Direct Answer
A steel detailer builds a precise 3D model of the structure in software like Tekla Structures, resolves connection geometry for every member, extracts 2D fabrication drawings and BOM from the model, coordinates RFIs with the engineer, and manages the submittal review cycle. They are the bridge between the engineer's design intent and the fabricator's production floor.
Full Explanation
On a given day, a detailer might: receive updated design drawings and revise the model, run interference checks between structural steel and MEP elements, generate piece mark drawings for 40 new members, write RFIs for connection conditions the design drawings don't fully define, incorporate engineer review comments, and update the BOM. Senior detailers also advise on connection efficiency — suggesting standard connections that reduce cost without compromising the design.
What This Means for Your Shop
The quality of your detailer directly impacts your production efficiency. A detailer who communicates proactively, flags issues before they become field problems, and delivers clean BOM outputs reduces your total fabrication cost more than you might expect.
Common Mistakes
Treating detailing as a commodity and selecting a detailer on price alone. A low-cost detailer who delivers error-prone drawings costs more in rework than a higher-rate detailer who gets it right the first time.
Recommended Process
Evaluate detailers on their track record with similar structure types, their Tekla/SDS2 proficiency, their RFI turnaround time, and their availability for your project schedule. Ask for references from fabricators, not just GCs.