ruinous

adjective3

1. •
   Causing ruin; destructive, calamitous.
2. •
   Extremely costly; so expensive as to cause financial ruin.

   • They were forced to completely replace the roof at ruinous expense.
3. •
   Characterized by ruin; ruined; dilapidated; as, an edifice, bridge, or wall in a ruinous state.