LOD stands for Level of Detail — the level of detail of an object in a BIM model. In practice the same abbreviation is also used for Level of Development: not only how detailed the geometry is, but how reliable the information held in it is.
That distinction is not word play. A window can look magnificent in the model while there is still no supplier, no U-value and no final dimension behind it. Level of Detail says something about the shape; Level of Development also says what you may rely on.
The levels
The most widely used scale comes from American practice and runs from 100 to 500:
- LOD 100 — symbolic. The object is present as an indication: a block, a plane, an area. Usable for massing studies, spatial feasibility and a first cost benchmark.
- LOD 200 — approximate. A generic element with approximate size, shape and position. You can see that a wall is coming and roughly how thick.
- LOD 300 — accurate. The element has the correct size, shape, orientation and location. This is generally the level at which work is tendered and from which setting-out dimensions can be taken.
- LOD 350 — with interfaces. LOD 300 plus the interfaces with other elements: fixings, penetrations, supports. This is the level at which clash detection between disciplines becomes meaningful.
- LOD 400 — fabrication ready. Detailed enough for manufacture and installation, including fabrication data.
- LOD 500 — as-built. The delivered object, verified on site, intended for operation and maintenance.
Note: the levels are an agreement, not a law. Different countries and clients use variants with different numbers or names.
LOD and LOI
Alongside LOD, LOI is often used: Level of Information — the level of the non-geometric data. Material, fire resistance, thermal value, product code, maintenance interval, warranty period.
It is the combination that counts. A model with high LOD and low LOI is a pretty picture with no substance; a model with high LOI and low LOD is a database of vague shapes. A good information delivery specification sets out both, per object and per stage.
The European standard EN 17412-1 approaches this from the demand side rather than the supply side, with the concept of Level of Information Need: first determine what decision has to be made, then deliver exactly the information needed for it — no more.
Why you agree it up front
This is why LOD appears in virtually every BIM execution plan:
- More detail is not better. A model that is too detailed too early costs unnecessary time, becomes sluggish and — the biggest risk — implies a certainty that does not yet exist. Someone then bases an order on a dimension that is not fixed.
- Too little detail causes failure costs. Run clash detection at LOD 200 and you find nothing, then find everything on site.
- It determines who draws what. Does the structural engineer model the reinforcement, or the supplier? The agreement on LOD and stage settles that division.
Set out, per stage, per discipline and per object type, which level applies, and agree who checks the model against it.
Related terms
- BIM
- BIM execution plan
- IFC
- Clash detection
- As-built drawing
- Object library
- Failure costs
Want to know more about building terms? Take a look at our knowledge base on fredsdiyplans.com.