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Thread: Maximum height in stories versus feet.

  1. #1
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    Maximum height in stories versus feet.

    I am drafting a mixed use zone district (hybrid with form-based elements) and have noticed most limit height by stories versus feet. I understand stories can be more flexible than exact feet, but why not just set the maximum height in feet higher to allow "wiggle room?" What's the advantage? Also, if you limit height in stories, how do you deal with roof pitches, architectural elements, etc?

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    Cyburbian Raf's avatar
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    You want to set it by height. Period. End of Story. Why? Fire Safety and Building Codes. At least here in California, the maximum height you can have without special ladder trucks (conventional construction) is generally 50-60 feet.
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    Cyburbian Richmond Jake's avatar
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    Quote Originally posted by CPSURaf View post
    You want to set it by height. Period. End of Story. ....
    Agreed. Here is our definition...

    HEIGHT, BUILDING: The vertical distance from grade to the highest finished roof surface in the case of flat roofs or to a point at the average height of the highest roof having a pitch. Chimneys, vents, rooftop mechanical equipment, solar energy systems, elevator shafts, church spires, and other similar features shall not be included in the calculation of height.
    Annoyingly insensitive

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    Cyburbian ColoGI's avatar
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    Quote Originally posted by CPSURaf View post
    Fire Safety and Building Codes.
    .
    Word.

    Worth mentioning: when street codes state 'minimum turn radius of x for fire', progressive Chiefs may allow you to show them the turn radius can be less with your design. One good thing about NU design is Fire's awareness of new road design.
    -------
    Give a man a gun, and he can rob a bank. Give a man a bank, and he can rob the world.

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    Unfrozen Caveman Planner mendelman's avatar
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    Quote Originally posted by CPSURaf View post
    You want to set it by height. Period. End of Story. Why? Fire Safety and Building Codes. At least here in California, the maximum height you can have without special ladder trucks (conventional construction) is generally 50-60 feet.
    But why the why? If the community doesn't want to have to purchase such ladder trucks then that makes sense.

    The reason some form-based codes have max height in stories versus feet is that the form-based code was likely designed with a eye toward design flexibility and maximum stories allows variability along a streetscape. All buildings could be 4 stories, but have individual story heights ranging from 10-15 feet. I guess it depends the direction your muni wants to go.

    The last place I worked had no maximum heights in the majority of the commercial districts, but did have a maximum height in feet in the downtown (although that was 90 feet with bonuses up to 140 feet).
    Last edited by mendelman; 23 Mar 2012 at 2:00 PM.
    I'm sorry. Is my bias showing?

    The ends can justify the means.

  6. #6
    Cyburbian
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    Quote Originally posted by jenalan View post
    I am drafting a mixed use zone district (hybrid with form-based elements) and have noticed most limit height by stories versus feet. I understand stories can be more flexible than exact feet, but why not just set the maximum height in feet higher to allow "wiggle room?" What's the advantage? Also, if you limit height in stories, how do you deal with roof pitches, architectural elements, etc?
    This is an excellent question with a direct answer(s). You regulate building height in stories to achieve an urban atmosphere, because regulating in feet could allow a Wal-Mart type of anti-urban structure to come in. Suppose a minimum height restriction of 35 feet it put in place -- this could allow a traditional urban home or town home, live/work unit, but it could also allow a big box store with one story which is 35' in height. The difference in effect on 'place' is immediately evident as between these two types of structures. That answers your first question.

    The second question, about roof height, is that when using stories, a story can be defined to be habitable space, excluding a roof or utility cap. The same can be done for feet limits, applying them to habitable floors or occupiable space, and regulating specific heights for building caps in addition to those. Portland, ME regulates downtown height this way. 210' for principal structure, with 45 additional feet for building caps which are tapered.

    I apologize if this info is redundant as I have not had a chance to read through

  7. #7
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    After reading the previous comments, I have to add to my initial response. Bldg codes are in fact always important, but as one poster implied by saying “at least in California,” they differ by state. In my state, means of egress etc. apply after a certain “level” is reached, not height. Usually the two will roughly correspond within some range anyway (for instance, while you may see a 22 foot floor height at the high end, or a 10 foot height at the low end, you’ll never see a 2’ story or a 200’ story…so within the range of 10’ – 20’ stories and feet roughly correspond.

    The fire truck issue is important for height, but if you are using a form based code it’s probably not going to mandate minimum heights of 60’ anyway—in my experience places that are urban enough to have a 5 story building minimum applied probably don’t need a minimum height requirement at all. The form based elements in those places are more properly applied to fenestration and other orientation or structural integration issues.

    Lastly, if you are using a form based code, you’re talking about coding for “place,” which is something your town has presumably expressed concern with. If this is the case, do not regulate by height in feet, as the place predictability will not be ensured.
    Also, regarding the turning radii comment someone else mentioned, one way to get around the turning radii issue is the keep streets really narrow and tight, but with larger bldg setbacks at the corners of intersections. Those areas can then be use to make wide turns by large vehicles (which can drive over the sidewalk if necessary while keeping regular traffic within the confines of the curbs), and this can be further facilitated if necessary by installation of 45 degree angled curbs (sometimes called Colorado or Cape Cod curbs). To make these spaces be less anti-urban, fill them with things easily movable—like sidewalk café tables. There is a great urban space in front of BOLOCO in Boston on Boylston Street which occupies this sort of arrangement.

  8. #8
    Cyburbian Trail Nazi's avatar
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    Height is very definitive and allows everyone to understand the same concept (planners and laypeople alike.)

  9. #9
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    Regulate by Stories, or Height and Stories, but Never Just Height in an FBC

    While everyone on here makes a good case, your question is specifically in reference to a form based code district, which is employed, presumably, to achieve a certain vibrancy from its underlying mix of uses and urban design. It is usually advisable to have a vertical mix of uses, which can’t happen if you have a host of structures which are one story tall even if they meet the 50’ minimum building height (think Target, Walmart, or others). This is the key difference here. It would be better to have a series of buildings—all three stories, for example—even if some were 35 feet and others 45 feet. If it is uniform building line and matching parapets about which you are concerned (the hub and spoke model of urban design, from Renaissance painters’ perspective theory), you can always use a combination approach—say a requirement of at minimum three stories, and a specified maximum story height per floor. Or just say minimum building height of 45 feet, each story to be a maximum of 15 feet. This results in a compromise—everyone understands what 50’ means, yet you also get vertical integration of uses (potentially) by having multiple storied buildings (remember, if you don’t care how many stories there are, a FBC isn’t necessary, because single story structures are the status quo…that’s another reason you want to disregard the advice of others on here and regulate in a FBC case with stories rather than height).

    The one problem with a hybrid approach (height in stories and setting maximum individual floor heights) is that it requires calibrating it to local building codes, builders’ requirements (which may differ for certain types of structures), and also if someone wanted to build a residential structure with 10’ floor to ceiling heights, in the example above (45’ overall height as a minimum) he or she may only have demand for three floors (like a commercial structure with 15’ floor heights next door) yet be forced to build 5 stories, because that’s what it would take to get over the 45’ minimum. (is this fair? Arguably not). A way around this is to set a relatively low minimum building height—but this gets back to the same problem of allowing a big box store when presumably the whole point of an FBC is to proscribe that type of design.

    Bottom line, in the case of an FBC, always regulate by stories, or both stories and height, but never height alone unless it is tall enough to rule out the big box stores (some of which have single stories of nearly 50’ and possibly more). In the last scenario, when you regulate by height which is tall enough to discourage big box stores, say by setting a minimum of 65 feet, are you then setting the bar too high for other structures? Would it rise to a taking if a minimum of 1,000 feet were imposed (a super-tall skyscraper)? Probably because there is no market for that, but where is the line drawn?

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