So You Want to Build an ADU?

Last month, the Austin City Council approved a resolution ending a controversial process to rewrite the city’s land use regulations, a project known as CodeNEXT. This week, Strong Towns is examining issues surrounding land development regulations in Austin and the CodeNEXT process. This is the fourth installment: read Part 1, Part 2, Part 3, and Part 5 of the series here.

Want to keep talking about this? On October 4 and 5, Strong Towns is hosting a Regional Gathering in Plano, Texas. Space is limited, but, as of today, tickets are still available.

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With Austin’s exploding population, housing is becoming limited. The price of existing traditional homes in Austin have skyrocketed, making it difficult for people of modest means to stay in the city. One popular way to offset these costs and to contribute to the limited housing market is to build an Accessory Dwelling Unit, or ADU: think a mother-in-law apartment or those micro-dwellings that Tiny Home revolution HGTV is always on about. ADUs are small, affordable housing alternatives that fit well on large lots zoned for single-family homes. The cost of construction tends to be relatively low. An ADU can also contribute to property values, provide a small rental income, or be sold off as a separate condo. But ordinances in cities like Austin may make the process more difficult than you would assume. It sounds pretty good, right?

So say your’e an Austinite reading this, and you get a little excited: you want to build an ADU! Well, not so fast. We’ve discussed the incredible range of obstacles cities have placed in the way of building ADUs. Now we’re going to take you through the steps of trying to build one in Austin.

To get more details, I talked to Liza Wimberley, co-owner of Waterlily Homes. Liza and her sister have been building ADUs in Austin for six years. She finds ADUs are in high demand for people who can’t afford a traditional single family home, especially in central Austin. But that doesn’t mean there aren’t a few hurdles in the process.

Inside an ADU by Waterlily Homes (Courtesy of Liza Wimberley)

While ADUs in Austin are allowed in some single family zoning districts, not all single family zoning is created equal. ADUs are allowed in the SF-3 zoning area, but not SF-2. So if you, hypothetical Austininite, head to the city website and look up your zoning only to find that you are SF-2, that’s it—an ADU isn’t an option for you. Neither is converting a home into a duplex, for that matter. If you live in a popular, interior neighborhood like Allandale, you’re definitely out of luck; the zoning there is all SF-2.

But it’s okay; you live in Brentwood, a neighborhood dominated by slightly more flexible SF-3 zoning. So you head down to the city hall to get your permit. Your lot is large enough to support a building more than 10 feet from the main home, and you are not located in a flood plain. You should be good to go.

Here’s hurdle number two. Because the folks at city hall tell you that your lot size indicates how large of an ADU you can build—and since you have medium lot, that it has to be small, since the structure cannot cover more than 40% of the land. Laws like this are typically used to promote drainage and prevent flooding. The ADU must also not connect to the main structure in any way.

Fine, you think. We’ll size the project down. But now the city tells you you’ll need to upgrade the water supply lines. After all, two separate homes are going to require two separate meters if you plan to use the unit as a rental. The city used to provide a service to do this for the tune of about $6,000. Then, a few years ago, they made the switch to requiring an independent contractor. The new cost, between the service and the city’s fees, went up to near $25,000, according to Wimberley. This is only the cost of splitting the meter.

Assuming the water meter fees haven’t stymied the project, the next thing to do is to survey is the land you are using. Trees will need particular attention; Austin has stringent rules for trees when it comes to new developments like ADUs, and for good reason. Trees can reduce flooding and promote air quality, something this auto-dominated city sorely needs.

But even when a tree is dead or invasive, it can be a hindrance to a new, small scale development project in the eyes of city hall. Liza recounted a specific instance where there was an unoccupied, crumbling home on a large lot. The plan was to demolish the crumbling home and add two ADUs in its place. In the middle of the lot stood a large maple tree that had been struck by lightning. Waterlily Homes hired an arborist, as is customary, who said the tree was in terrible shape and needed to come down. But instead of granting the permit, the city sent its own arborist, who disagreed with the finding and declared that the tree needed to be protected. Eventually a permit was granted and the cost of removing the near-dead tree in full came to between $3,000 and $4,000. This also included the cost of planting new trees in its wake.

A duplex in South Austin by Waterlily Homes

“I’m an environmentalist,” Wimberley said. “I don’t mind planting trees. I think it’s the right thing to do. But the whole thing seemed kind of messed up.”

In another instance she recounted, a tree on a developable property had been approved for removal. But when construction started, the crew found that removing the healthy tree wasn’t actually necessary. When the city arborist came, he asked why the tree was still there. “I didn’t realize the permit for removal meant it was mandatory,” said Wimberley. The arborist concluded it was and would not approve the permit otherwise.

For construction of the home itself, city ordinances once limited ADUs to no more than 850 square feet. But with the passage of more lenient regulations in 2012, homeowners can now build up to 1,100 square feet if the lot is large enough. For an 850 square foot project, the city estimates construction costs at around $150,000.

Wimberley and her sister have taken on many projects in the Austin area. That’s for the simple reason that there’s a lot of demand for ADU’s. For the last home she built, she said, “The family was more than happy to give up space in order to live closer in [to the downtown core].” Cost-cutting is also a factor; Wimberley has another friend who rents a studio ADU for just $100 per month in Austin.

But ADUs are not the only denser housing option with obstacles. Austin’s existing code requires 50% of the overall length of a duplex to be on a shared wall. It apparently helps make sure structures built in the SF-3 single-family zoning district continue to share the aesthetic character of the neighborhood. Attachment by carport or garage doesn’t meet the standard.

This ordinance has inspired some creative architecture in the city of Austin. Below you can see a blueprint for a site which utilized a “zipper wall” in order to meet the 50% requirement.

The Duplex “zipper wall” (Courtesy of Liza Wimberley)

“When I saw this I thought, ‘This is the pinnacle of the absurdity of the code in Austin,’” said Wimberley.

Wimberley has been the homeowner of a traditional, single-family house in Austin for 20 years. She finds a lot of pushback from her neighbors to the kind of housing her business provides. Many of them want to preserve single family and prevent multi-use buildings. “They don’t think it will help with pricing,” she said.

Austin wasn’t always such a booming city, and many families were able to buy comfortable houses in the city core for modest prices in the ‘80s and ‘90s. Since most of Austin’s neighborhoods are zoned for single-family homes, these lots are sizable and in desirable, interior areas of the city. But even if you managed to get in before the price of property skyrocketed, you may still be experiencing high property taxes or the kinds of building failures illustrated in Part 1 of our CodeNEXT series. That’s why ADUs are becoming a popular source of affordable housing and side income for homeowners. Unlike some of the large developer-led projects community activists fear, they do not threaten the character of a neighborhood or line the pockets of unscrupulous developers. But stringent rules and high fees make them incredibly difficult to afford—and ADUs become just another small solution that is out of reach for many people in Austin’s growing fight for housing.

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