Learn how to configure a precast double wall type. 
 To create a precast double wall: 
- Create a structural wall. 
  
-  In the wall type properties, click 
	  (Edit Type). (Edit Type).
-  In the Type Properties, click Duplicate and create a new Double Wall type. 
  
-  Under Type Parameters, click Edit in the Value column for the Structure parameter. 
  
-  In the Edit Assembly dialog, create 3 layers as follows: 
	 -  In the Function column, create 3 layers in the following order: Structure[1]; Thermal/Air Layer[3]; Structure[1]. 
		
-  In the Material column, add the following materials: Concrete; Air; Concrete. 
		
-  Input the desired thickness values for each layer. 
		
 Note: Check the Structural Material box for any of the layers that have the Structure[1] function to define the first shell of the double wall.