the idea is that with a model, we can look at your vray settings and see if there's a solution.

thanks for the assistance guys. ive just decided to go with a 2 render method. 1 without a floor plane (for the building) and one with floor plane that i just do a magic wand selection and delete unused area, within photoshop to create the transparent shadow. as for why i would need to do something that is easy....ill show you when ive dont about my 500th model

still vanishes with vray not loaded in...im totally baffled by this. never had this issue before!

My favourite technique comes from the fantastic plugin: Fractal terrain erode. Just select the face, plugins ) Erode, be careful with the iterations (the more it will take a lot of time and can be buggy...)