What is an ADU?

An Accessory Dwelling Unit (ADU) is a secondary, smaller residence that can be attached to, detached from, or built within a primary residence.  In most locations ADUs cannot be sold separately from the primary residence.  ADUs were a common building practice in the United States prior to WWII, but as suburban development and zoning restrictions increased, it became difficult to build ADUs without special permits, if at all, in many US cities.

A History ofADU Advocacy

Monarch Architecture’s founder, Adrienne Stolwyk, has been an advocate for Accessory Dwelling Units for over a decade.  Adrienne and other architects and citizens interested in advocating for an ADU policy created an organization called ECHO (Enhancing Columbia Housing Options) in 2013, which successfully lobbied the City of Columbia, Missouri to create an ADU policy that allowed ADUs by-right in R-2 and R-MF zones. 


Consulting with Kol Peterson was instrumental in developing an ADU policy that avoided many of the pitfalls that other municipalities have suffered from. Some cities allow ADUs but have onerous restrictions, such as owner-occupancy requirements, that make ADU construction legal but non-viable.

Why are there not more ADUs in Columbia?

Even with the passage of Columbia’s ADU ordinance and a subsequent incentive program waiving ADU permit fees, Columbia, MO has only issued around a dozen ADU occupancy permits since their becoming legalized.  While ADU business models, especially for prefabricated detached ADUs, are on the rise on the west coast, they continue to be built primarily by individual homeowners.  Coordinating the design and construction of a home, regardless of its size, is a daunting task for most folks.


Adding to the complexity is banks’ general unfamiliarity with ADUs and their lack of loan products specific to ADU construction, although that is changing in some markets. The other limiting factor is that currently in Columbia, MO only around 2,000 lots qualify by-right to build an ADU. 


The vast majority of Columbia, MO lots is zoned R-1 (single family), where the construction of an ADU requires a Conditional Use Permit.  The need to obtain this permit adds a bureaucratic hurdle.  If R-1 lots qualified by-right for ADUs, Columbia might see an increase in their construction by private homeowners and developers.

ADUs:Opportunity to Experiment!

Having long wanted to build an ADU and a straw bale house, Adrienne was able to combine these dreams into one with the construction of Monarch’s Office.  In 2023 Adrienne and her husband Adam completed the construction of a 24′ x 24′ straw-cell (straw bale + cellulose insulation) ADU.  This serves as the Monarch Architecture headquarters, but because it is permitted as a residence, it is ready to transition into residential use at any time. 


Straw bale construction, while now permitted within the International Residential Code, is new to the Columbia, MO market: Monarch’s ADU is the first permitted straw bale residence in the City.  Buying a vacant parcel and building a larger single family straw bale house felt risky and out-of-reach financially to Adrienne and Adam; the ADU allowed experimentation on a smaller and more manageable scale.

Interested in building an ADU at your house?

Whether you’re just curious about building an ADU on your property or thinking more seriously, reach out to Monarch Architecture.  Designing a small space can be tricky and we are happy to help!  Additional resources you  may find helpful include:
  • Backdoor Revolution, book by Kol Peterson
  • Maxable Space is geared toward ADU construction in California but has lots of design inspiration for all locations
  • The AARP is great ADU advocate as many retirees are interested in downsizing into ADUs, or housing a caretaker in one