Cal. Civil Code § 8458

(a) Except as provided in subdivision (b), a lien provided for in Section 8402 has priority over: (1) A mortgage, deed of trust, or other encumbrance that attaches after commencement of the site improvement. (2) A mortgage, deed of trust, or other encumbrance that was unrecorded at the commencement of the site improvement and of which the claimant had no notice. (3) A mortgage, deed of trust, or other encumbrance that was recorded before commencement of the site improvement, if given for the sole or primary purpose of financing the site improvement. This subdivision does not apply if the loan proceeds are, in good faith, placed in the control of the lender pursuant to a binding agreement with the borrower to the effect that (A) the proceeds are to be applied to the payment of claimants and (B) no portion of the proceeds will be paid to the borrower in the absence of satisfactory evidence that all claims have been paid or that the time for recording a claim of lien has expired and no claim of lien has been recorded. (b) A mortgage or deed of trust, otherwise subordinate under subdivision (a), has priority over a lien provided for in Section 8402 if a payment bond in an amount not less than 50 percent of the principal amount of the mortgage or deed of trust is recorded before completion of the work of improvement.