Guide · By Alex McCann, Managing Director
Erection Drawings vs Shop Drawings: What’s the Difference?
Shop drawings tell the workshop how to make each member or assembly: sizes, holes, welds, bolts, marks. Erection drawings tell the site crew where each marked piece goes and how it connects on site. Both should come from the same coordinated model, with marks that match.
01 / Short answer
The short answer
A general comparison of the two drawing sets in a structural steel package. What each set includes can vary from job to job, so check the scope of your package.
| Factor | Shop drawings | Erection drawings |
|---|---|---|
| Purpose | Tell the workshop how to make each member or assembly. | Tell the site crew where each marked piece goes and how it connects on site. |
| Who uses it | The fabricator and workshop team. | The steel erector and site team. |
| Scope | One piece or assembly at a time. | The whole structure, or an area or level of it. |
| Typical content | Sizes, holes, welds, bolts, marks and material lists. | Grids, levels, piece marks, field bolts, site welds and holding-down bolt references. |
| When it’s issued | For approval, then for fabrication. | With the fabrication package, ahead of steel arriving on site. |
| What goes wrong if it’s wrong | Members are made incorrectly and have to be fixed or remade. | Pieces go in the wrong place or don’t fit, which means site rework and delays. |
02 / Shop drawings
What shop drawings contain
Shop drawings are for the workshop. They turn the engineer’s design into the information needed to fabricate each member or assembly.
- Assembly drawings and single-part drawings
- Dimensions, hole positions and sizes
- Welds and bolts
- Piece and assembly marks
- Material lists
More on our structural steel shop drawings. If the steel is being hot-dip galvanised, the shop drawings also need to show vent and drain holes.
03 / Erection drawings
What erection drawings contain
Erection drawings are for the site. They show the whole structure, so the erector can find where each marked piece goes and how it connects.
- Grids and levels
- Plan and elevation views showing each piece mark
- Field bolts and site welds
- Holding-down bolt references
- Notes for the site team
Temporary bracing and the erection sequence are typically specified by the erector or the engineer. Erection drawings may reference them, but they’re not part of the detailing itself.
04 / Marks
Why the marks must match
Every piece on the erection drawings is identified by the same mark as its shop drawing. When both sets come from one coordinated model, the marks line up automatically.
Revision control matters just as much. If the shop drawings are revised but the erection set isn’t, or the other way round, a mark can point to the wrong piece – and the mismatch usually shows up as rework on site.
Coordination and RFIs keep both sets in step. See how we handle RFI management and design coordination.
05 / Glossary
Where GA drawings, BOMs and NC/DXF fit
- GA drawings / marking plans: general arrangement drawings showing the structure in plan and elevation with piece marks. They often serve as the erection set.
- BOM: a bill of materials extracted from the model, used for ordering, costing and fabrication planning.
- NC/DXF files: machine-readable files used for cutting, drilling and laser cutting in the workshop.
06 / RDM
How RDM handles a steel package
- 01
Brief & drawings in
Architectural and structural packages received, reviewed and scoped for detailing.
- 02
Modelling in Tekla
Structure modelled in Tekla Structures for accurate members, connections and quantities.
- 03
Checking & RFIs
Dimension and coordination checks against arch vs structural; RFIs registered and issued to the client.
- 04
Issue for approval
Drawings issued for review so stakeholders can approve before fabrication proceeds.
- 05
IFC & fab drawings
Approved packages issued for construction and fabrication, including IFC where required.
We produce erection drawings (GA/marking plans used as the erection set) and holding-down bolt plans, along with shop drawings, a BOM from the model, and NC and DXF files for laser cutting and fabrication. Drawings are prepared to Australian Standards, and turnaround times are provided with our quotes.
See our structural steel shop drawings service. Connecting to an existing structure? Read about 3D laser scanning and our guide to scan to Tekla. Unsure who is responsible for connections? Read who designs steel connections.
07 / FAQ
Frequently asked questions
Q01What’s the difference between shop drawings and erection drawings?
Shop drawings describe how to fabricate each piece. Erection drawings show where each piece goes and how it’s connected on site.
Q02Who uses erection drawings?
The steel erector and site team.
Q03What do erection drawings usually show?
Grids, levels, the location and mark of each piece, field bolts and site welds, and notes for the site.
Q04Do the marks on shop and erection drawings have to match?
Yes. Both sets should come from the same model and revision so each mark refers to the same piece.
Q05Are erection drawings the same as GA drawings?
The terms overlap; many detailers issue general arrangement or marking plans that serve as the erection set. Check what your package includes.
Q06Who designs temporary bracing and the erection sequence?
Usually the erector and/or engineer, not the detailer. Drawings may reference it.
Q07Does RDM provide erection drawings?
Yes. We produce GA/marking plans used as the erection set, plus holding-down bolt plans, alongside the shop drawings.
Q08How long does a package take?
Turnaround times are always provided with RDM’s quotes.
08 / Quote
Request a quote
Send your drawings and scope to info@rdmdrafting.com.au. Turnaround times are provided with every quote.