What Can Be Done Before IFC
Grid layout, column placement, and preliminary member sizing can be modeled from 50–75% design development drawings. This creates a structural skeleton that can be used for early coordination with mechanical, electrical, and architectural trades. Anchor bolt locations can sometimes be developed from preliminary foundation layouts if the structural engineer confirms column centerlines are stable.
- Structural grid import and column layout
- Preliminary member size assignment (subject to revision)
- Early coordination model for BIM clash detection
- Anchor bolt layout if foundation design is confirmed
- Preliminary material takeoff for mill order planning
What Cannot Safely Be Done Before IFC
Connection design, hole patterns, cope dimensions, and final piece mark assignment cannot be completed on pre-IFC drawings without significant rework risk. If the EOR revises member sizes, connection types, or structural layout after preliminary modeling is complete, every affected drawing must be regenerated — at the fabricator's cost unless the contract clearly allocates that risk.
How to Protect the Schedule When Starting Early
If the project requires early-start detailing, document the design-development revision state of the drawings used, identify which items are 'held for IFC confirmation,' and price the early-start work as a separate line item with a defined revision allowance. Any IFC revision that affects work already completed should be treated as a change order rather than absorbed into the original detailing fee.
IFC Status — What It Actually Means and Why It Matters
IFC stands for Issued for Construction — the drawing status indicating the engineer of record has completed design development, incorporated owner and consultant review comments, and released the drawings as the governing basis for construction. IFC drawings carry the EOR's stamp and signature. Drawings at earlier stages — Issued for Coordination (IFC-C), Issued for Review (IFR), or Design Development (DD) — are not construction-authorized. Working from pre-IFC drawings introduces the risk that member sizes, connection types, column locations, or entire framing areas may change before the IFC set is released. On a typical commercial project, the difference between a 75% design development set and the final IFC set can include member upsizes affecting 20–40% of the drawing count, connection type changes at moment frames, and revised column grid spacing that requires rebuilding affected zones from scratch. AISC Code of Standard Practice Section 4.2 addresses the detailer's right to complete and accurate information — early-start detailing is permissible but the risk allocation for pre-IFC revision work must be defined in the contract before kickoff.
Defining Revision Risk Allocation in the Contract
The most important protection for both the fabricator and the detailing firm when starting early is clear written risk allocation in the detailing contract. The contract should define: which drawing set revision was used to begin detailing (document number and date); what constitutes a 'design change' versus a 'detailing correction'; how revision work resulting from IFC-to-pre-IFC differences will be priced (typically time-and-materials against the defined hourly rate); and what advance notice the fabricator will provide when the IFC set is expected. A detailing firm that starts work on pre-IFC drawings without written risk allocation is absorbing schedule and cost risk that should belong to the project — and a fabricator whose contract holds the EOR's risk is passing that same risk downstream to the detailer without compensation. Address this before the modeling begins, not after the IFC set arrives with changes.
- Document the drawing set used at kickoff by number, revision, and date
- Define 'design change' vs. 'detailing correction' explicitly in the scope
- State the rate for rework caused by IFC-to-pre-IFC differences
- Include a notice requirement for IFC issuance so the detailer can plan model updates
- Confirm which held items cannot be released until IFC is received
Anchor Bolt Plans — The Exception to Waiting for IFC
Anchor bolt plans are the one deliverable that nearly always justifies early-start detailing, even before IFC, because their schedule consequence is unique: anchor bolts must be set in concrete before the slab is poured, and concrete cure time (typically 28 days for full strength) adds a fixed lag before steel erection can begin. Any delay in the anchor bolt plan means a direct delay to the erection start date. For this reason, it is standard practice to release anchor bolt plans from preliminary structural drawings as soon as the EOR confirms that column locations are stable — even if other framing details remain unresolved. The risk of anchor bolt plan changes is real but lower than most other detailing items, because column grid layout is typically established early in design and rarely changes significantly after 75% design development. Confirm with the EOR in writing that anchor bolt locations are design-stable before releasing for concrete work.
Model Versioning and Tracking Pre-IFC Work
When detailing begins on pre-IFC drawings, model version control is critical. Tekla Structures maintains a native version history through its model backup system, but the detailing PM should implement a defined versioning protocol: a model snapshot is saved at the start of pre-IFC work, labeled with the drawing revision it was built on; changes made after IFC receipt are applied to a new version; and the differences between versions are documented in a revision log. This versioning approach allows the detailer to identify exactly which members were affected by IFC changes, produce accurate rework estimates for change-order purposes, and provide the fabricator with a clear record of what was revised and why. Informally merging IFC-driven changes into the original model without versioning makes it impossible to separate billable revision work from original scope — which creates disputes that could have been prevented.
Coordinating Pre-IFC Starts With the EOR
Before beginning detailing on pre-IFC drawings, a brief coordination call with the EOR is valuable. The goal is to identify which portions of the structural design are stable versus which are still actively changing. Most EORs can identify their high-confidence areas — foundation grid, primary column layout, structural system type — versus areas that remain in flux — transfer beam sizes, connection design at complex conditions, mechanical room framing. This conversation takes 30 minutes and produces a map of low-risk areas to detail early and high-risk areas to hold. It also puts the EOR on notice that the detailer is relying on current information, which sometimes accelerates the IFC process. Document the outcomes of this call in writing — including the EOR's confirmation of which items are stable — to establish the basis for any future change-order claims.