Question 1

What does LOD mean in BIM?

Accepted Answer

LOD usually means Level of Development. It describes how reliable, developed and usable a BIM element is at a certain project stage.
LOD is not only about visual detail. It is also about how much information and certainty the model element has. For example, an early-stage object may show approximate size and location, while a later-stage object may include accurate dimensions, connections, specification data and fabrication-level information.
LOD helps project teams understand what they can safely use the model for. BIMForum’s LOD Specification is commonly used to define model element expectations in a structured way.

Question 2

What is the difference between Level of Detail and Level of Development?

Accepted Answer

Level of Detail usually refers to how much visual or geometric detail a model has. Level of Development refers to how reliable and complete the model information is for a specific purpose.
A model can look very detailed but still be unreliable for construction or fabrication. On the other hand, a simpler model can be more useful if its dimensions, parameters and classification data are accurate.
For BIM projects, Level of Development is usually more important than visual complexity.

Question 3

What LOD is needed for coordination?

Accepted Answer

For coordination, the required LOD depends on the project stage and discipline. In many cases, a coordinated model needs enough accuracy to check location, size, clearance, access and potential clashes with other building systems.
For example, an MEP contractor may need ducts, pipes, equipment and access zones modeled accurately enough to coordinate with structure, ceilings, walls and other services.
The goal is not to model everything in maximum detail. The goal is to model enough information to support reliable coordination decisions.

Question 4

What LOD is needed for fabrication or shop drawings?

Accepted Answer

Fabrication and shop drawing workflows usually require a higher level of model reliability than design coordination.
The model may need accurate dimensions, connection points, clearances, component references, material information and installation details. However, the exact requirement depends on the trade, project contract and fabrication process.
For subcontractors and manufacturers, the right LOD should be defined before modeling starts. This prevents both under-modeling and unnecessary over-modeling.

Question 5

Why should BIM models not be more detailed than necessary?

Accepted Answer

Over-detailed BIM models can become heavy, slow and difficult to manage. Too much geometry can reduce Revit performance, increase file size and make coordination harder.
Good BIM is not about adding every screw, bolt or internal detail. Good BIM is about adding the right level of geometry and information for the intended use.
For manufacturer BIM objects, this is especially important. A product model should be accurate, useful and lightweight enough to work well inside real project files.

LOD & Modeling

What does LOD mean in BIM?

What is the difference between Level of Detail and Level of Development?

What LOD is needed for coordination?

What LOD is needed for fabrication or shop drawings?

Why should BIM models not be more detailed than necessary?