Galvanized Duct Sheet-Metal Weight Takeoff
Duct sheet-metal weight from the perimeter, run, and gauge - the number that sizes the coil order and the hangers.
Example
You enter
- Duct width (in) 24
- Duct height (in) 12
- Run length (ft) 100
- Sheet weight for the gauge (lb/ft²) 1.156
- Seam / reinforcement allowance 1.15
You get
- Perimeter (ft) 6
- Area (ft²) 600
- Sheet metal to order 798 lb
Checked against published worked examples from: MEP Academy.
Details, formula, and sources
Scopeperimeter = 2 x (width + height); weight = perimeter x length x sheet weight x seam factor. A 24 x 12 in run, 100 ft long in 24-gauge galvanized, is about 798 lb once the SMACNA seam-and-reinforcement allowance is counted; a heavier 20-gauge run is over 1,140 lb. The gauge schedule is the lever; fittings are taken off separately.
Formula or tableperimeter_ft = 2 x (width_in + height_in) / 12; area_sf = perimeter_ft x length_ft; weight_lb = area_sf x lb_per_sf x seam_factor.
Source and editionDuct sheet-metal weight identity by name (developed area x per-gauge sheet weight x seam allowance); first-principles takeoff arithmetic.
Free accessThe developed-area geometry is public first-principles; the per-gauge sheet weight is entered from the metal (no copyrighted table reproduced).
What governsEstimate. AHJ and licensed professional govern.
API field nameswidth_in, height_in, length_ft, lb_per_sf, seam_factor, perimeter_ft, area_sf, weight_lb
- Sheet weight user-entered per-gauge weight (~1.156 lb/ft^2 24-ga, 1.656 20-ga galvanized); the metal governssheet-metal supplier
- Seam factor ~1.15 for seams, laps, and reinforcement per SMACNA duct construction standardsSMACNA