Structural steel detailing is the job of turning an engineer’s design drawings into shop drawings and erection drawings that a fabricator can build from piece by piece. The detailer works out every cut length, hole, cope, weld and bolt, so each beam and column arrives on site ready to fit.
Design drawings show what the frame has to be. Detail drawings show how to make it. If you are a homeowner with a steel beam on order, an owner reviewing a submittal, or someone thinking about detailing as a career, here is what the work involves.
Where Detailing Fits in a Steel Project
A steel job moves through a fixed sequence. The detailer sits between the engineer and the shop:
- Engineer of record (EOR): designs the frame and issues structural drawings showing member sizes, loads, grades and typical connection details.
- Detailer: usually hired by the fabricator. Builds a 3D model or drawing set of every piece, raises questions (RFIs) where the design is unclear, and produces shop and erection drawings.
- Approval: the EOR and architect review the shop drawings to confirm they match the design intent, then return them approved, approved as noted, or for revision.
- Fabricator: builds each piece in the shop from the approved drawings. Our guide to structural steel fabrication covers what happens there.
- Erector: assembles the pieces on site using the erection drawings. See structural steel erection for that stage.
What a Shop Drawing Shows
A shop drawing (sometimes called a piece drawing or detail sheet) covers one shipping piece or a group of identical pieces. A typical beam detail includes:
| Item | What it tells the shop |
|---|---|
| Piece mark | A unique ID, such as B12, painted on the steel so it can be found on site |
| Section and grade | For example W12x26, ASTM A992. Size notation is explained in how to read steel beam sizes. |
| Cut length | The exact length to cut, allowing for connection clearances |
| Holes | Diameter, location and gauge for every bolt hole |
| Copes and blocks | Notches cut from the flange so the beam clears the member it frames into |
| Attached parts | Shear tabs, clip angles, stiffeners and plates, each with its own sizes |
| Welds | Shown with standard symbols; see our weld symbols chart |
| Bolts | Grade, diameter, length and whether each is shop or field installed |
| Finish | Surface prep, primer, paint or galvanizing requirements |
Erection drawings
Erection drawings are plans and elevations showing where every piece mark goes, its orientation, and the field bolts and welds needed. They also show anchor rod layouts at the foundations, which is why detailers often produce an anchor rod plan early so the concrete contractor can set them before the steel arrives. More on those in our anchor bolts guide.
Connections: The Hardest Part of Detailing
Member sizes come straight from the design drawings. Connections are where detailing takes real judgment. A design drawing might show a beam framing into a column with a note such as “shear connection, design by fabricator,” leaving the detailer and the fabricator’s connection engineer to choose the type, number of bolts and plate sizes.
- Simple shear connections, such as single plates (shear tabs) and double clip angles, carry vertical load only.
- Moment connections also carry bending and need flange welds or flange plates. See our guide to moment connections.
- Bracing connections use gusset plates where diagonal braces meet beams and columns.
Who designs the connection depends on the contract. It may be fully designed by the EOR, or delegated to a licensed engineer working for the fabricator. A detailer without an engineering license lays out connections from the design data provided, but does not take responsibility for their structural capacity. Any connection that carries load has to be designed or checked by a licensed structural engineer.
Detailing for erection safety
Some details are driven by OSHA rules for ironworkers rather than by the structural design. The OSHA 1926.756 beams and columns standard (read October 2026) requires that solid web members are secured with at least two bolts per connection, drawn up wrench-tight, before the load is released from the crane. It also covers double connections, where beams on opposite sides of a column web share the same bolts: at least one bolt must stay connected to the first member unless a seat or similar device holds it while the second is installed. Detailers handle this by staggering holes or adding erection seats, so ironworkers are never left holding a beam with nothing bolted.
Software and Models
Detailing moved from hand drafting to 2D CAD and now mostly to 3D modeling. In a 3D model each beam, plate and bolt exists as an object, so the software can check for clashes, number the pieces and generate the drawings, bills of material and machine files that drive CNC saws, drill lines and plate burners. Many projects now also share the model with the general contractor and other trades for coordination.
Common Detailing Problems
- Incomplete design information. Missing connection loads or unclear elevations lead to RFIs and delays. Getting answers before modeling saves rework.
- Coordination clashes. Steel running into ductwork, plumbing or the edge of a slab. The model catches many of these if other trades share their layouts.
- Late revisions. A change after pieces are cut means scrapped steel. Revision clouds and dated revision numbers on each sheet keep everyone on the current version.
- Field fit-up. Existing buildings rarely match old drawings. For renovation work, such as replacing a basement support beam, the detailer needs field-measured dimensions, not dimensions from plans.
Detailing as a Career
Steel detailers are a specialty of drafting. The BLS Occupational Outlook for drafters (read October 2026) says drafters typically need an associate degree in drafting or a related field, or a certificate, and that they convert engineers’ and architects’ designs into technical drawings with CAD software. It reports a median pay for all drafters of $68,090 per year based on May 2025 data. BLS does not give a separate figure for steel detailers, so treat that number as a general guide.
Most detailers learn on the job in a fabrication shop or detailing firm. A solid grasp of shapes, bolting, welding symbols and how steel is actually erected is worth as much as software skill.
Structural Steel Detailing FAQ
What is the difference between design drawings and shop drawings?
Design drawings, from the engineer, show member sizes, loads and the overall frame. Shop drawings, from the detailer, show exactly how to cut, drill and assemble each individual piece.
Does a steel detailer need to be an engineer?
No. Detailers are usually not licensed engineers. Where connections need to be designed rather than just laid out, a licensed engineer does that design and the detailer draws it.
Do I need shop drawings for a single beam in my house?
For a simple residential beam, the fabricator often works from the engineer’s sketch and a basic cut sheet rather than a full submittal. You still need the engineer’s sizing and your local building department’s approval.
How long does steel detailing take?
It depends on the size of the job, how complete the design is, and how quickly RFIs and approvals come back. Review and approval cycles often take as long as the drawing work itself.
Who is responsible if a shop drawing has an error?
That depends on the contract. Generally the fabricator is responsible for the accuracy of its shop drawings, and the engineer’s approval confirms they follow the design intent. Check the project specifications for the exact split.
The Short Version
Detailing translates the engineer’s design into the cut lengths, holes, welds and bolts a fabricator needs, and the erection drawings an ironworker builds from. Good detailing catches problems on screen, where fixing them costs nothing, instead of on site, where it costs a lot.
Reference information only, not engineering advice. Disclaimer.