Use In-place Voids to Vary Revit Slab Thickness


Architects vary the slab thickness to accommodate differing floor finishes. The floor finish may vary as one moves from one side of the building to another. It is one of the worst things when a slight height difference is encountered as one walks from one finish to another. It is difficult to break a slab up after it has been cast, so really one must have these varying slab thicknesses ready-designed before construction time.

However, modeling this comes down to a choice of two things. Either one may have many slab thicknesses, which will not collectively host rebar (whether the Architect or Structural Engineer owns the element is another question)

Shown below is a situation where the floor screed interferes with the average height of the slab

The solution is to model a void in place and then to subtract that from the slab. Isolate the slab and the walls, set the working plane to the slab face, and then model am extrusion into the slab. Draw some sacrificial reference planes before the time to guide you. Delete them afterwards. Make sure to get the extrusion start and end correct, and the object to void.

Once that is done, cur the void from the slab before finishing the modeled in-place component.

Now we can see how the slab has a recess into which the thicker floor snugly fits.

If you need help modeling floor slabs or adopting Revit in your practice, please contact Micrographics so we may be of assistance.

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