For projects in the City of Austin, one of the most frequently asked questions we get at BRD is about the minimum site area requirements section in the Subchapter E: Commercial Design Standards ordinance. Let’s break it down!
Minimum site area regulations are required when a site has a Mixed Use (MU) combining district in the zoning designation. The MU combining district allows multifamily, townhouse, and condominium residential uses in commercial base zoning districts, which are otherwise prohibited. As such, Subchapter E establishes minimum site area requirements to control the density of any proposed residential use in an MU combining district. The minimum site area requirements are outlined in the tables below. Note that the MU combining district may only be combined with the commercial base zoning districts listed.
Importantly, a common misconception about the minimum site area requirements is that the City of Austin is requiring each unit to be the size indicated in the tables above. These figures should actually be used to determine the maximum allowed density: take the total lot size and divide by the minimum site area square footage allowed for the unit type. For example, on a 100,000 SF (2.3 acres) site that is zoned CS-MU, the maximum number of dwelling units permitted, if they were all one-bedrooms, is 100. Similarly, on a 100,000 SF site zoned LO-MU, the maximum number of dwelling units permitted, if they were all one-bedrooms, is 50. Minimum site area requirements are not intended to regulate the size of each dwelling unit for a project, only the maximum density.
More information about the MU combining district and minimum site area requirements can be found in Subchapter E Section 4.2.1.