For the design of 2D objects, you can use both Surfaces and Surface Sets. The design is basically performed as for Member Sets. However, there are no design-related special features to consider.
Design of Surfaces or Surface Set
Surfaces that are part of a surface set can be designed either as a surface or via the surface set. To avoid conflicting input and results, the associated surfaces for timber design are automatically deactivated when designing as a surface set. If you define the surfaces for design, the superordinate surface set is deactivated accordingly. You can check this rule in the input table Objects to be Designed by listing the objects in the 'Not valid / deactivated' column.
After the design, a note for all surfaces that have been verified via a surface set and thus deactivated is displayed in the results table Not valid / deactivated (see chapter Overview). Likewise, surface sets are marked there with a note if they were not designed.
Set Smoothing
When designing surface sets, the Smoothing Settings come into effect that you defined in the global settings for the surface results. With the default setting Continuous within surface sets, otherwise within surfaces, smoothing is performed across the common surface boundaries as soon as a surface set is present.