SEC. 91.106. PERMITS. 91.106.1. Permits Required. 91.106.1.1. Building Permits. No person shall erect, construct, alter, repair, demolish, remove or move any building or structure, nor shall any person commence any liquid washing, compressed air cleaning or steam cleaning of exterior surfaces of any building unless said person has obtained a permit therefor from the department. A separate permit shall be obtained for each separate building or structure except that a group of temporary structures erected on one site for a limited period of time may be included on one permit. Where the installation, alteration or repair of ventilation equipment or ductwork is not included within the scope of a valid building permit, a separate building permit shall be obtained for the work. Sandblasting, liquid washing, compressed air cleaning, steam cleaning of exterior surfaces of buildings adjacent to and within 20 feet of pedestrian walkways in dedicated streets in the limits of Fire District No. 1 shall be done only between the hours of 11:00 p.m. and 7:00 a.m., or on Sundays. Where complete plans for a proposed building are filed with the department and where a foundation only permit is issued with respect thereto in accordance with rules established by the Superintendent of Building, a building permit may be issued for the remainder of the building within one year after the issuance of the foundation only permit, provided the plans and specifications comply with all applicable Los Angeles Building Code provisions in effect at the time of issuance of the foundation only permit. (Amended by Ord. No. 180,619, Eff. 5/12/09.) 91.106.1.2. Grading Permits. (Amended by Ord. No. 172,592, Eff. 6/28/99, Oper. 7/1/99.) No person shall commence or perform any grading, and no person shall import or export any earth materials to or from any grading site, without first having obtained a permit therefor from the Department. No person shall perform any grading within areas designated “ hillside ” unless a copy of the permit is in the possession of a responsible person and available at the site for display upon request.