BIM & Tekla
Steel Detailing BIM Coordination Between Design and Fabrication
How steel detailers coordinate a BIM model with design and fabrication: ownership, comments, clashes that matter, member status and handover packages that stay reviewable.
Coordination is not a weekly screenshot. It is a written agreement about who owns geometry, which clashes are allowed to move a hole, and how a comment becomes a revision on a mark. Steel detailing sits in the middle of that agreement. The design team still owns member size and design criteria. The detailer owns manufacturing information once the contract assigns it. The fabricator owns mill orders and nest. When those three talk through a model without naming the owner, everyone assumes the other person froze the brace.
BIM makes that confusion faster, not rarer. A linked file can look authoritative while it is a week old. A clash list can bury the one duct that actually relocates a moment connection. A model comment can vanish when the authoring file is renamed. The cure is the same discipline you already need on 2D work: a comment log, a revision letter, and a status on the member. The model is another place those artefacts can live, not a reason to delete them.
This article is for detailing leads who must talk to designers and to the shop without pretending they are the same audience. It sits next to approval drawing comments and quality control. It stays away from invented software menus. If your office also runs a standardised approval set, keep that package in the loop — the MBS Approval Package does not replace coordination; it is one of the documents coordination has to keep true when a clash finally moves a member.
Who owns the model
Say it in the kickoff note. “We all share the BIM” is not an ownership rule. Ownership means who may change a grid, who may change a connection, and who issues the file that the others are allowed to trust.
| Object | Typical owner after award | Detailer does not silently change |
|---|---|---|
| Grids, levels, design member size | Engineer of record | Yes — raise it |
| Connection fittings per assigned scope | Detailer / fabricator | Not after issue without a revision |
| Openings that come from architecture/MEP | Those disciplines | Yes — RFI or comment |
| Marks, piece drawings, NC | Detailer / fabricator | Shop must be told of changes |
RFI versus model comments
A model comment is useful when the other party actually opens the model. An RFI is useful when the contract, the programme or a stamped drawing is at stake. Do not hide a design change in a viewpoint only the BIM coordinator still has installed.
When a comment is enough
Clearances, packing plates, a requested hole move inside an already approved typical, or a request to confirm a vendor drawing. Log it, close it, and if it hits an issued sheet, revise the sheet.
When you need an RFI
Member size, missing design information, a clash that requires the engineer or architect to move something they own, or a specification conflict. Those belong on the RFI log with a mark and a due date.
Clashes that actually matter for steel
Filter ruthlessly. Steel cares when a clash moves a member, a hole, a brace workpoint, an anchor rod, or a connection plate into fireproofing or a slab opening. Nut-to-deck touches and bolt-head-to-bolt-head noise can wait. If the weekly list cannot be read in half an hour, it is not a coordination tool.
- Brace or rafter versus a door, shutter or crane envelope
- Moment stiffeners versus slab or haunch geometry
- Anchor rods versus foundation reinforcement or pit walls
- Connection material versus a documented fireproofing zone
- Secondary members versus a penetration that is already frozen
Status of members
A model without status is a drawing index without revision letters. At minimum: not started, in detailing, issued for approval, comments open, released for mill, released for nest, hold. Colour is fine if the legend is on the transmittal. Colour without a legend is decoration.
Status has to match the drawing issue. A member coloured “released” while its piece drawing is still Rev A with an open comment is a lie the shop will believe. Align status with approval revisions.
Handover packages between design and fabrication
Handover is a dated bundle: native model or agreed export, PDF drawings, comment log, hold list, and the specification clauses that still govern. A live link to a working folder is not a handover. People will keep editing.
- Freeze the files and name them with date and revision.
- List what is for information versus for fabrication.
- Attach the open RFI/comment log, not a promise to “catch up later.”
- State which typicals are approved and which are still schematic.
- Tell the receiver how to report a clash so it returns with a mark number.
A practical workflow
- Write ownership and status definitions into the kickoff note.
- Agree which clashes will be reviewed and which will be ignored as noise.
- Run coordination against frozen backgrounds, not against whoever saved last.
- Raise RFIs for design-owned changes; log model comments for detailing-owned ones.
- Update issued drawings when a closed comment hits a mark.
- Hand over with a dated bundle and an open-item list.
Engineering tips
- Invite the connection designer or lead detailer to clash review, not only a BIM coordinator who does not read typicals.
- If a linked model is chaotic, take a weekly freeze. Live chaos is not coordination.
- Repeat grid and level checks after every background update. Most expensive steel clashes start as a moved grid.
- Close comments in the same system you opened them. Parallel Excel logs drift.
Common mistakes
Letting the federated view become the record
Reviewers stamp drawings. If the federated model disagrees with the PDF, the PDF still governs unless the contract says otherwise. Fix the authoring file.
Clash reports with no owner column
Unowned clashes return next week. Assign design, detailing or MEP before the meeting ends.
Changing a design member in the fabrication model to ‘make it fit’
That is a design change. Raise it. Silent fitting is how the as-built frame parts company with the analysis.
Handover by sharing a working directory
The receiver cannot know what was current. Zip or otherwise freeze a revision.
Checklist
- Ownership written down
- Status legend issued
- Clash filter agreed and used
- Comments carry mark or sheet numbers
- RFIs used for design-owned changes
- Issued drawings revised when comments close
- Handover bundle dated and complete
- Open items listed rather than remembered
Frequently asked questions
Who should run the coordination meeting?
Someone who can decide which clashes change steel. A meeting of screenshot collectors without a detailer or engineer will produce a longer list, not a smaller one.
How often should backgrounds be updated?
On a published cycle, not whenever someone saves. Weekly or at design issues is common. State the cycle so detailing is not rebuilding connections daily.
Does PEB work need this much coordination?
On a simple shed, less. On a PEB with cranes, sprinklers and a process platform, yes. Match the PEB design workflow to the interfaces that can still move a frame.
What if the design team will not share a model?
Coordinate on drawings, which you already know how to do. BIM coordination requires files. It is not mandatory if the contract never promised them.
Where this leaves the work
Design and fabrication will always pull the model in different directions. Coordination is the written limit on that pull: owners, statuses, a filtered clash list, and comments that can find a mark. Without those, a federated view is only a nicer way to be surprised.
Keep quality control and comment handling as the human systems. Put the model inside them, not above them.
This article provides general educational information. Project-specific structural design, calculations and drawings should be reviewed by appropriately qualified engineering professionals and checked against applicable project requirements and standards. StruTools does not replace engineering judgement or professional design review.