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Guide to Accessory Dwelling Units in Denver

Discover everything you need to know about accessory dwelling units in Denver, from definitions and requirements to the city's zoning laws.
Detached ADU in Denver

ADUs in Denver have a rich history, originating from the city’s early days. Referred to as “carriage houses,” these units served as independent living spaces. The roots of some of these structures can be traced back to the 1880s.

Pinpointing the exact decline in ADU popularity within Denver’s zoning regulations proves challenging. Nevertheless, in 1925, Denver introduced its initial zoning code, consisting of three districts: residential, hotel, and office. Notably, the residential district did not enforce any limitations on the number of units allowed on a property.

Things changed in 1954 when a new zoning code was introduced, establishing Single-Unit (SU) only districts. This new code limited the number of dwelling units on a property to just one in these districts. Furthermore, it stipulated that only “a family” could reside in a single dwelling.

Fast forwarding to today, Denver is currently experiencing a population boom and a housing crisis. As a response, in 2002, Denver introduced Blueprint Denver to tackle land use issues. The plan was revised in 2019 to facilitate the approval of ADUs. Nevertheless, navigating these laws, which are constantly evolving, can be quite complex. In areas like Denver’s Curtis Park neighborhood, carriage houses from the 1800s still exist and the tradition to convert to livable dwelling units is alive and well. In fact one of the most popular AirBNB properties in the state is a converted carriage house.   

In this article, we will provide you with all the essential information you need to know about ADUs in Denver.

What we’ll cover in this article:

  1. Denver’s definition of an ADU
  2. Steps to build an ADU in Denver
  3. Denver ADU requirements
  4. Denver ADU zoning map
  5. Denver ADU laws & ordinances
  6. Denver ADU program
  7. Cost of an ADU in Denver
  8. ADU services in Denver
  9. Denver ADU builders

#1 – Denver Accessory Dwelling Unit Definition

According to denvergov.org ADUs are “…secondary and subordinate units to a primary dwelling unit. They are secondary in their use classification, as they must be secondary to a ‘primary use’. They may not be sold off as a separate property, unlike a duplex which is a ‘two-unit dwelling use’ or two separate primary uses. Currently, ADUs are only allowed with a single-unit primary use, meaning that you cannot have an ADU with a duplex or a row-home. ADUs may be attached or detached. Detached ADUs are the most thought of type of ADU. They are a separate building at the rear of the lot which usually provides living space above a garage, similar to Denver’s historic carriage houses. Detached ADUs are regulated by the ‘Detached ADU’ building form standards and regulate building size by lot size. New attached ADUs are often less common, but can be a viable solution for smaller lot sizes or where existing structures already fill their lots. Attached ADUs are often found in basements with separate entries, or on a second or third level with exterior stairways. They can also be built as additions to the main house.”

In simple terms:

  • Secondary and subordinate units are attached or detached living spaces that are part of a primary dwelling unit.
  • ADUs are secondary in their use classification and must be secondary to a ‘primary use’.
  • ADUs cannot be sold separately as a separate property, unlike duplexes which have two separate primary uses.
  • Currently, ADUs are only allowed with a single-unit primary use, meaning you cannot have an ADU with a duplex or row-home.
  • Detached ADUs are separate buildings at the rear of the lot, usually with living space above a garage.
  • Detached ADUs are regulated by ‘Detached ADU’ building form standards and building size is determined by lot size.
  • Attached ADUs are less common but can be a solution for smaller lot sizes or where existing structures already fill the lots.
  • Attached ADUs can be found in basements with separate entries, on higher levels with exterior stairways, or as additions to the main house.

#2 – Building a Denver Accessory Dwelling Unit

To build an ADU in Denver, homeowners should take four main steps:

  1. Rezone their property for an ADU.
  2. Obtain ADU designs.
  3. Get ADU permitting.
  4. Build the ADU.

Homeowners have two options: they can either hire architects and construction companies separately and handle the zoning process themselves, or they can choose to work with a full-service ADU builder like Little Home Builder. Our team will handle everything from zoning to the final build and provide warranty coverage.

#3 – Denver ADU Requirements & Rules

ADU requirements and rules in Denver are subject to change as efforts are made to enhance accessibility in response to the housing crisis. In 2023, Denver introduced a revised ADU plan aimed at making ADUs more accessible to homeowners.

The requirements and rules for ADUs in Denver are dynamic and influenced by the specific zoning ordinances of your neighborhood and location. These regulations include form standards and use standards, which vary depending on whether your property is situated in a suburban, urban edge, or urban neighborhood.

Detached ADU in Denver

To provide a better understanding, we have provided a brief explanation of each form and use standard listed below, with regard to zoning ordinances for ADUs. For detailed information on the specific requirements and rules for your neighborhood, please follow steps #4 and #5.

Please note that these explanations are general and it is essential to refer to the official documents or consult the Denver government for precise and up-to-date information. If you find these guidelines overly burdensome, remember that full service ADU builders like Little Home Builder can handle zoning and permitting for you, in addition to architecture and build.

Form Standards

  • Height: Specifies the maximum height allowed for the ADU structure.
  • Bulk plane: Refers to the restrictions on the overall dimensions and size of the ADU, typically in relation to the existing primary structure on the property.
  • Rear setback distance: Establishes the minimum distance required between the rear property line and the ADU structure.
  • Side setback distance: Determines the minimum distance required between the side property lines and the ADU structure.
  • Deckhand balconies on a detached ADU: Addresses regulations regarding the construction and use of decks or balconies on a detached ADU.
  • Dormer encroachment: Specifies rules regarding the extent to which dormers can encroach upon building setbacks and height limits.
  • Minimum lot size requirement: Sets the minimum lot size required to build an ADU on the property.
  • Building coverage exemption: Identifies any exemptions or allowances for exceeding the maximum building coverage limits for ADUs.

Use Standards

  1. Maximum floor area: Establishes the maximum allowable square footage for the ADU’s interior space.
  2. Maximum structure length: Sets the maximum length of the ADU structure.
  3. Conversions of existing garages: Outlines regulations and requirements for converting existing garages into ADUs.
  4. ADUs accessory to two-unit and multi-unit primary uses: Addresses regulations specific to ADUs associated with two-unit or multi-unit primary properties.
  5. Owner occupancy of primary or secondary structure in single-unit zone districts: Specifies whether the owner is required to live in either the primary or secondary structure on the property in single-unit zone districts.

#4 – Denver ADU Zoning Map

Are you interested in checking the zoning regulations in Denver to determine if you can have an ADU on your property? The Denver government offers an ADU Zoning map, which is regularly updated, to make it easier for you. Simply enter your address to find out the specific zoning code that applies to your neighborhood.

ADU Zoning Map of Denver

#5 – Denver Accessory Dwelling Unit Laws & Ordinance

Denver ADU unit laws and ordinances vary by the neighborhood you are in. You need to determine what type of neighborhood you’re in and download the zoning ordinances for your neighborhood type. In order to find the exact laws do the following:

  1. Visit the Denver government site to identify your neighborhood type
  2. Download the zoning ordinances specific to your neighborhood type
  3. Refer to the table of contents in the zoning rules for your neighborhood type and look for the section titled “Detached Accessory Building Form Standards.”

By following these steps, you can access the exact laws and regulations that apply to building ADUs in your specific neighborhood in Denver.

#6 – Denver ADU Program

The ADU program in Denver is a housing initiative aimed at creating affordable housing options by allowing homeowners to build secondary living units on their properties. The program provides assistance, including technical support and financial counseling, to moderate- and low-income homeowners who qualify. The ADUs can be either attached or detached structures, such as converted basements, additions to the main house, or separate buildings at the rear of the lot. The program aims to address the housing needs of the community and promote sustainable urban development. Learn more about the program, see if you qualify and submit your application today.

#7 – ADU Cost Denver

Pricing will vary depending on the size and features of the ADU. According to various sources, the cost of building an ADU (Accessory Dwelling Unit) in Denver can vary. The average price range for permitting, designing, and construction is estimated to be between $200,000 and $340,000

At Little Home Builder we strive to be at the intersection of quality and affordability with full-service project management to save time, pre-designed plans to create efficiencies of scale and transparency every step of the way. The price range to build an ADU in Colorado starts around $200k.

Our pricing includes design and engineering, permit submission, foundation, construction, elevation, interior and exterior finishes, and more. The variable costs that are not included are permit fees from the city or county and hookup fees. When we deliver an estimate, it will include a breakdown of all costs, including the variables so that you understand your total investment.

#8 – ADU Services Denver

When considering ADU service providers in the Denver area, there are a few key factors to consider. First, determine if the business is locally-based or if it operates on a national level. Additionally, it’s important to find out if the business solely focuses on ADUs or if they have experience with a broader range of projects. Lastly, consider whether the business offers comprehensive ADU services or if they only specialize in certain aspects of the process.

Zoning ordinances are particularly crucial when it comes to ADUs. Opting for a local company ensures that they have a deep understanding of the local landscape and ordinances, enabling them to construct an ADU that meets all code requirements and can withstand the local climate.

For a time-efficient and cost-effective solution, you may want to consider a company that exclusively specializes in ADUs. These companies possess specialized knowledge and have learned from previous projects, ensuring that your ADU turns out fantastic and on time.

Building an ADU involves various tasks such as zoning applications, design, permitting, and construction. While you could hire different professionals separately, such as an ADU architect, contractor, and navigate zoning regulations yourself, coordinating all these aspects can be challenging, time consuming and could delay your completion. Choosing a full-service ADU company like Little Home Builder means they will take care of everything for you, from zoning to design, construction, and even warranty.

#9 – Denver ADU Builders

David Craftsman Patio ADU
Craftsman Cottage ADU by Little Home Builder

Little Home Builder is the premier accessory dwelling unit (ADU) builder in Denver. Our comprehensive services cover every step of the process, including zoning, architecture, and construction. Contact us today for a free consultation and let us help you build your ADU in the Denver area.

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