What is a structural steel quantity takeoff?
A structural steel quantity takeoff, often just called a steel takeoff, is the count and measurement of every steel member in a drawing set, recorded by shape, size, length, and weight per foot. It produces the piece count, the tonnage, and the takeoff sheet or BOM that a steel bid is priced from.
Key facts
- A takeoff is a count and a measurement, not a price. Pricing comes after, in the estimate.
- The deliverable is a takeoff sheet, sometimes called the BOM: one row per member type with mark, shape and size, quantity, length, weight per foot, total weight, camber, stud count, connection notes, and grid location.
- Columns and beams make up most of the count on a typical commercial job. Joists, braces, and miscellaneous steel fill in the rest.
- The two numbers every downstream decision sits on are piece count and tonnage. Tonnage drives material and freight. Piece count drives shop hours, handling, detailing, and erection picks.
- Sets are often incomplete. A missing column schedule or a callout that points at a detail that does not exist yet is normal, and the estimator has to decide how to carry it.
What a takeoff actually produces
You are building a list. Every structural member on every sheet, identified by shape and size, counted, and measured so its weight can be calculated. The list is what the rest of the bid is built from.
| Column on the sheet | What it holds | Why it matters later |
|---|---|---|
| Mark | The member's label on the plan | Finds the piece again on a change order |
| Shape and size | W12x26, HSS8x8x1/2, L4x4x1/4 | Weight per foot, material ordering |
| Quantity and length | Count and measured length | Pounds, then tons |
| Camber and studs | Callouts riding the beam line | Shop operations and cost |
| Connection notes | Type at each beam end | Shop hours, which tonnage alone does not predict |
| Grid location | Where it lives | Erection sequence and revision tracking |
The order estimators work in
The sequence matters because each step protects the next one from error. Columns come first, off the column schedule and the grid intersections, because they set the frame everything else hangs on. Beams come off the framing plans, plan by plan. Joists, deck, and braces follow, with braces read from the elevations. Connections are noted per beam end so the estimate can price labor later. The math to tonnage comes last, once the counts are settled.
Skip a step or run them out of order and you find out during the estimate, or worse, after the award.
What is the difference between a quantity takeoff and a material takeoff?
You will hear both. In structural steel they mean the same document. A quantity takeoff counts and measures members. A material takeoff is the same list read as an order, with waste and connection material added. The estimator produces the first; purchasing consumes the second.
Example
A six story office core with roughly 180 tons of steel might carry 1,400 pieces on the takeoff sheet. A single W12x26 beam at 30 feet is 780 pounds, or 0.39 tons. Multiply that kind of line across 1,400 rows and you see why the takeoff is the slow half of a steel estimate, and why one wrong weight per foot repeats across every row that uses it.
How Ferra handles this
Ferra reads the full drawing set, detects columns off the schedule and beams off the framing plans, and hands the estimator a takeoff sheet to review and export. The estimator confirms every number. See Steel Takeoff or the longer treatment in the honest guide to structural steel estimating.
Sources
- AISC Shapes Database v16.0, the weight per foot behind every tonnage number on the sheet.