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HomeMy WebLinkAboutDBIP Building Height Overview 10-8-20 FINALDOWNTOWN BUILDING HEIGHT OVERVIEW October 2020 BACKGROUND Last year the City Community Development Department decided to consider UDC revisions twice each year (April and October). City staff designate which specific UDC edits will be considered in each slate. The staff tries to group related revisions together into themes or topics. They slated building heights as a topic to be considered in October 2020, but that has been delayed by COVID until December 2020. There are a variety of building height code revisions to be discussed and considered ranging from floor-to-ceiling heights to overall building heights in different zoning designations. More details can be found on the City of Bozeman UDC Community Platform here: https://www.bozeman.net/government/planning/udc-discussions/maximum-building-heights These discussions will include the recommendations about building heights in the 2019 Downtown Plan. I have attached a document with excerpts from the Downtown Plan that address building heights. In essence the Plan states: Downtown’s height limits should be adjusted to enable buildings of seven stories outside of the historic core, rather than specifying 70 feet which more usually results in five-story buildings. For buildings with seven stories, urban design guidelines could be put in place to shape and break down the massing while still enabling the density needed for a vibrant, inclusive Downtown. For example, the floor plates on levels five through seven can be designed to step back from the building edge to break down the form. TIMELINE Here are some key dates of upcoming discussions about building heights: Tuesday, October 20th 12:00-1:30pm Location TBD Downtown URD Board Meeting Wednesday, October 21st 12:00-1:30pm Location TBD Downtown BID Board Meeting Tuesday, November 17th 12:00-1:30pm Location TBD Downtown URD Board Meeting Wednesday, November 18th 12:00-1:30pm Location TBD Downtown BID Board Meeting Tuesday, December 15th 6:00pm City Commission UDC Revision Work Session City staff will present the proposed UDC revisions for discussion (no action). The actual statutory ordinance process to formally edit the UDC would not happen until early 2021. 2019 DOWNTOWN BOZEMAN IMPROVEMENT PLAN Building Heights Excerpts Entire Plan available here: https://downtownbozeman.org/uploads/Pdfs/2019_DBIP_with_Appendix_FINAL_ADOPTED_4-15-19.pdf Guiding Principles: MORE THAN MAIN STREET • Reinforce Downtown as the city center, through new and existing buildings of urban density, considerable height and a diverse mix of uses. [DBIP p. 30] ALIGN HEIGHT WITH EXISTING ZONING AND COMMUNITY PLAN Currently, building heights Downtown are limited by the B-3 zoning district to a maximum of 55 feet in the “Core Area” (defined as Main Street and one half block north and south to the alleys from Grand Avenue to Rouse Avenue) and 70 feet in the rest of the B-3 zone. Recently codified transition language further limits the height of buildings on the edge of the B-3 District when they are adjacent to some residential zoning districts. The Downtown core area contains a mix of buildings that range from one-story storefronts to the seven- story Baxter Hotel and the nine story Armory Hotel. The diversity of building heights across the district adds interest and visual relief to the street, creating a rhythm of change and variation that is an important ingredient of dynamic downtown urban design. While height or density minimums are not regulated, in a downtown like Bozeman’s where affordability and vibrancy are values, it is also important to avoid underdevelopment. Appropriate scales of development are essential for future projects so that the community can meet its goals of sustainable infill, affordability, and a dynamic street life. Many Downtown buildings are designated as “storefront blocks” to promote retail and frequent entries that also add rhythm and walkability to a street. This comes with a requirement for a minimum height of 13 feet for the first floor, to add flexibility to all buildings in this zone to accommodate public uses like retail or lobbies. Improved diagram better illustrating current transition code requirements. [DBIP p. 114] The Community Plan update proposes that the Bozeman will have a diverse skyline with buildings that range from three- to seven-stories. Today’s Downtown height limit of 70 feet does not allow new buildings to reach seven stories due to the needed floor-to-floor heights for urban development, active ground floors, and contemporary building practices. Some buildings surpass this limit, like the historic Baxter or the new hotel and adaptive reuse project at the Armory which obtained a height deviation. Seven stories are already permitted by building conventions in other districts across the city when certain accommodations are made by the project. The 2009 DBIP decreed that Downtown should be home to buildings of the greatest height across the city. Bozeman has evolved since that aspiration, with many other districts carrying height and density as well. Still, to support a lively and vibrant Downtown for the long-term buildings in Downtown should continue to achieve comparable height to other mixed use districts across the community. To accomplish this, the Downtown height requirements should be considered in context of the Community Plan’s aspirations and zoning across the city. Downtown’s height limits should be adjusted to enable buildings of seven stories outside of the historic core, rather than specifying 70 feet which more usually results in five-story buildings. For buildings with seven stories, urban design guidelines could be put in place to shape and break down the massing while still enabling the density needed for a vibrant, inclusive Downtown. For example, the floor plates on levels five through seven can be designed to step back from the building edge to break down the form. A height increase to seven stories could also be an opportunity to address long-term affordability by incentivizing smaller units through height bonuses. Guidelines that are specific to the B-3 zone should build on ideas in Article 5, tailoring them to Downtown specific issues. [DBIP p. 115] Encourage a Mix of Scales SENSITIVE TRANSITIONS Downtown is in the unique position of needing to both continue to promote redevelopment and to ensure that there is a careful balance between adjacent residential scale neighborhoods and new Downtown projects. Density is an important element to these projects in order to foster desired traits like Downtown vibrancy and broader housing affordability. Still, there are concerns that future development will be too tall, bulky or close to residential single family homes. Babcock and Mendenhall Streets both have many surface lots and underutilized sites that are likely to be developed in the coming years. As the “outer core” of Downtown, this “halo” around Main Street is a logical - and important - place to locate buildings of greater height and mass, up to seven stories. It is walkable to transit connections and employment and away from single family housing. However, adjacent to the surrounding residential zones, buildings should begin to taper down and gradually adjust downward. This is the intent of the transition language today. Recent revisions to the UDC included the addition of standards requiring a more gradual transition between new buildings and existing residential properties. This transition language applies in places where B-3 zoning is immediately adjacent to residential zones. It includes provisions for new B-3 development that require a setback from the property line and a stepped back building form for upper stories, supporting the needs of both Downtown and nearby neighborhoods. Although the B-3 zone allows for development up to the lot line (zero lot line), new buildings within the transition zone are required to be set back five to ten feet (depending on the adjacent zone) and are limited to an initial 38 feet in building height from the property line adjacent to other zones. From there, the building form is held to a 45 degree step-back rule for zone edge development, up to the B-3 building height limit. Going forward this language will be tested on actual projects of varied size, each of which will have unique characteristics of site and design. [DBIP p. 116] From DBIP [p. 114] Note: this DBIP diagram was later incorporated into the City of Bozeman UDC to illustrate B3 transition requirements. From DBIP Code Appendix [p. 9] Discussion The current UDC maximum building height in the downtown B3 zoning district is 70 feet except in the ‘core area’ (Main Street between Rouse and Grand) which is limited to 55 feet. There are allowances for elevators towers and parapet features to extend a short distance above the height limits. As shown in the chart above, in certain situations buildings can exceed 85 feet in the UMU and B2 zoning districts. The 2019 Downtown Plans states: “The 2009 DBIP decreed that Downtown should be home to buildings of the greatest height across the city. Bozeman has evolved since that aspiration, with many other districts carrying height and density as well. Still, to support a lively and vibrant Downtown for the long-term buildings in Downtown should continue to achieve comparable height to other mixed use districts across the community.” As we begin to consider additional building height, one important distinction that needs to be consistently applied throughout the UDC is utilizing the term (and corresponding dimensions for) floor-to-floor heights. Currently there are some references to floor-to-floor heights and other references to floor-to-ceiling heights. Not only does this create confusion but it makes determining total building height a challenge if they are used interchangeably. Floor-to-floor heights is used exclusively or the following narrative and renderings to illustrate the potential building height revisions. In the Downtown B3 zone the UDC requires the ground floor requires to be 15 feet. Considering modern construction types, typical upper floors are approximately 12 feet. Using a 15-foot ground floor 12-foot upper floors would yield a total building height 87 feet. As a starting point, the proposed height increase outside the ‘core area’ would equate to an additional 17 feet of total building height; from 70 to 87 feet. Below is a chart showing the building height progression using this typical floor-to-floor height. FLOORS FLOOR HEIGHTS BUILDING HEIGHT 1 floor 15’ 15’ 2 floors 15’ + 12’ 27’ 3 floors 15’ + 12’ + 12’ 39’ 4 floors 15’ + 12’ + 12’ + 12’ 51’ 5 floors 15’ + 12’ + 12’ + 12’ +12’ 63’ 6 floors 15’ + 12’ + 12’ + 12’ +12’ + 12’ 75’ 7 floors 15’ + 12’ + 12’ + 12’ +12’ + 12’ + 12’ 87’ The Downtown Plan suggests requiring an upper floor step back of 10 feet above the fourth floor “to shape and break down the massing while still enabling the density needed for a vibrant, inclusive Downtown”. Jan Gehl, renowned urban planner, noted in his seminal book Cities for People that contact between buildings and people at street level is only possible from the lowest floors and quickly dissipates beyond 45 vertical feet. He said, “the challenge is to build splendid cities at eye height with tall buildings rising above the beautiful lower stories”. Building off the rendering in the Downtown Plan and now included in the UDC, the diagram above shows an example of a 7 floor building with a 15’ ground floor and 12’ upper floors. Current Downtown Building Heights The information below demonstrates that total building heights and the floor-to-floor heights within a given building vary. So, there is no ideal total building height and no exact floor-to-floor heights. For example, the US Bank building is 64’ and has 4 floors while newly constructed One11 apartment building is also 64’ but has 5 floors. There are five 5 floor buildings described below and their total building heights range from 60’ (Black Olive) to 72’ (Element). Building Floors Height Armory Hotel 8 91’ Baxter Hotel 7 81’ AC Hotel 6 72’ Element Hotel 5 72’ One11 Apartments 5 64’ US Bank 4 64’ Merin 5 63’ 5 West 5 61’ Black Olive 5 60’ Osborne 4 60’ Below are the same buildings with more details about their floor-to-floor heights and construction types to further demonstrate the amount of variability. Armory Hotel – 8 floors 91’ Approx. Total Height 12’-0” First Floor FTF 15’-0” Floors 2-3 10'-6" Floors 3-8 Construction: Steel Frame – steel pan poured concrete floors Baxter Hotel – 7 Floors 81’ Approx. Total Height to front parapet; 72’ sides; Sign 100’ AC Hotel – 6 Floors 72’ Approx. Total Height including parapet 16’ First floor FTF 10’-4” Floors 2-4 11’-0” Floors 5-6 10’-8” Floor 6 to roof structure Construction: 5 floors of wood over post tension concrete podium Element Hotel – 5 floors 72’ Approx. Total Height including stair towers 18’ First Floor FTF 10’-6” Floors 2-5 Construction: 4 floors of wood over post tension concrete podium US Bank – 4 Floors 64’ Approx. Total Height not including stair tower 12'-10" First Floor FTF (Mezz) 10'-3" Mezz-2 11'-0” Floors 2-4 10’-8” Floor 4-roof deck Construction: 4 floors steel framing and poured concrete ONE11 – 5 Floors 64’ Approx. Total Height 15’ First floor FTF 10’-8” Floors 2-5. Construction: 4 floors of wood over post tension concrete podium Merin – 5 Floors 63’ Approx. Total Height 15’ First floor FTF 10’-8” Floors 2-5. Construction: 4 floors of wood over post tension concrete podium 5 West – 5 floors 61’ Approx. Total Height (not including stair tower) 14’ 8” First Floor FTF 12’-6” Floors 2 & 3 (originally both office) 10’-6” Floor 4 & 5 Construction: 5 floors of post tension concrete slabs Black Olive – 5 Floors 60’ Approx. Total Height 15’-0” First floor FTF 10’-8” Floors 2-4 9’-2” Floor 5 Construction: 4 floors of wood over steel pan poured concrete podium Osborne Building – 4 Floors 60’ Approx. Total Height including parapet SoBo – 4 Floors (B-2M) 52’ Approx. Total Height including parapet 14’-6” First Floor Commercial 10’-6” 2-4, Construction: 4 floors of wood Cannery Flats - 4 Floors (B-2; PUD) 57' Approx. Total Height to peak 14'-2" First Floor FTF 11'-0” Floors 2-4 Construction: 4 floors of wood This information was compiled by Chris Naumann (Downtown Bozeman Partnership) with input from Rob Pertzborn (Intrinsik Architecture) and Susan Riggs (Groundprint Consulting).