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.
Sage Estimating Consultant
5D BIM Estimating/eTakeoff