Legalizing ADUs in San Antonio: Why One of Texas’s Oldest Cities Is Rethinking Zoning

In recent years, major Texas cities like Austin and Dallas have embraced zoning reform and gentle density to address housing shortages—but San Antonio, with its deep cultural roots and historic neighborhoods, has moved more cautiously. That changed in 2024, when the city took steps to overhaul its Unified Development Code (UDC) and promote accessory dwelling units (ADUs), commonly known as casitas.

These small, secondary homes—whether garage apartments, converted sheds, or backyard cottages—are now at the center of San Antonio’s effort to expand affordable housing, accommodate multigenerational families, and curb the forces of displacement. But in a city where heritage, land use, and neighborhood identity run deep, legalizing ADUs has sparked both optimism and debate.

This blog explores what San Antonio's new approach to ADUs means for housing, equity, and the future of urban growth in Texas's second-largest city.

A City of History—and Housing Challenges

San Antonio is home to more than 1.5 million people and growing. Known for its missions, military bases, and majority-Latino population, it has a unique urban fabric: sprawling suburban tracts alongside historic districts, tightly-knit West Side neighborhoods, and culturally rich East Side communities shaped by decades of segregation and resilience.

But despite its identity as one of the most affordable large cities in the U.S., that affordability is slipping. According to the 2023 Housing Policy Institute of San Antonio, more than 60% of renters are cost-burdened, spending over 30% of income on housing. Median home prices have risen by 40% since 2019, while wages have stagnated.

City leaders are increasingly aware that the housing supply is not keeping up with demand—and single-family zoning has played a big role.

What Are ADUs, and Why Do They Matter?

Accessory Dwelling Units (ADUs) are self-contained residential units located on the same lot as a primary home. They can be:

• Detached: backyard cottages or garage conversions
  
  
• Attached: additions to existing homes
  
  
• Internal: basement or attic conversions
  
  

Often referred to as casitas in San Antonio, ADUs offer homeowners a way to house aging relatives, earn rental income, or allow adult children to live nearby. In cities with limited land and rising costs, ADUs are a practical, small-scale solution for adding more housing—without changing the look and feel of a neighborhood.

In cities like Portland, Los Angeles, and Austin, ADU reform has become a cornerstone of housing policy. San Antonio, however, has historically been more restrictive.

The UDC Reform: Opening the Door for Backyard Homes

In 2024, San Antonio began the process of updating its Unified Development Code, a once-every-five-years opportunity to revise citywide planning and zoning rules. Among dozens of proposed changes, ADUs stood out as a priority.

Here’s what the proposed reform includes:

• Citywide legalization of detached ADUs in all single-family zones (currently allowed only in specific districts)
  
  
• Simplified permitting to streamline construction approvals
  
  
• Relaxed parking requirements, especially near transit routes
  
  
• Increased unit size caps, up to 1,000 square feet in many cases
  
  
• Lot size flexibility, allowing ADUs on smaller parcels than before
  
  

Crucially, the city is also considering removing owner-occupancy requirements, which currently prevent homeowners from renting out both the primary and secondary units. This rule has often discouraged ADU construction and limited rental housing supply.

Why the Shift Now?

According to Planning Commissioner Patricia Holman, who helped shepherd the reform package, the change is long overdue.

“San Antonio has historically zoned for single-family exclusivity, even in neighborhoods where small homes or backyard units were always part of the landscape. We're not inventing something new—we’re bringing zoning into alignment with the city’s real history and housing needs,” she said.

Holman’s team cited several reasons for the push:

• Housing affordability crisis
  
  
• Aging population—San Antonio has one of the oldest populations in Texas
  
  
• Multigenerational living norms, especially in Latino households
  
  
• Neighborhood stabilization, offering passive income for homeowners at risk of displacement
  
  

Additionally, Mayor Ron Nirenberg’s “Housing for All” plan set clear goals to add thousands of new housing units annually through both new construction and infill development—of which ADUs are a key part.

A Look at the Neighborhood Level

The response to ADU legalization has varied across the city.

In the West Side, a historically Mexican-American community with small lots and modest homes, some residents see ADUs as a lifeline.

Rosa Mendoza, 62, is one of them. She lives in the same house her parents bought in the 1970s. Rising taxes and home maintenance costs have made it harder to stay.

“I want to build a little casita in the back for my daughter and her son. That way I’m not alone, and we can both save money. But right now, it’s expensive and confusing,” she said.

In contrast, preservationists in older neighborhoods like Lavaca, King William, and Dignowity Hill have expressed concerns. Some worry that ADUs will disrupt historic aesthetics, strain infrastructure, or be bought up by investors for short-term rentals.

The Planning Department has proposed overlay options to allow neighborhood-specific guidelines—balancing design integrity with housing goals.

Challenges Ahead

Legalizing ADUs is one thing. Making them accessible and equitable is another.

1. Financing

Building a detached ADU in San Antonio can cost between $90,000 and $160,000, depending on design and utility hookups. Many homeowners—especially lower-income ones—can’t afford to build without help.

City leaders are exploring low-interest loan programs, design templates, and technical assistance to bridge the gap. Local nonprofits like the Alamo Community Group are also launching pilot programs to support ADU construction for aging homeowners.

2. Permitting Bottlenecks

Even with new rules, delays in the permitting process can slow or stop projects. Developers report long review times and inconsistent code interpretations. The Development Services Department is hiring more staff and digitizing workflows to help.

3. Displacement Risks

Some fear that ADUs could speed up gentrification in vulnerable areas if homeowners sell to outside investors. Advocates stress the need for equity protections—such as prioritizing local owners and discouraging speculative flips.

A Regional Shift

San Antonio’s ADU reforms are part of a larger trend across Texas. Austin has allowed ADUs on most lots since 2015 and recently removed occupancy minimums. Dallas has moved to allow “granny flats” in more neighborhoods. Even suburbs like Plano and Fort Worth are discussing reforms.

What makes San Antonio’s approach notable is its cultural and architectural sensitivity. The city isn’t just layering density on top of sprawl—it’s trying to do it in a way that respects its historical fabric and social dynamics.

The Path Forward

The UDC changes are expected to be finalized in late 2025. In the meantime, city planners are launching workshops and community meetings to spread awareness and gather feedback.

If successful, San Antonio could see hundreds—possibly thousands—of new ADUs built over the next five years. That won’t solve the city’s housing crisis, but it could relieve pressure on renters, keep families together, and unlock wealth-building potential for longtime residents.

Most importantly, it signals a shift: a recognition that neighborhoods can evolve without erasing their history—and that the future of San Antonio may be built not just with skyscrapers or subdivisions, but with casitas tucked behind front porches, shaded by mesquite trees, and filled with family.

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