Open warehouse zones
Repeatable long runs, available lifts, and released steel can support high field productivity and overlapping fabrication lots.
Home & Construction
HVAC Duct Project Schedule Calculator
Distinguish shop lead and commissioning from field productivity so the critical path is not reduced to surface area divided by one rate.
DUCT INSTALLATION CRITICAL PATH
Keep fabrication lead, field labor, testing, and balancing on separate tracks
Rectangular and round installation use separate productivity rates. Hangers and testing add labor; fabrication, inspection, and commissioning remain elapsed holds.
Total calendar duration-
Productive crew-days-
Elapsed holds-
Total labor hours-
Rectangular installation hours-
Round installation hours-
SUBJECT DECISION ILLUSTRATION
Real-world context followed by an exact current calculation record
The illustration explains the professional setting without pretending to be a data chart. The ledger below preserves the entered values and calculation path.
| Phase | Quantity basis | Productivity / capacity | Labor hours | Crew-days | Release condition |
|---|
How to use
Plan the duct path from coordination release through balancing
- Enter released rectangular and round surface quantities.
- Use separate field productivity rates for each construction family.
- Count hanger assemblies and enter labor per hanger.
- Add layout, coordination, testing, and closeout labor.
- Convert labor through the actual crew and productive workday.
- Add only fabrication, inspection, and commissioning holds controlling completion.
Schedule fundamentals
Five records define the represented path
- Released quantity
- Duct approved and available for fabrication or installation.
- Labor productivity
- Installed surface per labor-hour for one construction family.
- Hanger labor
- Layout, drilling, hardware, and assembly time entered per support.
- Shop lead
- Elapsed fabrication time before field release.
- Commissioning hold
- Testing, balancing, controls, or acceptance time after installation.
Calculation method
Convert phase quantities to labor, then add genuine elapsed holds
Rectangular and round surface divide by their respective labor productivity. Hanger count multiplies labor per assembly. Layout and testing are explicit labor. Total labor divides by crew-day capacity; fabrication lead, inspection, and balancing remain separate calendar holds.
Fabrication boundary
Shop lead may overlap field preparation
The model conservatively adds entered lead. A detailed schedule should connect approved submittals, BIM sign-off, release packages, fabrication lots, delivery zones, and installation sequence so overlap is credited only when real.
Field boundary
Surface productivity changes with location and system
Pressure class, gauge, reinforcement, joint system, duct size, height, congestion, lifts, prefabrication, access, firestopping, insulation, weather, and crew experience affect installation rates.
Commissioning depth
Installed duct is not automatically ready for turnover
Leak testing, cleaning, access verification, insulation inspection, controls completion, equipment readiness, test-and-balance, punch work, and documentation can control acceptance after physical installation.
Detailed calculation process
Duct schedule equations and default substitution
Hrect = Arect / PrectHround = Around / ProundHhangers = Nhangers × hhangerHtotal = Hlayout + Hrect + Hround + Hhangers + HtestDcalendar = Htotal/(Ncrew hday) + Dfabrication + Dinspection + Dcommission
- Rectangular labor = 1,450 / 9 = 161.111 hours.
- Round labor = 620 / 13 = 47.692 hours.
- Hanger labor = 72 × 0.55 = 39.6 hours.
- Total labor = 24 + 161.111 + 47.692 + 39.6 + 28 = 300.403 hours.
- Crew capacity = 4×8 = 32 labor-hours/day; productive duration = 9.388 crew-days.
- Holds = 6+1+2 = 9 days; conservative total = 18.388 days.
The current cards and phase ledger provide the live reconciliation.
Result interpretation
Identify the controlling release, not merely the longest labor phase
Large rectangular labor may dominate productive time, while shop approval or balancing can still control completion. Validate predecessor logic before deciding that more installers will recover the schedule.
Decision analysis
Use zone releases and actual production to update the forecast
Track approved, fabricated, delivered, hung, tested, insulated, balanced, and accepted quantities by zone. Replace planning rates with measured project rates without silently rewriting the original baseline.
Evidence and data lineage
Retain releases, productivity, and holds
Keep model/drawing revision, approved duct schedule, release packages, quantities by family and zone, pressure class, joint and support systems, crew calendar, productivity source, fabrication status, delivery sequence, access constraints, testing and balancing requirements, inspection bookings, baseline date, actual hours, forecast revisions, and unrounded results.
Limits and exclusions
What this duration omits
- No logic links, zone overlap, weekends, overtime, learning, congestion, or resource leveling.
- No BIM approval, procurement, lift, penetration, firestop, insulation, controls, power, or equipment schedule unless entered.
- No rework, failed testing, design change, damage, weather, or other-trade delay model.
- No contractor commitment, safe-work plan, or guaranteed date.
Key terminology
Duct schedule terms
- Release package
- Approved scope authorized for fabrication.
- Shop lead
- Elapsed time from release to delivery.
- Productivity
- Installed quantity per labor-hour.
- Crew-day
- Entered crew working one productive day.
- TAB
- Testing, adjusting, and balancing.
- Closeout
- Final testing, punch, records, and acceptance work.
Worked decision cases
Equal quantities can follow different paths
Occupied hospital renovation
Infection control, shutdowns, small work windows, inspections, controls, and ceiling congestion can dominate a smaller surface quantity.
Authoritative basis
References for duct construction, inspection, and commissioning
Important note
This is a planning duration. The contractor and project team govern fabrication releases, safe installation, workforce, testing, balancing, inspections, sequencing, and contractual completion.
Frequently asked questions
Why separate rectangular and round productivity?
The fabrication, joining, handling, and installation methods can differ materially.
Does fabrication always add to field duration?
No. Detailed logic may allow overlap; enter only the lead that controls the represented path.
Are hangers included in surface productivity?
Not in this model; their count and labor are explicit.
Why is balancing an elapsed hold?
It often depends on complete systems, controls, equipment, access, and specialist availability.
Can more workers halve the schedule?
Not necessarily; access, congestion, supervision, task sequence, and holds limit acceleration.
Does the result include insulation?
Only if its labor is intentionally included in one of the entered labor allowances.