If a roommates pet scratches up your furniture to the point of needing reupholstered. Is your roommate 100% liable for costs?

I'm going to take a crack at this one and give my opinion... I would think that your roommate would not be liable for the costs especially if you both made the agreement that a pet would be OK in the house, etc. My opinion though!

You would have to review your contract with the roommate. I doubt that most rental contracts would cover this situation and if it is not specifically cited in the contract, you probably have little recourse. If it was your property and rental, you may be able to claim the security deposit for damages caused by the pet if there was a pet clause.

Your roommate should step up and do the honorable thing to repair your furniture, or at least help in the cost of repairs. For now, I would insist that steps be taken to prevent further damage. You might start looking for a new roommate.