Base setback lines are hereby established parallel to the center line of all public streets and ways as follows:

Except as provided in Subsection B(1)(a) through (d) hereof, no building shall hereafter be erected, structurally altered, or relocated so that it is closer to the base setback line than the setback distance hereinafter specified by the regulations of the zoning district in which it is located.

Where the mean of the setbacks of the buildings on the immediately adjacent lots on each side of the subject lot is greater than the minimum setback required within a zoning district, the Building Inspector shall not issue any building permit for the subject lot but shall promptly refer the matter to the Plan Commission. In such event, building setback lines appropriate for the location of the subject lot and for the type of development and use contemplated which are more restrictive than the regulations of the zoning district in which the subject lot is located may be required by the Plan Commission. Examples of the application of this provision would include, but are not limited to, requiring greater setbacks on cul-de-sac lots to achieve the necessary lot width at the setback line, requiring greater setbacks that are compatible with setbacks of existing adjacent development, or setting special yard requirements to protect natural resource elements. In determining appropriate building setback lines in such cases, the Plan Commission shall consider the following, together with such other factors as the Plan Commission may deem relevant:

The setback required by Subsections B and C shall be measured from the nearest enclosed or roofed portion of a building; provided, however, that the first two feet of an overhanging eave and gutter shall not be included.

The only structures permitted within such setback area shall be necessary highway and traffic signs, public utility lines and poles, walls and fences as regulated by § 485-41, rural mailboxes, signs as permitted under the district regulations, structures other than buildings as regulated by § 485-40, underground buildings as regulated by § 485-37, and enclosed canopies for lighting and rain protection in conjunction with such uses as automobile sales lots or drive-in commercial facilities, provided that such canopy structures are approved by the Plan Commission, and those structures included in Subsection B(2) above.

Additions to and replacements of existing structures lying between the base setback line and the existing street right-of-way may be made subject to approval of the Plan Commission and provided the owner will file with the City, and record as part of the deed for such property, an agreement in writing to the effect that the owner will remove all new construction, additions and replacements erected after the adoption of this chapter at his expense when necessary for the improvement of the street and will claim no damage for the same.

Vision setback lines at the intersection of public streets and of a street with a railroad or alley, where the grade is not separated, are hereby established as follows:

In the vision setback area no structure of any kind shall be permitted which exceeds a height of 2 1/2 feet above elevation of the center of the intersection, except for necessary highway and traffic signs, public utility lines, and open fences through which there is clear vision, nor shall any plant material or natural growth be permitted which obscures safe vision of the approaches to the intersection.

The requirements for vision setback shall not apply within the B-4 Central Business District.

No building shall hereafter be erected, structurally altered, or relocated so that any roofed or enclosed portion thereof is closer to any lot line than the offset distance hereinafter specified by the regulations for the district in which it is located, except as follows:

In all districts which allow common wall construction or do not require an offset, all buildings which are hereafter erected, structurally altered, or relocated having any rooms required by the Building Code to have light and ventilation by windows opening directly to the outer air shall provide courts as follows:

Street setback and vision corner. Where a zero street setback is permitted by the district regulations, buildings over 35 feet in height shall recess the first story at least five feet from the base setback line. Building support columns are exempt from this five-foot requirement.

Common wall construction. Where common wall construction is permitted by the district regulations, the building may be built upon the property line provided local and State Building Code requirements for common wall construction are met throughout the height of the building facade being located on the property line.

Offsets. Where common wall construction is not involved, buildings over 35 feet in height shall provide the minimum offset required by the district regulations, but in no case less than 10 feet, plus one additional foot of offset for each story over three stories in height.