Much ADU About Affordability


Evolve Austin's Recommendations for Accessory Dwelling Units in CodeNEXT

Accessory Dwelling Units (ADUs) contribute to many of the goals of Imagine Austin, such as affordability, improved mobility, and preserving neighborhood character, making them fundamental to meeting Austin’s future housing needs. They are a highly effective way for a homeowner to “stay in place”, as endorsed by Council, and can create opportunities for reduced cost of living via rental or ownership throughout the city.

ADUs are already part of the fabric of many existing Austin neighborhoods. ADUs within central neighborhoods often offer better transportation choices for residents, reducing automobile dependence and overall vehicle miles traveled. This housing type allows for small-footprint living, including for families and aging-in-place, and is an affordable option compared to single family housing.

However, the high cost associated with constructing and permitting an ADU under the existing code, particularly City & Austin Water Utility fees and requirements, limits ADU construction to neighborhoods where these costs can be absorbed by owners and, by extension, is a barrier to the City’s affordable housing goals. To remove these financial and regulatory barriers, the following recommendations should be included in CodeNEXT:

  • Eliminate minimum parking requirements for all ADUs; parking requirements for ADUs add cost and can limit or prevent ADU construction on a site.
  • Eliminate minimum 10’ setback requirement between the primary residence and detached ADU; setbacks reduce an owner’s ability to design around existing trees and site conditions. No minimum setback between an ADU and primary structure should be required if the adjacent walls are properly fire-rated according to local Fire Code.
  • Allow ADU’s on any size lot; ADUs should be allowed by right on all lot sizes so long as they comply with setback and impervious cover requirements.
  • Exclude ADU’s from the total square footage limit on a site, where present; ADU size should be determined independently, while building coverage and impervious coverage for ADU’s should continue to apply to the entire site.
  • Allow water sub-metering for all ADUs; infrastructure connections, such as the $25,000 cost of an additional water meter, add considerable and often prohibitive costs to ADU construction.
  • Streamline the permit process and City fee structure; a simpler and more predictable permitting process is necessary to encourage ADU construction.
  • Remove the requirement to add sidewalks in right-of-way for a new ADU where a primary residence already exists; right-of-way improvements represent burdensome costs to ADU construction.
  • Remove any limitation of ADUs to one story; multiple stories, in accordance with height restrictions, provide flexibility to work around trees and reduce impervious cover.
  • Maintain the current maximum 1100sf ADU size limit; the current limit can accommodate a variety of household needs, and facilitate single story ADU’s, essential for aging in place and for citizens with limited mobility, by exempting impervious cover used for Visitability access.
  • Maximize all entitlement bonuses for ADUs under the Affordable Housing Bonus Program; create a viable path to participation for R-type zonings, which do not have bonus unit incentives.

ADUs can be an effective complement to existing architecture. Variations such as carriage houses have been around for centuries. We support the Historic Landmark Commission’s ADU recommendations with the following important modifications:

a. Allow larger ADUs than allowed in the base zoning in the rear of existing houses by right, with the condition of retaining the house;
     1. Establishes a family friendly preservation incentive without requiring the house to be remodeled.

b. Allow existing houses equal to or less than 1,375 square feet to be classified as ADUs while remaining at the front of the lot. The maximum allowable area for new construction behind the front ADU should be within a reduced square footage or percentage of the lot size to preserve scale and character. 
1. Establishes an incentive to preserve existing older housing stock that is simply undersized by today’s standards.
     2. These homes are typically removed under current code

c. Allow attached accessory apartments/ADU’s without age restrictions or similar limitations on existing houses as long as they maintain the roofline of the existing house.
     1. Attached apartments are the most flexible and lowest cost way to preserve existing housing and stay in place.
     2. They should be encouraged and facilitated wherever possible under CodeNext.

CodeNEXT should continue to embrace ADUs and facilitate their construction throughout the city, as called for in the Strategic Housing Blueprint recently adopted by the City of Austin.