BIMForum LOD Spec Guide
Written by Kelar Pacific

Construction Design Phases vs BIM Levels of Development – Part 3 of 4

What are the Definitions of BIM Levels of Development?

The following reflects the general consensus of the most widely used LOD Definitions:

  • LOD 100: A Conceptual Model where parameters like area, height, volume, location and orientation are defined.
  • LOD 200: An Approximate Geometry Model where elements are modeled with approximate quantities, size, shape, location and orientation.*
  • LOD 300Precise Geometry Modeling and shop drawings where elements are defined with specific assemblies, precise quantity, size, shape, location and orientation.*
  • LOD 350Includes Model Detail and element that represent how building elements interface with various systems and other building elements with graphics and written definitions.
  • LOD 400: Model elements are modeled as Specific Assemblies with Complete Fabrication, assembly, and detailing information in addition to precise quantity, size, shape, location and orientation.*
  • LOD 500As-Built Elements are modeled as constructed assemblies for Maintenance and operations.*

*Can include non- geometric information to the model elements.

How do you use BIM LOD Specification Workbooks?

BIM LOD Specification Workbooks are often required by the client and updated with each revision of a project’s BIM file. If so, it’s important for the prime and subcontractors to base the related progression of their cost estimates and schedules accordingly. The example below is created by the BIM Forum.

The BIM Specification is not a set of requirements as to what is modeled, when, or by whom. Rather it is a language by which users can define these requirements for their own firms or projects. A BIM Specification provides the following benefits:

  • Helps teams including owners to specify BIM deliverables and get a clear picture of what will be included in a BIM deliverable.
  • Helps design managers explain to their teams the information and detail that needs to be provided at various points in the design process, and to track progress of their models.
  • Allows downstream users to rely on specific information in models they receive from others.
  • Provides a standard that can be referenced by contracts and BIM execution plans.

View or download a copy of the LOD Specification Worksheet:
BIM Forum 2016 Level of Development Specification Workbook (Excel)

BIM Lod Specification Workbook Example

We will conclude this 4 part topic on Construction Design Phases vs BIM Levels of Development in Article 4.

Ed Wenz

Sage Estimating Consultant

5D BIM Estimating/eTakeoff

Affiliations:

AGC, ASPE, SD Navisworks GC, CM and Specialty Contractor Users Forum

BIM Levels of Development - Kelar Pacific
Written by Kelar Pacific

Construction Design Phases vs BIM Levels of Development – Part 2 of 4

It’s important for contractors to understand the various LOD’s for each trade at any point so they can provide related cost and scheduling that is measured by the same design standards being used by the client and the designer. The understanding of how complete a model element is effects not only the Cost Estimates and Schedules, but also Constructability.

 LODs – Levels of Development

Definition (BimForum.org) –  The Level of Development (LOD) Specification is a reference that enables practitioners in the AEC Industry to specify and articulate with a high level of clarity, the content and reliability of Building Information Models (BIMs) at various stages in the design and construction process.

Level of Development vs. Level of Detail

LOD is sometimes interpreted as Level of Detail rather than Level of Development. There are important differences:

  • Level of Detail is essentially how much detail is included in the model element.
  • Level of Development is the degree to which the element’s geometry and attached information has been thought through – the degree to which project team members may rely on the information when using the model.
  • In essence, Level of Detail can be thought of as input to the element, while Level of Development is reliable output.

Does the project contractor utilize the designer’s LODs or Design Phases?

The LODs are not defined by design phases. Rather, design phase completion, as well as any other milestone or deliverable, can be defined through the LOD language. There are several important reasons for this approach:

  • There is currently no detailed standard for the design phases.
  • Building systems progress from concept to precise at different rates, so at any given time different elements will be at different points along this progression.
  • Design Phases are often utilized by the Prime Contractor as “Design Milestones.” These Milestones are utilized by the contractor’s estimators and schedulers. Their subcontractors should use LODs specific to their trade.

Levels of Design LOD Description - Kelar Pacific

  • LOD’s – Typically Utilized by Designers

We will continue this 4 part topic on Construction Design Phases vs BIM Levels of Development in our next Article 3.

Ed Wenz

Sage Estimating Consultant

5D BIM Estimating/eTakeoff

Affiliations:

AGC, ASPE, SD Navisworks GC, CM and Specialty Contractor Users Forum

LOD Level of Development - Kelar Pacific
Written by Kelar Pacific

Construction Design Phases vs BIM Levels of Development – 1 of 4

Design Phases of Construction

The construction industry has utilized the “Design Phases of Construction” as milestones for measuring how complete the overall design of a construction projects was. Generally they include, but are not limited to, variations and percentages complete of Schematic Design, Design Development and Construction Documents.

The emergence of BIM – Building Information Modeling in the last decade has grown significantly. The percentage of “companies using BIM jumped from 17 percent in 2007, to 49 percent in 2009, to 71 percent in 2012.” (Source: Contractors Center Point).

With much of the design work now being done in BIM, the industry has developed more accurate methods of defining how complete a project would be at any point during the design process. This is done with Levels of Development, or LOD’s.

How do the BIM LOD’s relate to the historical Design Phases?

So now the question becomes “How do the BIM LOD’s relate to the cost estimating methods of the historical Design Phases?” The following outline provides a general overview of how they relate to each other with a couple of major differences:

  • “LOD’s express completeness down to the element and trade levels of design” where as Design Phases are overall milestones of the entire project.
  • “There’s no such thing as a singular Level of Development for a BIM design.”

Other questions raised by much of the construction industry include:

  • LOD 100 to 500 – What are the expectations and limitations for each, and by the designer or the contractor’s perspective?
  • How does each LOD impact the accuracy of 5D Estimating/Cost and 4D Scheduling/Time?

The Critical Path of Design

BIM designers are typically aware of the critical path of the design where more attention will initially be placed into the major elements such as Foundations, Substructure, Superstructure, Exterior Enclosure etc. Although it’s a reasonable approach to any critical path, does it support enough detail for:

  • The rest of the elements and trades requested to provide budget cost estimates?
  • Do the designers know how much detail is required for each trade to provide a cost estimate within 3-5% of the final design?
  • Does the owner or CM understand this as well?

We will go into Construction Design Phases vs BIM Levels of Development further in our next Article 2 of 4.

Ed Wenz

Sage Estimating Consultant

5D BIM Estimating/eTakeoff

 

Affiliations:

AGC, ASPE, SD Navisworks GC, CM and Specialty Contractor Users Forum