Importance of Pre-Construction BIM Coordination
Projects are growing in complexity. Mechanical, electrical, and plumbing systems should fit in the available space, be easily accessible and maintainable, and meet code requirements. In case of uncoordinated project planning, clashes of various systems will become a reality and cause significant costs due to rework and delays. Recent research proves that BIM can help to save up to 15-20% of project costs, and clash detection can reduce field problems by 30-50%.
BIM coordination offers an opportunity to verify alignment of MEP, structure, and architecture before moving forward in the project life cycle. In fact, it allows solving the problems virtually instead of doing this on the field, which is time-consuming and costly. MEP BIM modeling helps to translate design into construction ready output through modeling of HVAC, piping, electrical, and plumbing systems in one model.
Here are the key steps of the BIM coordination process in pre-construction phase.
1. Project information and BIM execution setup
Prior starting to coordinate models, confirm that the BIM Execution Plan (BEP) is signed and agreed upon all project participants. It includes modeling requirements, level of development (LOD), data exchange format and others.
Setup verification points are:
• Project scope, responsibilities, and model exchanges dates
• Approval workflow and sign-off procedure
• Software versions, file formats, and naming conventions
• Common Data Environment creation for central access to the model
• Communication and reporting protocols
It is vital to agree upon these points from the very beginning to avoid any misunderstandings later.
2. Model readiness for BIM coordination
The models are not ready for BIM coordination at the same moment. Before doing clash detection, check if the models are ready for the coordination phase.
To do this, you need to verify if:
• Base points, levels, grids, coordinates, and orientation are consistent across all models
• The necessary LOD and information amount is provided for the current phase of the project
• MEP BIM modeling deliverables are relevant to the current construction stage of the project
Construction coordination models usually require LOD 350 or more. LOD 400 is for fabrication and assembly.
3. Discipline wise coordination checks
Each discipline model needs to be checked prior multi-trade coordination.
Architecture model check includes verification of shafts, ceilings, equipment rooms, access zones, openings. The model should not contain any obstruction for the MEP routing.
Structure model should include beams, slabs, penetrations, clearance around load-bearing elements. It is usually the most problematic model, so early detection is essential.
In mechanical model, it is important to verify duct routing, pipe routing, equipment placement, access space, and maintenance zones. There should be sufficient space for filters and coils.
In electrical model, it is necessary to check cable trays, lighting fixtures, panels, containment route, and service clearances. There are specific working clearances for electrical rooms and panels.
In plumbing and fire protection, check drainage slopes, risers, sprinkler head placement, service coordination. It is important that fire protection systems should be integrated and will not interfere with other MEP systems.
4. Clash detection and issue resolution
Clash detection is a core of the BIM coordination process. You need to do clash detection between the models of relevant disciplines with the help of special software such as Autodesk Navisworks, Revit, or Solibri.
Three kinds of clashes should be detected:
• Hard clashes: geometric intersection of two models
• Soft clashes: violation of clearance or buffer zone between two models
• Workflow clashes: conflicts with installation order
The best practice is to plan clash tests and prepare a "clash matrix". Based on the construction schedule, define the combinations of disciplines to do clash detection and prioritize it. Run clash detection as early as possible as it is much easier and cheaper to solve the problems during the design phase. Resolve each issue assigning owner, deadlines, and resolution status. Update the model and revalidate it to make sure that all major conflicts are closed.
5. Constructability and installation review
The model is not always constructible. It means that there are some issues with its building that you need to take care of.
Questions to answer:
• Is the routing constructible for the field installation?
• Does the installation sequence make sense?
• Is prefabrication possible for particular assemblies?
• Are the maintenance access and equipment replacement spaces realistic?
With BIM models, you can check constructability, access, sequence, installation conditions before starting construction. You should model and check service zones and equipment replacement clearances because even though component fits in the model, it can be hard to install, inspect, and maintain it safely. MEP BIM modeling services help to achieve fabrication-ready coordination with model refinement to dimensions, materials, and connections.
6. Drawing and shop model validation
It is essential to confirm if the coordinated model corresponds to the latest drawings and specifications. Any discrepancy between the model and contract documents can lead to costly field changes.
You need to verify if:
• Shop drawings, fabrication models, and schedules correspond to the coordinated model
• Annotation, dimensions, tags, and system identification are consistent
• The final output is ready for field implementation and contractor review
For example, coordinated services plans, sections, and elevations should be created basing on the model.
7. Data deliverables and handover preparation
Pre-construction BIM coordination creates not only 3D model but also various data deliverables. Make sure that you have the following list of deliverables:
• Federated models
• Clash reports with the status of each issue resolution
• COBie data for structured asset information handover
• Asset information for facilities management
File exports, naming standards, document version control should be confirmed. Also, verify that the model has all data necessary for commissioning and facility management. Create sign-off record for construction release.
8. Coordination responsibilities and approval workflow
It is important to assign responsibility for BIM coordination process to avoid misunderstandings and miscommunications. Define the following:
• The owner of each discipline model
• The person who will approve the final coordinated model
• The person who will update models in case of necessary changes
• Meetings schedule for model review and clash closure
• Escalation procedure for technical conflicts
Coordination is the process which involves various project participants. BIM manager or coordinator usually leads the integration process, but general contractors, subcontractors, architects, and engineers should actively take part in it.
9. Pre-construction sign-off checklist
Before releasing the construction authorization, it is necessary to confirm that:
• Model is aligned across all disciplines
• Major clashes are solved and documented
• Access and maintenance clearances are checked and verified
• Fabrication and shop outputs are verified
• Data deliverables are approved
• Construction release is authorized
Frequently Asked Questions
What is included in the BIM coordination checklist before construction?
The BIM coordination checklist includes BIM Execution Plan validation, model readiness verification, discipline-wise coordination check, clash detection and resolution, constructability review, drawing and shop model validation, data deliverables preparation, and sign-off procedure.
Why MEP BIM modeling is important before starting site work?
MEP BIM modeling detects conflicts between HVAC, electrical, plumbing and structural systems before the start of construction. It helps to prevent costly rework, delays, optimize space utilization, and improve system accessibility for maintenance.
How often should the clash detection be performed during pre-construction?
It should be done on regular basis through the whole design and pre-construction phases, but not only once before construction starts. The early clash detection in the design phase allows solving the problems easier and cheaper. Weekly or bi-weekly coordination meetings with the updated clash report are typical.
What level of detail should be in the construction-ready MEP models?
Construction-ready MEP models typically require LOD 350 or higher. LOD 400 is used for fabrication and assembly-level detail, including dimensions, materials, and connection specifications. The appropriate LOD depends on project objectives and phase requirements.