Austin, TX Building Safety: Anti-Mansionization (2026)

Subchapter F applies inside a defined urban-core boundary running Highway 183, Ben White Boulevard, South I-35, William Cannon Drive, Manchaca Road, and Loop 360 to the Colorado River, and covers single-family, small-lot single-family, single-family attached, townhouse, condo, and secondary-apartment uses, plus bed and breakfasts, cottage and urban home special uses, and daycare uses. 3. 2 caps building height at 32 feet outside the 100-year floodplain and 35 feet inside it, and turns off the general height-exception rule in Section 25-2-531 for everything except chimneys, vents, antennas, and non-occupied energy equipment.

6 adds side and rear 'setback planes': an inwardly sloping 45-degree plane that starts 15 feet above the side property line and a matching rear plane, together forming what the code calls a 'tent' over the buildable area, so a house cannot bulk up near the property line even if it stays under the height cap. 6(D) lets a second story added to a pre-October 1, 2006 one-story house use a more lenient plane measured from the original wall plate height. Subchapter F expressly supersedes the general site-development, family-residence, and duplex regulations in Sections 25-2-492, 25-2-555, and 25-2-773 where they conflict, but yields to the separate Urban Home, Cottage, and Secondary Apartment regulations and to neighborhood plan, conservation, and historic overlay districts.