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.

The Official Zoning District Map shall be identified by the signature of the Chairman of the Board of Supervisors, 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 106, as amended, of Union Township, Washington 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 thereof except in conformity with the procedure 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 § 280-144 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.

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

Boundaries indicated as appearing to follow platted lot lines shall be construed as following such lot lines;

Boundaries indicated as appearing to follow municipal limits shall be construed as following municipal limits;

Boundaries indicated as following railroad lines shall be construed to be midway between the main tracks;

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 Map shall be determined by the scale of the map.

Any use not specifically listed in the authorized uses for a 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. The authority for the Zoning Hearing Board to grant approval of a use which is not specifically listed in the authorized uses for a zoning district shall be limited to the C-1, C-2, C-3, H-I and A-P Districts where "comparable uses not specifically listed" is included in the list of uses by special exception in the zoning district, subject to the applicable express standards and criteria specified in § 280-102A(10) of this chapter.

Accessory uses or structures which are customarily accessory to principal structures or uses which are authorized as conditional uses or uses by special exception shall be permitted as accessory uses by right.

In all zoning districts, single-family dwellings and two-family dwellings shall be the only principal structure on a lot. Except where secondary dwellings for resident farm workers are authorized by this chapter, a single-family dwelling shall be the only dwelling permitted on a 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 authorized nonresidential uses may occupy the same building; provided that, in all cases, 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.