Controlling the visbility of voids with an on / off parameter in Revit

Ever wanted to be able to turn a void on and off in a Revit project? My colleague Johnny Furlong has come up with this awesome work around:

Create a new HOSTED family, e.g. face, wall, ceiling based – depending on where your family will be based. I will be using a Metric face based generic model.

Create a void through the solid geometry – make sure that the voids cuts all the way through 2 faces of the geometry. You can choose which shape you want the void to be and as usual it can be controlled by reference planes etc. Save this family as *name*_uncut.

Now you have your uncut void family saved, you will want to create and save another instance of the same family as a CUT family. Select the void, click the cut geometry button and cut the void from the geometry. Save this family as *name*_cut.


You will now want to create a new family to embed these 2 families you have just created into. New family > Generic model – Create some solid geometry with an extrusion, depending on what shape / purpose you will be using it for. Load both your *name*_uncut & *name*_cut you have just created into your new family.

Place your *name*_cut family onto the solid extrusion you have just created in your unsaved generic model family. (you can repeat this step for as many voids as you need in your extrusion).

You will need to create 4 parameters. Decide at this point whether you want them to be instance or type parameters. Click on the ‘Family Types’ button on your Ribbon. The first parameter you will want to add is the control / On Off switch. Name the parameter ‘OnOff’ and make it a Yes/No parameter.

You will need to create 3 additional ‘<Family Type…>’ parameters – You will want to choose the same family type that you used to create your cut and uncut families; in this case all 3 will be ‘Generic model’ types.

Create an On <Generic Model> parameter and in the value field pick your *name*_cut family & Create an Off <Generic Model> parameter and in the value field pick your *name*_uncut family. Finally you will want to make an Switch <Generic Model> parameter – you can pick either the uncut or cut family for the value at this point. Once all 3 of these have been created, in the formula field for the Switch parameter enter the following; ‘if(OnOff, On, Off)’ – The On and Off values in the formula is in relation to the name of your families.


Click ‘OK’ and select the cut / void family which is embedded in your extrusion in the ‘Label’ field choose the Switch parameter.

While the void is still selected, go to your properties and UNTICK the ‘Visible’ checkbox – This will ensure that the orange void box will not appear when you insert the family into a project. You can also check that the Label parameter is set to ‘Switch’.

Load your family into your project – and there you go! Tick / Untick the ‘OnOff’ parameter checkbox to turn your void on and off.


I hope this helps – If you are having trouble following the instructions, leave a comment below and I will make a short video running through the whole process.

If you want to download the sample families I have used in this walkthrough you can download them here


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About Ben Malone

Information Manager for BIM.Technologies in London

4 responses to “Controlling the visbility of voids with an on / off parameter in Revit”

  1. Anthony Oxford says :

    Ben – Thanks for this, I found it useful for a girder family where I wanted to turn the notches on and off (as the OOTB tool isn’t sufficient). As an alternative, I found that once I’d loaded in the cut and uncut families, instead of creating the parameters you mentioned, you can simply label the cut family itself which gives you the option of selecting the cut or uncut family from a drop down list in the project, thus allowing you to turn it on or off.

  2. vandomkim says :

    Really appreciate your help, and I did my changeable family. But there is another issue. When I untick it, the item will totally gone, I even cannot select it and on again. the only way I can imagine is to create a schedule for generic model and find it. is it any other way to easily find it and modify it?

    • Ben Malone says :

      Hi there, I’m glad you found this useful. You could as you say, use a schedule to re-select the item once it’s hidden.

      Another option would be to take a note of the Element ID once loaded into the project and then you can use the “search / select by ID” function on the Manage tab to select the hidden item, this will then be selected and you can unhide again via the type dropdown.

      Hope that helps


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