Short answer
They are stages of design completion. A 30% set is early design with approximate member sizes, a 60% set has most of the structure sized but still changing, and IFC (Issued for Construction) is the final set the work is built from. The earlier the set, the less reliable the takeoff.
What each stage means for steel
| Stage | What the steel looks like | How to estimate |
|---|---|---|
| 30% (schematic or early design development) | Framing grid and a few typical members, many sizes missing | Conceptual: weight per square foot or per building type |
| 60% (design development) | Most members sized, connections undefined, details thin | Takeoff with allowances and a larger contingency |
| 90% | Nearly complete, some open items | Takeoff close to final, carry specific risks |
| IFC | Complete and stamped for construction | Full takeoff, ready to price firm |
Exact percentages vary between owners and design teams, so check what the set title block actually says. "For bid", "for permit" and "for pricing" are other labels you will meet, and they do not always mean the set is complete.
How should you price an early set?
Be honest about what you do not know. At 30 percent, a lump-sum or per-square-foot budget is appropriate, with a stated range, because the engineer has not sized the steel yet. At 60 percent, you can take off what is shown and carry allowances for what is not, marking each allowance as such in the bid.
Rules of thumb are only valid for the building type they came from. A warehouse and a multi-story office use very different steel per square foot. See Conceptual steel estimating rules of thumb and Steel per square foot.
How do early sets cause trouble later?
Steel grows between the early set and IFC. Members get heavier, connections get designed, bracing is added. If you priced a 60 percent set as if it were final, the difference shows up as a change order, or as a loss if the contract was fixed price.
Protect yourself by stating the drawing revision your price is based on, listing assumptions, and keeping quantities and unit prices separate so you can re-price. Our guide to drawing revisions covers the workflow, and How do you handle addenda and revisions in a steel bid? gives the short version.
What comes after IFC?
After IFC, the fabricator produces shop drawings (or has them detailed). Those show every piece, connection and bolt and are submitted for approval before fabrication. Shop drawing quantities will differ from the contract drawing takeoff, because connection material is now drawn. See What is structural steel detailing?.
What to check when a new set arrives
- Read the title block and revision table of each structural sheet: what is the stage and the date?
- Find the sheet index. Are all the structural sheets there? Missing sheets are common in early sets.
- Look for "by others", "future" or "TBD" notes. Each is scope you cannot price firm.
- Check whether schedules are complete or have blank rows.
- Note what is not yet designed: connections, stairs, canopies, equipment supports.
- Decide how you will carry the unknowns: allowance, exclusion or RFI.
Writing that list down takes ten minutes and prevents most disputes later.
Who decides what is "IFC"?
The design team issues the set and labels it. Contractors do not decide. But the label is not a guarantee of completeness. An IFC set can still have gaps, and addenda and bulletins keep arriving. Treat the label as the design team's statement of intent and your own review as the test.
Also note that on design-build or fast-track work, the steel package may go out for pricing before the rest of the set is final. In that case, bid what is shown, state the revision, and list assumptions about what is missing.
Do early sets need a different takeoff method?
Yes. At 30 percent, the practical method is conceptual: weight per square foot for the building type, adjusted for span, loads and height, with a stated range. At 60 percent, take off the members shown and carry connection and detailing allowances. At IFC, run the full takeoff. With SteelFlo you can run a takeoff at any stage on the sheets you have, which is useful to firm up a budget as the set matures, but the output is only as complete as the drawings.
Stop counting steel by hand.
Upload your drawing set and SteelFlo puts a box on every steel label it finds, on every page. You verify the boxes and export a bill of materials.