Commercial Ductwork Takeoff & Sheet Metal Estimating Services
Granular HVAC sheet metal takeoffs, galvanized duct poundage summaries, spiral ducting, fitting counts, and fabrication labor calculations for commercial mechanical and ventilation contractors nationwide.
Forensic Duct Takeoffs for Mechanical Contractors
Sheet metal bidding requires exact weight calculations, fitting geometry factors, and clear separation between shop fabrication hours and field erection labor. JLG Estimating delivers digital takeoffs that translate architectural and mechanical blueprints into actionable sheet metal work orders.
We quantify supply air, return air, outside air, relief air, and exhaust duct networks. Every takeoff accounts for gauge transitions, unistrut hanger spacing, transverse joint connections (TDF/TDC, S&D), acoustic liner, and fire/smoke life-safety dampers.
Duct Poundage by Gauge
Detailed poundage takeoffs organized strictly by sheet metal gauge and pressure class:
- Rectangular galvanized ducting (18ga, 20ga, 22ga, 24ga, 26ga)
- Round spiral lockseam ductwork & flat oval ducting
- Low-pressure, medium-pressure & high-pressure systems
- Stainless steel & aluminum specialty exhaust ducting
Fittings & Transitions
Fitting counts digitized individually with appropriate fabrication complexity weighting:
- Radius elbows with turning vanes & square throat elbows
- Transitions, square-to-round adapters & offsets
- Conical taps, shoe taps, spin-ins with volume dampers
- End caps, access doors, flexible duct connectors
Insulation & Life Safety
Quantification of thermal performance, acoustic lining, and building code dampers:
- Internal acoustic fiberglass liner (1-inch and 2-inch thickness)
- External fiberglass duct wrap with FSK vapor barrier
- Dynamic fire dampers & motorized smoke dampers
- Trapeze unistrut hangers, threaded rod & seismic cables
Structured Ductwork Takeoff Output Formats
Every ductwork takeoff is structured so your fabrication shop and field superintendents can immediately verify quantities.
| Duct Category | Unit of Measurement | Specification Standard | Excel Workbook Grouping |
|---|---|---|---|
| Rectangular Galvanized | Pounds (Lbs) & Sq. Footage | 2-in to 4-in w.g. Pressure Class | Tab 1: Rectangular Supply, Return, Exhaust |
| Round Spiral Lockseam | Linear Feet by Diameter | Single Wall & Double Wall Acoustic | Tab 2: Spiral Mains & Branch Runouts |
| Fittings & Transitions | Itemized Unit Piece Counts | TDC/TDF Flanged & Slip/Drive | Tab 3: Elbows, Transitions, Taps, Caps |
| Duct Liner & Wrap | Square Feet (Gross & Net) | 1-in / 1.5-in / 2-in FSK & Neoprene | Tab 4: Thermal & Acoustic Insulation |
| Air Devices (Diffusers/Grilles) | Itemized Unit Counts | Lay-In & Hard Ceiling Integration | Tab 5: Air Distribution Terminal Devices |
| Fire & Smoke Dampers | Unit Counts by Dimension | UL Rated 1.5 & 3-Hour Assemblies | Tab 6: Life Safety Accessories |
SMACNA Standards & Pressure Class Takeoff Methodology
Accurate commercial sheet metal takeoff cannot rely on generic duct surface area. Sheet metal poundage and fabrication labor are directly governed by the specified static pressure classification and SMACNA gauge selection tables. We evaluate engineering specifications to align your takeoff with real fabrication costs:
1. Pressure Classes & Gauge Thickness
Low-pressure downstream ductwork (1/2-inch to 2-inch water gauge) typically utilizes 24-gauge or 26-gauge galvanized steel with slip-and-drive connections. Medium to high-pressure primary supply mains (3-inch to 6-inch water gauge) require heavier 20-gauge or 18-gauge sheet metal with reinforced TDC/TDF transverse flanging to resist deflection. We segregate poundage by pressure rating.
2. Fitting Complexity & Scrap Factors
Straight coil-line ductwork carries a much lower fabrication labor rate than multi-plane transitions, offset transitions, and radius elbows with turning vanes. Our takeoffs isolate straight duct footage from custom hand-laid fittings, applying realistic metal scrap allowances so your raw material procurement is exact.
3. Specialty Exhaust: Welded Grease & Fume Ducts
Commercial kitchen commercial hoods mandate 16-gauge carbon steel or 18-gauge 304/316 stainless steel with liquid-tight continuous field or shop welding under NFPA 96. We quantify cleanout doors every 10 feet, welded companion flanges, and multi-layer zero-clearance ceramic fire blanket insulation wrap.
Shop Fabrication vs. Field Installation Demarcation
Estimating sheet metal requires clear separation between shop hours and field erection hours to properly apply shop burden vs jobsite labor crew rates:
Shop Labor Operations
Coil line decoiling, plasma cutting, longitudinal Pittsburgh lock forming, TDC roll forming, turning vane cutting, acoustic liner pinning, and sealant application. We provide clean poundage and fitting counts ready for your shop productivity factors.
Field Erection Labor Factors
Trapeze unistrut hanger installation, upper attachment concrete anchors, high-bay scissor lift handling, joint gasketing, damper installation, and acoustic flexible duct connections to terminal diffusers.
Duct Air Leakage Testing (DALT)
Modern energy codes (IECC, ASHRAE 90.1) mandate certified pressure testing on medium and high-pressure supply duct sections. We highlight the linear footage and test boundary sections requiring SMACNA leakage class verification.
Need Mechanical Equipment Included?
If your bid package includes rooftop air handlers, VRF condensers, chillers, or exhaust fans, review our complete commercial HVAC estimating services for full mechanical equipment coordination.
Explore HVAC Estimating →Need Turnkey Bid Assembly?
Ensure your ductwork bid includes customized labor burden hours and a clear scope letter protecting against plan discrepancies. Explore our commercial bid estimating services.
Explore Bid Estimating →Priority Regional Ductwork Takeoff Services
SMACNA sheet metal poundage, fabrication linear footages, and life safety damper takeoffs.
Texas Ductwork Takeoff Services
SMACNA galvanized duct poundage, spiral duct for creative tech spaces, welded grease duct, and IECC 2021 air leakage testing.
Texas Ductwork Scope →Florida Ductwork Takeoff Services
Coastal aluminum and 316 stainless ductwork, vapor-sealed FSK insulation, and Miami-Dade NOA hurricane wind dampers.
Florida Ductwork Scope →Frequently Asked Questions
Common questions regarding our commercial ductwork takeoff services.