The Township is hereby divided into zoning districts, as shown on the Official Zoning District Map, which, together with all explanatory matter thereon, is hereby adopted by reference and declared to be a part of this chapter.[1]

The Official Zoning District Map shall be identified by the signature of the Chairman of the Board of Commissioners, attested by the Township Secretary and certified by the Township Engineer, and shall bear the seal of the Township under the following words: "This is to certify that this is the Official Zoning District Map referred to in Article III of Ordinance Number 687, as amended, of Collier Township, Allegheny County, Pennsylvania," together with the date of adoption of this chapter.

All amendments affecting district boundaries shall be noted on the Official Zoning District Map by the Township Engineer, including the date of adoption, and shall be attested to by the Township Secretary.

No changes of any nature shall be made in the Official Zoning District Map or matter shown thereon except in conformity with the procedures set forth in this chapter. Any unauthorized change of whatever kind by any person shall be considered a violation of this chapter and punishable as provided under § 27-2602 of this chapter.

The Official Zoning District Map, which shall be located in the Township Municipal Building, shall be the final authority as to the current zoning status of land and water areas, buildings and other structures in the Township.

The Township is divided into the districts set forth by this chapter and as shown by the district boundaries on the Official Zoning District Map. The zoning districts are:

Where uncertainty exists as to the boundaries of districts as shown on the Official Zoning District Map, the following rules shall apply.

District boundaries indicated as appearing to follow the center lines of streets, highways or alleys shall be construed to follow such center lines.

District boundaries indicated as appearing to follow platted lot lines shall be construed as following such lot lines.

District boundaries indicated as appearing to follow municipal boundaries shall be construed as following municipal boundaries.

District boundaries indicated as following railroad lines shall be construed to be midway between the main tracks.

District boundaries indicated as approximately following the center lines of streams, rivers or other bodies of water shall be construed to follow center lines, and in the event of change in the location of streams, rivers and other bodies of water, shall be construed as moving with the actual body of water and following the center line.

Distances not specifically indicated on the Official Zoning District Map shall be determined by the scale of the map.

In the S-C, R-1, R-2, R-2-A, R-3, R-3-A, R-4 and R-5 Districts, any use not specifically listed as an authorized use in the zoning district shall not be permitted in that zoning district.

In the B-1, B-1-A, B-2, B-3, B-4, PEDD and I-1 Districts, any use not specifically listed in the authorized uses for the zoning district shall not be permitted in that zoning district, unless such use is authorized by the Zoning Hearing Board as a use by special exception in accordance with the applicable express standards and criteria for "comparable uses not specifically listed" specified in § 27-1905 of this chapter.

In all zoning districts where single-family dwellings or two-family dwellings are an authorized use or are a legally nonconforming use, the single-family dwelling or two-family dwelling shall be the only principal structure on the lot.

In all zoning districts where authorized by this chapter, two or more multifamily dwellings may occupy the same lot, two or more nonresidential buildings may occupy the same lot, and two or more nonresidential uses may occupy the same building, provided, in all cases, that all applicable requirements for each of the structures or uses can be met on the lot.

In all zoning districts, all accessory structures shall be located on the same lot with the principal structure to which they are accessory. Any accessory structure shall not be built unless or until the principal structure it serves exists on the lot.