Smart roof editing in Archicad: When to crop, When to trim, When to use SEOs

[Andrea Polgar]

Archicad provides various modeling features for precise building geometry adjustment. Let's see those which are for adjusting other elements to roofs/shells and for creating complex shapes using Boolean operations.

• Crop to Single-plane Roof,
• Trim Elements to Roof/Shell, and
• Solid Element Operations (SEO).

Each targets specific workflows—static cropping, dynamic associative trimming, and complex Boolean operations—helping designers manage everything from roof detailing to advanced 3D intersections.

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The fundamental difference lies in their behavior and application:

• Crop is for a one-time, permanent cut that is not linked to the roof.

• Trim creates a live, associative connection that updates automatically.

• SEO is for advanced, rule-based modeling using Boolean logic (subtract, add, intersect) between any elements.

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Crop to Single-plane Roof

This command makes a permanent cut on an element using a single-plane roof. The change remains even if you move or delete the roof.

• Where to find it: Navigate to Design > Roof Extras > Crop to Single-plane Roof.

• How to use it:

  1. Select the element(s) you want to crop (e.g., a wall).

  2. Go to the command to open the dialog box.

  3. Choose whether to crop the element's top or bottom.

  4. Click Crop. The selected part of the element is permanently removed.

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Trim Elements to Roof

This is the standard method for fitting elements like walls, columns, and beams to a roof or shell. The connection is associative, meaning the trimmed elements will automatically adjust if the roof's geometry or position changes.

• Where to find it: Navigate to Design > Connect > Trim Elements to Roof/Shell or right-click the selected element and choose Connect > Trim Elements to Roof/Shell.

• How to use it:

  1. Select the element(s) to be trimmed.

  2. Activate the "Trim" command.

  3. Click on the roof or shell to define it as the trimming body.

  4. Click on the side of the element you wish to keep.

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Solid Element Operations (SEO)

SEO provides the most modeling freedom, allowing you to use any 3D element to modify another through Boolean operations. This is ideal for creating complex shapes, custom openings, and non-standard intersections.

• Where to find it: Open the palette by going to Design > Solid Element Operations.

• How to use it:

  1. Select the element you want to change and click Get Target Elements in the SEO palette.

  2. Select the element that will dictate the change and click Get Operator Elements.

  3. Choose an operation (e.g., Subtraction, Intersection, Addition).

  4. Click Execute.

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Comparison overview

Feature	Crop to Single-plane Roof	Trim Elements to Roof	Solid Element Operations
Primary Use	Permanent, one-time cuts	Associative fitting to roofs/shells	Complex Boolean modeling
Associativity	No (static)	Yes (dynamic)	Yes (dynamic link to operator)
Flexibility	Works only with single-plane roofs	Works with roofs and shells	Works with any 3D elements
Example	Creating a wall with a fixed sloped top without needing a roof object	Ensuring attic walls automatically adjust to any roof design changes	Carving a tunnel through a terrain mesh or subtract foundation from the terrain