1. Project Context
This walkthrough demonstrates a typical MEP coordination failure scenario during the GMP validation phase of a school renovation project. The example involves a $14M high school renovation where the general contractor has received bids from preferred mechanical and electrical subcontractors.
2. The Scope Gap
During a typical constructability review, an MEP estimator overlays the Mechanical Equipment Schedule with the Electrical One-Line Diagram. A common finding is a specification conflict between Divisions 23 and 26.
Equipment that is furnished by one division and installed or wired by another is one of the most common places for scope to fall between trades. Variable frequency drives, disconnects and control wiring sit exactly on that line.
In this scenario, the mechanical schedule lists Air Handling Units (AHUs) requiring Variable Frequency Drives (VFDs). The mechanical specs state: "VFDs provided by Div 23, installed by Div 26." However, the electrical drawings show standard motor starters, not VFDs, and the electrical specs explicitly exclude "mounting of mechanical VFDs and associated control wiring."
Neither trade has claimed the VFD mounting, disconnect, and control wire scope — creating an unclaimed scope gap that will surface as a change order if not caught before GMP execution.
3. The Pre-Bid RFI
Plan Review: MEP Coordination
Generic takeoff services just click lines. Our estimating team reviews the architectural details against the structural and MEP notes. When we find a conflict, we highlight it on the plans and generate an RFI before you bid.
A typical pre-bid RFI would ask: 'Please confirm which trade is responsible for mounting the VFDs, providing the fused disconnects ahead of the drives, and pulling the 0-10v control wire from the BAS panel to the drives. Neither Div 23 nor Div 26 has claimed this scope.' The engineer's response clarifies responsibilities and eliminates the ambiguity.
4. The Bid Leveling Catch
When reviewing the actual bids submitted to the GC, a typical finding is that the lowest electrical bidder has rigidly followed the electrical drawings and explicitly excluded mechanical equipment mounting and DDC wiring.
If the GC awards the contract based on the raw low number, the GC faces a change order on day one to mount the drives, upsize the disconnects, and pull the low-voltage wire. Using the "Plug" methodology in bid leveling reveals the true lowest responsible bidder.
Electrical (Div 26) - Bid Leveling Matrix
| Scope Line Item | Subcontractor A | Subcontractor B | Subcontractor C |
|---|---|---|---|
| Raw Base Bid | $1,450,000 | $1,520,000 | $1,550,000 |
| GC Plug: VFD Mounting, Disconnects & Control Wire (RFI #12) | + $85,000 | INCLUDED | INCLUDED |
| True Leveled Bid | $1,535,000 | $1,520,000 | $1,550,000 |
5. Outcome in This Example
With the plug added, Subcontractor B, who included the VFD mounting labor, becomes the lowest complete bid in this example. Awarding on the leveled number rather than the raw low number keeps the illustrative $85,000 of unclaimed scope out of contingency and settles which trade owns it before construction begins.
Walkthrough Summary (Example)
- Project Type K-12 renovation (illustrative $14M)
- Failure Point Div 23 / Div 26 Interface
- Illustrative Plug $85,000 (example)