SLAB EDGE REBATES

Rebates in slab edges are usually shown (and dimensioned) in concrete set-out drawings, and in section details.

It is best practice to model slab edge rebates, rather than draw them in specific views using annotation.

This is so they appear in all views and are not 'forgotten' during documentation leading to embarrassment on site during construction.

Revit doesn't have a fool proof method to create slabe edge rebates. Choose a method that suits your circumstances.

1. Void In-Place Family

HOW TO:

• 1. Create an in-place family, make it FLOOR category.

  2. Set workplane to match top of floor slab (usually the Level it is on).

  3. Use Reference Lines (NOT Reference Planes) to define edge of rebates.

  4. Dimension reference lines and make them instance parameters.

  5. Create voids and lock to reference lines and slab edge. Generally extrusions are adequate.

  6. If you want to make depth a parameter a quick way is to make the void parameter Start into an instance parameter (call it Depth). But the value must be NEGATIVE or the void will be in the wrong direction.

  7. Use Cut command to subtract the void from floor before completing in-place family.

If you want to make the Depth parameter positive add another parameter to drive the void's Start parameter using formula:

VoidDepth=Depth-(Depth*2).

If you need to create multiple in-place families a quick way is to copy an existing one containing correct parameters, edit it as needed, then rename it in the Project Browser (it will be listed under Floors).

There is no practical way to include hatching in the in-place family. Better to lock Filled Regions to edges in views where they are required.

You can edit the boundary of the floor if you only move them parallel to their original position, if you try changing the angle of any edge, the slab edge in-place family gets deleted.

WHEN TO USE:

• • When slab rebates are complicated - different widths, depths etc.

  • Floor edges are unlikely to change significantly.

  • Soffit below rebate is flat (use Slab Edge below if not).

  • You are NOT going to export the model in formats other than Revit (some formats don't handle voids).

2. Slab Edge

HOW TO:

• 1. Create a new Hosted Profile family using template Metric Profile-Hosted.rft.

  2. In Family Categories and Parameters change the Profile Usage parameter to Slab Edge.

  3. Draw the slab edge with rebate. Note that you can not draw voids. You need to draw enough of the edge of the slab to include the rebate's maximum width.

  4. Dimension the depth of the slab edge, depth of rebate and width of rebate. Make them all Type parameters.

  5. DON'T make the overall width of the slab edge a parameter - it needs to be constant.

  6. Save the family, prefix its name with SLAB EDGE_.

  7. Load the family into your project. (you can drag and drop it into a view).

  8. Edit floors you will be applying the slab edge by cutting them back by the overall width of the slab edge set in the family just made.

  9. Under the Floor icon select Slab Edge. Pick one edge of a floor you want to apply it to.

  10. Select the slab edge you just put in, pick Edit Type, then Duplicate button. Give it a name.

  11. Change Profile parameter to the profile you just loaded.

      1. Under the Floor icon select Slab Edge. Pick all other edges of floors you want to apply it to.

      2. Note that edges picked together will behave as one slab edge even if they are on disconnected edges.

  12. Use the Join command to join slab edges to the main floor. They will then display as one slab in sections.

You can edit lengths of slab edges by moving the blue dot at their ends.

Using this method you can put more than one slab edge type on to a floor edge.

If you create a slab edge type using a profile without a rebate you can use it for areas where this is no rebate.

BUT:

- different slab edge types will not join at a corner.

- different slab edge types will leave a line between them.

You can create new slab edge types by selecting an existing one in the project browser (under Profiles), right clicking over it and select Type Properties, Duplicate button, then change parameters. You then need to create a new Slab Edge type and assign the new profile to it.

WHEN TO USE:

• • When slab rebates are simple.

  • Floor edges are likely to change significantly.

  • Soffit below rebate is not flat.

  • You are going to export the model in formats other than Revit.