§ 17.12.060. Building height controls.

A.

Height Controls Established. No building or other structure shall penetrate the height control plane except as permitted by this section. Height controls shall be imposed from:

1.

All setback lines in AG, AR2a and residential districts;

2.

All street setback lines in nonresidential districts;

3.

The boundary between an AG, AR2a, RS and RS-A, R and R-A, RM or MHP district and a nonresidential district;

B.

Special Height Regulations For Single-Family and Two-Family Dwellings. Single-family and two-family dwellings shall not exceed three stories. In all districts with a minimum lot size of less than forty thousand square feet, accessory structures shall not exceed one story or sixteen feet in height, whichever is less. In all residential districts with a minimum lot size of at least forty thousand square feet, accessory structures located to the rear of the principal dwelling may be two stories or twenty-four feet in height, whichever is less, provided that the full side and rear setbacks required by the applicable district are provided and the lot has an area of at least forty thousand square feet. If not so established in historic overlay districts, the zoning administrator shall establish height regulations based upon the recommendation of the historic zoning commission.

C.

Special Height Regulations for Single-Family and Two-Family Dwellings Within the Urban Zoning Overlay District.

1.

Single-family and two-family dwellings shall not exceed three stories to a maximum height of forty-five feet. Maximum height shall be measured from either the natural grade or, if present, from the ceiling of an exposed basement not more than seven feet above the natural grade. The natural grade shall be determined based on the average elevation of the four most exterior corners of the structure, to the eave or roof deck. Natural grade is the base ground elevation prior to grading.

2.

In all districts with a minimum lot size of less than forty thousand square feet, an accessory structure located to the rear of the principal dwelling may have vertical walls rising no higher than sixteen feet from the side and rear setback lines. The roof on the structure shall rise from the side walls at a roof pitch no steeper than the predominant roof pitch of the principal dwelling, except that the vertical walls may extend to the underside of the roof at the gable end of a gabled roof. The top elevation of an accessory structure shall not exceed the top elevation of the principal dwelling.

3.

In all residential districts with a minimum lot size of at least forty thousand square feet, an accessory structure located to the rear of the principal dwelling may have vertical walls rising no higher than twenty-four feet in height exclusive of a pitched roof, provided that the full side and rear setbacks required by the applicable district are provided and the lot has an area of at least forty thousand square feet. The top elevation of an accessory structure shall not exceed the top elevation of the principal dwelling.

If not so established by the design standards of an historic overlay district, the zoning administrator shall establish height regulations based upon the recommendation of the historic zoning commission.

D.

Permitted Height Obstructions. In the mixed-use and nonresidential districts, the following structures shall be exempt from the height control standards of this section.

1.

On-premises signs subject to the provisions of Chapter 17.32;

2.

Chimneys or flues;

3.

Elevator or stair bulkheads, roof water tanks, or cooling towers;

4.

Flagpoles;

5.

For religious institutions, ornamental towers, spires or belfries having no floor area within that portion of the tower exceeding the height limit or penetrating the height control plane;

6.

Parapet walls not more than four feet high.

E.

Special Height Restrictions Along Highways Designated Scenic Under T.C.A. Section 54-17-101 et seq.

1.

For purposes of this subsection D, the following terms shall have the meanings shown:

a.

"Coverage area" means the total surface area proposed to be covered by a structure.

b.

"Natural elevation" means the average elevation of the coverage area prior to grading, to be computed by dividing the sum of the elevations of points taken at twenty-five foot intervals around the perimeter of the coverage area by the total number of such points.

c.

"Measuring segment" means the full segment of scenic highway abutting the property on which the building is to be built.

d.

"Measuring segment elevation" means the average elevation of the measuring segment, to be computed by dividing the elevations of points taken along the centerline of the measuring segment at twenty-five foot intervals divided by the total number of such points.

e.

"Maximum building height" means the difference between the maximum elevation of a building, including any object to be affixed thereto, and the natural elevation.

2.

The "maximum building height" of any building to be built within three hundred feet of, and on a parcel of property abutting, a road designated a scenic highway by Tenn. Code Ann. Section 54-17-101 et seq., as amended, shall not exceed the following:

a.

For a building site having a natural elevation lower than the measuring segment elevation, maximum building height shall be no more than thirty-five feet higher than the measuring segment elevation.

b.

For a building site having a natural elevation higher than the measuring segment elevation, maximum building height shall be no more than thirty-five feet higher than the natural elevation.

F.

Special Height Regulations for All Uses (Excluding Single-Family and Two-Family Dwellings) Within the Urban Zoning Overlay District, but not including the DTC district:

1.

In all districts, a principal or accessory structure may exceed the maximum height at the setback line and/or penetrate the height control plane as shown in Tables 17.12.020B and 17.12.020C, or the maximum height in the build to zone for thirty percent of the façade fronting each public street and/or the maximum heights specified in Table 17.12.020D, based on the review and approval of a Special Exception by the board of zoning appeals.

2.

The top elevation of an accessory structure shall not exceed the top elevation of any principal building or structure located within the development.

3.

An applicant shall provide evidence to the board that the proposed building height shall not create an adverse impact on air, light, shadow, or wind velocity patterns due to the configuration of the building relative to the maximum permitted height standards (including height control plane) and its juxtaposition to, and with, existing structures in the vicinity, or approved, but not yet built structures. In addition, the applicant shall demonstrate that the proposed building height contributes to, and does not detract from, a strong pedestrian-friendly streetscape.

4.

The board shall consider a recommendation from the Historic Zoning Commission, if the property is located within an historic overlay district, and a recommendation from the planning commission as provided in Section 17.40.300. The planning commission shall recommend on the proposed development's consistency with the goals, objectives and standards of any redevelopment district as well as the general plan, including any community, neighborhood or other design plan.

(Ord. BL2015-1153 §§ 16, 17, 2015; Ord. BL2015-1053 § 1, 2015; Ord. BL2012-183 § 4, 2012; Ord. BL2007-1431 § 1, 2007; Amdt. 1 to Ord. BL2006-1047, § 5, 2006; Ord. BL2006-1047 § 5, 2006; Ord. 2002-1015 § 1 (part), 2002; Amdts. 2, 8 with Ord. BL2000-364 § 1 (part), 2000; Amdt. 1 with Ord. BL2000-317 § 1, 2000; Amdt. 1 with Ord. 98-1268 § 1 (part), 1998; § 1(9) of Amdt. 1 with Ord. 96-555 § 3.5, 1997)