I am a GC, the owner is refusing to pay the 4/5 payments. We have stopped work. Do I need to file a Prelim Notice to the Owner before a Notice of Intent to ensure they are held responsible?
If this is a residential project, a preliminary notice will be required if the building permit contains the contact info for a mechanics lien agent. On commercial projects, GC's generally don't have to send preliminary notice in order to preserve their right to lien. Further discussion here: Virginia Preliminary Notice FAQs.
It sounds like you may be familiar with how a Notice of Intent to Lien works, but this article helps illuminate how valuable the notice can be for forcing payment: What is A Notice of Intent to Lien And Should I Send One?