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🏗️ BIM/VDC Basics

Building Information Modeling (BIM) and Virtual Design and Construction (VDC) are transforming how construction projects are designed, coordinated, and built.

What is BIM?​

Building Information Modeling (BIM) is a digital representation of a building's physical and functional characteristics.

Key concepts:

  • 3D model - Visual representation
  • Data-rich - Contains information about components
  • Collaborative - Multiple stakeholders work together
  • Lifecycle - From design through operations

What is VDC?​

Virtual Design and Construction (VDC) uses BIM models to virtually build the project before physical construction.

Key concepts:

  • 4D scheduling - Time added to 3D model
  • 5D cost estimating - Cost data added
  • Clash detection - Find conflicts before construction
  • Visualization - See project before building

Benefits of BIM/VDC​

Design Phase​

  • Better coordination - All trades in one model
  • Clash detection - Find conflicts early
  • Visualization - See what you're building
  • Design optimization - Test alternatives

Construction Phase​

  • Better coordination - Fewer field conflicts
  • Prefabrication - Build off-site accurately
  • Layout accuracy - Precise field layout
  • Progress tracking - Visual progress updates

Operations Phase​

  • As-built model - Accurate record
  • Facility management - Use model for operations
  • Maintenance - Component information available

BIM Levels​

Level 0: 2D CAD​

  • Traditional 2D drawings
  • No collaboration
  • Paper-based

Level 1: 3D CAD​

  • 3D models
  • Still mostly 2D deliverables
  • Limited collaboration

Level 2: Collaborative BIM​

  • 3D models with data
  • Common file formats (IFC)
  • Each discipline has own model
  • Most common today

Level 3: Integrated BIM​

  • Single shared model
  • Cloud-based collaboration
  • Real-time updates
  • Future standard

Common BIM Software​

Design Software​

Autodesk Revit:

  • Most common
  • Architecture, structure, MEP
  • Industry standard

Archicad:

  • Popular with architects
  • Good for design
  • Less common in US

Tekla Structures:

  • Steel and concrete
  • Detailed fabrication models
  • Common for structural

Coordination Software​

Navisworks:

  • Clash detection
  • Model coordination
  • 4D scheduling
  • Common for GCs

BIM 360/Construction Cloud:

  • Cloud-based collaboration
  • Model viewing
  • Issue tracking
  • Document management

BIM Workflow​

1. Design Phase​

Architect creates model:

  • Building layout
  • Basic systems
  • Design intent

Engineers add:

  • Structural systems
  • MEP systems
  • Coordination

2. Coordination Phase​

GC coordinates:

  • Combine all models
  • Clash detection
  • Resolve conflicts
  • Create coordinated model

Trades review:

  • Check their scope
  • Identify issues
  • Request changes

3. Construction Phase​

Field use:

  • Layout from model
  • Prefabrication
  • Progress tracking
  • As-built updates

Clash Detection​

What is Clash Detection?​

Finding conflicts between different building systems before construction.

Common clashes:

  • Hard clash - Physical intersection (pipe through beam)
  • Soft clash - Clearance violation (equipment too close)
  • Workflow clash - Sequencing conflict

Clash Detection Process​

  1. Combine models - All disciplines in one file
  2. Run clash detection - Software finds conflicts
  3. Review clashes - Determine if real issues
  4. Resolve clashes - Coordinate solutions
  5. Verify resolution - Re-run clash detection

4D Scheduling​

What is 4D?​

4D = 3D model + Time

  • Model components linked to schedule
  • Visualize construction sequence
  • See project build over time

Benefits:

  • Better sequencing - See logical order
  • Identify issues - Conflicts in sequence
  • Communication - Visual schedule
  • Planning - Better project planning

5D Cost Estimating​

What is 5D?​

5D = 3D model + Time + Cost

  • Model components linked to costs
  • Automatic quantity takeoff
  • Cost estimation from model

Benefits:

  • Faster estimating - Automatic quantities
  • More accurate - Model-based quantities
  • Visual estimates - See what's included
  • Change tracking - Cost impact of changes

Getting Started with BIM​

For Contractors​

Start simple:

  • View models - Use free viewers (Navisworks Freedom)
  • Request models - Ask for models on projects
  • Learn basics - Understand what BIM is
  • Attend training - Software training

Build capability:

  • Hire BIM coordinator - Dedicated BIM person
  • Invest in software - Navisworks, BIM 360
  • Train team - Field and office staff
  • Develop processes - BIM workflows

For Subcontractors​

Start with:

  • Receive models - Get models from GC
  • Review in viewer - Use free software
  • Coordinate - Attend coordination meetings
  • Provide feedback - Identify issues

Advance to:

  • Create models - Model your scope
  • Clash detection - Check your work
  • Prefabrication - Use models for fab

BIM Requirements​

Owner Requirements​

Common requirements:

  • BIM execution plan (BEP)
  • Level of development (LOD) specifications
  • Model deliverable requirements
  • Clash detection requirements
  • As-built model requirements

Contract Requirements​

Typical requirements:

  • Model creation responsibilities
  • Model sharing requirements
  • Coordination requirements
  • Deliverable requirements
  • Standards compliance

Common Challenges​

Technical Challenges​

  • Software compatibility - Different software versions
  • File sizes - Large models slow systems
  • Model quality - Incomplete or inaccurate models
  • Updates - Keeping models current

Process Challenges​

  • Coordination - Getting everyone to coordinate
  • Timing - Models not ready when needed
  • Standards - Inconsistent modeling standards
  • Training - Team needs training

Best Practices​

For Contractors​

  1. Request models early - Get models during bidding
  2. Review models - Check for completeness
  3. Coordinate regularly - Weekly coordination meetings
  4. Use for layout - Field layout from models
  5. Update as-built - Keep model current

For Subcontractors​

  1. Review models - Check your scope
  2. Attend meetings - Coordination meetings
  3. Provide feedback - Report issues early
  4. Model your work - If required
  5. Coordinate - Work with other trades
Start Simple

You don't need to be a BIM expert to benefit. Start by requesting models, viewing them, and using them for coordination. Build capability over time.