A mechanical bid rarely falls apart on the equipment schedule. Capacity, electrical characteristics, accessories — every serious estimator prices the schedule row by row, because the schedule row is the bid item and everyone knows it. Where mechanical bids actually lose money is at the seams between Divisions 21, 22 and 23 and everything around them: the wiring splits that read differently unit to unit, the temporary conditioning duty that's formally someone else's but lands here anyway, and the pads and openings that get "confirmed by others" right up until nobody has confirmed them.
This is a working list of where those seams sit, built from what actually shows up across real Canadian ICI tenders. Not a code summary — a list of the specific questions worth answering before the number leaves the office.
What's reliably yours
- HVAC systems, complete — equipment, ductwork, hydronic and refrigerant piping, insulation, and testing, adjusting and balancing per Divisions 21–23 as assigned. The equipment schedules are the price list; read them as such.
- Plumbing systems, complete — fixtures, domestic water, sanitary, storm, gas and specialties per Division 22. The fixture schedule and the riser scope drive the count more than the drawings do on their own.
- Fire suppression, where assigned — sprinkler and standpipe systems per Division 21, often carried as a licensed specialty sub sitting under the mechanical umbrella. Extract the assignment rather than assuming it either way.
- Equipment supply-and-set per the schedules — every scheduled unit with its capacity, electrical characteristics (voltage, phase, MCA, MOP) and accessories. The schedule row is the bid item; missing a unit means missing a line, not just a detail.
Where the fight actually happens
Controls and BMS: whose protocol, whose wiring
Building automation sits inside mechanical on some tenders and goes direct to a controls vendor on others, and the tender rarely announces which up front. What needs extracting is three separate things, not one: who supplies the controls hardware, who wires it, and what protocol or integration requirement the building automation system demands. A BACnet integration clause buried in a general note can mean commissioning hours that never show up anywhere near the equipment schedule.
Control and interlock wiring — the line vs. low-voltage split
Line-voltage power to equipment is Division 26 work almost everywhere, but the control and interlock wiring — the low-voltage signal wiring that starts and stops the unit, trips it on a fire alarm interlock, or ties it to a duct detector — splits between Divisions 23 and 26 inconsistently, often within the same schedule. "Control wiring by Division 26" is a real sentence that shows up in real specs, and it's worth real money either way it's assigned. Extract it verbatim, unit by unit, rather than assuming the first one sets the pattern for the rest.
Temporary heat and conditioning
Providing temporary heat during construction, or running permanent equipment early to condition the space before substantial completion, is formally a Division 01 general-requirements duty. In practice it lands on the mechanical trade often enough that "by others" needs confirming rather than assuming. The two costs worth separating are the temporary system itself and the warranty exposure of early-running permanent equipment — start a rooftop unit's compressor warranty clock in month two of a twelve-month schedule and that's a real conversation to have before bid day, not after.
The other half: what isn't yours, even when it looks close
- Line-voltage power wiring — power to equipment is Division 26 work. The exception that eats this exclusion alive is starters, VFDs and disconnects, which split unpredictably enough that they get their own watch-for below rather than a clean answer here.
- Concrete housekeeping pads — usually the concrete trade's to pour, but extract the pad schedule anyway. This estimator is the one who locates and sizes them; concrete just builds what mechanical tells it to.
Five things that hide outside the equipment schedule
- Starter, VFD and disconnect ownership — worth repeating. Furnished under Division 23 and wired under Division 26, or the reverse, this is the classic Div 23/26 gap and it recurs once per piece of equipment, not once per tender. Sweep every schedule note and spec line that assigns them rather than checking the first three units and calling it done.
- Electrical characteristics mismatches. Voltage, phase, MCA and MOP on the mechanical schedule against what the electrical drawings actually provide — flag every scheduled unit for coordination, because a single mismatched unit found at rough-in is a change order, not a rounding error.
- Commissioning and TAB scope. Cx participation hours, seasonal testing requirements, and whether testing, adjusting and balancing runs independent or in-house are real labour, usually stated in Division 01 or 23 08 — and easy to treat as boilerplate rather than a line item.
- Roof openings, curbs and supports. Curb supply versus curb installation, structural support steel, and roofing coordination meet at every rooftop unit — three trades converging on one opening, and any one of them can assume it's someone else's.
- Owner-furnished equipment. OFCI units that this trade sets and connects still need a supply-versus-install line extracted per item, because "owner-furnished" tells you who buys it, not who's on the hook to rig, set and pipe it in.
Who you're actually sharing the mechanical room with
| Trade | What to reconcile before you price |
|---|---|
| Electrical | Starters, VFDs, disconnects, control power and fire alarm interlocks — the Division 23/26 boundary needs every assignment extracted, not assumed. |
| Structural & steel | Equipment loads, roof and floor openings, support steel and hanger attachment; a late equipment pick can force a structural change nobody priced. |
| Concrete | Housekeeping pads, trenches and sleeves through slabs — located by mechanical, built by concrete, so the pad schedule needs to exist and be right. |
| Fire alarm contractor | Duct detectors, fan shutdown and damper interlocks split supply, install and wiring across three trades at once. |
| General contractor | Temporary heat responsibility, and the warranty consequences of running permanent systems early. |
The pass that catches most of this
Read the equipment schedules the way they deserve — every unit, not the first few that set a pattern — because the starter/VFD/disconnect split and the electrical characteristics check both repeat per unit, not per tender. Then read Division 01 specifically for temporary heat and commissioning language before assuming either is somebody else's line. The equipment schedule is the price list; the boundary items above are what turn a correctly priced schedule into a bid that doesn't get disputed at rough-in.