Units of measure for HVAC
Each piece of HVAC work has its own unit, and keeping them apart is what makes the estimate checkable. These are the units estimators use and how each is measured.
| Item | Unit | How it's measured |
|---|---|---|
| Rectangular duct | lb | Duct surface area by size and gauge converted to weight; fittings add weight too. |
| Round and spiral duct | LF | By diameter, with fittings counted. |
| Grilles, registers, diffusers | each | Counted by type from the plans and air device schedule. |
| Equipment | each | Rooftop units, split systems, fans and VAV boxes from the equipment schedule. |
| Refrigerant and condensate piping | LF | Measured by size between equipment. |
| Duct insulation | SF | Duct surface area where the spec requires it. |
How estimators take off HVAC
- List equipment and get quotes. Take equipment from the schedule and price it from supplier quotes, with rigging and crane time.
- Measure ductwork. Rectangular duct by size and length converted to pounds; round duct by diameter and length.
- Count air devices and accessories. Grilles, registers, diffusers, dampers and flex connections by type.
- Add piping, insulation and controls. Refrigerant, condensate and hydronic piping by length; insulation by area; controls per point or as a subcontract.
- Price labor and closeout. Use crew production per pound or foot of duct and per device, then add start-up and test and balance.
Waste factors and order quantities
Waste covers cut-offs, breakage, laps and spillage, and it's added to the net quantity before rounding up to what the supplier sells. These are typical planning figures; your own job history is the better number.
| Item | Factor | Notes |
|---|---|---|
| Sheet metal | 5 to 10% | Typical planning figure for scrap and seams on shop-fabricated duct. |
Crew production rates
Labor is quantity divided by production. These rates are per 8-hour crew-day for commercial work, from the same library as the crew-day production estimator: typical mid-range planning values with a low-to-high range, not a promise of output. Crew skill, layout, access and weather move them, and your own crews' records beat any library.
| Activity | Crew | Low | Typical | High | Labor |
|---|---|---|---|---|---|
| Rectangular galvanized duct | 2 sheet metal workers | 500 | 650 lb | 800 | 2.5 hrs per 100 lb |
| Round spiral duct, 10 to 16 in | 2 sheet metal workers | 150 | 200 LF | 260 | 8.0 hrs per 100 LF |
| Grilles, registers and diffusers | 2 sheet metal workers | 20 | 26 each | 35 | 0.62 hrs per each |
- Rectangular galvanized duct 500 to 800 lb, typical 650
- Round spiral duct, 10 to 16 in 150 to 260 LF, typical 200
- Grilles, registers and diffusers 20 to 35 each, typical 26
Worked example: 18,000 lb of rectangular galvanized duct
The activity is rectangular galvanized duct, with a crew of 2 sheet metal workers at the typical rate of 650 lb per crew-day:
- Crew-days: 18,000 lb ÷ 650 = 27.7 crew-days.
- Labor hours: 27.7 crew-days × 2 workers × 8 hours = 443 hours.
- Range: 22.5 crew-days at the high rate to 36 at the low rate, a spread of 13.5 crew-days on the same quantity.
- Equipment: Scissor lift, about 27.7 equipment-days.
Multiply the labor hours by your burdened hourly cost to price the labor. The spread between the low and high rate is why production is the assumption to check first on a HVAC bid: the same takeoff can carry very different labor. Run your own quantities in the crew-day production estimator, and get the burdened rate from the labor burden calculator.
What drives the cost
- Height and access. Duct hung high or in congested ceilings needs lifts and slows production.
- Equipment and rigging. Crane days, curbs and supports can be large; say who provides them.
- Controls. The line between equipment-mounted controls and a full building automation system must be clear.
- Closeout. Test and balance, commissioning support and training are real costs.
Common exclusions and clarifications
A HVAC price is only as good as the scope it describes. These exclusions come from our scope library for hvac and sheet metal (CSI 23 00 00); list the ones that apply so the GC levels your number fairly.
- Structural supports, curbs and roof openings unless listed as included.
- Line-voltage power wiring and disconnects.
- Building automation system integration beyond equipment-mounted controls.
- Roof patching and flashing at penetrations.
- Crane service over one day unless listed as included.
- Commissioning agent fees.
Clarifications that often go with them:
- One crane day included for rooftop equipment unless noted.
- Controls limited to equipment-mounted controls.
Pick, edit and export these in the scope inclusions and exclusions library, or load them straight into a proposal with the bid proposal builder.
Free tools for HVAC estimating
- Crew-day production estimator: turn HVAC quantities into crew-days, duration and labor hours with the rates on this page.
- Labor burden calculator: find the true cost of a crew hour, with taxes, insurance and benefits.
- Scope inclusions and exclusions library: pick proposal-ready HVAC exclusions and clarifications.
- Bid proposal builder: send a branded HVAC proposal with the scope language loaded.