Establishing Levels & Clean Slabs

Up to this point, we’ve:

Built attributed slab boundaries with program and height data
Baked them cleanly into Rhino for downstream use
Set up a workflow where geometry itself carries structured information

Now we’re ready to establish levels and slabs in Revit. This step is critical: it translates our attributed 2D boundaries into 3D Revit elements that will serve as the backbone of the building. Done correctly, this creates a robust and parametric link between your Rhino massing logic and your BIM model.

Why Start Fresh?

In the last section, we emphasized breaking definitions into functions. Rather than building on top of the large attribute script, we’ll:

Open a new Grasshopper definition
Reference the baked slab curves with attributes already attached
Use those attributes to drive levels and slabs in Revit

This keeps our scripts lean and avoids carrying unnecessary complexity forward.

Step 1: Bring in Baked Slabs

Drop a Geometry Pipeline component.
- Layer = BAKED_SLABS
- Geometry Type = Curves
Add an Elefront Get All Keys/Values (getKV) component.
- Connect the pipeline output.
- Verify the outputs:
  - Keys = Program, Height, Bake_Name
  - Values = e.g. Retail, 20 ft, etc.

At this point, you have geometry + attributes reconnected in a clean new definition.

Step 2: Extract Elevations

To establish levels, we need the Z-heights of each floor.

Connect curves → Area → take Centroid (C).
Deconstruct Point → extract Z values.
Use Sort List with Z as the key.
- This guarantees levels are created in order from bottom to top.
- Also sort the slab curves with the same keys, so everything stays aligned.

Step 3: Create Levels in Revit

Get the number of slabs with List Length.
Create a Series:
- Start = 1 (so we get Level_1 instead of Level_0)
- Step = 1
- Count = number of slabs
Use Concatenate to build names like: LEVEL_1, LEVEL_2, LEVEL_3
Add a Revit → Add Level component:

Elevation = sorted Z values
Name = concatenated strings

Check Revit → You should see a clean stack of levels. Delete any default L1/L2 levels from your template (Revit will warn about deleted views; we’ll recreate them later).

Step 4: Create Clean Slabs

Ensure slab boundary curves are sorted with the same keys as levels.
(Optional but recommended) Guardrail for planarity:

Area → centroid → XY Plane
Project to Plane → flatten curves

Use Revit → Add Floor:

Boundary = projected curves (grafted)
Level = corresponding level (grafted)
Type = select from Type filter (e.g. “6" Concrete”)

Check Revit: floors should place cleanly at each level.

Step 5: Write Program into Revit

From getKV Values, extract Program with a List Item.
Sort the program list with the same Z key used for slabs.
Graft the list to match floor branches.
Use Revit → Parameter filtered to Floors, select Comments.
Use Element Parameter:

Elements = Floors
Parameter = Comments
Values = Program list

Now each floor in Revit carries its program directly in the Comments field.

Step 6: Recreate Plan Views

Since we deleted template levels, create new floor plans:

In Revit: View → Plan Views → Floor Plan
Select all new levels
Click OK

You now have fresh views for each level.

Side Challenge 9

Try extending this workflow with two refinements:

Zero-Padded Level Names – format series numbers so they read LEVEL_01, LEVEL_02, ….
Auto Roof Level – detect the top Z, add a “ROOF” level at Top + Offset.

Summary

In this section, we:

Referenced baked slabs with attributes in a new definition
Extracted elevations and created ordered Revit levels
Built clean Revit floors, ensuring planarity and alignment
Wrote Program into each slab’s Revit Comments field
Recreated floor plans for all levels

At this stage, you’ve established a coherent skeleton for your building in Revit: levels, slabs, and associated metadata. This is the foundation for structural systems, façade systems, and compliance checks in later modules.

On to the next tutorial!