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

The residential proximity slope is defined in Sec. 412(b) as 'a plane projected upward and outward from every site of origination,' starting at the line where the vertical plane through the site's boundary meets the grade of the restricted building. A 'site of origination' under Subsection (a)(3) is any private property in an R, R(A), D, D(A), TH, TH(A), CH, MF-1, MF-1(A), MF-1(SAH), MF-2, MF-2(A), or MF-2(SAH) district, or an identifiable low-rise residential portion of a planned development or conservation district capped at 36 feet.

4-degree (1-to-3) slope that runs an infinite horizontal distance, while CH, MF-1, MF-1(A), MF-2, and MF-2(A) property projects a steeper 45-degree (1-to-1) slope that terminates 50 feet out. In practice this means a new house, addition, or apartment building rising near a single-family lot line has its permitted height shaved down the closer it sits to that boundary, even if the district's flat maximum-height number would otherwise allow a taller structure, which is exactly the tool Dallas uses to blunt out-of-scale infill next to smaller homes.

Subsection (d) lets the building official use plat or zoning map dimensions, or scale measurement, to calculate the restricted distances, and Subsection (e) exempts certain structures identified in the maximum building height section, Sec. 408, such as rooftop mechanical equipment and specific utility or cellular facilities meeting listed conditions.