All regulations in this title pertaining to the districts established in Chapters 17.10 through 17.46 are subject to the general provisions, conditions and exceptions contained in this chapter.

If any ambiguity arises concerning the appropriate classification of a particular use within the meaning and intent of this title, or with respect to matters of height, area requirements or zone boundaries as set forth herein, the planning commission shall ascertain all pertinent facts and by resolution set forth its findings and interpretations and thereafter such interpretation shall govern.

The following manufacturing uses are not allowed in the city:

All of the uses listed in this section, and all matters directly related thereto are declared to be uses possessing characteristics of such unique and special form as to make impractical their inclusion in any class of use set forth in the various districts herein defined, and therefor the authority for the location of the operation of any of the uses designated herein shall be subject to the issuance of a use permit in accordance with the provisions of Chapter 17.64. In addition to the criteria for deter-mining whether or not a use permit should be issued as set forth in Chapter 17.64, the planning commission shall consider the following additional factors to determine that the characteristics of the listed uses will not be unreasonably incompatible with uses permitted in surrounding areas:

Accessory buildings shall be constructed with, or subsequent to the construction of the main building.

Public utility distribution and transmission line towers and poles, and underground facilities for distribution of gas, water, communication and electricity shall be allowed in all districts without limitation as to height or without obtaining a use permit thereof; provided, however, that all routes of proposed gas, water communication transmission lines and electric transmission lines shall be submitted to the city planning commission and then to the city council for their recommendation. Such recommendation shall be received prior to acquisition of rights-of-way therefor.

In cases where a lot in an R-1, R-2, R-3 or R-4 district contains an existing dwelling which does not conform to side yard setback requirements for the district in which it is located, an addition to such dwelling shall not be required to have any greater side yard setback than the dwelling to which it is attached.

In any district with a height limit of less than fifty feet, public and semi-public buildings, schools, churches, hospitals and other institutions permitted in such district may be erected to a height not exceeding fifty feet, provided that the front, rear and side yards shall be increased one foot for each one foot by which such building exceeds the height limit hereinbefore established for such district.

Upon securing a use permit any building in any C, H-C, H-S, M or P-D district may be erected to a height exceeding that herein specified for such district, provided that the cubical contents of the building shall not be increased beyond that possible for a building erected within the height limit hereinbefore specified.

Fences, hedges and walls may be erected in any district subject to the following conditions:

Architectural features on the main building, such as cornices, eaves and canopies may not extend closer than three feet to any side lot line. Eaves and canopies may extend a maximum of three feet into the required front or rear yard. Fireplaces, not exceeding six feet in breadth, may extend not closer than three feet to any side lot line.

Open, uncovered, raised porches, landing places or outside stairways may project not closer than four feet to any side lot line, and not exceeding six feet into any required rear yard or front yard.

Whenever an official plan line has been established for any street, required yards shall be measured from such line and in no case shall the provisions of this title be construed as permitting any encroachment upon any official plan line.

Where an accessory building is attached to the main building, it shall be made structurally a part of and have a common roof with the main building, and shall comply in all respects with the requirements of this title applicable to the main building. Provided, however, that garage entrances on a dwelling, or dwelling fronting on any lot line shall be located not less than twenty feet from said lot line. Unless so attached, an accessory building in an R district shall be located on the rear one-half of the lot and at least ten feet from any dwelling building existing or under construction on the same lot, or any adjacent lot. Such accessory building shall not be located within thirty feet of the far side of any alley; or within four feet of the side line of the lot unless located on the side property line. In the case of a corner lot, an accessory building may not project beyond the front yard required or existing on the adjacent lot.

In R-1 and R-2 districts, where fifty percent or more of the lots in a block have been improved with buildings at the time of the passage of the ordinance codified herein (not including accessory buildings), the minimum required front setback shall be the average of the improved lots, if said setback is more or less than the aforestated requirements.

Single-family dwellings only may be erected on any parcel of land, the area of which is less than the building site area required for the particular district in which said parcel is located.

The width of side yards on single-family dwellings constructed pursuant to Section 17.48.170 may be reduced to ten percent of the width of such parcel, but in no case to less than four feet.

In any R district, where a dwelling unit is located on a lot so that the main entrance is located on the side of the building, the required side setback, from the front setback line to such entrance, shall be not less than ten feet.

Dwelling groups shall be constructed so that the following minimum distances are provided: