TX HB878

Prohibits municipalities with 85,000+ population in counties with 1 million+ residents from requiring residential lots larger than 2,500 square feet, wider than 16 feet, or deeper than 30 feet, and caps minimum density requirements at 31.1 dwelling units per acre

Restricts regulations on "small lots" (4,000 square feet or less), limiting setbacks to no more than 5 feet, prohibiting covered parking requirements, and allowing at least three full stories up to 10 feet each in height

Requires political subdivisions to allow accessory dwelling units (ADUs) on single-family or duplex lots with maximum setbacks of 5 feet, minimum size allowances of 800 square feet or 50% of primary dwelling, and no impact fees for ADUs under 800 square feet

Mandates ministerial permit processing for ADUs with approval or denial within 60 days, with automatic approval if deadline is missed; prohibits parking requirements, owner-occupancy mandates, and ADU-specific fees or exactions

Authorizes counties with under 1 million population to regulate land use in high-density residential areas (more than 2 dwelling units per acre) for health, safety, and quiet enjoyment, with minimum lot sizes of 10,000 square feet; this provision takes effect September 1, 2027