruding into the fire egress corridor.
Unresolved Issue
The clash was discovered on-site during MEP rough-ins. The structural column was already cast, and moving the drywall partition wall would violate the minimum width requirement for the egress corridor.
Decision Owner & Review Outcome
Decision Owner
The Lead Mechanical Coordinator, in collaboration with the Project Architect, had to identify a routing alternative and obtain approval from the Project Director.
Review Outcome
The team decided to keep the partition wall in its original location to maintain the fire egress corridor width. The drainage riser was rerouted through an adjacent wall partition, requiring extra elbows and a slight horizontal offset. This adjustment avoided structural modification but added material costs and slightly reduced the drainage flow rate.
Discussion & Feedbacks
Cross-discipline impacts are so hard to track without a matrix.
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