An increasing number of jurisdictions, including Denver, Englewood, Boulder, Golden and Arvada, are allowing the construction of a second dwelling unit for homes zoned for single-family. The common term for them is “Accessory Dwelling Unit” or ADU. Golden, unlike the other cities, allows an ADU on properties zoned for either one or two dwelling units.
The ordinances that allow such units include rules that distinguish a home with an ADU from, say, a duplex. For example, they cannot have their owned legal description and can’t have separate water and sewer connections.
Sixty-two ADUs have been approved under Golden’s 2009 ADU ordinance. Denver has permitted 263 ADUs just since Jan. 1, 2016.
Arvada had Jefferson County’s first ADU ordinance, enacted in 2007. Its key points were:
> The property owner must live on site, in either the main house or in the ADU.
> The ADU is limited to 800 SF, or 40% of main home’s size. Minimum size is 200 SF.
> No more than 1 bedroom is allowed.
> No more than two persons may live in a unit up to 600 SF, or three persons in a unit between 600 and 800 SF.
> One on-site parking space is required.
> The ADU’s design must be consistent with that of the principal unit, and the entrance, if visible from the street, must be clearly subordinate to the primary home’s entrance.
These are only some of the requirements with which a homeowner must comply when adding an ADU to his or her property.
The cities differ in some of their requirements. For example, Arvada forbids a home business in an accessory dwelling unit, but Golden’s code does not reference that usage.
ADUs can be within the primary structure (such as a walk-out basement) or in a separate structure, either above a detached garage or as a standalone structure.
There are many uses for ADUs. One use is to create a rental unit, helping homeowners with their ownership costs. Another is to provide a “mother-in-law” unit that provides an elderly family member with independent living but in close proximity to family. Conversely, an elderly homeowner might use an ADU to provide living quarters for a caregiver who needs to be close by. Ditto for a family which has hired a nanny for their young children.
In Golden, each ADU requires an allocation under Golden’s 1% growth limitation. Only Boulder, among the other cities that allow ADUs, has such an ordinance.
California, with its high housing costs, appears to be the national leader in the adoption of ADUs. Here’s some useful information from an article I found online from the New York and Michigan Solutions Journalism Collaborative:
Parts of California have welcomed ADUs for decades while others operated under much stricter rules. This created a complex patchwork of local regulations that was difficult for residents and builders to navigate. The new laws relaxed regulations around setback requirements, minimum lot sizes and other elements that previously made building ADUs difficult in some areas.
Legislative changes at the state and local levels appear to have opened the floodgates for ADU permits in parts of California, including San Jose, where ADU permits issued per year went from 192 in 2018 to 416 in 2019, according to www.BuildinganADU.com.
In Redwood City, a smaller city in the Bay Area, ADU permit issuance doubled during the same period.
The idea appears to be popular among older homeowners: 84 percent of people 50 and older would construct an ADU in order to provide a home for a loved one in need of care, and according to a 2018 study on ADUs by AARP.
The federal government backed the idea of accessory dwellings in the 1990s, with a Task Force on Regulatory Barriers to Affordable Housing recommending removing restrictions on accessory apartments to enable elders to age in place, according to 2008 research in the Journal of Aging and Policy.
Data on the effectiveness of ADUs for caregiving families is scarce, beyond anecdotal evidence and numbers illuminating their popularity in cities where they’re legal and encouraged.
California’s openness to ADUs is part of the state’s strategy to tackle its crushing housing market, which with runaway prices and low housing stock threatens to shut out residents who’ve been living in Bay Area cities like San Francisco or San Jose for decades.
I have become familiar with a local company, Verdant Living, that specializes in the construction of ADUs, or “backyard bungalows.” Their website is www.VerdantLiving.us. Owner John Phillips pointed me toward another useful website, www.AccessoryDwellings.org.
Golden Real Estate's Blog 
Comment by Gary Osburn, Secretary of the Lake Arbor HOA:
Thanks for your informative article. It needs to be known that even though some cities are allowing ADUs, many covenant-controlled communities do not permit them at this time. Since most protective covenants were written and adopted years or decades before ADUs became known, ADUs are generally considered a violation of the existing covenants and will not be approved. Even if some homeowners in a covenant-controlled community wish to allow ADUs, it requires a change to the covenants through formal majority homeowner approval. This is not an easy process and may be resisted by homeowners not enamored by ADUs. Until covenants are revised to allow ADUs, architectural review committees aren’t allowed to approve them. Arvada’s building department apparently requires homeowners to get HOA approval before the city will issue a building permit for an ADU. This helps HOAs have a say in the process. At a minimum, readers should be aware that even if cities are okay with ADUs, neighbors may not be so accommodating and HOAs may have little latitude in allowing them.
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