At UC Berkeley, 25 really smart students are building a house for $25,000. It’s a tiny budget, for a tiny house.

The tiny house is called THIMBY, or Tiny House in my Backyard. Imagine a cabin mounted on a trailer. That’s THIMBY.

THIMBY will be state-of-the-art efficient. It gathers power from the sun and stores it in batteries. It captures and recycles gray water from the shower and sink, and filters it for reuse. It uses a “poop oven” to zap human waste into fertilizer.

With a lofted bed, and space below for cooking, working and showering, THIMBY comfortably fits one or two people. THIMBY’s footprint is about the size of two parking spaces placed end to end. Like many tiny houses these days, it’s built on a trailer.

THIMBY is being built at the Richmond Field Station for a tiny house competition put on by the Sacramento Municipal Utility District. The Cal engineers, architects, designers, and physicists are building a showcase of efficient housing design, but they are also building a small, low-cost structure—the kind that is gaining increasing popularity as people explore how tiny houses can fill unused space in cities, house the homeless, and form into villages. THIMBY could become housing for visiting scholars at UC Berkeley’s Global Campus in Richmond.

“We see tiny houses as one potential solution,” says Ian Bolliger, a PhD student and THIMBY’s project manager. “They’re kind of perfect infill units—they can go in existing infrastructure, and if they’re cheap and sustainable, it hits all targets of what you might want in the housing infrastructure of the future.”

Making space for more people without forcing out existing residents is a key dilemma of the housing crisis, affecting cities across the Bay Area, from San Francisco and Oakland to Berkeley and Richmond. While large apartment buildings can take years to go up, advocates say tiny houses can go in now. Squeezing into backyards and vacant lots, tiny houses could increase density, allowing more people to live in a given area, with minimal disruptions to the existing community.

At the moment, though, tiny houses on wheels like THIMBY are illegal. Well, maybe not exactly illegal—it’s more like they’re not explicitly legal. Actually, it’s most accurate to say that, as far as the state of California is concerned, tiny houses on wheels don’t exist.

THE MEMO

In February, the state of California released a five-page memo “intended to clarify the legality … of any residential structure that may be commonly referred to as a tiny home.”

In the memo, the state Department of Housing and Community Development is clear that when it comes to houses, there are rules: “State laws mandate that residential structures meet state standards.” A tiny house that does not meet standards is “a noncomplying residential structure in which occupancy is illegal and is subject to punitive action.”

The natural question is: What state standards must a tiny house on wheels meet? On this, the memo is not exactly clear.

According to the Department of Housing, a tiny house must fall under one of six existing housing categories to be legal. It may be considered a standard house, subject to the California residential building code. It could be considered a “manufactured home,” “factory-built housing,” or a “camping cabin.” If the tiny house is on wheels, it might be seen as a “recreational vehicle” or “park trailer.”

When tiny house pioneer Jay Shafer built his first minuscule domicile in 2000 in Iowa, he put it on wheels, so it would be considered an RV, and he wouldn’t have to follow standard building codes. Shafer’s solution created a legal gray area that continues to engulf tiny houses on wheels.

Today, the THIMBY team is building its home according to RV building codes (ANSI A119.5, to be exact). Still, this doesn’t make it an RV. And even RVs aren’t meant to be used as permanent dwellings, according to the state’s memo. On the last page of the document, there’s a short summary. It separates tiny houses into two categories: those on wheels, and those on a foundation. Tiny houses on foundations are governed by the residential building code. Tiny houses on wheels, the memo says, must conform to RV, camping cabin or park trailer standards.

Those standards would limit tiny houses to RV and mobile home parks, and they would prevent people from living in tiny houses year-round. The way people use RVs is different than the way people use tiny houses on wheels. People expect to live in tiny houses full time — perhaps in someone’s backyard.

This raises the question: Would it be legal to live in the THIMBY house?

“This question is so difficult to answer because tiny houses aren’t illegal because of one law,” said Roopika Subramanian, a Cal law student who has worked with the THIMBY team examining tiny-house policy. “It’s a number of layered laws that make them illegal.” There are at least three layers: city, county, and state laws.

Subramanian said tiny houses face many legal barriers. One important category is minimum habitability requirements, or basic rules about what a living space needs to have: plumbing, electricity, light, windows, a minimum size, etc. Many of these rules date back to the late 1800s and early 1900s when Jacob Riis’s muckraking book How the Other Half Lives exposed the horrific tenement conditions in New York City, she said.

The rules put in place back then are important, Subramanian said, because tenants still rely on them today to restrain ruthless landlords. At the same time, she said, some of the rules are holding back tiny home builders who want to build small, who don’t need a sewage connection, who are choosing this type of house, not being exploited by a landlord.

Tim McCormick is an alternative housing wonk who splits his time between Portland and the Bay Area. He is experimenting with Houselets—open-source, DIY cube-housing made from steel beams. (Think: a giant erector set.) McCormick sees confusion and frustration in the tiny house community over rules that seem to be “inflexible and not very accommodating.” Nowadays, he said, small, low-cost structures appeal to people who are priced out of the traditional housing market, who want flexibility, who want to live more simply and cheaply. Current laws in California usually mean that experiments like Houselets and THIMBY aren’t allowed.

“The way our land-use and zoning works is largely developed from a suburban development era. That time is over, or it’s faltering,” McCormick said. “We’re trying to retrofit it or reform it to make more sense. Indeed, the facade of traditional housing regulations is starting to show some cracks. Two recent changes to code could be the first indications that the law is catching up with housing experiments. Both changes were passed in 2015. One is already in place and the other takes effect in 2017.

They may be harbingers of tiny houses coming into the mainstream, and the beginning of a large-scale experiment in alternative living and urban infill.

FRESNO & THE ICC

The first change, in Fresno, California, gives tiny houses something they badly needed: a formal definition under the law. In November, 2015, the Fresno City Council put tiny houses on wheels into the building code, a first for a large American city.

In 2015, Fresno was updating its entire development code, a 500-page document that contains zoning rules and building codes. Tucked into a section on backyard cottages is the fateful definition of tiny houses: “A Tiny House may be considered a Backyard Cottage if it meets all the requirements of this section.”

And so, tiny houses on wheels found a home. At least in Fresno.

The requirements, listed later, lean toward thinking of tiny houses as RVs, at least in terms of code requirements. Fresno’s code mandates that a tiny house must be licensed with the California DMV and built according to RV standards. It must be towable, but cannot move under its own power. It must be highway legal. Finally, it must look like a conventional house, and have at least 100 square feet of living space, including cooking, sleeping and toilet facilities.

The rule change in Fresno is a significant step forward, tiny house advocates say. “Kudos to Fresno for naming what a tiny house is, giving a definition, and allowing structures as small as 100 square feet into a single family home neighborhood,” said Betsy Morris, a sustainable communities consultant based in Berkeley. “That is exceptional.”

Still, Morris has concerns about Fresno’s new code. She said the definition of tiny houses is so tight that it excludes many of the tiny houses that are currently being built and used.

For David Ludwig, an architect and tiny house advocate based in Marin County, Fresno’s code changes are significant. “It’s a big deal in terms of creating an example,” he said. “So now, we have the law, and I’ve already copied it and sent it to Sonoma County and Marin County. They really need to look at this Fresno law and consider adopting a version of it for their own counties.”

Still, the singular nature of Fresno’s changes worries Ludwig. He’s concerned that it was “a glitch” and not duplicable, because the code change wasn’t the result of community pressure. The change was instigated by Dan Fitzpatrick, a developer, public servant, and tiny house advocate, who suggested to the council that they include tiny houses on wheels in the code.

Fitzpatrick was well-positioned to have the ear of Fresno’s City Council. He used to be Fresno’s redevelopment director, for example. Today he’s chapter chair of the American Tiny Home Association, and he’s also on friendly terms with Pat and Nick Mosley, who run American Tiny Houses out of Fresno. The Mosleys have been building and selling tiny houses on wheels since 2014.

Councilmember Esmeralda Soria championed the change, and in January 2016, one of the Mosleys’ tiny homes served as a backdrop as Soria and Fresno Mayor Ashley Swearengin gave a press conference announcing the historic inclusion of tiny homes on wheels in the city’s code.

Still, outside of Fresno, Ludwig said, many city councils, county boards, and other legislative bodies are “afraid of damaging the status quo in any perceptible way.” New ways of thinking are needed to create true affordable housing, according to Ludwig. “It’s an entrenched mindset,” he said. “People in local government see the answers in the context of existing systems. The problem with these established models is that in every layer of the solution there’s a profit.” The landowner, realtor, banker, developer, management team all make money. “By the time you add five layers of profit, it’s not affordable anymore,” he said.

Fresno may have been a glitch, or it might have been the first domino to fall. But one other major entity has made tiny house-friendly changes that have flown under the radar, but may have large consequences. The International Code Council, based in Washington, D.C., writes building codes that many states and cities adopt. In 2015, the ICC relaxed rules in its International Residential Code, reducing the required size for a habitable room from 120 to 70 square feet. California’s Housing and Community Development Agency confirmed that the state has adopted these new codes, and that they will go into effect January 1, 2017.

For tiny houses, which range from 100 to 400 square feet, this change in minimum room size could have big implications. For Shafer, the tiny house innovator who has long been lobbying for changes to the code, it is a validation of the message he’s been spreading for a long time: in housing, bigger is not better.

Shafer says that small houses are safer, more efficient, and more sustainable than larger ones. In earthquakes, he says, bigger buildings are more likely to kill you.

Shafer doesn’t see tiny houses as a fad or a trend. Instead he sees oversized McMansions as a housing experiment that has proven to be unsustainable and unaffordable. “All of nature is designed to be efficient,” he says. “The only thing outside that seems to be the human ego.”

LIVING SMALL, LEGALLY

Defining a tiny house on wheels is the first step to living in one legally. It’s easier to follow the rules once there are rules. But once a tiny house is built, it must be placed somewhere. In housing parlance, it must be sited. Those are the two challenges facing anyone who wants to live in a tiny house legally: building and siting.

Ludwig, the architect and advocate, said that people building tiny homes are mostly do-it-yourselfers not concerned about meeting code requirements, and reluctant to compromise their visions. Ludwig said that going forward, it will be important for tiny house builders to follow building codes. “Meeting the code doesn’t mean you have to lose your dream,” he said. “Every project we [architects] do is limited by code.”

The most important thing, Ludwig said, is for builders to have their plans reviewed by an architect or engineer and to document the building process to prove the work was done to code.

Ludwig and others pointed to Pacific West Associates, a firm based in Casper, Wyoming, that is becoming well known for registering and certifying tiny houses. Pacific West, Ludwig said, reviews tiny house builds and issues a certificate of compliance and a Vehicle Identification Number (VIN), which he calls a “key element to the whole tiny house idea.”

Once a person has built their tiny house to code, they now must “site” it, that is, find a home for their tiny house. Of course, they could just plop it down any old place. This is known as boondocking—camping where you’re not supposed to camp, Ludwig said. Sleeping in an RV on city streets is boondocking. So is sleeping in a car. Ludwig has boondocked hundreds of nights in his Airstream trailer, he said—and the key is to keep a low profile and avoid complaints from neighbors.

An RV can blend in on city streets. Not so much an adorable cabin on wheels parked in a residential neighborhood or industrial area. You might think that placing a tiny house on a friend’s property is a simple solution. But even this private arrangement is public business, Ludwig and Subramanian pointed out.

Take the issue of poop, for example. Many tiny houses use variations on a composting toilet—a toilet that works without plumbing. (The THIMBY house uses a “poop oven.”) While many tiny house enthusiasts swear by composting toilets, they are almost always illegal, Ludwig said.

Human societies have spent thousands of years working to control human waste in the name of public health, he said. That’s why today we have laws requiring houses to have plumbing. These laws make sense, Ludwig said, but they frustrate tiny-home owners who know their composting toilets aren’t creating a nuisance or a health hazard.

Plumbing is one just example. Other barriers include zoning laws, minimum habitability requirements, and homeowners’ association rules. A thicket of regulations can quickly engulf a tiny house.

But laws written in one era—whether on privacy, intellectual property, employment, or housing—don’t always fit the circumstances of another era. “The law typically feels a bit antiquated,” Subramanian said. “You’re usually trying to fit whatever case you have into an existing box, but it doesn’t quite fit. I think that’s what we see here.”

If well-meaning people and well-meaning laws are coming into conflict, it’s conceivable that the laws could be changed. But here in the Bay Area, there doesn’t seem to be a concerted effort pushing local and state officials to make laws friendlier to tiny houses. There is a tiny house movement that exists in meet-ups, in online groups, and in underground tiny house villages. It hasn’t coalesced into a lobby. Yet.

“It’s possible that tiny house advocates could try to change the building code at some point if they have the capacity to do so. The difficult thing is, changing the law requires a lot of time and capacity and coalition building,” Subramanian said. “Time will tell whether the tiny house community will come together and advocate for that kind of change.”

Changes like Fresno’s and the ICC’s make it a little easier to build a tiny house to code, but it’s still not easy to find a place to put it. In October, eight tiny houses will roll into Sacramento for judging in the utility district’s competition. One of them will be THIMBY, the UC Berkeley team’s project.

They will be compact, efficient, clever and cute, but they will exist in a legal gray area. I asked Subramanian: Why is SMUD sponsoring a tiny-house-on-wheels competition, when the legality of living in tiny houses on wheels isn’t clear?

“I think this competition is really about bringing awareness about tiny houses and minimal living,” she said. “Perhaps another part of it is just SMUD experimenting, wanting to see what students come up with and find out whether these are a good idea.”