Cal. Bus. & Prof. Code § 5807
(a) A Certified Interior Designer shall use a written contract when contracting to provide interior design services to a client pursuant to this chapter. The written contract shall be executed by the Certified Interior Designer and the client, or the client’s representative, prior to the Certified Interior Designer commencing work. The written contract shall include, but not be limited to, all of the following:
(b) Subdivision (a) shall not apply to any of the following:
(2) Interior design services rendered by a Certified Interior Designer to any of the following: