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A fabricator once told us that the most expensive words on a jobsite are “it doesn’t fit.” By the time a beam is cut, a connection is welded, and a crew is standing on a lift trying to force a piece into place, the cost of a clash has already multiplied several times over. Tekla Structures exists precisely to catch that problem before steel ever leaves the shop — but only when the shop drawings behind it are built with fabrication reality in mind, not just design intent. In this article, we walk through how properly built Tekla shop drawings prevent the clashes that derail schedules, and where those clashes tend to hide when detailing is rushed.
Why Clashes Happen Without a Coordinated Tekla Model
In short: Clashes happen when structural, architectural, and MEP models are detailed in isolation instead of being coordinated inside a single 3D environment — a gap that a well-built Tekla model is specifically designed to close before fabrication begins.
Steel does not fail on the jobsite because someone made a careless mistake. It fails because two trades made independently correct decisions that never got checked against each other. A duct routed through a beam web, a sprinkler line crossing a brace, a stair stringer landing on top of a foundation bolt pattern — none of these are drafting errors in isolation. They are coordination failures, and coordination failures are exactly what Tekla Structures was built to prevent.
We have walked onto projects where the structural model was detailed correctly against the design drawings, yet still generated field clashes, because the detailing team never ran it against the architectural and MEP models. A shop drawing can be dimensionally perfect and still be functionally wrong if it was never tested against the rest of the building.
The Cost of a Field-Discovered Clash
A clash caught in the model costs a few minutes of a detailer’s time. The same clash discovered in the field costs a crane sitting idle, a crew standing around, and in many cases, a re-fabricated piece shipped back to the shop. We price this difference for clients regularly, and it is rarely close — field rework routinely runs several multiples higher than a model correction, before accounting for schedule delay.
Why “It Passed Design Review” Is Not the Same as “It’s Fabrication-Ready”
Design drawings communicate structural intent; they are not built to catch bolt clashes, weld access issues, or erection sequencing conflicts. That translation from design intent to buildable steel is exactly what our structural steel detailing process is responsible for, and it is where clash detection has to happen — not after the drawings are already issued for fabrication.
Common Blind Spots in Non-Coordinated Models
Bolt head clearance at tight connections, weld gun access in confined bays, and camber interaction with deck bearing are three of the most frequent blind spots we catch during model review. None of these show up on a 2D design drawing — they only surface once the connection geometry is built in 3D and checked against real-world access constraints.
How Tekla Shop Drawings Catch Problems Before They Reach the Shop
In short: Tekla Structures runs clash detection directly inside the 3D model, flagging geometric conflicts between members, connections, and adjacent trades before a single shop drawing is issued for fabrication.
The real value of Tekla is not that it draws steel faster — it is that it tests steel before it is built. Every bolt, plate, and member exists as a real 3D solid, which means two pieces of steel that occupy the same physical space will show up as a clash the moment the model is checked, rather than the moment a fitter tries to assemble them.
Our process runs clash checks at multiple stages: once after primary framing is placed, again after connections are detailed, and a final pass once miscellaneous steel and deck are added. This staged approach means a clash introduced late in the process — say, a stair landing added after connections were finalized — gets caught immediately instead of surfacing three weeks later on the shop floor.
Model-Based Coordination With Architectural and MEP Trades
We import architectural and MEP reference models directly into the Tekla environment so that ductwork, piping, and finishes are checked against structural steel in the same coordinate space. This is where the majority of avoidable clashes get caught, because it is the one check that a purely structural detailing process — one that never looks outside its own discipline — will always miss.
How This Ties Back to Fabrication-Ready Output
A clean clash report is only useful if it actually changes the drawings that reach the shop. Our explanation of how Tekla Structures generates shop and erection drawings covers exactly how a resolved 3D model translates into dimensionally accurate, clash-free output — not a separate 2D drafting exercise disconnected from the model.
Where Clashes Hide: Connections, Joists, and Miscellaneous Steel
In short: The majority of field clashes we see cluster around three areas — bolted and welded connections, joist and deck bearing conditions, and miscellaneous steel like stairs and rails — because these are the components most often detailed late or in isolation.
Connection-Level Clashes
Connections are dense with hardware in a small physical space, which makes them the single most clash-prone element in any steel package. A gusset plate sized correctly for capacity can still conflict with an adjacent brace, or a bolt pattern can leave no room for a wrench to turn. Our connection design process checks not just load capacity but physical access and erectability, because a connection that cannot be bolted in the field is not a usable connection, regardless of how correctly it was engineered on paper.
Joist, Deck, and Miscellaneous Steel Conflicts
Joists and deck interact with primary framing at bearing seats and headers, and miscellaneous steel — stairs, ladders, guardrails — often gets detailed after the primary structure is already locked in. That sequencing is exactly when clashes creep in. Our steel joist and deck detailing work and our miscellaneous steel detailing process are both run against the same coordinated model as the primary structure, rather than as an afterthought layered on top of it, which is where most late-stage field conflicts originate.
What a Clash-Free Drawing Package Looks Like From Us
In short: A clash-free drawing package reflects a model that has already been checked against architectural, MEP, and internal structural conflicts, with resolved issues documented — not just a drawing set that “looks complete.”
| Package Element | Rushed Detailing Process | Our Coordinated Process |
|---|---|---|
| Clash Detection Timing | After drawings are issued | Multiple checkpoints during modeling |
| Trade Coordination | Structural model only | Structural + architectural + MEP overlay |
| Connection Review | Capacity only | Capacity and physical access/erectability |
| Miscellaneous Steel | Detailed in isolation | Checked against coordinated primary model |
| Field RFIs | High, reactive | Low, resolved before issuance |
A drawing set built this way does not just look finished — it has already survived the coordination checks that would otherwise happen on the jobsite, at a much higher cost.
Frequently Asked Questions
Can Tekla Structures catch clashes automatically, or does someone need to check manually?
Tekla’s clash detection tools flag geometric conflicts automatically once models are combined, but the tool only finds what it is asked to check. Our detailers run structured clash passes at defined project stages so nothing is caught by accident or missed entirely.
Does clash detection only matter for large or complex projects?
No. Smaller projects often carry tighter tolerances and less schedule buffer, which means even a minor bolt clearance clash can cause a disproportionate delay. We apply the same coordination process regardless of project size.
What happens if a clash is found after the drawings are already issued?
It becomes a field problem instead of a model problem, which typically means a change order, a re-fabricated piece, or a delayed erection sequence. Catching the clash inside Tekla before issuance is significantly less costly than resolving it on-site.
Conclusion
A clash caught on a screen costs minutes. A clash discovered on a jobsite costs schedule, budget, and trust with the general contractor. Tekla Structures gives detailing teams the tools to prevent that outcome, but only when the process behind it treats coordination as a built-in step, not an optional extra. We structure every project — from primary framing through connections, joists, deck, and miscellaneous steel — around that discipline, so the drawing set your shop receives has already been tested against the building it is going into. If your next project needs a detailing partner who treats clash prevention as standard practice rather than a value-add, we would welcome the conversation.
