1. The "Furnished By/Installed By" Trap
The most common margin-killer in commercial estimating happens at the borders between CSI divisions. The mechanical engineer specifies a roof-top unit (RTU) with a variable frequency drive (VFD). The mechanical schedule says "VFD furnished with unit." The electrical drawings show a power drop to the RTU but nothing for the VFD control wiring.
Who owns the low-voltage control wiring The mechanical sub assumes electrical. The electrical sub assumes mechanical (or controls). On bid day, neither carries the number. Two months later, the GC eats a $12,000 change order to wire the VFDs.
Real-World Catch (Div 23 / Div 26 Interface)
The RFI That Saved $28,500
The Problem: A 400-room hotel design required fire/smoke dampers (FSDs) throughout the corridors. Mechanical drawings showed the dampers. Electrical drawings showed no power or fire alarm relays to those dampers.
Our Action: We submitted a pre-bid RFI forcing the engineer to assign the wiring. Electrical picked it up. Our GC carried the $28.5k in their base bid and avoided a mid-project margin hit.
2. Leveling the Subcontractor Bids
You receive three electrical bids for a core-and-shell office:
- Bidder A: $1.2M
- Bidder B: $1.35M
- Bidder C: $850k
If you carry Bidder C, you are going to get crushed. Bidder C almost certainly missed the switchgear lead time and didn't price the temporary power requirements for the tower crane. Bid leveling is not just comparing the bottom line; it's normalizing the inclusions and exclusions.
Download Our Subcontractor Bid Leveling Sheet
Stop comparing apples to oranges. Use the exact Excel template our estimators use to normalize MEP bids across 40+ specific inclusions/exclusions.
Download Excel Template (.xlsx)3. Reflected Ceiling Plan (RCP) Clashes
If your estimator is only looking at the M-sheets and E-sheets, you are going to fail. We overlay the architectural RCPs with the mechanical duct layouts and lighting plans. Why Because architects love to design wood slat ceilings and intricate drywall clouds without leaving space for the linear diffusers and return air boots.
If the ductwork has to be compressed, rerouted, or transitioned to fit the architectural intent, the sheet metal fabrication cost jumps 20%. We catch this during takeoff.