170.04 SETBACK ADJUSTMENTS.
      1.   Lots Adjoining Alleys. In calculating the depth of a required side or rear yard setback for a lot adjoining a dedicated public alley, one-half of the alley may be credited as a portion of the yard. However, no residential structure may be nearer than five feet to the near side of the alley.
      2.   Encroachments on Required Yards. Every part of a required yard shall be open and unobstructed from finished grade upward, except as specified herein.
         A.   Architectural projections, including roofs that cover porches, enclosed porches, window sills, belt courses, cornices, eaves, flues and chimneys, and ornamental features may project two feet into a required yard.
         B.   Terraces, patios, uncovered decks, and ornamental features that have no structural element more than three feet above or below the adjacent ground level may project six feet into a required front yard. However, all such projections must be set back at least three feet from an adjacent side lot line; or 15 feet from any street property line.
         C.   Fire escapes, fireproof outside stairways, and balconies opening to fire towers may project a maximum of 3 feet into required yards, provided that they do not obstruct the light and ventilation of adjacent buildings.
         D.   For buildings constructed upon a front property line, a cornice may project into public right-of-way, unless such property is constructed on a State or Federal Highway. Maximum projection is the smaller of four feet or five percent of the right-of-way width.
         E.   In commercial districts, a canopy may extend into a required front yard, provided that the canopy is set back at least five feet from the front property line, covers less than fifteen percent of the area of the required front yard, and has a vertical clearance of at least eight feet six inches.
         F.   Swimming pools shall be subject to the same location and setback requirements as accessory buildings.
         G.   Lamp posts with a maximum height of ten (10) feet, and flag poles up to maximum height of base district may be located within required yards, provided they are set back at least five (5) feet from property lines. The spread of a flag when fully extended shall not extend onto public right-of-way.
         H.   Garage Setbacks: Any garage that fronts on a public street must be set back at least 20 feet from such street, regardless of the setback requirement within the zoning district. This shall not be interpreted to waive a larger required minimum setback required by the zoning district.
      3.   Setbacks on Arterial Streets. Notwithstanding any other provision of this ordinance, the City may require a setback for all buildings built or altered, or off-street parking areas developed along a State or Federally designated highway that exceeds those normally required for the zoning district. Lots of record under five acres in size; lots of record duly platted and approved prior to the effective date of this ordinance, or where a properly dedicated and accepted frontage road right-of-way exists are exempt from these provisions and are instead subject to the setback requirements of their respective zoning district.
      4.   Setback Adjustments.
         A.   Setbacks on Built-Up Blockfaces. These provisions apply if thirty percent or more of the buildings on that blockface have front yard setbacks different from those required for the specific district.
            (1)   If a building is to be built on a parcel of land within 100 feet of existing buildings on both sides, the minimum front yard shall be the mean front yard setbacks of the adjacent buildings.
            (2)   If a building is to be built on a parcel of land within 100 feet of an existing building on one side only, the minimum front yard shall be the front yard setback of the adjacent building.
            (3)   If a building is to be built on a parcel of land not within 100 feet of an existing building on either side, then the minimum front yard shall be the mean front yard setback of all existing buildings on the blockface.
            (4)   No setback adjustment pursuant to this section shall create a required front yard setback more than five feet greater than that otherwise required by the applicable zoning district.
         B.   Corner Lots.
            (1)   Required setbacks shall not reduce the buildable width of any corner lot to less than 25 feet. Appropriate setback adjustments shall be allowed to maintain this minimum width.
            (2)   No setback adjustment shall permit encroachment into the vision clearance triangle.
      5.   Double Frontage Lots. Residentially zoned double frontage lots on a major street, and with no access to that street may have a 25-foot minimum front yard setback along said street. All other double frontage lots must provide full front yard setbacks from each adjacent street.
      6.   Adjustment of Setbacks and Lot Area for Partial Takings.
         A.   If a portion of a lot is conveyed to the state, the city, or any other political subdivision of the state through condemnation or under threat of condemnation, and the conveyance results in a structure or use of a structure upon the remaining lot becoming nonconforming or more nonconforming with a required yard or minimum lot area, then notwithstanding the limitations set forth in Chapter 174, if such structure is thereafter damaged to any extent or is totally destroyed by any means, the structure may be repaired, restored, or rebuilt to its prior condition, if all of the following conditions are satisfied:
            (1)   The nonconformity was created by the conveyance through condemnation or under threat of condemnation;
            (2)   Appropriate relief is obtained from the board of adjustment for any nonconformity with the applicable zoning requirements, to the extent that such nonconformity preexisted such condemnation or conveyance;
            (3)   The repair, restoration or rebuilding of the structure does not create any additional nonconformity of the structure beyond that originally created by such conveyance or allowed by any relief granted by the board of adjustment;
            (4)   The repair, restoration, or rebuilding is commenced within six months of such damage under authority of a building permit and is diligently pursued to completion; and,
            (5)   One of the following conditions are satisfied:
               a.   The acquisition document for such conveyance contains language stating substantially as follows: "The provisions of Section _______ of the City of Denison Zoning Ordinance shall apply to this acquisition"; or
               b.   The zoning enforcement officer determines that the circumstances of such conveyance affirmatively support a finding that any resulting nonconformities with the required yards or minimum lot area were not considered in determining the compensation paid for such conveyance.
         B.   If a portion of a lot is conveyed to the state, the city, or any other political subdivision of the state through condemnation or under threat of condemnation, and the conveyance results in a single-family dwelling upon the remaining lot becoming nonconforming or more nonconforming with a required yard or minimum lot area, then the remaining lot shall be treated the same as a lot of record existing as of the effective date of this ordinance, for the purposes of applying the provisions in Section 170.03 regarding the construction of a single family detached dwelling.
         C.   Any adjustment to the minimum lot area made under authority of this section shall automatically lapse in the event the lot is joined with other adjoining land under common ownership that collectively satisfy the applicable minimum lot area.
         D.   Any adjustment to a required yard made under authority of this section shall automatically lapse in the event the lot is joined with other adjoining land under common ownership that collectively satisfy the applicable minimum required yard.
      7.   Satellite Antennas.
         A.   Antennas with a surface area over 6.3 square feet which are accessory to a primary use and are designed to receive and transmit electromagnetic signals, or to receive signals from satellites, shall not be located within any front yard of the primary use.
         B.   Antennas with a surface area of over 6.3 square feet are subject to the following additional regulations:
            (1)   Such antennas shall be located no less than ten feet from the property line of an adjacent property line.
            (2)   The maximum height shall be 15 feet and the maximum diameter shall be 11 feet.
            (3)   Each antenna shall be screened by a six foot high wood or masonry fence, or by natural plants or trees of equal minimum height.
      8.   Vision Clearance Zones. Except in the CBD District, no structure or obstruction, including fences, walls, or landscape materials, shall be built to a height of between 24 inches and 10 feet above the established curb grade on the part of the lot within a vision clearance zone. The vision clearance zone shall be a triangle defined by:
         A.   20 feet back from the intersection of curb lines and right-of-way edges of alleys.
         B.   75 feet from the intersection of the centerlines of intersecting local streets.
         C.   90 feet from the intersection of the centerlines of intersecting collector or arterial streets.