What Structural Engineering Covers
Structural engineering is a licensed professional discipline that includes: determining design loads (gravity, wind, seismic, thermal); selecting member sizes based on structural analysis; designing connection types and specifying governing loads; verifying code compliance; preparing and stamping engineering documents; and accepting professional liability for structural adequacy. Only licensed PEs can perform these functions. Structural engineering defines what gets built and ensures it is safe.
What Steel Detailing Covers
Steel detailing is a technical discipline that includes: building a 3D model of the structure from the EOR's design; translating connection designs into precise shop geometry; producing fabrication drawings with all dimensions, hole patterns, and weld symbols; generating CNC files, BOMs, and other fabrication data; managing the submittal and revision process; and coordinating with the fabricator, GC, and EOR on technical questions. Detailing defines how the structure is built — not whether it is structurally adequate.
Where the Line Can Blur and Why That Matters
Experienced detailers routinely identify structural problems — connections that don't fit geometrically, members that appear undersized for the span, discrepancies between structural and architectural drawings. Identifying these issues is part of a good detailer's practice. Resolving them — deciding whether a connection is adequate, whether a member needs to be resized — is engineering. A detailer who resolves engineering questions without PE involvement is practicing engineering without a license, regardless of their experience level. Document every engineering question as an RFI and route it to the appropriate licensed engineer.
What Detailers Are Trained to Do — and What They Are Not
Structural steel detailers are trained in 3D parametric modeling (Tekla Structures, SDS/2), AISC connection geometry and standard practice, drafting conventions per AISC and AWS A2.4, shop drawing production, CNC data generation, and the constructability of steel assemblies. They are not trained — and are not licensed — to perform structural analysis, verify member adequacy against AISC 360, determine seismic design requirements under ASCE 7, or calculate weld capacities for non-standard joints. The distinction is not a criticism of the detailer's expertise; it is a recognition of the legal and professional structure of the construction industry.
Connection Design as the Most Common Overlap Zone
Connection design is the discipline most commonly at the boundary between detailing and engineering. Standard connections — shear tabs, clip angles, standard end plates designed from AISC Design Guide 9 or 10 tables — can be detailed without engineering calculations when the governing loads fall within the tabulated ranges and the EOR has accepted this approach. Non-standard connections, connections subject to fatigue or seismic demands, and connections that deviate from prequalified types all require PE involvement. Experienced detailers know which connections fall in each category; less experienced firms sometimes produce non-standard connection geometry without recognizing the need for engineering review.
- Standard shear connections per AISC Design Guide 9 — typically tableable, detailer can apply
- Extended moment end plates per AISC Design Guide 16 — requires engineering calculation, not just table lookup
- Seismic prequalified connections per AISC 358 — specific geometry required, PE confirmation mandatory
- Gusset plate connections for braced frames — requires buckling analysis under AISC 360 Chapter E
- Column base plates per AISC Design Guide 1 — tabulated for standard cases, PE required for overturning or uplift
The Practical Workflow for Staying in Scope
The most effective way for a detailer to stay within their professional scope is a systematic RFI discipline: any question that requires a structural judgment is documented as an RFI and routed to the EOR before any drawing decision is made. This is not inefficiency — it is the professional practice that protects the fabricator from relying on an unqualified opinion. A detailer who answers engineering questions informally (verbally, via email, through a drawing callout) may be providing guidance that lacks any engineering backing, and the fabricator who acts on it bears the risk.