@tomaz.ogrizek. I'm not sure if I understand your problem correctly. To close the gaps around it, you can use the 'Ploppable Decals' from Ronyx69, for example. I used these here. As far as I know, these are mod-dependent.

Hey, this asset makes my ploppable surfaces like grass, pavement, asphalt disapear. Even if I PO it. Can the author check why this would be?

lovely, this game definitely needs some underground parking assets!