The accessory dwelling unit's color and materials must match those of the primary residence. The director shall review accessory dwelling unit applications to ensure the addition is integrated with the primary structure with respect to roof design, height, compatible materials, color, texture, and design details. If the accessory dwelling unit is an addition to a site with known historic resources or has been determined to have historic value by the director, all improvements shall retain the historical and/or architectural value and significance of the landmark, historical building, or historical district as specified by section 33-1475. The improvements shall be compatible with and retain the texture and material of the primary building(s) and/or structure(s) or its appurtenant fixtures, including signs, fences, parking, site plan, landscaping and the relationship of such features to similar features of other buildings within an historical district.