But i keep on hearing from some folks that they model this as 2 separate walls.
Exterior siding wall revit.
Download wood siding revit files for free with bimsmith.
This should be close except for the side.
To show the siding wall pattern in photorealistic rendering.
Get the highest quality bim content you need from the manufacturers you trust.
We can see the pattern in shaded hidden lines views but not in photorealistic rendering.
This will give us result like this.
We apply this revit pattern to the wall structure as the exterior finish.
Nbs reference description.
Regarding modeling exterior walls i ve always just modeled it as one wall including interior finish to stud substrate and finish.