Above the maximum height of a front wall at the street line as set forth in Section 81-262, a building may only encroach beyond the half-setback line if it complies with the provisions of this Section and if the area of compensating recess equals or exceeds the area of encroachment in Zone B and Zone C in accordance with the provisions of Section 81-264 (Encroachments and compensating recesses).

(a)        Special limitations

No encroachment beyond the half-setback line shall be within 30 feet of a side lot line. (See illustration of Prohibited and Allowed Encroachment Beyond Half-Setback Line)

PROHIBITED AND ALLOWED ENCROACHMENT BEYOND

HALF-SETBACK LINE

(81-265a)

(b)        General provisions

The length, depth, height and area of encroachments along any street frontage all contribute to a building's impact on daylight access. In order to determine whether the depth of a building's encroachment into Zone C is justified, the length of the encroachment, measured parallel to the street line, and its height above curb level must also be evaluated. The extent of encroachment also must be considered in relation to the extent of the area of compensating recess in the same street frontage zone. The purpose of the length and height rule is to ensure, in the case of encroachments beyond the half-setback line, that the closer a building comes to the street line, the less will be the length of its encroachment, its height or both. (See illustration of Elements Analyzed)

The elements comprising this analysis are represented by symbols and are as follows:

(1)        

De        (depth of encroachment) means depth of encroachment beyond the setback line. Depth of encroachment is measured perpendicularly to the setback line.

D        (depth of setback line) means depth of setback line from the street line or depth of ten-foot setback line from the street line, whichever depth is greater.

(2)        

Le        (length of encroachment) means total length of encroachment outside the half-setback line. Length of encroachment is measured as the total length of the encroachments' projections on the street line.

L        (length of front lot line) means the length of the front lot line along the particular street. However, the length of the front lot line for the purposes of this Section shall not exceed 300 feet, irrespective of the actual lot line length.

(3)        

Le        (length of encroachment) as defined in paragraph (b)(2) of this Section.

Lr        (length of recess) means total length of setback line not encroached upon by a building.

(4)        

H        (height of encroachment) means the height of the encroachment above curb level.

L        (length of front lot line) as defined in paragraph (2) of this Section.

(5)        

Ar        (area of compensating recess) means area of compensating recess in the particular street frontage zone. Area of compensating recess is calculated to a depth of 100 feet from the street line.

Ae        (area of encroachment) means area of encroachment beyond the setback line. Area of encroachment is calculated to a depth of 100 feet from the street line.

Values for the elements in paragraphs (b)(1) through (b)(5) shall be found for each street frontage zone on which there is any encroachment beyond the half-setback line.

ELEMENTS ANALYZED

(81-265b)

The elements, weighted according to the effects on daylight access, are represented in the formulas and charts that control the depth, length and height of encroachments, as set forth in paragraph (c) of this Section.

Encroachments of proposed buildings or enlargements beyond the half-setback line are permitted only if in compliance at every point with the formulas in paragraph (c) of this Section. Aside from this general requirement, specified points at which the length, depth, height and area rules shall be applied are presented in paragraphs (d) and (e) of this Section.

(c)        Encroachment limitations by Formulas 1 and 2

Where applicants elect to have their buildings regulated by the formulas, buildings shall comply with both Formula 1 and Formula 2 as set forth in this paragraph. Elements of the formulas and the symbols by which they are represented are as set forth in paragraph (b) of this Section.

The maximum height of encroachment (H) allowed by Formula 1 may be modified for certain conditions, as follows:

(1)        For short frontages

For any frontage less than 200 feet in length, the maximum

found by applying Formula 1 may be increased by the following multiplier:

(2)        For large areas of compensating recess

To the extent that the aggregate area of compensating recess (Ar) exceeds the aggregate area of encroachment (Ae), the maximum

found by applying Formula 1 may be increased by the following multiplier:

For the purposes of this modification, the measurement of the area of compensating recess (Ar) and the area of encroachment (Ae) in each particular street frontage zone shall be made on the encroachment grid at the height level for which encroachments beyond the half-setback line are checked. The encroachment grid shall include all street frontage zones. (Ar) shall include all areas of compensating recess in the particular street frontage zone, whether or not connected, and (Ae) shall include all encroachments in both Zone B and Zone C in the same street frontage zone, whether or not such encroachments are connected.

(d)        Measurement of encroachments

The points at which the formulas are applied will depend upon the shape and dimensions of the encroachments beyond the half-setback line and shall be in accordance with the provisions of this paragraph and paragraph (e) of this Section.

Where the encroachments along a single street frontage are not connected outside the half-setback line, each encroachment shall be measured separately in accordance with the provisions of paragraph (e). However, at any given height, where such non-contiguous encroachments occur, the encroachments shall be examined together, and the length of encroachment (Le) shall be the total of the (Le) for the individual encroachments. (See illustration of Non-contiguous Encroachments)

NON-CONTIGUOUS ENCROACHMENTS

(81-265d)

(e)        Heights and depths at which formulas are applied

Heights and depths at which the formulas shall be applied are set forth in this paragraph. In addition to meeting the requirements of paragraphs (e)(1) and (e)(2) of this Section, the applicant shall demonstrate that there is no height at which the proposed building or enlargement fails to comply with the formulas in paragraph (c) of this Section.

(1)        Standard requirement where length of encroachment is uniform

Where the length of the encroachment (Le) is uniform for the entire height of the encroachment (H) and the entire depth (De) at every height, the length, depth and height rules expressed in the formulas shall be applied only at the height where (De/D) is greatest and at the outermost edge of the encroachment. (See illustration of Uniform Length of Encroachment)

UNIFORM LENGTH OF ENCROACHMENT

(81-265e1)

(2)        Standard requirement where length of encroachment is not uniform

Where the length of the encroachment (Le) is not uniform, the rules shall be applied at the height level where (De/D) is greatest and also at the height level where the length of encroachment (Le) is greatest. If the greatest length of encroachment is uniform for part of the building's height, the rules shall be applied at the highest level at which such greatest length of encroachment occurs. (See illustrations Where Length of Encroachment Is Not Uniform).

If for a particular height level, the length of the encroachment (Le) varies with the depth of the encroachment (De), the largest (Le) of this encroachment shall be used together with the largest (De) in applying the rules as if the encroachment were of uniform length as provided in paragraph (e)(1) of this Section.

WHERE LENGTH OF ENCROACHMENT IS NOT UNIFORM

(81-265e2)

(f)        Encroachments by existing buildings

When a zoning lot contains an existing building which encroaches beyond a half-setback line or a ten-foot setback line, an enlargement or development on such zoning lot shall comply with the following provisions:

(1)        Existing buildings below specified heights

(i)        Except as provided in paragraph (f)(1)(ii) of this Section, an existing building not more than 120 feet in height shall not be considered in applying the length and height rules even though a portion of such building encroaches beyond the half-setback line or ten-foot setback line along a 60 foot wide street and an existing building not more than 150 feet in height shall not be considered in applying the length and height rules even though a portion of such building encroaches beyond the half-setback line or ten-foot setback line along a street 75 or more feet in width.

(ii)        However, the area occupied by the existing building shall be included in the calculation of (Ar/Ae) for the modification of Formula 1 allowed in the case of large areas of compensating recess, as set forth in paragraph (c)(2) of this Section.

(2)        Existing buildings above specified heights

Where an existing building more than 120 feet in height encroaches beyond the half-setback line or ten-foot setback line along a 60-foot wide street or where an existing building more than 150 feet in height encroaches beyond the half-setback line or ten-foot setback line along a street 75 or more feet in width, the following provisions, in addition to those of paragraph (d)(3) of Section 81-264 (Encroachments and compensating recesses), shall apply:

(i)        no new construction on the zoning lot shall encroach beyond the half-setback line along any street, and

(ii)        the length and height rules of this Section shall not apply.