Colorado communities are tweaking their codes to allow “tiny houses,” the abodes built by people aiming to spend less and lighten their environmental impact.

But homeless activists who set up small structures in Denver hit a wall. When the Denver Homeless Out Loud activists recently occupied Sustainability Park beneath shiny downtown office towers, police arrested 10 for trespassing.

That park is slated for redevelopment into bigger housing units in a rapidly gentrifying area. The activists, some still camping on a patch of public grass, haven’t had their tiny houses returned.

The clash drilled home a core problem of the growing national tiny house movement: finding a legal place to put them.

And questions the activists raised about affordable shelter, greenspace, food crops and culture are challenging the current citywide densification.

Denver Housing Authority and Denver Environmental Health officials say they are open to a proper policy discussion.

Denver’s housing code dating to 1956 says structures must cover at least 150 square feet — not including halls, bathrooms and closets — plus 100 square feet for each additional resident. A 200-square-foot tiny home for two would be illegal even if built on private property. Zoning rules, too, limit what innovators can do.

PHOTOS: More images of tiny houses in Colorado

“We’re aware of the tiny house moment. We’ve been watching it for several years,” says Karl Schiemann, Denver Environmental Health supervisor of residential health and housing inspection. “We’re definitely open to having conversations about it.”

Municipal leaders in Durango, Buena Vista, Telluride and Walsenburg have changed or are working on rule changes to embrace possibilities for tiny houses.

Town trustees in Buena Vista face queries from residents and recognize a national trend, town clerk Mary Jo Bennetts said. They’ve begun updating Buena Vista ordinances, including requirements for water and sewer hookups “so that we are ahead of the game,” Bennetts said.

A tiny house conference last summer in Colorado Springs unexpectedly drew tens of thousands of participants from around the country. The foothills town of Lyons has allowed WeeCasa, a village touting “try before you buy” for guests, who then can buy houses ranging in size from 78 to 500 square feet.

Last week, architects and planners convened in Portland, Ore., for a “Build Small, Live Large” summit exploring “cottage clusters” and “elegant space-efficient designs.”

Yet in Denver and most major cities, officials enforce minimum-size rules based on health. The codes are cast as necessary to prevent crowding and poor ventilation that officials say could hurt residents’ physical and mental well-being.

Tiny house activists argued tight structures 200 square feet and smaller are viable, creative options for Denver residents seeking a sustainable and self-reliant lifestyle. They paid up to $2,500 for the structures they erected in Sustainability Park near urban farming plots.

The DHA owners of the property, eight blocks overall near 26th and Lawrence streets, allowed a three-year experiment in the park encouraging gardening and entrepreneurial design activities. Now the redevelopment plans by a city-selected contractor called Treehouse include leaving 18,000 square feet open for continued urban farming.

But Denver Homeless Out Loud, including recent college graduates and homeless people, has been pushing to create an inclusive, self-governed village community on what they see as public space.

“Homeless people are not going to be able to afford living in the new housing,” said formerly homeless Marcus Hyde, 26, an organizer who has worked at a shelter. “Tiny housing is a way to build greener and smaller. … Where are we supposed to go?”

Homeowners in the Curtis Park area approved Denver’s redevelopment plans yet also are struggling to address homelessness and a widening rich-poor gap, Curtis Park Neighbors president Joel Noble said.

“The notion that a tent city, or a city of tiny houses, can solve the problems of homelessness doesn’t ring true,” Noble said. “But we have not done enough as a city to house the homeless.”

The recent occupation “is not the right answer,” he said. “Denver has not found the right answer.”

DHA officials rejected the activists’ notion that former public housing land could be tiny house turf.

“The concept they’re proposing is not something that is feasible to be done at this point. … We’re building consistent with a neighborhood-approved redevelopment plan,” DHA director Ismael Guerrero said. “There’s certainly room for a policy discussion of that concept, but to do it illegally, on private land, is inappropriate.”

The tiny house movement is growing, despite difficulties.

After Denver police arrested the activists, a TV crew for “Tiny House Nation” continued to film construction of two other tiny houses in Sustainability Park for crafted “reality” episodes. Those houses had wheels, however, and their owners later moved them.

A Sprout Tiny Homes factory, 60 miles east of Pueblo at La Junta, produces structures with and without wheels, executive Diane Graham said.

Small housing has potential in big cities to provide better living options for residents, she said, aware of the efforts in Denver.

“Tiny homes could be a perfect solution, if the city would just listen. You could get just as many people on that space with well-conceived tiny homes,” Graham said. “If you’re homeless, a 200-square-foot unit would be awesome, compared with being homeless. There’s got to be a way to get homeless people off the streets. It doesn’t need to be a two- or three-bedroom apartment. They don’t need or want that space. So let people build what people want.”

Bruce Finley: 303-954-1700, bfinley@denverpost.com or @finleybruce