Implementing BIM: The Execution Plan & Clash Detection Workflow

Welcome

Hello, and welcome. This is Super Structures General Contractors — a national general contractor headquartered in Powhatan, Virginia — here to help you and your clients build something that lasts. We're glad you're with us, and we look forward to connecting with you.

Alright, Implementing BIM: The Execution Plan & Clash Detection Workflow. Don't let the plain title fool you. Here's the part that actually matters on the job: BIM pays off only when a written execution plan says who models what, to what level, and by when, and the team then runs clash detection area by area to a signed-off, frozen model before anything is fabricated. Learn it well and you'll run coordination that actually finishes, instead of a meeting series that drags on while the field builds around it.

The intro course explained what a model is and what a clash is. This lesson is about running it on a real project: the document that sets the rules, the sequence that gets the model clean, and the handoff from the model to fabrication and layout.

Who runs BIM on a construction project

• The project BIM coordinator (sometimes the VDC coordinator) federates the models, runs the clash tests, keeps the issue list, and runs the meetings. On a large job this is a full-time person; on a small job it may be a consultant, or by written agreement the mechanical sub's detailer.
• Trade detailers at each mechanical, plumbing, electrical, and fire-protection sub model exactly how their systems will be installed. They are the people who can actually move a duct.
• The design team provides the architectural and structural models that everything else is coordinated against.
• The super and PM are the customers: they need a clean model for each area before that area is built.

The single most important sentence in this lesson: if modeling is not in the subcontract, it will not happen. The scope exhibit must state that the sub models its work, to what level, in what format, attends coordination meetings, and meets the area sign-off dates.

What goes in the BIM Execution Plan

The BIM Execution Plan (BEP) is the project's rulebook. A usable one covers:

• Goals and uses — coordination, prefabrication, layout points, quantities, and what the owner gets at turnover.
• Roles and contacts — who the coordinator is and who models each system.
• Coordinate system — one shared project base point, project north, units, and the elevation datum. More phantom clashes come from models on different origins than from any other cause.
• Model breakdown — by building, level, and zone, with file naming.
• LOD by milestone — the trade coordination models carry fabrication-level detail for the systems being coordinated.
• Software, versions, and exchange formats — native files plus an open exchange format and the coordination review format.
• Clash rules — tolerances, clearance zones (maintenance access, and code clearances such as the working space in front of electrical equipment under NEC 110.26), and the order of precedence for who moves.
• Coordination schedule — areas in the order the building will be built, with sign-off dates set ahead of fabrication lead times.
• Sign-off and change control — what frozen means and how changes after sign-off are handled.

Internationally, ISO 19650 describes the information-management process and the common data environment that holds the models; the BEP is its answer to the owner's information requirements. You do not need to adopt the standard to borrow its discipline.

Setting up the federated model

Begin with the architectural and structural models and verify them against the current issued-for-construction drawings and bulletins. Check that grids, levels, and base points line up across every model before any trade starts detailing; an hour here saves weeks. Then each trade submits on a fixed weekly cadence to the shared location, and the coordinator federates and runs the tests.

A typical precedence order, which the BEP should state explicitly: structure and architecture are fixed; gravity systems that need slope (sanitary and storm) go next; then large ductwork; then pressure piping; then cable tray and conduit; then sprinkler mains; branch lines last. Flexible systems move for inflexible ones.

Running the clash detection cycle

• Set up tests per area and per trade pair, with the clearance tolerances from the BEP, so each test answers one question.
• Group clashes into issues. Five hundred raw clashes in a corridor are usually forty real problems. Each issue gets an ID, a location, a screenshot, an owner, a due date, and a status.
• Run the meeting from the issue list, not by scrolling the model. Weekly, per area, with the detailers who have authority to change their models. Decisions are recorded in the issue log the same day.
• Resubmit, re-run, repeat. Track the open-issue count per area week over week; a count that is not falling means a trade is not working between meetings.
• Sign off the area when hard clashes are zero and soft clashes are resolved or formally accepted. Every trade signs. The area is frozen, and from then on changes go through a change procedure.

From the signed-off model to the field

The coordinated model drives shop drawings, spool and rack drawings for prefabrication, sleeve and insert drawings, and the layout points covered in the next lesson. Penetrations through structure are collected on a sleeve drawing and sent to the structural engineer for review rather than assumed. And before trades install against the structure, verify that the structure was built where the model says, because the model assumes it was.

Going Deeper (Intermediate)

The most common failure is a stale structural model: the detailers coordinate against steel that was revised two bulletins ago. Assign someone to confirm, at every design revision, that the models match the sheets. Second most common: the architect's ceiling heights are the thing that has to give, and nobody raised it with the architect until the area was supposedly done. Put a design-team representative in the meeting for congested areas.

Area sequencing matters. Coordinate the earliest-built and most congested areas first, usually mechanical rooms and low corridors, and stay ahead of construction by the fabrication lead time plus a buffer.

Advanced / Pro-Level

Pros run coordination on metrics: open issues per area over time, areas signed off versus planned, and the number of post-sign-off changes, which is a direct measure of design stability. They watch the contract: design models are often provided for information only with no reliance allowed, and the contractor's coordination model is a means-and-methods document, so the BEP must say what governs when the model and the sheets disagree. They link the clash issue log to the RFI log whenever a resolution needs a design answer, and they tie coordination zones to the schedule so a late sign-off shows up as a schedule risk, not a surprise.

Practice Challenge

The Level 2 corridor was signed off three weeks ago and the mechanical sub has fabricated the duct. The architect issues a bulletin dropping the corridor ceiling six inches for a lighting change. What happens? (Answer: this is a post-sign-off change — the coordinator re-runs the area against the bulletin, the affected trades identify what no longer fits, the PM issues notice and prices the impact including the fabricated duct and the re-coordination time as a potential change, and nothing is re-fabricated until the owner directs; the field keeps installing in unaffected areas.)

In Practice

A coordinator with a BEP, a weekly cadence, and an issue list signs off areas a month ahead of the crews and the prefab racks fit. A coordinator who runs the clash software on whatever models show up and scrolls through them in a two-hour meeting is still coordinating Level 1 when the drywall goes up on Level 3.

Common Mistakes to Avoid

• Hiring a coordinator but leaving the modeling requirement out of the subcontracts
• Federating models on different base points and chasing phantom clashes for a month
• Scrolling through the model in meetings instead of working an issue list with owners and dates
• Letting the field start an area before it is signed off
• Treating the design structural model as the as-built structure

Takeaway: BIM pays off only when a written execution plan says who models what, to what level, and by when, and the team then runs clash detection area by area to a signed-off, frozen model before anything is fabricated.

Educational content only — not design, engineering, surveying, or legal advice, and not a substitute for training, your company's procedures, or review by a licensed design professional or surveyor. Software and hardware are described as generic categories and no product is endorsed. Follow the applicable codes and regulations as adopted in your jurisdiction, your contract, and the manufacturer's instructions for every instrument and device.