Whenever any building or portion thereof, has become substandard as described in Section 17920.3 or is a building as described in 17920.10, of the Health and Safety Code, and when determined to be a nuisance as defined in Section 17920 of the Health and Safety Code by the enforcement agency, the following shall apply:

The enforcement agency shall notify the owner of the building and any mortgagee or beneficiary under any deed of trust, of record, as follows. The notice shall state the conditions causing the building to become substandard or in violation of Section 17920.10 of the Health and Safety Code, and shall order the building, or portion thereof, vacated and shall institute proceedings for the correction or abatement thereof, either by demolition, closing or repair, within 30 days after the date of the notice. If, in the opinion of the enforcement agency, these conditions can be corrected or abated by repair thereof, the notice shall state the repairs which will be required.

If the building is encumbered by a mortgage or deed of trust, of record, and the owner of the building has not complied with the order of the enforcement agency on or before the expiration of 30 days after the mailing and posting of the notice, the mortgagee or beneficiary under the deed of trust may, within 15 days after the expiration of the 30-day period, comply with the requirements of the order of the enforcement agency, in which event the cost to the mortgagee or beneficiary shall be added to, and become a part of, the lien secured by the mortgage or deed of trust, and shall be payable at the same time and in the same manner as may be prescribed in the mortgage or deed of trust for the payment of any taxes advanced or paid by the mortgagee or beneficiary for and on behalf of the owner.

If the order of the enforcement agency has not been complied with on or before the expiration of 45 days after the mailing and posting of the notice, the enforcement agency may institute an appropriate action or proceeding to correct or abate the condition, as would be taken to correct or abate any nuisance or any violation of any other provision of this article or, as an alternative procedure, the enforcement agency may institute proceedings for the abatement of the nuisance, after notice and hearing, before the governing board of the agency as follows.