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  #1  
Old Posted Mar 8, 2023, 7:14 PM
mhays mhays is offline
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How one city started a wave of accessory dwelling units

Seattle and the State of Washington are broadly pursuing new housing supply. One recent move was Seattle's liberalization of accessory dwelling rules in single-family neighborhoods in 2019.

While single-family zoning is on the way out in Washington (this month?), it's currently 60% of the land in Seattle vs. 20% where real density is allowed. The 60% hasn't helped with our supply or price problems.

The City acted in 2019. The goal was more units, affordability, and equity across neighborhoods. Most SFR lots now allow two ADUs, including one detached. The ADUs have to be small, and the main house can't be very large either. They don't need parking. Owners don't need to live onsite. (At the same time they cut McMansion sizes.)

The numbers have been impressive -- 988 ADUs permitted in 2022. That's up from 60 in 2005 and 280 in 2019.

It's not all roses. They tend to be expensive and 11% of the current inventory is Airbnbs (not that those aren't useful). But they're substantially cheaper than most houses, and they'll move slowly downmarket over time. Mostly, we need large amounts of new housing.

The details seem to matter, a lot. Not requiring parking, for example, seems to open things way up. What are other cities doing on the policy and/or production fronts?

The Seattle Times wrote a pretty good report today.
https://www.seattletimes.com/seattle...single-houses/

Also the City keeps a useful portal.
https://aduniverse-seattlecitygis.hu...com/pages/data
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  #2  
Old Posted Mar 8, 2023, 7:32 PM
austlar1 austlar1 is offline
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Here are Austin's ADU requirements. Extra parking is usually required: Accessory Dwelling Units

An Accessory Dwelling Unit (ADU) is a separate dwelling unit on the same property as a single-family home that is smaller in size and regulated by the City of Austin’s Land Development Code § 25-2-774 Two-Family Residential Use. Some of the requirements for ADUs in the City of Austin are as follows:

Minimum lot size for ADUs on SF-3 zoned lots is 5,750 square feet.
Maximum size of an ADU is 1,100 square feet or 0.15 FAR whichever is smaller.
Buildings must be separated by a minimum of 10 feet (front to back and side to side).
An ADU requires parking be added in addition to parking requirements for the main structure (two parking spaces for a single-family home). If the site is located more than a quarter mile from an activity corridor (as defined by the Comprehensive Plan), then the addition of an ADU would trigger the need for an additional parking space. If the site is less than or equal to a quarter mile from an activity corridor, additional parking is not required. For more information: ADU Areas of Reduced Parking on Interactive ArcGIS Map
Use as a short-term rental is limited to a maximum of 30 days per year for ADUs constructed after October 1, 2015.
Use as a Type 2 short term rental is prohibited.

"Activity Corridors" are designated to create higher density areas where people can easily connect with transportation, businesses and services. This usually means a busy thoroughfare with substantial commercial activity. Most Austin homes are probably located more than a quarter mile from an Activity Corridor, so the requirement for additional parking is onerous. Existing deed restrictions may also preclude construction of an ADU. Also, I have no idea what percentage of homes in Austin are zoned SF3. I do know that a substantial number of ADUs have popped up in Austin neighborhoods in the past few years, but I have no idea of the exact number. There was an effort to get the entire city zoned for ADUs about a year ago. I think it was a proposal that received a lot of attention and went nowhere. Perhaps someone more knowledgeable about Austin zoning can provide better information.

Last edited by austlar1; Mar 8, 2023 at 7:45 PM.
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  #3  
Old Posted Mar 8, 2023, 9:12 PM
mhays mhays is offline
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The parking requirement really is onerous. Two spaces is already really high just for a house. A third off-street space basically means you need an alley or some awkward/expensive solution from the main street frontage. Austin has some alleys but it looks like a lot of neighborhoods don't have them.

A 10' separation between structures might be a big impediment too. It doesn't sound like much, but a lot of smallish potential sites probably run into issues because of it...both the capacity to add an ADU and the ability to keep a sizeable yard.
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  #4  
Old Posted Mar 10, 2023, 5:43 PM
mhays mhays is offline
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Portland has been a big ADU producer. https://accessorydwellings.org/2021/...data-for-2020/

Denver not so much, though it builds a lot of housing. https://www.denvergov.org/files/asse...oundreport.pdf

Minneapolis is seeing very limited missing-middle growth, and as of 2019 wasn't seeing many ADUs. https://www.minnpost.com/metro/2019/...t-working-out/

Every situation is really different. All three cities have missing-middle options other than ADUs. All are building quite a bit of housing overall. The details of ADU legislation vary tremendously, and the details of other options vary tremendously.

I've just taken a quick look so far.
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  #5  
Old Posted Mar 11, 2023, 6:42 AM
jmecklenborg jmecklenborg is offline
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Quote:
Originally Posted by mhays View Post

Every situation is really different.

ADU's are very expensive to build (to code). This means they usually only make sense to build in the most expensive cities.

Banks don't want to lend to build ADUs because they're financed with custom loans, not conventional mortgages that can be sold.
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  #6  
Old Posted Mar 11, 2023, 5:08 PM
mhays mhays is offline
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That's a good point. Though Portland is pretty affordable vs. a lot of others.

And a huge reason to get rid of any parking requirement. With smaller housing, an off-street parking space would be a huge percentage of overall cost, in addition to the geometry challenge.

Even with the expense, a lot of ADUs are new construction vs. squeezing in that little house off the alley or converting the basement. I wonder how banks look at that, both for families trying to build new places with a little income potential and developers doing a lot of these.
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  #7  
Old Posted Mar 13, 2023, 8:37 PM
jmecklenborg jmecklenborg is offline
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Originally Posted by mhays View Post

And a huge reason to get rid of any parking requirement. With smaller housing, an off-street parking space would be a huge percentage of overall cost, in addition to the geometry challenge.
This illustrates the paradox of ADUs - that it's not really economical to build one in a truly dense neighborhood near transit since it's rare that you can physically get the equipment behind the house necessary to build the thing quickly.

If you're dealing with a true row house, you'd have to bring all materials directly through the house and out the back door to the courtyard. You're going to have to run concrete straight through the house, which is risky, or carry hundreds of bags of concrete back there by hand. How does the tenant get back there? By walking through your house every time?

I own a free-standing house with 60" spaces on each side between it and adjacent buildings. You can get some equipment back there but not the bigger stuff, plus there is no staging space for construction vehicles and materials. Get ready to shell out big $ to build a tiny house by hand.
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  #8  
Old Posted Mar 13, 2023, 9:30 PM
austlar1 austlar1 is offline
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ADU's in suburbanized Sunbelt type cities are actually well suited to that particular environment. Many of these homes (especially in inner ring neighborhoods built before the 1980s when most homes were built on 8,000 to 12,000 square foot lots) have adequate space on either side of the primary dwelling to allow for access to the rear of the property for construction and ordinary egress purposes as well as probably having room for additional parking or driveway space. This is where the added density of ADU development could prove optimal. Sadly, these very same neighborhoods tend to be inhabited by homeowners who have little interest in (or demonstrate outright hostility towards) creating that additional density. The result is pared down ADU zoning with a host of built in obstacles similar to the fairly new rules created in Austin. I don't know that this will ever really change. Even new homeowners moving into these inner ring neighborhoods seem to quickly adopt that "I've got mine, Jack" mindset and embrace NIMBY attitudes.
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  #9  
Old Posted Mar 13, 2023, 9:58 PM
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Steely Dan Steely Dan is offline
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Quote:
Originally Posted by jmecklenborg View Post
This illustrates the paradox of ADUs - that it's not really economical to build one in a truly dense neighborhood near transit since it's rare that you can physically get the equipment behind the house necessary to build the thing quickly.
Not an issue in fully "alleyed" cities.

Also, ADU does not exclusively mean "new construction in the rear yard". Some ADU programs also allow for the liberalizing of laws to make it easier for homeowners to add attic and/or garden apartments to their existing homes.



Quote:
Originally Posted by austlar1 View Post
Even new homeowners moving into these inner ring neighborhoods seem to quickly adopt that "I've got mine, Jack" mindset and embrace NIMBY attitudes.
Of course.

Everyone loves the sound of "more affordable housing" in the abstract, but homeowners generally view anything that might negatively impact their own individual home's value as cancerous.

What do we want? "More affordable housing!"

Where do we want it? "Somewhere else!"
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Last edited by Steely Dan; Mar 13, 2023 at 10:27 PM.
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  #10  
Old Posted Mar 13, 2023, 10:42 PM
mhays mhays is offline
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I'd love to see evidence about how ADUs affect house values. My guess is they'd increase rather than decrease due to each one having more development potential. That assumes they don't turn into dens of zombies or hobos like the nimbys appear to think. And whatever armageddon happens when someone else parks a car in front of their house.

In truth the residents are probably mostly service workers, newly-married couples, grad students, etc. (the horror!), as well as some grandmamas and grown kids as well (even worse!), plus a few airbnbs thrown in. We have 11% airbnbs so far but I bet that diminishes in percentage as more of these get built.

The economic case seems to make sense given the volume here as well as in Portland. Both have historically lacked missing middle options, being mostly houses and flats. Maybe in cities with more middle options they'd be tougher.

PS, anywhere in Seattle that allows rowhouses will get them front and back. That's the 20% of the city that allows real density. ADUs are about the 60% that doesn't.
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  #11  
Old Posted Mar 14, 2023, 1:16 PM
jmecklenborg jmecklenborg is offline
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Originally Posted by Steely Dan View Post
Not an issue in fully "alleyed" cities.

Also, ADU does not exclusively mean "new construction in the rear yard". Some ADU programs also allow for the liberalizing of laws to make it easier for homeowners to add attic and/or garden apartments to their existing homes.

Unfortunately, doing things properly is horrendously expensive. I wouldn't be surprised if building a simple 1-bedroom apartment in my basement would cost over $50,000. How long does it take to earn a return on that investment? Does it add resale value? The answer to those questions is probably 20 years and probably not.

Any landlording class is going to teach you to look for homes where an extra bedroom can be added at minimal cost, not a completely separate apartment.
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  #12  
Old Posted Mar 14, 2023, 1:23 PM
jmecklenborg jmecklenborg is offline
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Quote:
Originally Posted by Steely Dan View Post

What do we want? "More affordable housing!"

Where do we want it? "Somewhere else!"

The only new "affordable" housing is often illegal housing. That means living in an office building's broom closet, living in a friend's detached garage, etc.

New construction is always extremely expensive. Electricians, plumbers, etc. - they don't work for free.
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  #13  
Old Posted Mar 14, 2023, 3:16 PM
mhays mhays is offline
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Truly affordable, sure. The only real method is super-micros, which can go all the way down to "college dorm" style. And of course no parking.

But a small ADU can be a hell of a lot more affordable than a house or a typical townhouse.

And they'll move slowly downmarket as they age. That's the main way we achieve affordability without subsidy.

It is remarkable that people expect big, cheap market-rate housing AND good wages for everyone. Those things don't match. The math was easier when houses were small and simple.
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  #14  
Old Posted Mar 15, 2023, 5:51 PM
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It is remarkable that people expect big, cheap market-rate housing AND good wages for everyone. Those things don't match. The math was easier when houses were small and simple.
Households keep getting smaller while the houses themselves get bigger.

In a recent thread someine even suggested that 2,300 SF was inadequate for a family of four.
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  #15  
Old Posted Mar 22, 2023, 1:01 PM
jmecklenborg jmecklenborg is offline
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Cincinnati's mayor wants to make ADU construction as easy as possible:
https://www.bizjournals.com/cincinna...nny-flats.html

Cincinnati Councilman Mark Jeffreys and Mayor Aftab Pureval unveiled a plan Thursday to legalize accessory dwelling units, sometimes referred to as “granny flats,” throughout the city wherever there currently is single-family zoning.

[...]

Under the proposed ordinance, an ADU on a 4,000 square foot lot or larger cannot occupy more than 15% of the total lot area. For lots less than that, the combined coverage of the primary home and the ADU cannot exceed 60% of the total lot area.

Other provisions include:

-The ADU cannot exceed 25 feet in height
-There must be 10 feet between the primary dwelling and the ADU if it is not already attached to the house.
-A separate structure ADU cannot be in the front yard.





There is no mention of parking requirements in the article.
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