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Thread: Why do we distinguish between single-family lot sizes? (US zoning specific)

  1. #1
    Unfrozen Caveman Planner mendelman's avatar
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    Why do we distinguish between single-family lot sizes? (US zoning specific)

    I have a question.

    Why do many zoning codes set one size of lot as the minimum for a residential zoning district and another size for a separate residential zoning district?

    Where I work, we have 4 single family residential zoning districts with minimum prescribed lot size:
    • RE - 20,0000sqft
    • R-1 - 15,000sqft
    • R-2 - 10,000sqft
    • R-3 - 8,750/9,900sqft
    What is the objectively, substantive difference between a 20,000sqft lot and a 15,000 sqft lot? Why do so many zoning codes make such, seemingly, abitrary distinctions, especially when the use is exactly the same - one single-family house?
    Last edited by mendelman; 07 Feb 2006 at 4:15 PM.
    I'm sorry. Is my bias showing?

    The ends can justify the means.

  2. #2
    Cyburbian ssc's avatar
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    Quote Originally posted by mendelman
    What is the obectively, substantive difference between a 20,000sqft lot and a 15,000 sqft lot? Why do so many zoning codes make such, seemingly, abitrary, distinctions, especially when the use is exactly the same - one single-family house?
    There are lots of reasons to vary lot sizes. Here are a few:

    Availability of municipal water/sewer
    Road capacity
    Preservation of a rural (or urban) development pattern
    Capacity of local schools, community facilities, etc.

  3. #3
    NIMBY asshatterer Plus Richmond Jake's avatar
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    Recognizing the existing development pattern? Other than that, who knows?
    Last edited by Richmond Jake; 07 Feb 2006 at 2:48 PM. Reason: typo to avoid the wrath of Maister

  4. #4
    Super Moderator luckless pedestrian's avatar
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    all of the above (hey, wait, I agreed with RJ, that's a problem...)

    plus, it's likely political, and/or influenced by local realtors in the 80's

    we have 3 lot sizes, just like the 3 bears: small (5k), medium (20k) and large (80k) -

  5. #5
    Chairman of the bored Maister's avatar
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    Quote Originally posted by mendelman
    I have a question.

    Why do many zoning codes set one size of lot as the minimum for a residential zoning district and another size for a separate residential zoning district?

    Where I work, we have 4 single family residential zoning districts with minimum prescribed lot size:
    • RE - 20,0000sqft
    • R-1 - 15,000sqft
    • R-2 - 10,000sqft
    • R-3 - 8,750/9,900sqft
    What is the obectively, substantive difference between a 20,000sqft lot and a 15,000 sqft lot? Why do so many zoning codes make such, seemingly, abitrary, distinctions, especially when the use is exactly the same - one single-family house?
    The last time I raised this question at work I was met with stony silence.
    I suspect you are already aware that official explanations pretty much run along the lines listed by RJ and ssc.

    My take on the unspoken reasons - they establish boundaries for socio-economic classes (you know.....keep 'them' out) so folks can live in comfort zones with their own kind
    People will miss that it once meant something to be Southern or Midwestern. It doesn't mean much now, except for the climate. The question, “Where are you from?” doesn't lead to anything odd or interesting. They live somewhere near a Gap store, and what else do you need to know? - Garrison Keillor

  6. #6
    Cyburbian ssc's avatar
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    [QUOTE=mendelman]I have a question.
    • R-2 - 10,000sqft
    • R-3 - 8,750/9,900sqft
    QUOTE]

    Okay, I do think there is a place for varied minimum lot sizes, but I just looked at your post again. What DO all those people in R2 do with their extra 100 sf????

  7. #7
    Chairman of the bored Maister's avatar
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    [QUOTE=ssc]
    Quote Originally posted by mendelman
    I have a question.
    • R-2 - 10,000sqft
    • R-3 - 8,750/9,900sqft
    QUOTE]

    Okay, I do think there is a place for varied minimum lot sizes, but I just looked at your post again. What DO all those people in R2 do with their extra 100 sf????
    I didn't notice that division.....but it must be tied to a MAJOR economic class distinction at that crucial 100 s.f. interval
    People will miss that it once meant something to be Southern or Midwestern. It doesn't mean much now, except for the climate. The question, “Where are you from?” doesn't lead to anything odd or interesting. They live somewhere near a Gap store, and what else do you need to know? - Garrison Keillor

  8. #8
         
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    I worked in a community that was set-up much like Mendelman's example. It got to a point that citizens would complain in public hearings that the adjacent proposed single-family zoning would allow lots a few thousand square feet smaller than their's. They would demand a landscape buffer because their lots were a bit bigger than the new ones. They were all single-family detached homes! It seems to come down to economic segregation. The thinking being, "If you can't afford a house or lot as big as mine I don't want you living near me or if you are then I don't want to see you". Funny thing is there were junky mobile homes scattered all over that place. Where I work now the raw water costs to the developer and the irrigation costs to the homeowner are so high that lots sizes are not such an issue. Everyone wants a smaller lot.

  9. #9
    Cyburbian
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    obviously this is a major downside to good ole fashioned euclidian zoning. One word no one has used by explanation is density. And the density reveals other elements such as scale, design, character etc...If you want to direct density to certain areas (for infrastructure delivery, by example) lower minimums can accomplish this.

    Now your examples seem a little odd as they are so close together.

  10. #10
    Unfrozen Caveman Planner mendelman's avatar
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    I can understand what ssc says, but the reality is that with a single family pattern traffic is not really a problem until you get to 15+ units/acre. I would think that if a municipalitywas supplying water/sewer service, higher densities (aka small(er) lots) would be desireable to gain economy of scale, schools are not really a problem unitl the units are occupied, because you can only estimate the number of children per house, but could be completely off and over build. But I do agree that preservation of existing development patterns is usually the most common.

    For us, it is pretty much the case of preserving existing patterns, although 70% of our current municipality has been built after the introduction of our current standards.

    I can understand difference in sizes if lots within the municipality are serviced with water/sewer, while others are on septic - you need more land for septic.
    Last edited by mendelman; 07 Feb 2006 at 4:43 PM.
    I'm sorry. Is my bias showing?

    The ends can justify the means.

  11. #11

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    Our system is based on General Plan density ranges, with specific lot sizes. For example, we have an "RLM" (Residential Low Medium) land use that dictates density between 5 and 8 du/acre. This reflects General Plan expectations as far as population growth, availability of services, road capacity, etc. We then add a number to dictate minimum lot size. Pretty much a crazy quilt in some areas.

  12. #12
    Cyburbian wahday's avatar
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    Quote Originally posted by mendelman
    I would think that if a municipalitywas supplying water/sewer service, higher densities (aka small(er) lots) would be desireable to gain economy of scale, schools are not really a problem unitl the units are occupied, because you can only estimate the number of children per house, but could be completely off and over build.

    I can understand difference in sizes if lots within the municipality are serviced with water/sewer, while others are on septic - you need more land for septic.
    This is interesting because we just faced these issues in my general part of town (Albuquerque). In the south valley, the lot sizes are large because the area is considered "semi-urban" and "rural" with a fair amount of agricultural land. One reason for keeping the du/acre low is to preserve ag land as a local food supply over the long term. Another is to decrease density as one moves away from the core in an attempt to encourage more profitable development within the city (I live in the County). Of course, this hasn't really worked - nasty fringe development just moved somewhere else...

    The capacity of the sewer lines is also restrictive. The issue is not how much it costs to install, but how much volume the system can handle. This came up as an issue in discussing the possibility of a transfer of development rights from farms to "village center" concentrated mixed-use areas in the valley (clustering dense development in some areas to preserve others). There was some concern that the existing sewer system could not handle the increased load (no pun intende...). The valley is also so close to the water table that they will also not allow septic because it leaches into the groundwater.

    The school issue is the most interesting, though. A new area of fringe development recently sprang up on the southwest mesa and original pop. estimates predicted about 750 elementary aged kids, so they built a school to handle it. Only, while they were building the school, they re-zoned the area and allowed almost double the density (but didn't tell the school district). The result was that 1000 kids showed up on the first day of school - doh!

    Now they have 52 portable buildings and are busing some kids almost 45 minutes to another school with extra space.

  13. #13
    Cyburbian dankrzyz's avatar
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    It's a method that is used to control density (du/ac) and house value... and it's a poor tool to control both.

  14. #14
    Cyburbian Plus Whose Yur Planner's avatar
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    Quote Originally posted by gkmo62u
    obviously this is a major downside to good ole fashioned euclidian zoning. One word no one has used by explanation is density. And the density reveals other elements such as scale, design, character etc...If you want to direct density to certain areas (for infrastructure delivery, by example) lower minimums can accomplish this.

    Now your examples seem a little odd as they are so close together.
    Thats and agricultural preservation are the unofficial explanations for minimum lot sizes.
    When did I go from Luke Skywalker to Obi-Wan Kenobi?

  15. #15
    NIMBY asshatterer Plus Richmond Jake's avatar
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    Quote Originally posted by gkmo62u
    ... One word no one has used by explanation is density....
    I should have added that my county does not have minimum parcel size in any of its 6 residential zone districts. Density established by the Comp Plan regulates the number of units per acre.

  16. #16
    Forums Administrator & Gallery Moderator NHPlanner's avatar
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    We use soils based lot sizing in our residential districts, except where sewer is available (which isn't very much).
    "Growth is inevitable and desirable, but destruction of community character is not. The question is not whether your part of the world is going to change. The question is how." -- Edward T. McMahon, The Conservation Fund

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