Introduction to Parameters in Revit

 What are parameters?

All Revit files are composed entirely of Families.  Revit assigns default parameters depending on the ‘type’ of family the 3D element is a part of.  All parameters are associated with families.

Examples are: Door, Window, View, Tag

Parameters are pieces of information in the families in Revit.

   1.        Instance vs. Type Parameters

Type Parameters

Type Parameters apply to all elements of a particular type.  If a Type Parameter is changed, it changes this piece of information in all of the types of the element.

Examples are: Column Type Dimensions, Type Marks or Tags, Materials

All Type Parameters assigned to an element’s type can be seen and modified here in the project:

            

This information can also be seen in the family editor, which will be discussed in a future training session.

Instance Parameters

Instance Parameters apply to only to one element.  If an Instance Parameters is changed, it only changes this piece of information in the selected element.

Examples are: Column upper and lower levels, Room ID Numbers

All Instance Parameters assigned to an element’s type can be seen and modified here:

Instance parameters can be defined as a traditional parameter which defines part of the family OR as a ‘Reporting Parameter’.  A Reporting Parameter reads information from an instance and reports this information as a parameter.

An example of a reporting parameter would be a parameter which reports the height of a column or pedestal.  In Revit, the height is defined relative to project levels and not as a discrete length.  Adding a reporting parameter will read what the actual column height is, as defined by the levels, and report what the length is.

   2.        Project  vs. Shared Parameters

Project Parameters

Project parameters are applied within families only to define geometry and other pieces of information in a simple, quick manner.

Revit limits the way information in project parameters can be accessed.  Project parameters cannot be seen or listed in schedules, linked files, tags, or material takeoffs.  These parameters are used only to help define the family.

Shared Parameters

Shared parameters are applied in project files and families to define information that can be linked, shared, tagged, and queried between files.  Any piece of information which needs to be accessed in this way needs to be defined as a shared parameter. 

Revit automatically creates some parameters as ‘shared’ based on the family definition.  These aren’t found in an external text file because ALL Revit programs understand and know to read certain parameters. Examples of these are Materials & Type Marks

Custom Shared parameters are defined in a separate text file and are used in all of the files in the entire project.  It contains the definition of all of the shared parameters which the project uses.  It is EXTREMELY important that this file is not modified or deleted, because it is the link between all project Revit files which allows them to communicate information with each other.

   3.        Adding Parameters to Revit Families & Files

As mentioned before, Revit has a set of default parameters is associates with different families.  These are the parameters most people are used to working with.

Users can also create custom parameters which allow the user to input additional information into the model beyond what Revit is able to store ‘out of the box’.

To add a new parameter to a project of family, select the ‘Project Parameters’ button shown below:

The following menu will prompt: 

The top left section, called ‘Parameter Type’ allows the user to define whether the parameter will be a Project or Shared parameter.  If the user selects a Shared Parameter, they will have to select or create the shared parameter text file which the Revit file will reference.

The bottom left section, called ‘Parameter Data’, allows the user to define the name of the parameter, discipline, type of parameter, and which group of data it should be grouped with.  Lastly, the user can define whether the parameter is a Type or Instance Parameter.

Note – If a ‘Shared parameter’ is selected above, the user will only be able to define ‘Group parameter under’ and whether it is an instance or type parameter.  The Name, Discipline, & Type of Parameter are already defined in the shared parameter text file.

To the right is the ‘Categories’ menu.  This section allows the user to define which families the project will attach this parameter to.  For instance, if one is creating a ‘door leaf definition’ parameter, the user would likely only want to apply this parameter to Door families.  This parameter wouldn’t apply to a column or finish family, and so the user can unselect them here.

   4.        Parameter Uses & Future Training

Parameters are very useful and form the core of the value BIM brings to a project.  Parameters are the ‘I’ – information - in BIM.

The shared parameters discussed today are the core of what is used to create tags, schedules, 4D animations, material quantity take-offs and other important BIM-generated tools.