The rules in Section 4.1.7 apply to all zones unless stated otherwise.
A. Area, Lot, and Density
1. Tract
A tract is a contiguous area of land, including all proposed and existing rights-of-way, lots, parcels, and other land dedicated by the owner or a predecessor in title. A tract does not include land conveyed to a government for more than nominal consideration.
2. Site
A site is an area of land including all existing and proposed lots and parcels in one application, except proposed and previous dedications and rights-of-way.
3. Lot
A lot is a contiguous area of land that is described by a plat recorded in the land records for which a building permit can be issued.
4. Lot Area
The lot area is the geographic extent defined by lot boundaries.
5. Lot Width
a. At the Front Lot Line
The lot width at the front lot line is measured between the side lot lines, at the front lot line, along a straight line; however, if the front lot line is curved, lot width at the front lot line is measured along the chord of the front lot line.
b. At the Front Setback Line
The lot width at the front setback line is measured between the side lot lines, at the front setback line, along a straight line.
c. At the Front Building Line
The lot width at the front building line is measured between the side lot lines, at the front edge of the building, along a straight line.
6. Density
Density limits are expressed in units per acre, lots per acre, or FAR, as indicated in each zone.
1. Structure Setbacks
a. Defined
A structure setback is the minimum distance that a principal building or accessory structure must be located from a specified lot line or right-of-way.
b. Measurement of Setbacks
There are front, side street, side, and rear setbacks. Through lots have 2 front setbacks. A lot abutting an alley is not a through lot.
i. The front setback is measured from the front lot line to a structure.
ii. The side street setback is measured from the side street lot line to a structure.
iii. The side setback is measured from the side interior lot line to a structure.
iv. The rear setback is measured from the rear lot line to a structure.
2. Build-to Area
Defined
a. The build-to area is the area on the lot from the lot line or right-of-way to the maximum setback where a certain percentage of the front or side street building façade must be located.
b. A drive aisle is prohibited in the build-to area. All other structures and uses customarily allowed on the lot are allowed in the build-to area, including an access driveway perpendicular to the right-of-way.
3. Parking Setbacks
a. Defined
A parking setback is the minimum distance that a surface parking lot must be located from a specified lot line or right-of-way. Structured parking must satisfy principal building setbacks.
b. Measurement of Parking Setbacks
There are front, side street, side, and rear parking setbacks. Through lots have 2 front parking setbacks. A lot abutting an alley is not a through lot.
i. The front and side street parking setback is measured from the edge of the lot line or right-of-way to a surface parking lot.
ii. The side parking setback is measured from the side lot line to a surface parking lot.
iii. The rear parking setback is measured from the rear lot line or the edge of the right-of-way if there is an alley to a surface parking lot.
4. Coverage
a. Defined
i. Coverage is the area of a lot or site occupied by a building, including an accessory building, structured parking, or other roofed structure such as a porch, patio, deck, or steps.
ii. Coverage does not include paved areas such as a driveway, a pedes-trian walkway, a bay window measuring 10 feet in width or less and 3 feet in depth or less, an uncovered porch or patio, deck, a swimming pool, or roof overhang.
b. Exemptions
Handicap facilities are exempt from coverage if the size of the accessibility improvement does not exceed the minimum design specifications in the Maryland Accessibility Code and Montgomery County Building Code.
5. Setback Encroachments
Any building or structure must be located at or behind the required building setback line, except:
a. Building Features
i. Any unenclosed porch, deck, terrace, steps, or stoop may project a maximum of 3 feet into any side setback, or any side street setback of less than 25 feet and may project a maximum of 9 feet into any front setback, rear setback, or any side street setback where the side street setback is a minimum of 25 feet. This encroachment includes an unenclosed roofed porch or terrace.
ii. Any roofed and unenclosed steps or stoop may project a maximum of 3 feet into any side setback, or any side street setback of less than 25 feet and may project a maximum of 9 feet into any front setback, rear setback, or any side street setback where the side street setback is a minimum of 25 feet. Any roof covering unenclosed steps or a stoop may project a maximum of 3 feet into any setback.
iii. An unenclosed balcony may project a maximum of 6 feet into a required setback, if such projection is a minimum of 2 feet from the vertical plane of any lot line.
iv. A sill, leader, belt course, or similar ornamental feature may project a maximum of 6 inches into any setback. Where a wall is located on a lot line, any such projection may extend across a lot line under Chapter 50 (Section 50-20).
v. A chimney or flue as part of a detached house, duplex, or townhouse may project a maximum of 2 feet into any setback.
vi. A chimney or flue as part of an apartment may project a maximum of 4 feet into any setback, if such extension remains a minimum of 2 feet from the vertical plane of any lot line.
vii. Any building eave, cornice, or light shelf may project a maximum of 2 1/2 feet into any setback, if such extension remains a minimum of 2 feet from the vertical plane of any lot line. Where a wall is located on a lot line, any such projection may extend across a lot line under Chapter 50 (Section 50-20).
viii. Any bay window, oriel, entrance, vestibule, or balcony, 10 feet in width or less, may project a maximum of 3 feet into any setback. The total length of all bay windows and oriels on a building façade is a maximum of 50% of the linear footage of the façade.
ix. Any unenclosed fire escape or outside stairway may project a maximum of 5 feet into any side street, side, or rear setback.
b. Mechanical Equipment and Utility Lines
i. Mechanical equipment associated with residential uses, such as an HVAC unit or security lighting, may project a maximum of 5 feet into any front or rear setback.
ii. A permanent rainwater collection or harvesting system may project a maximum of 3 feet into any side street, side, or rear setback.
c. Solar Panels
A solar panel may project a maximum of 3 feet into any side setback, or any side street setback of less than 25 feet and may project a maximum of 9 feet into any front setback, rear setback, or any side street setback where the side street setback is a minimum of 25 feet.
d. Other Encroachments
The following features may encroach into any setback:
i. any fence or wall under Section 6.4.3.C;
ii. a handicap facility to the extent necessary to meet the minimum standards of the Americans with Disabilities Act; and
iii. any sign under Division 6.7.
C. Height
1. Building Height in Agricultural, Rural Residential, and Residential Zones
a. Building height is measured from the average grade either to the mean height level between the eaves and ridge of a gable, hip, mansard, or gambrel roof or to the highest point of roof surface, regardless of roof type.
b. Average grade is calculated using the weighted average of point grades for each wall length along pre-development or finished level of ground (whichever is more restrictive), along the front of the building parallel to the front setback line. The weighted average of point grades for each wall length is calculated by multiplying each front facing wall section times the grade elevation adjacent to that section, summing all products, and dividing by the total length of the front wall.
2. Building Height in Commercial/Residential, Employment, and Industrial Zones
a. For a building located within 35 feet of a street right-of- way, building height is measured from the level of approved curb grade opposite the middle of the front of a building to the highest point of roof surface of a flat roof or to the mean height level between eaves and ridge of a pitched roof. If a building is located on a terrace, the height may be increased by the height of the terrace. For a corner lot or a lot extending through from street to street, the height is measured from the curb grade opposite the middle of the building façade along either right-of- way; however, under Section 7.3.4, Site Plan, the Planning Board may approve an alternative point of measurement as part of site plan approval. The alternative measurement point must be taken from the approved curb grade along either right- of-way. In approving an alternative point of measurement, the Planning Board must consider compatibility and building height variation on the site.
b. If a building is set back from the street line 35 feet or more, then the building height is measured from the average elevation of finished ground surface along the front of the building.
Any height encroachment not specifically listed is prohibited.
a. The following roof structures may occupy a maximum of 25% of the roof area: a spire, belfry, cupola, dome not intended for human occupancy, chimney, flue or vent stack, flagpole, monument, water tank, television antenna or aerial, air conditioning unit, or similar structure or mechanical appurtenance (not including a rooftop renewable energy system). A larger area may be approved by the Planning Board under optional method development in the Commercial/Residential and Employment zones.
b. The maximum height does not apply to solar panels and any roof structure listed in Section 4.1.7.C.3.a, except that in the TLD, TMD, THD, and R-30 zones, an air conditioning unit or similar structure or mechanical appurtenance may exceed the established height limit by a maximum of 8 feet.
c. In the CRT, CR, Employment, and Industrial zones, the following may exceed the established height limit by up to 8 feet, except when located within an airport approach area:
i. rooftop deck, patio, shade structure;
ii. rooftop garden, landscaping;
iii. parapet wall;
iv. rooftop rainwater collection or harvesting system; and
v. rooftop renewable energy system, such as a solar panel or wind turbine.
d. An accessory structure located on the roof must not be used for any purpose other than a use incidental to the principal use of the building.
e. A public building may be a maximum of 120 feet; but the minimum front, rear, and side setbacks must be increased 1 foot for each foot above the maximum height allowed in the zone.
4. Height in Airport Approach Areas
The height of any building or structure, including any structure regulated under Section 4.1.7.C.3, must be limited to provide a clear glide path from the end of the usable landing strip. The glide path is a plane surface laid out according to the operating characteristics of the aircraft for which the airport is designed, and under the criteria in the airport's conditional use approval.
The first 500 feet of such glide path must be wholly within the airport.
D. Form
1. Transparency
a. The minimum percentage of windows and doors that must cover a ground story facade is measured based on facade wall area between 0 and 12 feet above the adjacent sidewalk.
b. The minimum percentage of windows and doors that must cover an upper story facade is measured based on facade wall area from the top of the finished floor to the top of the finished floor above. When there is no floor above it is measured from the top of the finished floor to the top of the wall plate.
2. Blank Wall
a. Blank wall is the area of the exterior street facing facade of a building that does not include windows or doors, or columns, pilasters, or other articulation greater than 8 inches in depth.
b. Blank wall is measured vertically and horizontally.
3. Entrance Spacing
a. Entrance spacing is the maximum distance between entrances. One entrance must be provided for a specified length of building façade fronting a street or open space, as indicated in Division 4.5 and Division 4.6.
b. An angled entrance may be provided at either corner of a building along the street to meet the street-facing entrance requirements.
(Legislative History: Ord. No. 18-08, § 7.)