Over the past 2 decades, Cascadia'due south biggest metropolis has planned for growth according to the so-chosen " urban village strategy " that steers new housing, mostly in the form of apartment buildings, to mixed-used commercial centers with good transit. At the same time, the policy conspires to leave untouched Seattle's neighborhoods of detached houses—"unmarried-family zones," in planner-speak.

The proposed rezone across the city would probable yield the equivalent of simply two typical mid-rise apartment buildings.

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When Seattle embarked on the urban village strategy in the mid-1990s, some residents fought the changes, and city leaders compromised past subverting the core principle that within designated growth centers much more housing would be allowed. Instead, the city left swaths of urban village land—places benefiting from public investment in transit, parks, community centers, and other amenities—nether the tight constraints of unmarried-family unit zoning.

Recognizing the barrier to housing choices left by this legacy, Seattle's 2015 Housing Affordability and Livability Agenda (HALA) recommended completing the unfinished business of the 1990s. It chosen for changing all single-family zones located inside urban villages to zoning that is really urban—that is, that allows plenty of homes. The Seattle City Council is currently because a proposal that purports to make that happen. It would "upzone" half dozen percent of the city's abundant single-family land.  (Unmarried-family zoning currently covers more than one-half of the metropolis .)

Ending unmarried-family zoning in Seattle's designated growth nodes is long overdue. The justification for doing so is particularly acute today, when the metropolis is absorbing more than newcomers than ever in its history , when information technology is crippled with an intense and worsening shortage of housing, and when it is trying to become off fossil fuels by clustering its growth around transit and walking hubs. Unfortunately, the city's proposed plan for realizing that vision is a disappointing half-measure out, arguably not worth the intense political effort now underway to win adoption.

Overall, the proposed rezone would yield a trivial number of new homes: likely no more than across the whole city annually than come in two typical mid-rise apartment buildings. Nearly ii-thirds of the upzoned single-family land would be converted to "residential small lot" (RSL) zoning, a nomenclature that barely loosens the status-quo prohibition of homes appropriate for a mixed-employ, transit-rich urban neighborhood. Consider:

  • RSL allows two primary homes on a typical size lot—that is, a duplex—rather than one. But in many cases, you can't really build two. In any event, duplexes exercise not make an "urban village."
  • On smaller lots, it would drastically reduce the immune foursquare footage of housing from what is allowed in single-family zones.
  • The proposed limit on accessory home units in RSL could terminate upwardly making the RSL "upzones" reduce not just foursquare footage simply as well the number of homes allowed.
  • Homebuilding in RSL would exist subject to Mandatory Housing Affordability (MHA) fees that would undermine the urban center'due south intent for RSL to yield "homes that may exist more affordable than available housing in single-family zones."
  • Because RSL may reduce the allowed size—and therefore the value—of housing that can be congenital, it would create a morass of legal ambiguity effectually the urban center'southward MHA plan, inviting lawsuits and hamstringing homebuilding.

In short, Seattle's proposed single-family upzones are a good idea, but badly implemented by the current draft before the city quango. In this article I'll explore why the strategy may be counter-productive, with special attending to RSL zoning, and suggest means to improve the proposal—potential lessons for prosperous cities throughout Cascadia and North America.

Single-family ocean change

My colleague Margaret Morales documented how the extent of single-family zoning has expanded steadily since Seattle first adopted it in 1923 . The metropolis'due south urban village strategy , implemented in the 1990s, farther cemented the primacy of single-family by confining most multifamily zoning to designated centers. The city'south consistent intent couldn't be clearer: Seattle'due south 2005 Comprehensive Plan , for instance, enshrined the goal to "preserve and protect depression-density, single-family unit neighborhoods."

And it has worked: in 2017, some 88 percent of new homes synthetic in Seattle went  into the sixteen pct of the city's country that is situated in designated urban centers and villages. The dearth of new homes in unmarried-family zones helps to explain why much of Seattle's single-family land has actually lost population since 1970 .

The 2015 HALA plan signified a body of water change for state-use policy in Seattle. The plan's nigh far-reaching proffer—to allow multiple dwellings on single-family lots every bit long every bit the overall building envelope was no bigger than already permitted—would have yielded a render to the earlier pattern of duplexes, triplexes, and other pocket-size multifamily homes. That proposal did non survive the controversy that its proclamation sparked. But the city is moving alee with a less ambitious HALA recommendation: to upzone all country zoned single-family unit that lies within designated growth areas (officially called either urban centers or urban villages, depending on their size).

Map of Seattle's Crown Loma urban hamlet, outlined in the solid blackness line. Stake yellow = single-family zoning; night yellow = midrise mixed-utilize; chocolate-brown = lowrise; red = commercial; dashed blackness line indicates a x-minute walk from the transit stop. Map source: City of Seattle.

Completing the urban village strategy

In the mid-1990s, when establishing the new urban villages and their zoning, city leaders buckled in the face of opposition from residents who didn't want more than housing choices in their neighborhoods. The resulting watered-downward plan left many urban villages with strips and patches frozen in unmarried-family zoning, contradicting the city's strategy to focus new housing near new public amenities such every bit improved transit, parks, and community centers.

For example, the map to a higher place shows the urban village of Crown Loma, near eight miles northwest of downtown Seattle. The solid black line marks the urban village purlieus. Pale yellow indicates single-family zoning, and the dark yellow, brown, and red areas are multifamily zones. As shown in the interactive map here (click on "preferred alternative map" and navigate to Crown Colina), the metropolis's plan would upzone all of the single-family zoning inside the Crown Loma urban village.

The proposed unmarried-family upzone

Seattle planners included the single-family unit upzones as role of the city'southward Mandatory Housing Affordability (MHA) scheme to couple affordability requirements with multifamily upzones throughout the city. The proposal would upzone i,248 acres of single-family unit lots in and near urban villages and centers, about 6 percentage of the city'south total 21,000 acres of unmarried-family unit land .

Of this sliver of single-family land to be rezoned, 62 percent (768 acres) would change to "Residential Modest Lot" (RSL) zoning, which will bring surprisingly little increase in housing options, as I explain beneath. Some 38 percent (471 acres) would become "lowrise" zones , a more-robust increase in housing options that allows townhouses, rowhouses, and small apartments but is still rather modest considering that all the areas in question are in designated urban villages and centers where mid-ascent buildings are often the norm. The remaining 0.7 percent (9 acres) would convert to midrise zoning and permit apartments in the four- to 8-story range.

Sketches of housing types allowed in Seattle'due south proposed RSL zone. Prototype past ZGF Architects for Metropolis of Seattle.

The new RSL zone

Seattle divers RSL zoning more than 20 years ago, but it has so far only assigned vii acres to the category. By the urban center's definition , RSL "allows for the development of smaller detached homes that may exist more affordable than available housing in unmarried-family zones." RSL is like a half-step between single-family and lowrise zoning.

Modified for the MHA program , the proposed new RSL zoning allows detached houses, cottages, fastened townhouses, and stacked flats. The most common outcome in RSL would likely be a new smallish, for-sale house built behind an existing firm. Parameters governing homebuilding in RSL and single-family unit zones are given in the appendix. Homebuilding in Seattle'due south new RSL zones would be discipline to MHA requirements —either inclusion of beneath-market rate units or payment of an in-lieu fee that goes to a urban center affordable housing fund.

The city's proposal to upzone single-family to RSL—with its numerous variations, minutia, and myriad possible scenarios on the ground—is a lot to digest. Let's cutting to the hunt and explain the major problems with the RSL proposal, and provide a listing of suggestions for how to prepare them.

The 768 acres of RSL upzone would likely yield about 1,202 homes over xx years, a mere 60 per year.

In theory, upzoning single-family to RSL raises the allowed density of primary homes by a gene of two.5, on average. Seattle planners estimated that in the real world , however, the RSL rezone would increase the "chapters for housing growth" by near half that. For the full package of MHA rezones they projected that over xx years about i fourth of the capacity for growth would be used for new homes. I applied that same ratio to make it at a net proceeds of 1,202 homes over 20 years for the proposed RSL rezone, equivalent to 60 new homes per yr. (For details on this estimate, encounter the appendix.)

For the unabridged proposed unmarried-family unit rezone, applying those same city assumptions yields five,634 homes congenital over xx years, or 282 per year. Compared with RSL, the portion of the country rezoned to lowrise would yield most 3.5 times more than capacity for homes (roughly half-dozen times more homes per acre).

To put these numbers in perspective, 2 typical midrise apartment buildings provide about the same number of homes every bit the estimated almanac gain from the entire single-family rezone. In Seattle since 2013, homebuilders accept completed more than half-dozen,000 new apartments annually, with a tape 8,753 in 2017 . In other words, the single-family rezone growth projections are nearly negligible in the big motion picture.

Rezoning from single-family to RSL would in many cases reduce the legal square footage of housing.

In Seattle, a typical building lot in single-family neighborhoods is 5,000 square feet (fttwo ), only sizes vary. On parcels of less than 3,700 ft2 , RSL zoning allows only one house, limited in size to two,200 fttwo  of floor space. On the same lot, unmarried-family unit zoning currently allows a three-story house upwards to iii,885 ft2 , so a rezone from single-family to RSL would reduce the indoor living infinite past 43 percent. Roughly 900 of the six,100 lots that the city has proposed to upzone from single-family unit to RSL are three,700 ft2  or less.

On a 5,000 ft2  lot, RSL restricts total floor space to three,750 ftii , divided between 2 split units. On the same lot in the existing unmarried-family unit zone, a three-story house could max out to 5,250 ft2  (though in practise it'southward rare for new homes to approach that maximum). Clearly, the RSL "upzone" is in many instances really a downzone, and this fact has troublesome implications for the MHA program, equally I'll get to soon.

Farther squeezing capacity, RSL's 2,200 ft2  size limit also applies to additions to homes. That means owners of houses two,200 ft2  or more than that go rezoned from single-family to RSL would lose the risk to construct additions . (Relatedly, additions are exempt from MHA requirements , which creates an incentive for owners to add onto battered former houses rather than demolishing them and starting fresh, impairing design flexibility and raising the cost of construction, and likely producing less free energy-efficient homes.)

Mandatory Housing Affordability fees would undermine the urban center's intent for RSL zoning to yield "homes that may be more affordable than available housing in single-family zones."

Imagine you ain a single-family unit firm in an expanse rezoned to RSL and want to subdivide your lot and build a 2d firm to sell. For a 2,000 ftii  dwelling, to get your building permit you'd have to pay an MHA fee of up to $41,500 depending on the location, calculation up to 8 percentage to the cost of construction (bold a cost of $250 per ft2 ). That's tens of thousands more dollars of your own money that yous have to put at take a chance, because you lot have no guarantee on what the selling price of the domicile may cease upwardly by the time it's finished. If you're non feeling confident enough that the payback from the auction will encompass your time, effort, and adventure, the MHA fee could tip the scales, convincing you not to bother.

Professionals make decisions the same way. Let'south say a homebuilder needs a xv per centum render on investment to win funds from her banker and investors. A duplex projection that would yield 15 percent without MHA yields perchance less than x percent with it, killing that project. Minor-scale builders likely to piece of work in RSL zones are usually more vulnerable to this kind of added expense, as compared with deep-pocketed firms that develop big projects. Whether by directly accelerating hire increases, or by sacrificing new homes that would have helped alleviate Seattle's housing shortage , MHA fees that exceed the existent-estate value awarded past upzones work confronting affordability .

Seattle's programme for upzoning single-family areas within urban villages underscores the political concession that is rarely spoken by city officials simply is jarring in its inequity one time exposed: MHA fees don't utilise to the form of housing that's the worst for affordability—single-family houses. MHA instead places the brunt on the construction of smaller, more state-efficient, and less expensive forms of housing. In other words, in the name of improving affordability, MHA punishes housing options that are part of the solution, while letting the worst offenders off the hook. It's like an income revenue enhancement that exempts millionaires.

In many instances, an RSL rezone would reduce the value of those lots.

The core principle of MHA is that the value added by allowing more than development should outset the cost of the affordability requirements , and then that the policy doesn't discourage homebuilding. Assessing that value exchange entails comparing what can be built before and after the MHA rezone (as I've analyzed for other zones here , hither , hither , here , and hither ).

Assay of the existent-estate economics of RSL (detailed in the appendix) indicates that in financial terms, converting single-family to RSL would in many cases amount to a downzone. For the above-described instance of a 3,700 ft2  lot on which RSL would only let a single 2,200 ft2  house, by my approximate the rezone would reduce the value a builder could derive from redeveloping the property by a whopping $350,000. For a 5,000 fttwo  lot on which RSL would allow 2 homes, the loss of value would be less farthermost, in the range of about $25,000 to $200,000, depending on the house sizes. Similarly, Seattle's MHA study found that for construction of a 4,500 ft2 , three-unit of measurement, stacked flat flat building, the subtract in value caused by the rezone to RSL would make information technology a money loser.

The primary cause of these fiscal downzones is RSL's physical size restrictions, and piling on MHA charges makes it that much worse. Many owners of unmarried-family backdrop would take a substantial hit to their property values if rezoned to RSL. In such cases, redevelopment would happen at a slower pace than information technology would under the original single-family zoning.

Including the RSL 'upzone' in Seattle'southward MHA program will create a legal morass.

Washington country law requires jurisdictions to provide an offsetting "incentive" in exchange for any affordable housing mandates they impose. As discussed in a higher place, in some cases a rezone from single-family unit to RSL actually reduces the square footage of housing that can exist built—in the worst case, by over 40 percentage.  Other proposed MHA rezones could reduce property values (run into here , here , here , and here ), only RSL is the just rezone that actually allows structure of less residential space in many instances, obliterating large percentages of some homeowners' property values. In such cases, the RSL rezone is a "taking" of value, not a "giving" of an incentive, and therefore fails to comply with country law.

RSL with MHA seems like an open invitation for lawsuits against the urban center—lawsuits with good odds of success. As an escape hatch from this type of legal challenge, metropolis code does permit for waiving MHA'due south mandates if they would impose "severe economical hardship." But the inevitable, bogged-downward bureaucratic procedure to settle claims would introduce toxic filibuster and uncertainty that inhibit homebuilding in RSL zones and would push the burden of proof, and the legal costs, from the metropolis itself to individual homeowners in RSL zones.

RSL may forgo opportunities for accessory habitation units.

The proposed RSL zone volition permit each business firm on a lot to have ane accessory dwelling unit (ADU), either as part of the chief business firm, or in a split backyard cottage as long every bit the lot is at to the lowest degree iv,000 ft2 . As well, Seattle currently restricts ADUs to ane per lot in single-family zones. Planners have proposed, and the city council appears inclined to approve, upping the allowance to two ADUs , but the city has not all the same determined if that increment volition apply to RSL. If it does, a typical 5,000 ft2 lot could yield six total dwellings, a big plus for housing choices. If not, the gain in homes yielded by a rezone would be much smaller. In that scenario, for example, homeowners non interested in building a second principal house could build merely i ADU under RSL, when they could take built ii if the zoning was left every bit unmarried-family.

Further restricting ADUs: different in single-family zoning, in RSL ADU square footage counts against the 2,200 maximum unit size . Owners of houses 2,200 fttwo  or more than that get rezoned from single-family to RSL would lose the run a risk to construct a backyard cottage. At the same time, ADUs are exempt from MHA charges , which could incentivize builders to trade off larger ADUs for smaller primary dwellings.

Seattle's RSL rezone is barely worth doing every bit proposed.

The upshot for Seattle's plan for single-family unit zones in urban villages is that RSL zoning, equally currently conceived, is far too constraining. It'due south equally if Seattle leaders, intimidated by the same forces that blocked change in the original urban villages push button of the 1990s, are compromising once again, proposing an upzone that seems assuming on its face just turns out to be then booby trapped with hidden barriers that it will change niggling on the ground.

In theory, RSL zoning allows two, perchance iii, homes instead of ane, but in practice, it undermines itself with and then many size restrictions and constraints, plus MHA fees, that it would often work out to be not an upzone but a downzone. It will yield a meager stream of boosted dwellings: maybe 60 a twelvemonth across the entire metropolis. Its legal snags with MHA will, at all-time, inflict delay and uncertainty on homebuilding and at worst induce its own overturning by land courts. Further, it would lock in zoning that undermines city goals: political forces don't align for changing zoning in whatsoever neighborhood more than than perhaps once per decade, if not once per generation. And lastly, it'due south a terrible precedent for any future upzones of single-family neighborhoods across more of the city.

How tin can Seattle fix it and yield consequential gains for affordability?

  • Upzone more single-family to higher density zones: RSL would lock 768 acres of land near transit and shops into inappropriately low-density housing patterns. Addressing Seattle's affordability and climate goals demands, at a minimum , lowrise zoning. By the city's judge, every acre of lowrise would yield about as many net new homes as half-dozen acres of RSL. Boosting all the way to midrise zoning, fifty-fifty if it's on a smaller expanse, may exist a better prescription for housing choices in neighborhood centers. Typical midrise apartments yield peradventure 20 times more added homes per acre than RSL.

    By the metropolis's estimate, every acre of lowrise would yield well-nigh as many cyberspace new homes equally half dozen acres of RSL.

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  • Raise the RSL zone'south density limit: RSL imposes also low a limit on habitation density. For example, RSL's maximum of ane home per 2,000 ftii  of lot expanse precludes triplexes on 5,000 ft2  lots—the nearly common residential lot size in Seattle. A meliorate density target: one unit per 1,000 ftii , which would enable a modest, v-unit building on a 5,000 ftii  lot. RSL also restricts flat buildings specifically to a maximum of three units, no matter how large the lot. This brake (intended to encourage homes with ground level entries) should be removed to maximize homebuilding flexibility.
  • Ratchet downwards the size of unmarried-family houses but not multifamily buildings: In many cases, rezoning unmarried-family to RSL would reduce the total square footage of housing that tin exist built, fifty-fifty if it'southward split into multiple homes. The urban center'south affordability goals would be better served by zoning that restricts the size of single-family houses but raises that limit for buildings that contain multiple units, incentivizing the construction of more than homes on a lot. The master drawback of McMansions is not that they are big, simply that they are large and but accommodate i household.
  • As an alternative to RSL, model the single-family upzones after HALA recommendation SF.2 to allow more homes on a lot without allowing larger buildings: This scheme raises the number of households that can live within buildings without changing the calibration of the buildings themselves, and so it wouldn't much modify the concrete grapheme of a neighborhood. Yet information technology would allow more than homes than RSL does, because it regulates development scale by lot coverage, setbacks, and acme, but not by a density limit.
  • Allow 2 ADUs per RSL home: At that place's no reason to brand RSL more restrictive than the allowance for two ADUs the metropolis has proposed for single-family zones. The owner of an upzoned belongings with an existing business firm should have the option of keeping the house and adding two ADUs. Small lot sizes would preclude backyard cottages, every bit they already do in single-family zones.
  • Exempt RSL from MHA: Every bit with all of the city's multifamily zones, exacting fees from homebuilders in RSL is an exercise in round logic, undermining the MHA program'southward own intent to help affordability past pushing up prices and rents. MHA in RSL is a particularly dubious proffer considering of the scenarios in which rezoning from unmarried-family would actually be downzones. The new RSL zone is untested and rife with the take a chance of unintended consequences. RSL builders would tend to be small-scale and vulnerable to added expenses imposed by MHA, and the rate of homebuilding will probable be so low that MHA would create negligible revenue for Seattle's affordable housing fund. Coupling MHA to RSL paints a behemothic legal target on the entire policy. State law allows localities to downzone property, even if doing and then reduces holding values. (Politics are another matter!) On the other hand, land law explicitly forbids imposing affordability mandates or fees without compensating incentives. All told, MHA in RSL is likely to be more problem than it'south worth.

Decision

Though it would change only 6 pct of the city's land zoned for unmarried-family, Seattle'due south proposal constitutes the biggest change to unmarried-family since zoning was first put in place almost a century ago. The city's ambition is commendable: to correct a sad political deal on single-family zoning that continues to demolition city goals to create diverse, walkable neighborhoods with abundant housing options. Unfortunately, Seattle'due south plan falls far brusk of that ambition.

The simple reason: the upzones wouldn't allow enough homes. The 2 key fixes: (i) relax RSL's limits on density, floor infinite, and ADUs, and (ii) upzone a larger portion of the single-family unit to lowrise and midrise. Further, to avert risking unintended consequences and legal snags for a relatively pocket-size payoff, the city tin exempt RSL from the MHA plan. With these improvements, Seattle'south single-family unit upzone will serve the city'south goals to create neighborhoods that welcome people of all incomes while treading more lightly on the planet.

APPENDIX

How much capacity for new homes would the rezone add?

Assuming an average lot size of 5,000 fttwo unmarried-family zoning allows a maximum density of nine primary dwellings per acre. Theoretically, RSL'south density limit of ane dwelling per two,000 ftii of lot would allow 22 dwellings per acre—2.five times higher than unmarried-family—such that the 768 acres upzoned to RSL could yield a net proceeds of ten,031 homes.

However, multiple factors skin down that theoretical maximum in the real-earth—in particular, many lots already accept loftier-value buildings on them. Accounting for such factors, Seattle planners estimated that rezone to RSL would yield a net proceeds in "capacity for housing growth" of roughly half the theoretical maximum, or four,908 homes. For the residue of the proposed unmarried-family upzone, planners estimated that the 471 acres rezoned to lowrise would yield a net capacity increase of 17,410 homes, and the nine acres rezoned to midrise would yield 688.

All that totals to boosted chapters for 23,006 homes created by the proposed single-family upzone. That's about i third of the 69,520 units of new capacity created by the unabridged "citywide" MHA rezone (the citywide rezone accounts for almost one-half of all the new capacity that will be created past the city's complete package of MHA rezones). For reference, in 2012 the unabridged city had an estimated 224,000 units of zoned capacity.

How much of the added chapters would really get used for new homes?

Every bit defined by the city, the in a higher place capacity numbers are a "theoretical calculation of the total corporeality of development allowed nether electric current zoning over an indefinite time horizon." To assess how much bodily housing production the MHA rezones would cause over twenty years, Seattle planners applied another layer of assumptions based on projections previously done for the urban center'south Comprehensive Plan. They estimated that the "preferred alternative" MHA rezone would result in 17,026 new homes really congenital over twenty years—that is, just 24 percent of the capacity for 69,520 would be consumed for new dwelling house construction.

The metropolis's 20-year project does not split growth by zone, merely for a rough approximation I practical the same 24 percent ratio to the single-family upzone chapters, which comes out to 5,634 homes built over twenty years, or 282 per yr. Under the same assumptions, the RSL portion of the upzone would yield nigh 1,202 homes over twenty years, or 60 per yr.

Residual land value analysis of rezoning from single-family to RSL

One common metric for testing real estate development scenarios is "residual state value" (RLV). The RLV is how much a developer can pay for land on which to build and notwithstanding achieve a reasonable return on investment (ROI) after paying all the other expenses of development. If a modify to zoning reduces the value of redeveloping a bundle of land, the RLV drops by a corresponding corporeality, and vice-versa.

The table above shows a simplified financial breakdown of constructing a 4,000 ft2 firm under Seattle's existing single family zoning, compared with amalgam 2 1,875 ft2 homes on the same lot rezoned to RSL. As shown in the bottom row, the RLV for unmarried-family is about $25,000 more than that for RSL. Translation: for this particular scenario and assumptions, building the homes allowed under RSL zoning would generate marginally less value compared to what could be built under existing unmarried-family unit zoning.

However, if the house was 5,000 ft2 instead of 4,000 ftii (up to 5,250 ft2 is allowed), the loss of RLV caused by the rezone to RSL jumps to $217,000. Worse yet, plugging in the higher up-described case of a 3,700 ft2 lot on which RSL would only let a single 2,200 ft2 home, the rezone would reduce the RLV by a whopping $353,000, slashing the original unmarried-family RLV by 40 percent.

RSL likewise allows small apartments, but because the financials are different for rental housing, RLV analysis is beyond the scope of this article. However, Seattle'due south MHA study found that development of a 4500 ft2, three-unit, stacked apartment apartment building in RSL would have such a low RLV that it would non be financially feasible to construct.

RSL off-street parking requirements

Like single-family zoning, RSL would require ane off-street parking space for each abode. Seattle exempts parking requirements for lots inside urban villages located within a quarter mile of frequent transit. But equally illustrated in this Seattle Times map, some of the proposed RSL will not be exempt (run into Crown Loma, for case). A requirement of one stall per unit of measurement would create a serious barrier to the construction of multiple RSL homes on a single lot, especially if the density limit is raised, every bit recommended above. There simply isn't infinite on small lots to fit much parking. To enable the RSL zone to ameliorate support city goals for affordability, Seattle should consider exempting RSL from off-street parking requirements.