Hi John M Cook,

You can draw the concrete slab with the floor tool and the roof with the Freehand roof tool (roof tab)
As for the screens, this is how I do --> With the Window Designer Power Tool, I created windows with a blind panel --> in live view apply (on the pane) a texture called Net (Materials--> Custom Library--> Punch Bonus Materials--> Miscellaneous)
You can use also a 2D panel created in the 3D workshop (textured as indicated above)
Therefore, I create the porch with walls, and set the windows after, as you can see in the image attached
If you prefer, you can create Custom screens in the 3D workshop or you can simulate them with a Custom Fence--> chain linked

Patricia