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Levels, Grids and Coordinates in Revit

Get levels, grids and coordinates wrong early and every linked model afterwards will feel slightly off.

Levels, grids and coordinates are the foundations of every Revit model. If they're wrong, every linked model and every drawing is affected. Taking care to set them up properly at the start saves a great deal of trouble later.

Levels

Levels define floor heights and create associated plan views. Good practice includes:

• Creating levels for every floor, roof and significant height, such as top of steel or ceiling zones if useful
• Naming levels clearly and consistently
• Agreeing level values with the structural engineer
• Avoiding too many levels, which clutters views

Levels can be relative to a project zero or to a site datum, so agree which is used and make it clear in drawings.

Grids

Grids provide horizontal references for structure and setting out. Agree grid naming with the structural engineer, such as numbers in one direction and letters in the other, and copy or monitor grids from the structural model where appropriate. Pin grids once set, so they're not moved by accident.

Project base point and survey point

Revit uses two key points:

• Project base point: the reference for the building, often at a grid intersection
• Survey point: the link to real-world coordinates, such as a site survey grid

Together with the internal origin, these define how the model relates to the site and to other models. Revit's behaviour around these points has changed across versions, so check the documentation for your version.

Shared coordinates

Shared coordinates let models from different disciplines align correctly. Typically, one model, often the Architectural or site model, establishes the shared coordinates, and others acquire them. Once set, everyone links models using shared coordinates.

Keep the model near the origin

Revit works best when geometry is near the internal origin. Placing a building kilometres away from the origin, such as at survey coordinates, can cause graphical and accuracy problems. Use shared coordinates to relate to the real world instead.

True north and project north

Set true north for accurate site orientation and solar studies, while keeping project north aligned with the building for drawing clarity.

Document the setup

Checking alignment

At each model exchange, check that linked models align at grids and levels. Misalignment is usually a coordinate issue that should be fixed at source, not by moving links.

1. 01Levels
2. 02Grids
3. 03Project base point and survey point
4. 04Shared coordinates
5. 05Keep the model near the origin
6. 06True north and project north

Common problems

• Models linked by origin instead of shared coordinates
• Levels with different values in Architectural and structural models
• Grids moved accidentally

Getting levels, grids and coordinates right at the start is one of the best investments a BIM team can make.

If your team needs extra production capacity for work like this, take a look at our Architectural production services, or tell us about your project.