Taking a look at how the building shader is applied to a model
Using Blender to create my uvMaps & using texture paint mode to create the image files for the dirt & moss masks.
Merging created images in paint.net for specular mask image
This video helped me to understand how all this works so please go check it out
https://youtu.be/kPXrp8RADEo
https://farming-simulator.com/index.php?lang=en&country=gb