House Speaker Tina Kotek has outlined a plan to allow duplex, triplexes and four-plexes in low-density neighborhoods throughout the state – an idea that would effectively end single-family zoning in many urban areas.

The legislative concept from Kotek, a Portland Democrat, would require cities with more than 10,000 residents to allow the higher-density development in neighborhoods zoned for single-family houses. The proposal also calls for allowing “cottage clusters,” or small detached homes that share a common yard.

More than half of Oregon’s population lives in the cities that would fall under the new zoning. The plan would include towns as small Cottage Grove and Prineville, each with 2017 populations just over 10,000.

The Legislature could beat Portland to the punch. The city is weighing a policy that would do the roughly the same thing at Kotek’s proposal, but it’s not scheduled to go before the City council until next summer. (The basic outline was approved in 2016, but the city has spent years writing the code.)

"The state's housing crisis requires a combination of bolder strategies,” Kotek said in a statement. “Oregon needs to build more units, and we must do so in a way that increases housing opportunity for more people. Allowing more diverse housing types in single family neighborhoods will increase housing choice and affordability, and that's a fight that I'm willing to take on."

The proposal was first reported by Willamette Week. It hasn’t been introduced as a bill yet, though lawmakers are meeting in interim hearings in Salem this week ahead of next year’s legislative session.

The proposal will likely prove popular with homebuilders and housing activists, who share a desire to increase the supply of homes in an effort to make them more affordable.

But proposals for increased density have drawn the ire of neighborhood groups over construction and crowding. One Portland neighborhood has already sued to block the city policy from taking effect.

The League of Oregon Cities, which often opposes legislation that would preempt local authority, did not immediately take a strong position on the proposal.

“We are working to find solutions to housing needs across the state that reflect the goals, needs and values of each city,” Erin Doyle, a lobbyist for the organization, said in a statement. “We look forward to working with the speaker’s office to create solutions that work for our cities and citizens.”

If approved, cities would have 16 months to develop and implement the zoning code language required. The state would provide funding for the code updates, and cities could place some restrictions on the siting and design of the new homes.

At the same time, the state Department of Land Conservation and Development would write code that would be automatically applied in cities that don’t adopt their own.

The policy also calls for a new incentive for such homes. It would require cities to defer system development charges — construction fees paid by builders for infrastructure related to new homes, such as utilities, schools and parks — until the new home receives final approval for occupancy.

The state in 2017 passed similar legislation, also proposed by Kotek, that required cities with 2,500 or more residents to allow the construction of at least one “auxiliary dwelling unit” — an apartment or backyard cottage — alongside single-family houses.

Minneapolis last week decided to allow up to three units on single-family lots, making it the first major city in the U.S. to do abolish single-family zoning. Its zoning changes won’t go into effect until next year.

-- Elliot Njus

enjus@oregonian.com; 503-294-5034; @enjus