The Structural Steel Model Handoff: What Files You Should Receive (And Why)

At project close — or mid-project when things get complicated — fabricators often discover that the "complete drawing package" they were promised doesn't include everything they actually need. The PDF shop drawings are there. But the native model file? That's extra. The KISS file for your shop management software? Not in scope. The IFC for the GC's coordination model? Nobody discussed it. These gaps usually trace back to a contract that defined deliverables in vague terms, a detailer who never clarified what "standard delivery" meant, or both. Getting the file handoff right is partly a contract issue and partly a communication issue — and it starts before work begins. This post defines the complete deliverable set for a structural steel detailing engagement: what you should expect to receive, what formats matter for your shop, and what language should be in your contract before anyone opens a model file.

Why File Delivery Is a Bigger Issue Than Most Fabricators Realize

Most shops don't discover the gaps until they need something. You're three months into fabrication, a field RFI comes in, and the EOR wants to see the model. Your detailer is off the job. You have PDFs. You don't have a native .db1 file, you don't have an IFC, and you don't have a written record of what revision the approved drawings reflect. Now you're rebuilding context from scratch under schedule pressure.

Or: you've onboarded a new detailer mid-project and they're asking for the previous detailer's model to continue work. The previous shop says the model file isn't included in what they delivered. You have no contractual leverage to require it.

These aren't edge cases. They happen regularly on commercial and institutional projects. The fix is specifying deliverables explicitly before the purchase order is cut — not after the drawing package arrives.

The Core Deliverable Set

Every structural steel detailing engagement should produce the following. Some items are scope-dependent; that distinction is noted.

Shop Drawing PDF Set

This is the stamped, revision-controlled drawing package submitted to the EOR for approval. It should include piece marks, member dimensions, weld symbols per AWS D1.1, bolt specifications per RCSC, and all connection details. If the project spec requires an engineer of record stamp on connection designs, that should be documented in the contract, not assumed.

PDFs should be issued in sequential revision clouds — Rev 0, Rev 1, Rev 2 — with a delta list or revision block that identifies exactly what changed. "Revised per EOR comments" is not a revision description. Every revision should be traceable.

Erection Drawing PDF Set

Separate from shop drawings. Erection drawings show the overall framing layout, member locations, column base plate settings, anchor bolt patterns, and sequencing notes relevant to the erection contractor. These drawings should be clearly keyed to the structural drawings of record and should reflect the final IFC model geometry.

Native Model File

This is the deliverable that fabricators most commonly fail to receive — or fail to require. For Tekla Structures, that's the .db1 file and its associated project folder structure. For SDS/2 shops, it's the full project directory. The native model is not a PDF. It is the working 3D model that contains every member, connection, weld, bolt group, and material assignment as modeled by the detailer.

Why does it matter? Because the native model is the single source of truth. If you need to re-detail a section, check a connection geometry, generate revised NC files, or hand the project off to another detailer, you need the model. PDFs are a derivative output. They do not replace the model.

File ownership should be explicit in your contract. The model was built using your project data — the drawings of record, the structural engineer's input, your shop standards. There is a reasonable argument that the model file belongs to you. Make that argument in the contract, before work starts.

IFC Export

On BIM-coordinated projects, the GC will require an IFC export for clash detection and coordination in Navisworks, Revit, or similar platforms. The IFC should be a current export from the native model, not a conversion of a PDF, and it should be versioned to match the current approved drawing revision.

If BIM coordination is required by the project spec, IFC delivery should be listed as a specific line item in your detailing contract. If it's not listed, you may not get it — or you'll pay for it as an add-on when the GC asks for it.

NC/CNC Files

If your shop runs CNC equipment — beam lines, plate processors, coping machines — NC files are part of the deliverable set. These are machine-readable files generated directly from the Tekla model that drive your equipment. The format depends on your machinery: DSTV, Tekla's native NC output, or vendor-specific formats.

Who owns the scope decision for NC files? That depends on your shop's setup and your agreement with the detailer. Some fabricators generate NC files in-house from the native model. Others want the detailer to deliver them directly. Either way, the arrangement should be documented. If your detailer isn't generating NC files and you're running a CNC shop, confirm your in-house software can read the native model format they're delivering.

Anchor Bolt Plans

Anchor bolt plans are frequently treated as an afterthought and delivered late. They shouldn't be. The GC needs them early — often before the structural steel package is approved — because anchor bolts need to be set before the steel arrives. The detailer should be producing anchor bolt plans from the model, coordinated with the structural drawings, and issuing them on a timeline that supports the GC's concrete pour schedule.

Bill of Materials / KISS File

The bill of materials is the material take-off that feeds your purchasing and shop management workflow. If your shop uses KISS (Key Interconnect Steel Software) or similar platforms, you need the KISS file — not just a PDF summary. A proper BOM from the Tekla model includes piece marks, member designations, quantities, lengths, and material grades. This file drives your material ordering, shop scheduling, and cost tracking.

If your detailer delivers a PDF summary instead of a structured BOM file, that's a gap. Ask for the KISS export or equivalent format your shop management software can ingest.

Revision Control: What a Proper System Looks Like

Every revision issued after IFC should include: a clear revision number, a date, a description of changes specific enough to be useful, and revision clouds on the affected drawings. The delta between revisions should be traceable without having to compare two full drawing sets side by side.

Loose revision control creates fabrication errors. A W8x31 gets fabricated to Rev 0 dimensions because the shop didn't know a Rev 1 was issued, or didn't know it affected that piece mark. A proper revision delivery system — with a transmittal log and explicit callouts — prevents that. Your detailer should be maintaining a drawing log that tracks what was issued, when, and at what revision level.

What Your Contract Should Say

Before work begins, your detailing contract should specify:

- Deliverable formats: Native model format (Tekla .db1, SDS/2 folder), PDF drawing sets, IFC version, BOM/KISS file format

- File ownership: Who owns the native model file and under what terms

- Revision delivery timeline: How quickly revised drawings are issued after EOR comments are received

- NC file responsibility: Whether the detailer delivers NC files or delivers a model the fabricator can process

- IFC coordination: Whether BIM coordination is in scope and what the deliverable standard is

Vague contract language — "complete drawing package," "all necessary files" — is how gaps happen. Name the files. Name the formats.

Red Flags in File Delivery

Watch for these during the proposal and contract phase:

- Watermarked-only PDFs with no path to an unwatermarked release — this can create problems at the EOR's office and on the shop floor

- No native model in the deliverable list — if the contract doesn't mention a .db1 or SDS/2 file, assume you're not getting one

- Missing BOM or KISS file — a PDF material summary is not a substitute for a structured BOM your shop management system can import

- IFC and NC files listed as "available upon request" — that language means additional cost or additional friction, not standard delivery

How NRSteel Structures Its Handoff

By default, NRSteel delivers: stamped shop drawing PDFs with full revision clouds, erection drawing PDFs, the native Tekla .db1 model file, anchor bolt plans, and a structured BOM/KISS file. IFC exports and NC file delivery are scope items — they're addressed in the proposal and included in the contract when the project requires them.

We document the deliverable set in writing before work starts. When revisions are issued, we send a transmittal with a delta description specific enough to route to the right people in your shop. The model file belongs to you — that's in our standard agreement.

If you're setting up a new detailing relationship and want to compare what you're being offered against what a complete handoff looks like, NRSteel is glad to walk through it. Get in touch to discuss your next project and what the file package should include.