Update 8/23/2023: On Aug. 23, City of Boulder planners are presenting a draft ordinance to the House Advisory Board that would allow duplexes and triplexes in single-family neighborhoods and tweak density requirements to encourage smaller, more affordable homes. City council is expected to hold a public hearing and vote on the ordinance on Sept. 21.
Update 6/15/2023: On June 15, in an expected move, the city council directed city staff to draft an ordinance that would allow duplexes and triplexes on larger lots in single-family neighborhoods, where they’re currently prohibited. A majority of councilmembers also said they want to increase the city’s occupancy limit from three unrelated people to five in low-density residential zones.
Earlier this year, Colorado lawmakers sought to outlaw single-family zoning in certain areas of certain cities. The bill died on the last day of the legislative session, in part due to opposition from city leaders who stood to lose power over land-use decisions.
The Boulder City Council, however, voted to lobby in support of the bill. Now, with its demise, councilmembers are considering similar zoning reforms on their own.
On Thursday, June 15, the city council is expected to direct city planners to draft an ordinance to allow duplexes and triplexes in neighborhoods where they are currently prohibited. An ordinance could be voted on as soon as September, according to city officials.
The changes would be part of a larger housing reform package that has been in the works since 2021, when councilmembers made it one of their top priorities to increase the supply of housing in Boulder. The goal is to drive down costs so more people can live here.
“At the end of the day, our school enrollment is dropping, and we are not getting the needed families in those areas,” Councilmember Matt Benjamin said during a recent city council study session.
At the request of councilmembers, city officials are also drafting code changes that would loosen open space and floor area requirements in higher-density residential areas to encourage developers to build smaller housing units. Another potential ordinance would increase the number of unrelated people who can live together from three to as many as five.
The city has been collecting feedback from residents on the overall zoning reform plan. Supporters believe it will improve housing affordability. Opponents cite additional car traffic, potential sewage issues and a loss in property values, among other concerns, according to a city staff memo.
The proposal to allow duplexes and triplexes in single-family neighborhoods would apply to the city’s low-density zoning districts. Together, these districts include about 13,500 of the city’s 47,000 housing units. But they cover most of the city’s residential land area. The current restrictions on multifamily housing have created a suburban aesthetic in areas such as Martin Acres, Mapleton Hill and Newlands.
The changes would not be immediate — nor all that drastic.
City officials are not proposing to change density standards that cap the number of dwelling units per acre. Nor are they proposing to change development standards, such as floor area ratios or height limits, which effectively limit the overall buildable area on a given lot.
In practical terms, this means only property owners whose lots are large enough to subdivide and build another single-family detached home would now have the option to convert their home to a duplex or triplex.
Over time, the changes could allow for as many as 1,500 additional housing units, according to Karl Guiler, a policy adviser for Planning and Development Services.
Separately, earlier this month, Gov. Jared Polis signed a law that effectively prohibits cities like Boulder from enforcing residential housing growth caps. Boulder’s law, commonly known as the Danish Plan (after Paul Danish), was passed in 1976 as part of an effort to slow growth. The latest iteration of the growth ordinance caps new home building permits at 1% per year.
The city’s ordinance exempts housing units in mixed-use areas — those that allow homes and businesses — and deed-restricted affordable housing from the annual limit. As a result, in the last decade, the growth gap hasn’t blocked the construction of new housing, according to city officials.