SMACNA-Aware HVAC Takeoff Software
DuctIQ is HVAC takeoff software that understands the fabrication side of a mechanical bid. When a drawing does not call out a steel gauge, DuctIQ falls back to the SMACNA minimum for the duct size and labels it as such — so your shop drawings carry a defensible gauge instead of a blank.
It reads the mechanical drawing, measures the duct, counts the fittings, and produces fabrication-ready shop drawings with the callouts a sheet metal shop expects.
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Why SMACNA awareness matters in takeoff
Gauge drives material cost and fabrication. On many drawings the gauge is not spelled out for every run, which leaves the estimator or detailer to apply the standard schedule by hand — and a wrong gauge on a shop ticket is a real, expensive mistake.
DuctIQ closes that gap. When a gauge is given, it uses it. When it is not, it applies the SMACNA minimum gauge for the size and marks it clearly as a minimum, so the number is both useful and honest.
SMACNA minimum gauge reference (½" w.g. galvanized)
Here is the low-pressure galvanized minimum gauge schedule DuctIQ falls back to when a drawing leaves the gauge blank — a quick cheat sheet you can sanity-check a takeoff against. Rectangular is keyed on the largest side; round on diameter.
A higher pressure class, reinforcement, or a gauge the drawing specifies all override these minimums, so always confirm against the project's pressure class and specification before fabrication.
| Galvanized min. gauge | Rectangular (largest side) | Round (diameter) |
|---|---|---|
| 26 ga | up to 12" | up to 14" |
| 24 ga | 13"–30" | 15"–26" |
| 22 ga | 31"–54" | 27"–36" |
| 20 ga | 55"–84" | 37"–50" |
| 18 ga | over 84" | over 50" |
SMACNA low-pressure (½" w.g.) galvanized minimum gauge by duct size — the schedule DuctIQ applies when a drawing omits the gauge, always labelled as a minimum. Higher pressure classes or a specified gauge override these; confirm against your spec.
From plan to fabrication spec
The takeoff carries through to the shop. Each fitting drawing shows gauge, material, and seam/connection alongside the cut dimensions, in the A×B / C×D convention shops use. The estimator gets quantities to bid; the detailer and shop get fittings they can build from.
- Duct measured in linear feet by size and system.
- Fittings counted and dimensioned for fabrication.
- Gauge taken from the drawing when specified.
- SMACNA minimum gauge applied and labelled when it is not.
- Material and seam/connection shown on each fitting.
Honest by design
A takeoff tool that quietly invents a gauge is dangerous. DuctIQ is built to be explicit: a derived gauge is always labelled as a SMACNA minimum, never presented as a verified specification. That keeps the responsibility — and the final call — with the estimator and detailer.
Fast and fabrication-correct — not a trade-off
Most AI takeoff tools lead with a stopwatch — a number in ten or fifteen minutes. DuctIQ is in that range too: most mechanical sets process in minutes, many well under ten. But a fast duct quantity that carries the wrong gauge is not a saving — it is a fabrication error waiting at the shop. SMACNA awareness is what keeps the speed from costing you a build-ready spec.
So DuctIQ pairs the fast first pass with two things a pure speed pitch skips: a labelled SMACNA-minimum gauge wherever the drawing is silent, and a line-by-line review where every duct run, fitting, and gauge is yours to confirm before it reaches a shop ticket. You get the minutes-not-hours turnaround and a takeoff the detailer can stand behind.
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Related HVAC takeoff guides
Further reading
- SMACNA Gauge and Seam Basics for Sheet Metal Takeoff
- Round vs Rectangular Duct Takeoff: What Actually Changes
- How Accurate Is AI HVAC Takeoff Software?
Frequently asked questions
Is a SMACNA-aware takeoff slower than a plain one?
No. DuctIQ processes most mechanical sets in minutes — many well under ten — and the SMACNA minimum gauge is applied automatically as it builds the fittings, so you get fabrication-ready callouts without a separate pass. The review that follows is where you confirm gauges and quantities, not a delay in producing them.
Does DuctIQ apply the full SMACNA standard?
DuctIQ applies SMACNA minimum gauge by duct size as a clearly-labelled fallback when a drawing does not specify a gauge. It is a takeoff and shop-drawing aid, not a substitute for a detailer's review against the project's pressure class and specification.
What happens when the drawing does specify a gauge?
The specified gauge is used as-is. The SMACNA minimum only appears when no gauge is given, and it is always labelled as a minimum.
Does it show material and seam too?
Yes. Each fitting drawing carries material and seam/connection alongside the gauge and cut dimensions.
Can a detailer override the gauge?
Yes. The derived gauge is a labelled starting point for review, not a locked value — the detailer remains in control of the final spec.
Is this useful for estimating as well as detailing?
Yes. The same takeoff gives the estimator reviewable duct and fitting quantities to price, and gives the shop fabrication-ready detail.
What gauge does SMACNA require for ductwork?
For low-pressure (½" w.g.) galvanized duct, the SMACNA minimums step with size: 26 ga up to 12" rectangular (14" round), 24 ga to 30"/26", 22 ga to 54"/36", 20 ga to 84"/50", and 18 ga above that. Higher pressure classes, reinforcement, or a specified gauge override these — confirm against your project's pressure class and spec. The reference table above lays out the full schedule.
Where does DuctIQ get the SMACNA minimum gauge it applies?
From the published low-pressure galvanized schedule by duct size — the same values in the reference table on this page. DuctIQ only applies it when a drawing omits the gauge, and always labels it a minimum so the detailer confirms it against the spec.