DENVER (KDVR) — State and city leaders alike continue to search for solutions for Colorado’s housing crisis.

One solution gaining traction is accessory dwelling units, or ADUs. It’s not a new concept but a lot of folks are still asking what they are. Some localities in Colorado are making more plans to use them.

ADUs are smaller housing units that could provide some relief to Colorado’s housing crunch. Experts say it is how they could be implemented in Colorado that has some hesitant about them.

“Well the housing crisis in Colorado is plenty bad. As we all know, ask anyone who lives in Colorado,” said Jeff Engelstad, Professor of Practice at the Burns School of Real Estate and Construction Management at the University of Denver.

Coloradans need more housing. It’s a big focus for communities across the state with many possible solutions. ADUs are a part of the conversation again.

“They used to be called mother-in-law houses or granny flats, you know things like that, where you would be these accessory dwelling units either attached or detached from your property and you could rent to someone or maybe have a relative stay there,” said Engelstad.

The units can be tricky for one particular reason.

“You know for a long part of history, that was a violation of the underlying zoning laws and that has always been the rub with it. It’s this notion of single-family zoning. And single-family zoning, back into its history, it was really designed to preserve the character of single-family neighborhoods,” Engelstad explained.

Advocates of this type of housing say those laws are antiquated given today’s societal norms. In Colorado, Gov. Jared Polis tried to get a bill passed that would have changed state zoning laws to make building these units easier. It failed on the last day of this year’s legislative session.

“The issue is not for or against ADUs,” said Engelstad. “The issue is I’m for the way the governor and the state want to do it or I’m against the way they want to do it and I would like to see more local control.”

Since the session ended, commissioners in Arapahoe County voted to allow ADU construction in unincorporated parts of the county. Denver City Council voted to relax some rules around ADUs so more units can be built.

The Denver Housing Authority and the West Denver Renaissance Collaborative walked members of the media through one of their 14 completed ADUs and are encouraging people to apply now for their ADU pilot program if they want to be a part of the construction of these units starting next year.

“This pilot program is very new in Denver,” said Renee Martinez-Stone, Denver Housing Authority Director of Planning and Data. “It has been historically very difficult to build an ADU. We’ve called them a product of the privilege and we are working to change that in Denver. We have been identified as one of the top ADU pilot programs in the country to watch.”