How to Create a Hyperbolic Paraboloid Roof in Archicad?

Issue Description

You are trying to model a complex roof shape resembling a hyperbolic paraboloid, which is a doubly-curved surface with a convex form along one axis and a concave form along the other. This shape is ideal for creating thin shell roofs that are both aesthetically pleasing and structurally efficient. However, you are unsure how to achieve this using the Shell Tool.

Solution

Creating a hyperbolic paraboloid roof involves using the Shell Tool to define the complex shape. Here’s how you can do it:

1. Prepare Reference Walls:

   Start by creating reference walls that will serve as planes to define the orientation, shape, and position of the splines (or edges) that will be extruded to form your hyperbolic paraboloid roof.

   Ensure these walls are high enough to accommodate the height of your roof.

2. Use the Shell Tool:
   1. Activate the Shell Tool and in the Toolbox.
   2. Set the Shell Geometry Method to Ruled.
   3. Set the Shell Construction Method to Detailed.

3. Click on the face pf one of the reference walls, to use it as an editing plane, and start defining the shell's profiles. You can use straight lines or edit the profile as a spline.

4. Double click when the first profile is ready.

5. Move to the opposite wall to use it as an editing plane for the opposite profile. Click again (for example on t to create the first part of the shell.

   • TIP: Archicad gives you a hint on the lower left corner on what to do next. The shell in this example only has two main faces but you can add as many faces as needed.

      

     

      

6. Adjust and Refine the Shell:
   1. On the floorplan use a polyline, spline, or Arc/Circle tool do define the outline of the paraboloid
   2. Select the Shell > Right click > Define Shell Contour
   3. Then hold the space bar and click on the previously drawn spline/ellipse to  crop the shell's contour. This helps in achieving a precise hyperbolic paraboloid form.

      You can further refine the shape by adding more reference points or adjusting the existing ones.

7. Apply materials or Composites to your shell to match the desired construction.
8. Use the Trim to roof command  to cut the walls/columns in your project to fit the shell perfectly.

If you need more help…

Check out more content on the Support Site, Graphisoft community, or the Graphisoft Learn Portal. You can also contact Technical Support for further assistance.