Legal Question in Real Estate Law in California

You both own an equal interest in the house so yo can not sell without his permission. If you can not get him to agree to a sale of the house, you would have to file for partition, which could cost about $15,000 in lawyer costs and fees.

You could sell only your half interest. You could theoretically sell it to a member of the public, but in the real world nobody would be interested, so your market is essentially the other co-owner.

The serious exit strategy for an unhappy co-owner is a partition action, which is a special kind of lawsuit that asks the court to order the house sold and the net proceeds divided fairly. Although a contested partition action might cost $15,000 (or more), most are settled out of court soon after being filed and served, often one party buys out the other, or they agree to a private sale process. Any issues between the co-owners that can't be resolved by negotiation can be referred to quick, binding arbitration.

I have handled several nearly identical matters, and have one in court (Contra Costa County) now. Please contact me directly if interested in a further free consultation on mechanics and costs of filing for partition.