Legal Question in Real Estate Law in California

The contract would be binding with the tenant. Commercial tenants enter into legally binding contracts for their tenant improvements all the time. The law of binding contracts is no different for residential tenants, but you probably should make sure the landlord consents for two reasons. One, you don't want to be working on his property without his or her consent in the event something goes wrong. I'm sure you're an outstanding plumber, but there's always a risk of water damage with any plumbing project, for example. Two, on the off chance you don't get paid, it's always nice to have the mechanic's lien option available. Notice to the owner is required if you are contracting with a tenant, in order to preserve lien rights.