How Strong Project Teams Do BIM Differently – Part 2

By MEGAN SALAZAR

What Actually Needs to Be Modeled and Why

Your model does not need every bolt, but it does need the right things.

One of the biggest misconceptions about BIM is that more detail is always better. In reality, the most important thing is putting the right detail in the right places.

We do not need to model every nut and bolt. But if we miss the large, space consuming elements or the things that drive constructability, we end up coordinating an idealized world that does not match the field.

Here is what consistently makes the difference on complex projects:

1. Focus on congested and higher-risk areas

Not every square foot needs the same modeling effort. The areas that benefit most from higher fidelity are:

• Bathrooms and vestibules where many systems compete in very tight rooms
• Baggage handling and back of house zones where racks, conveyors, low headroom and safety clearances pile up
• Ceiling spaces in public or architectural areas where ceiling heights and aesthetics are non-negotiable
• Critical rooms including data centers, IT closets and electrical closets where design may be at a lower level of detail

If a space is small, crowded or involves many overlapping trades, treat it as a priority zone. It likely needs more than diagram-level geometry to make reliable decisions.

2. Do not overlook the secondary elements that cause primary problems

Many clashes come from items that seem secondary on paper but dominate space in reality and thus are often overlooked. These include –

• Brackets and supports
• Studs, soffits, framing and backing
• Trays, racks, and cable routes
• Fireproofing thickness that eats up real clearance
• Ceiling grids and framing that define the actual available plenum
• Non-negotiable access clearances for data racks, electrical panels, valve access, etc.

If it occupies space or blocks access, it can create conflicts. Model it at the level needed to validate fit, access, and sequencing.

3. Model critical rooms and devices as they truly exist

Some locations become pinch points later and deserve special attention:

• Fire alarm rooms with all panels, conduit, sleeves and troughs
• DXRs and control devices, especially wall mounted and duct mounted units that drive exact locations
• Equipment in tight rooms where service clearances and access paths matter just as much as the equipment itself

When these are fully represented, trades can rough in with confidence instead of waiting on guesswork.

4. Run a simple reality check before coordination begins

Ask one question before the first clash test: Are the biggest and most space-impacting elements in this model right now?

Make a quick pass through the key drawings, details and specifications. Confirm that the big shapes and controlling features are present, including structure, major MEP (mechanical -electrical-plumbing) systems, architectural buildouts, ceilings, fireproofing, supports and the items listed above. A short review up front prevents weeks of fixing “ghost clashes” later when you discover the real issue was never modeled.

5. Set practical thresholds and acceptance criteria

Give the team clear rules so everyone knows what must appear in the model:

• Minimum size thresholds for conduit, pipe, and cable tray that must be shown
• Required clearances for access and service that must be protected in tight rooms and above ceilings
• Model views and checklists that define what a zone needs before it can be called coordinated

When the rules are simple and visible, model quality becomes predictable across areas and trades.

6. Close the loop with field truth

Use quick field checks to keep the model honest:

• Short site walks with drafters and field leads in the exact area being coordinated
• Spot verification of tie in points and lift access before sign off
• Reality capture where it adds value such as a fast laser scan (NavVis VLX or other SLAM scanners are great for this) or a set of weekly 360 photos

As much as BIMers love to jump to the model to solve issues, one field photo is worth a thousand clash screenshots.

Why this matters

Right place and right detail let the team make real decisions. Early routing, access, and sequencing get solved on screen so crews do not spend time solving them at height. The model becomes a tool that the field actually trusts.

Megan Salazar is VDC manager at EnTech.