Selection trees and search sets
Clash tests and 4D links are only as good as the sets they use. Learn to find elements by property and build search sets that update automatically when models refresh.
In this lesson you will
- Use the Selection Tree and Properties
- Find items by properties
- Understand selection sets vs search sets
- Build a reusable set structure
Selection Tree and properties
The Selection Tree shows the structure of each appended file — by file, layer/level, category and element. Selection resolution (e.g. First Object, Geometry) controls what a click selects. The Properties window shows the element's data exported from the authoring tool: category, family, type, system name, level.
Find Items
Find Items searches by rules: Element › Category = Ducts AND System Name contains SA (supply air). Combine conditions with AND/OR. It's the way to select precisely in large models.
Selection sets vs search sets
| Selection set | Search set | |
|---|---|---|
| Stores | The specific elements selected | The search rules |
| After a model refresh | May miss new elements | Re-runs and includes new elements |
| Use for | One-off groups | Clash tests, 4D, appearance profiles |
A set structure
Create folders of search sets by discipline and system: STR – Beams, STR – Columns, MECH – Ductwork, ELEC – Cable trays, HYD – Pipes > 50 mm. Name them consistently and export them (Sets › Export Search Sets as XML) to reuse on the next project. Good sets depend on good, consistent properties in the authoring models — which is why the BEP should define them.
Quick reference
| Command / tool | How to start it | What it does |
|---|---|---|
| Selection Tree | Home tab | Browses model structure |
| Find Items | Home tab | Searches by properties |
| Save Search / Save Selection | Sets window | Creates sets |
| Export / Import Sets | Sets window | Reuses sets across projects |
Common mistakes
New ducts missing from clash tests after refresh.
Use search sets, not selection sets.
Searches find nothing.
Check the property names exported from the authoring tool.
Exercise
Build coordination sets
- Create search sets for structural framing, columns, ductwork, pipework and cable trays.
- Organise them in discipline folders.
- Refresh a model after adding an element and confirm the set updates.
- Export your sets to XML.
You should end up with: A reusable, self-updating set library.
Checklist
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Lesson quiz
Search sets re-run their rules and include new elements after a refresh.
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