How to Read a Revit Family Type Catalog: A Beginner's Guide for Pune BIM Students

How to Read a Revit Family Type Catalog: A Beginner's Guide for Pune BIM Students

Somewhere in the first month of a BIM course, almost every student in Pune hits the same small wall: they load a door or window family from the library, a long list of sizes pops up, and nobody has explained where that list actually comes from or how to change it. That list is called a type catalog, and it is simpler than it looks once you know what you are staring at.

What a Type Catalog Actually Is (Not a Special File Format)

A type catalog is not part of the Revit family file itself. It is a plain text file, saved with the exact same name as the family and a .txt extension, sitting in the same folder. When you load that family into a project, Revit quietly checks the folder for a matching .txt file and, if it finds one, shows you the list of pre-built sizes instead of loading every single type inside the family at once. Open one of these files in Notepad and you will see rows of numbers separated by tab characters, with a header row describing what each column means, things like width, height and a type mark. There is no hidden logic here. It is closer to a spreadsheet than to actual Revit geometry.

Opening the .txt File Without Breaking It

The mistake most students make is opening the type catalog directly in Excel, editing it, and saving it back as a normal Excel file. Revit will not read that. The file has to stay saved as plain text, with tabs separating each value, exactly as it started. The safer habit is to open it in Notepad, or in Excel using "open" rather than double-clicking, edit the values you need, and save it back specifically as a Text (Tab delimited) .txt file with the original name unchanged. Get the separator or the header row wrong and the family will either fail to load its type list or load with blank, unusable sizes.

The Two Mistakes Almost Every First-Project Student Makes

The first is editing the .txt file while the family is still loaded in an open project, then wondering why nothing changes. Revit reads the catalog at the moment you load the family, not continuously afterward. You need to close and reload the family for a saved change to actually show up as a new size option. The second is renaming the .txt file, or moving it into a different folder than the family it belongs to, thinking the connection is stored inside the Revit family. It is not. The two files are linked purely by matching filenames sitting in the same folder, and breaking that pairing quietly removes your type list with no warning message at all.

Why This Small Skill Matters More Than It Looks

Most real project teams do not model every custom door or window size from scratch. They keep a small library of type-catalog-driven families and simply extend the list of sizes as a project needs them, which is faster and keeps file sizes smaller than duplicating whole families. Knowing how to open, correctly edit and reload a type catalog is one of those unglamorous skills that separates a student who can only use what is already in the library from one who can extend it for a real Pune project team on day one. It comes up early in the Revit Architecture portion of our BIM workflow training, precisely because it trips people up before anyone tells them the rule.