ruinous

Causing ruin; destructive, calamitous.

Extremely costly; so expensive as to cause financial ruin.

They were forced to completely replace the roof at ruinous expense.

We are rapidly reversing the economic calamity we inherited from the previous administration, including ruinous price increases and record-setting inflation, inflation like we've never had before.

Characterized by ruin; ruined; dilapidated; as, an edifice, bridge, or wall in a ruinous state.