Steel takeoff for general contractors
GCs don't fabricate steel, but they need to know whether steel numbers make sense. A GC steel takeoff is about tonnage, piece counts, scope coverage and the gaps between trades, so the budget holds and fabricator bids can be leveled honestly.
- Conceptual psf checks
- Leveling fabricator bids
- Gaps between trades
- Tracking changes
Three jobs
- Budgets before bids. The owner wants a steel number before fabricators have priced it. A quick takeoff, or at least a pounds-per-square-foot check, beats a ratio from a different building type.
- Leveling. Fabricator bids differ in scope more than in price. A GC who knows the tonnage and item list can see who left out stairs, misc. metals or deck.
- Changes. When drawings change, the GC needs to know what moved before the fabricator's change order arrives.
Pounds per square foot, with real data
At schematic design you may only have a framing concept. Two published AISC references give sanity checks, not prices:
- Rule of thumb for braced buildings: Ioannides and Ruddy's Rules of Thumb for Steel Design (AISC, 2000) gives steel weight (psf) ≈ stories ÷ 3 + 7. That's about 8 psf for a three-story building and 16 psf for 27 stories. The authors call it an oversimplification, useful only to check whether a detailed number is reasonable.
- A real benchmark building: AISC's 2018 conventional steel framing study of a four-story, 192,730 sf office building came out at 728 tons, 7.55 psf and 939 pieces, with gravity beams about 5.55 psf of that.
Rule of thumb: 3/3 + 7 = 8 psf → 90,000 × 8 = 720,000 lb = 360 tons
AISC study rate: 7.55 psf → 340 tons
Check against a takeoff of the actual framing plans once available.
Long spans, transfer girders, moment frames, heavy roof equipment, cantilevers and seismic design all push these numbers up, sometimes a lot. Use your own completed jobs by building type whenever you have them.
Enough, not everything
| Category | Capture | Why |
|---|---|---|
| Tonnage by category | Columns, beams, bracing/moment frames, joists, deck (sf) | Budget and leveling |
| Piece count | Total and by category | Erection check; AISC's study ran about 1.3 pieces per ton |
| Misc. metals list | Lintels, embeds, bollards, ladders, rails, stairs, roof frames | Most-missed scope |
| Finish | Primed, galvanized, AESS, intumescent-compatible primer | Big cost swings |
| Connection basis | Shown by EOR or delegated (AISC 303 §3.2.3) | Engineering and risk |
| By-others items | Anchor rod setting, survey, grout, field paint, fireproofing | Under AISC 303 these default to the GC |
That last row matters. Under the AISC Code of Standard Practice, the owner's designated representative for construction, usually you, sets anchor rods and embeds (§7.5.1), surveys them (§7.5.4), grouts base plates (§7.7), and handles field painting and touch-up (§7.17). If no one in your bid carries them, you own them.
Use the list
| Check | Question |
|---|---|
| Tonnage | Is the stated tonnage close to your takeoff? |
| Joists and deck | Included, excluded or separate? Deck type and gauge? |
| Misc. metals | Which items are in? Furnish only or furnish and install? |
| Stairs and rails | Included? Finish? Pan fill by whom? |
| Connection design | Included if delegated? Sealed calcs? |
| Erection | Included? Crane? Number of mobilizations? |
| Exclusions | Anchor rods, grout, touch-up, testing, MEP supports, deck openings |
| Schedule | Shop drawing durations assume what review time? |
| Validity and escalation | How long is the price good? Escalation clause? |
The lowest number is often the smallest scope. Plug the gaps on your leveling sheet with your own values so you compare like with like.
Where scope falls through
- Lintels: Division 05 or the mason? Loose lintels are often specified in 05 50 00 but shown on architectural sheets.
- Embeds: furnished by steel, set by concrete? Who supplies embeds for precast and curtain wall?
- Deck openings and reinforcing: shown on structural drawings, or only on MEP drawings that nobody sends to the fabricator?
- MEP supports and dunnage: "by mechanical" on M-sheets, "by steel" in the spec.
- Roof screens and RTU frames: steel, roofing or mechanical?
- Elevator pit ladders, sill angles, divider beams and hoist beams: Division 14 or 05?
- Fireproofing compatibility: primer that the SFRM manufacturer doesn't accept is a repaint cost.
Track what moved
Keep the takeoff by sheet and item with revision letters. When an addendum or bulletin comes in, compare sheets and update only the changed rows. You'll know roughly what the change should cost before the fabricator's change order arrives, and you'll know whether it was a scope change or something already in the bid documents.
Member counts off the drawings, with the sheet attached.
RenderDraw's AI takeoff proposes steel member counts and lengths from plans, framing plans and schedules, links every row to its source, and sends low-confidence items to your estimator before the handoff to pricing.
- Counts and lengths by member. Proposed from the drawings and kept tied to the framing plan or schedule they came from.
- Uncertain items flagged. Items the AI can't confirm go to review instead of being guessed.
- Addenda through the same review. Send the changed sheets through takeoff and review, then reprice the members that changed.
- Your estimator decides. Connections, erection, coatings, risk and margin stay your call.
Test it on a real steel package
Send one structural set, ideally with an addendum. Sample files stay private while RenderDraw assesses the request. No obligation.
RenderDraw does not publish accuracy percentages or time-saved claims. Test it on your own plan set.
Questions estimators ask.
How do general contractors estimate structural steel?
At concept stage with pounds per square foot from comparable buildings, then with a takeoff of tonnage by category, piece count, misc. metals and finishes once framing plans exist. The takeoff is used to set the budget and to level fabricator bids.
How many pounds of steel per square foot does a building use?
It varies by building type and design. AISC's 2018 four-story office study came out at 7.55 psf, and an AISC rule of thumb for braced buildings is stories ÷ 3 + 7 psf. Long spans, moment frames and heavy loads go higher.
How do you level steel bids?
Compare each bid line by line against your own item list: tonnage, joists and deck, misc. metals, stairs and rails, connection design, erection, exclusions, schedule and price validity. Fill gaps with your own values before comparing totals.
What does the GC usually own on a steel job?
Under AISC 303-22, unless the contract changes it: setting and surveying anchor rods and embeds, grout under base plates, and field painting and touch-up. Many GCs also pick up MEP supports and deck openings that aren't on the structural drawings.
Can RenderDraw help a GC take off steel?
RenderDraw's AI takeoff proposes member counts, lengths and other quantities from the drawings with the source sheet attached, which a GC estimator can review and roll into tonnage and an item list. Get a free sample takeoff.
Know the steel before the bids arrive.
Send the structural set. RenderDraw proposes a member list and quantities with sources so you can check budgets and level bids.
- Upload the plans, specs and schedules, plus an addendum if you have one.
- RenderDraw reviews the set and the scope you want tested.
- We follow up with extracted quantities, flagged items and next steps.
Where these numbers come from
We checked this guide against the standards, manufacturer documents and industry references below (last reviewed November 2026). Figures marked as rules of thumb are typical ranges, not requirements; your project documents, local code and your own cost history govern.
- AISC Conventional Steel Framing Study: Office (2018) — 728 tons, 7.55 psf, 939 pieces for a four-story, 192,730 sf office
- Ioannides & Ruddy, Rules of Thumb for Steel Design (NASCC/Modern Steel Construction, 2000) — stories/3 + 7 psf
- ANSI/AISC 303-22 Code of Standard Practice (free from AISC) — §§3.2.3, 7.5, 7.7, 7.17
- AISC: Can't Afford to Miss on Structural Steel Projects (GC quick reference)