No, design professionals are covered under Civil Code §§ 3319-3321:
Under Civil Code §§ 3319, 3320, and 3321, which taken together cover both private and public works, prime design professionals are entitled to prompt payment. In the case of public works, the penalty for late payment is 1½ percent per month in lieu of interest. The agency must pay the prime design professional progress payments within 30 days of a written demand for payment in accordance with the contract, and the final retention within 45 days after receipt of such a written demand. The agency may withhold 150 percent of amounts disputed in good faith.
Section 3321 requires that prime design professionals make payments to sub-consultant design professionals not later than 15 days after receipt of payment from a public agency.
Section 3319, which applies to private works of improvement, permits a design professional to insert into its contract a late payment penalty in lieu of interest.
§ 1:112.Payments by and to prime design professionals, Cal. Constr. L. Manual § 1:112