What is the difference between shop drawings and erection drawings?

Shop drawings — assembly and single-part drawings — tell the fabricator how to make each piece: dimensions, holes, welds, copes, camber and finish. Erection drawings tell the site where each finished assembly goes, with marks, grids, levels and the field bolts required. One is a manufacturing instruction, the other an assembly instruction, and both come from the same model.

Who is responsible for designing steel connections?

It depends on the contract and the regional code of practice. In many projects the engineer of record designs the connections and the detailer details them exactly as designed. In others the responsibility is delegated to the detailer, in which case a qualified structural engineer performs and checks that design and it is submitted for the engineer of record's approval. The arrangement should be explicit before detailing starts.

Which software is used for structural steel detailing?

Tekla Structures, SDS/2 and Advance Steel cover most of the market. All three produce drawings from a model and export fabrication data such as NC1/DSTV and DXF. The choice affects connection automation, drawing production and interoperability, so it is usually driven by what the fabricator consumes rather than by preference.

How long does a steel detailing package take?

It depends on tonnage, complexity, how many connection types are involved and how complete the design information is at the start. The honest way to answer it is with a drawing-by-drawing programme agreed at intake and reported against, rather than a rate quoted before anyone has read the design.

ARTICLE

Steel Detailing Services: Achieving Structural Precision in the AEC Industry

Steel detailing is the least visible discipline in a steel project and the one with the shortest route to a site problem. This is what the package contains, what governs it, and where the failures actually come from.

14 August 2026 7 min read

Why steel detailing decides the programme

A structural engineer designs a frame. A fabricator makes pieces of metal. Between them sits a translation job: turning design intent expressed in member sizes and load paths into several thousand pieces, each with a mark, a length, a set of holes, a bevel and a place in an erection sequence.

That translation is steel detailing, and it is where a project's tolerance for ambiguity runs out. A design drawing can say that a beam connects to a column. A shop drawing has to say with what, in which holes, at what gauge, with which bolt grade, and whether the plate is on the near side or the far side. Everything downstream — cutting, drilling, welding, painting, transport, erection — is executed against that answer.

A missed dimension is caught by a checker in a minute, by a fabricator in a day, and by an erection crew in a week, and only the first of those is free.

What a detailing package actually contains

A complete package is more than a folder of drawings. It is a coordinated set in which every document agrees with every other one.

Erection drawings — the site's document. Plans, elevations and sections showing where each assembly goes, with marks, grids, working points, levels and field bolts.
Assembly drawings — one per fabricated assembly: how its parts fit, with welds, bolts and overall dimensions.
Single-part drawings — the shop floor's document. Each individual piece with its cuts, holes, copes, bevels, camber and surface treatment.
Connection details — to the engineer of record's design, or designed by the detailer's engineer where the contract delegates that responsibility.
Anchor bolt and embed plans — issued ahead of the rest, because concrete does not wait for steel drawings.
Bills of material — advance for procurement, final for reconciliation, with bolt lists and assembly weights.
Fabrication data — NC1/DSTV files for saws and drill lines, DXF for plate nesting, and exports for the fabricator's management system.

The measure of a good package is not that each of these is correct in isolation. It is that they cannot disagree, because they were all produced from one model.

From design intent to fabrication release

The order matters. It starts with a review of the inputs — structural drawings, specification, connection design basis, architectural and services models, the existing RFI log. The purpose is to find the contradictions before anything is modelled: undefined connections, members shown at different sizes on plan and section, levels that do not reconcile, a specification calling for one standard while the drawings assume another.

Then the model is built, connections are detailed, and drawings are produced from it. The package goes to the engineer for approval, comments come back, and the model and drawings are revised together. Only then is the package released for fabrication — and that release should be an explicit decision by a named person, not the passive fact that a folder happens to be current.

Two disciplines separate a smooth cycle from a painful one: raising RFIs early and tracking them to a written answer, and revision control that shows what changed, so a reviewer who approved revision B sees the delta rather than re-reading forty sheets.

Where packages go wrong

Detailing failures are rarely exotic. They repeat.

Coordination, not calculation. The steel is right and the services are right, and they occupy the same 300 millimetres. It is only found early if the models are federated and tested.
Interfaces. The frame meets a concrete core, a precast wall, a curtain wall bracket or an equipment supplier's skid, and the interface belongs to nobody. Interfaces are where scope gaps and revision mismatches live.
Drift between model and drawing. A change is made in one and not the other. Automated reconciliation eliminates this defect completely, which is a rare thing to be able to say.
Standard details reused where they do not suit. A typical connection is applied at a location whose geometry, load or access does not take it.
Erectability. The assembly is correct and cannot be installed in the sequence the site intends, or cannot be bolted because there is no access for a spanner.
Late change without a delta. Something changes, the set is reissued, and nobody can say precisely what moved. The shop then fabricates a superseded piece.

None of these need unusual complexity. They need a large set, a fast programme, and checking that relies on human attention holding out.

Standards and compliance

Detailing is governed more tightly by standards than outsiders assume, and they differ by region in ways that reach the drawing.

In North America, AISC 360 governs design while AISC 303, the Code of Standard Practice, governs the detailing relationship itself — responsibilities, tolerances, what the fabricator may assume, and what has to be shown. Where seismic provisions apply, AISC 341 changes the connections and the demands on them.

Across Europe, EN 1993 with the National Annex of the country of construction governs design and EN 1090-2 governs execution, including the execution class that sets inspection, tolerances and weld quality. The execution class belongs on the drawings; packages that omit it cause arguments later. The United Kingdom applies the same Eurocodes with the UK National Annex, and Australia and New Zealand use AS 4100 with AS/NZS 5131 and its construction categories.

Then there are the conventions that make a drawing readable: welding symbols to AWS A2.4 or ISO 2553 depending on region, title block data to ISO 7200, and information container naming under ISO 19650 where the project runs a formal common data environment.

The same frame is detailed differently under each of these, and a package produced without deciding which one governs has decided by accident.

What technology changed, and what it did not

Three-dimensional detailing environments — Tekla Structures, SDS/2, Advance Steel — removed a whole category of error by making drawings a view of a model rather than independent documents. Direct output of NC1/DSTV and DXF data removed another, by taking the shop's re-keying step out of the process.

What has changed more recently is checking. Most of what a good checker does on a steel package is deterministic: confirming that every mark on a drawing exists in the model and in the bill of material, that dimension chains close, that bolt edge distances satisfy the governing specification, that weld symbols are complete, that the revision on the sheet matches the register. That work is exhaustive, repetitive and unforgiving of tiredness — precisely the profile of work a machine should do, and increasingly does. Automation also produces the repetitive parts of the model and the sheets, so volume no longer trades against consistency.

What has not changed is judgement, and it is worth being clear about it. Deciding whether a connection is sensible, whether an assembly can actually be erected in the sequence proposed, whether a designer's detail should be questioned rather than drawn — that is engineering, and it belongs to an engineer who reviews the package and signs it. Automation makes that signature safer to give. It does not replace it, and anyone who says otherwise has not been on site when a package was wrong.

Choosing a detailing partner: what to ask

Capability claims are easy to make and hard to compare. A short list of questions separates them.

Which standard will this package be detailed and checked against, and where is that recorded? A partner who cannot answer this in one sentence will decide it by accident later.
What is checked automatically before a human review, and can I see the check record? The answer distinguishes a checking process from a checking intention.
Who signs the package? Named, senior and accountable — or diffuse.
How are RFIs and revisions tracked, and what arrives when I ask what changed?
What happens when the programme accelerates? Extra capacity that arrives as extra people also arrives as extra inconsistency, unless the standard is enforced by the system rather than the individual.
What is handed over at the end? The model, the register, the issue history and the check record — or a folder of PDFs.

Precision in steel detailing is not a quality anyone can promise in a sentence. It is a property of a process: ambiguity removed at the start, repetitive work produced consistently, deterministic checks run exhaustively, and an engineer who reads the result and puts their name on it.