Analysis
BACKGROUND
In the City Code (Section 114-1), Story is defined as follows:
Story means that portion of a building included between the surface of any floor and the surface of the floor next above it; or if there be no floor next above it, then the space between such floor and the ceiling next above it. A basement shall be counted as a story if its ceiling is equal to or greater than four feet above grade.
Under the Florida Building Code, the following are the pertinent definitions:
STORY. That portion of a building included between the upper surface of a floor and the upper surface of the floor or roof next above (also see “Basement,” “Building height,” “Grade plane” and “Mezzanine”). It is measured as the vertical distance from top to top of two successive tiers of beams or finished floor surfaces and, for the topmost story, from the top of the floor finish to the top of the ceiling joists or, where there is not a ceiling, to the top of the roof rafters.
BASEMENT (for flood loads). The portion of a building having its floor subgrade (below ground level) on all sides. This definition of “Basement” is limited in application to the provisions of Section 1612.
BASEMENT. A story that is not a story above grade plane (see “Story above grade plane”). This definition of “Basement” does not apply to the provisions of Section 1612 for flood loads.
STORY ABOVE GRADE PLANE. Any story having its finished floor surface entirely above grade plane, or in which the finished surface of the floor next above is:
1. More than 6 feet (1829 mm) above grade plane; or
2. More than 12 feet (3658 mm) above the finished ground level at any point.
Until recently, building height was measured from grade, which is the elevation of the sidewalk at the center of the property. The City Code was amended in 2014 to allow the measurement of building height starting from base flood elevation (BFE). In 2015, the Code was amended to allow the measurement of building height starting from base flood elevation plus up to the maximum freeboard (BFE + 1’-5’).
All zoning districts have an overall maximum height limit in feet, as measured from base flood elevation plus allowable freeboard; within this allowable number of feet is a corresponding limit on the number of stories. For example, in the RM-1 district, the maximum height limit is 50 feet and 5 stories, and in the RM-3 district the maximum height for oceanfront lots is 200 feet and 22 stories.
It is important to note that the amount of horizontal floor area within a building, which correlates to the number of ‘stories’, is limited by maximum allowable FAR within a particular zoning district. In order to simplify the overall measurement of building height, the Land Use Committee recommended the removal of the existing limits on number of stories altogether, and a separate referral is pending at the Planning Board. In this regard, the fixed maximum height, measured in feet from BFE plus freeboard, would remain. This measurement is constant and the number of horizontal floors would continue to be limited by the maximum FAR for the district.
PLANNING ANALYSIS
The overall measurement of allowable height and volume for single family homes is a bit more complex, as ‘unit size’ is used for regulating overall size, as opposed to ‘FAR’. Additionally, unlike commercial buildings, or multi-family buildings with ground floor, accessory commercial space, the first habitable floor of all new single family homes must be constructed at or above base flood elevation plus one foot (BFE + 1’).
Currently, single-family districts (RS zoned properties) have a maximum height limit measured in feet from base flood elevation plus allowable freeboard (maximum of BFE plus five feet). Additionally, the RS districts have a story limit of two habitable floors above base flood elevation plus allowable freeboard.
Under the current Code, when the first habitable level of a home is more than six feet above grade, due to minimum base flood elevation and freeboard requirements, the RS district regulations permit ‘non air-conditioned space’ below the first habitable floor. Currently, this non air-conditioned space is limited to a maximum interior height of 7’-6”, and is not counted toward the overall height limit of the building in feet, nor is it counted in allowable unit size. Additionally, up to, but not exceeding, 600 square feet may be used for parking cars. When originally adopted in 2014, this provision was only applicable to the lowest areas of the City, as the overall height of a home was measured from base flood elevation. Now that single family home height is measured from BFE plus up to 5 feet of additional freeboard, there have been increasing instances where one and two story homes are being located above allowable ‘non air-conditioned space’.
Absent this ‘non air-conditioned space’ below the first habitable level, a home owner proposing BFE + 5’ for new construction would be forced to use fill and place a new home on top of a large, elevated berm. Such an approach would create environmental, water retention, drainage and water run-off issues that would affect the site, the neighboring properties and adjacent rights of way. Additionally, it would result in accessibility issues to the main house, as well as create an architectural and compatibility issue with the built context of the surrounding area. In this regard, unlike other cities in South Florida that allow homes to be built on large, sloped berms, Miami Beach is not defined by that particular single family typology. Although having non air-conditioned space below the first habitable level of a new or elevated home may result in the appearance of a three story home, this is a far more successful architectural transition than utilizing an oversized berm.
As more new homes in the City are expected to be built well above existing grade in all RS districts and in some cases older or historic homes may be raised as well, further study of the current regulations limiting the height of allowable ‘non air-conditioned’ space has been undertaken. In this regard, factors such as the future raising of roads and sidewalks, the relationship of allowable non air-conditioned space to elevated yards and the need to provide tangible transition spaces in order to access the main level of a home, have been taken into consideration.
The attached draft ordinance furthers existing regulations regarding non-air-conditioned ‘understory space, created by new, elevated single family homes. The following is a summary of the proposed revisions to Sec. 142-105, which are included within the draft ordinance:
• Understory areas shall be permitted to be used only for open air activities, parking, building access, mechanical equipment, non-enclosed restrooms and storage. Such areas shall be designed and maintained to be free of obstructions, and shall not be enclosed and/or air-conditioned at any time, with the exception of limited access areas to the first habitable floor.
• Understory areas below the lowest habitable floor can utilize non-supporting breakaway walls, open-wood lattice work, louvers or similar architectural treatments, provided they are open at least 50% on each side.
• All parking and non-air-conditioned areas located directly below the first habitable floor shall continue to not count in the unit size calculations.
• All parking, including required parking, must now be provided within the understory area, and clearly delineated by a different surface finish or bollards. No parking or vehicle storage may be permitted within a required yard, unless approved by the DRB or HPB, in accordance with the applicable design review or certificate of appropriateness criteria.
• The maximum width of all driveways at the property line shall not exceed 15% of the lot width, and in no instance shall be less than 9 feet in width and greater than 18 feet in width.
• At least 70 percent of the required front yard and street side yard areas shall consist of sodded or landscaped pervious open space. For purposes of this section, the required front yard shall be measured from the front setback of the principal structure to the front property line and the required street side yard shall be measured from the street side setback of the principal structure to the street side property line. All allowable exterior walkways and driveways within the front and street side yards shall consist of pavers set in sand or other semi-pervious material. The use of concrete, asphalt or similar material within the required front or street side yards shall be prohibited.
• A continuous soffit shall be lowered a minimum of 2’-0” from the lowest slab of the first level above the understory area in order to screen from view all lighting, sprinkler, piping, plumbing, electrical conduits, and all other building services.
• Understory ground elevation. The minimum elevation of the understory ground shall be constructed no lower than future crown of road as defined in Chapter 54. All portions of the understory area that are not air-conditioned shall consist of pervious or semi-pervious material, such as wood deck, gravel or pavers set in sand. Concrete, asphalt and similar material shall be prohibited within the non-air-conditioned portions of the understory area.
• Understory edge. All allowable decking, gravel, pavers, non-supporting breakaway walls, open-wood lattice work, louvers or similar architectural treatments located in the understory area shall be setback a minimum of five feet from each side of the underneath of the slab of the first habitable floor above, with the exception of driveways and walkways leading to the property, and access walkways and/or steps or ramps for the front and side area. The front and side understory edge shall be designed to accommodate on-site water capture from adjacent surfaces and expanded landscaping opportunities from the side yards.
• Understory building access. Air-conditioned elevator and stair vestibules for access to the first habitable level of the home shall be permitted under the first habitable floor and shall be located as close to the center of the floor plan as possible and be visually recessive such that they do not become vertical extensions of exterior building elevations. The total area of enclosed and air-conditioned building access shall be limited to no greater than three percent of the lot area. All air-conditioned floor space located directly below the first habitable floor shall count in the total unit size calculations.
Attached are the following illustrations, which provide a graphic representation of the above noted modifications:
• Exhibit A: Proposed code changes as applied to a 60 foot lot
• Exhibit B: Proposed code changes as applied to a 100 foot lot
• Exhibit C: Existing code as applied to a 60 foot lot
• Exhibit D: Existing code as applied to a 100 foot lot
• Elevation Graphics
In addition to these proposed modifications to the allowable understory areas of a single family home, 2 minor text amendments are also proposed, as follows:
1. Sec. 142-105 - Roof Decks.
Currently, roof decks are permitted as a height exception above the main roofline of a single family home, provided they do not exceed a combined deck area of 25 percent of the enclosed floor area immediately one floor below. Additionally, regardless of deck height, roof decks must be setback a minimum of ten feet from each side of the exterior outer walls when located along a front or side elevation, and/or from the rear elevation of non-waterfront lots. The DRB or HPB may forego the required rear deck setback, in accordance with the applicable design review or appropriateness criteria.
Currently, there is no provision for landscaping on roof decks, as an allowable height exception. In order to better address landscape areas proposed for roof decks, the following additional language is proposed:
Built in planters, gardens or similar landscaping areas, not to exceed three and one-half feet above the finished roof deck height, may be permitted immediately abutting the roof deck area. All landscape material shall be appropriately secured.
2. Sec. 142-1132. - Allowable encroachments within required yards.
Currently, porches, platforms and terraces are an allowable yard projection, but only up to 30 inches in height above the grade elevation of the lot. Since single family homes are now required to be constructed well above grade elevation, the following additional language is proposed, in order to better facilitate access to homes with higher first floor elevations:
Within single family districts, such projections and encroachments may be located up to the first habitable floor elevation and include stairs, steps, ADA-compliant ramps and related walkways, not exceeding 5’-0” in width, which provide access to all porches, platforms, terraces and the first floor when elevated to meet minimum flood elevation requirements, including freeboard.
Lastly, electric vehicle charging stations and fixtures, located next to an off-street parking space, have been added to the list of allowable setback encroachments.
UPDATE
At the direction of the Land Use Committee, a single family workshop was held on December 11, 2017. At this workshop planning staff provided a PowerPoint presentation on the proposed Ordinance. A number of people attended the workshop and spoke regarding the proposal. A summary of the workshop, including public input, is attached.
No substantive changes have been made to the draft ordinance, as first presented to the Land Use Committee on October 11, 2017.