Thinking about adding a backyard home for family or extra income? In Brentwood, an accessory dwelling unit can be a smart way to create flexibility without leaving the neighborhood you love. You want clear steps, realistic expectations, and simple answers before you invest time or money. In this guide, you will learn how ADUs work in Austin, what to verify on your Brentwood lot, and how to move from idea to permits with fewer surprises. Let’s dive in.
What is an ADU in Austin
An accessory dwelling unit is a secondary home on the same lot as your primary house. In Brentwood, you commonly see four types:
- Internal ADU. You convert part of your existing home into a separate unit.
- Attached ADU. You add a connected suite with its own entrance.
- Detached ADU. You build a new structure, often behind the main house.
- Converted accessory structure. You turn a garage or outbuilding into living space that meets code.
Homeowners choose ADUs for multigenerational living, long-term rental income, or potential short-term rentals. Many also see an ADU as a way to build equity over time.
Start with zoning and eligibility
Brentwood lies within Austin city limits, so City of Austin zoning and the Land Development Code apply. Whether your lot allows an ADU depends on your specific zoning category and any overlays that may affect the property. Many single-family zones allow one ADU, but the standards vary.
Before you design anything, confirm the following for your parcel:
- Zoning designation and any neighborhood or historic overlays.
- Floodplain status and drainage constraints.
- Private deed restrictions or HOA covenants that may limit rentals or additional structures.
If private covenants conflict with city rules, those restrictions can control what you can build or rent. A title company or real estate attorney can help you review recorded deed restrictions.
Size, placement, and lot coverage basics
Local code sets limits for height, placement, and overall size. It also regulates how much of your lot can be covered by buildings and hardscape. These standards affect where an ADU can sit and how big it can be.
Pay close attention to:
- Setbacks along rear and side property lines, which often shape ADU placement.
- Lot coverage and impervious cover, which can trigger drainage or stormwater requirements if you exceed certain thresholds.
- Roof overhangs and eaves, which may count when measuring setbacks.
Because standards change over time, verify today’s rules with the City of Austin before you finalize design or budget.
Parking and access
Austin has updated parking rules in recent years, and ADU requirements can depend on your lot and proximity to transit. Some properties may need an additional off-street space while others may qualify for exceptions.
If you plan to add a new driveway or curb cut for separate access, you may need a permit from the city’s transportation department. Narrow lots and certain streets can limit new curb cuts, so confirm feasibility early.
Utilities and meters
ADUs must connect to water, wastewater, and electric service that meet current standards. Depending on design and use, you may share existing meters or install separate ones.
Here is what to check with utility providers:
- Water and wastewater. Ask about connection points, capacity, tap fees, and whether a separate meter is required for your ADU.
- Electric and gas. Confirm service capacity and whether a panel upgrade or new meter is needed to support the additional load.
- Stormwater and drainage. Added impervious cover can trigger drainage plans or on-site controls. Review early so you can integrate solutions into your site plan.
Utility fees such as tap, capacity, and meter installation costs can affect your total budget. Include them in your early cost planning.
Building code and safety requirements
Your ADU must meet current building codes for structure, plumbing, electrical, mechanical, and energy standards. That includes safe egress, minimum ceiling heights, ventilation, insulation, smoke and carbon monoxide detectors, and any required fire separation.
If you convert or build above a garage, expect structural and fire separation upgrades. For multigenerational use, many homeowners add universal design features such as a no-step entry and wider doors, even when not required, to improve comfort and long-term usability.
Renting your ADU: long term and short term
If you plan to rent the unit long term, Texas Property Code landlord-tenant rules and local health and safety standards apply. Make sure your lease and maintenance plan reflect those requirements.
Short-term rentals are regulated by the City of Austin. If you want to list your ADU for short stays, verify eligibility, registration procedures, and any neighborhood or occupancy limits. Fair housing laws apply to all rental practices.
Permit process, timeline, and fees
Your permitting path depends on your lot and design. Most homeowners can expect these steps:
- Preliminary research. Verify zoning, overlays, utilities, floodplain, and deed restrictions.
- Site assessment and concept. Order a survey and draft a basic site plan showing setbacks, access, trees, and impervious cover.
- Pre-application check. Consider a conversation with Development Services if your site is complex or has overlays.
- Permit submittal. An architect or engineer prepares plans and calculations for review.
- City review. Development Services routes plans for zoning, utilities, transportation, and site plan review if needed.
- Approvals and inspections. Pay fees, pull permits, and schedule inspections through construction to final.
Timelines vary. A simple internal conversion can move faster, while a detached ADU with site work and utility upgrades can take several months. Plan review time, revisions, or appeals can extend timelines.
Fees typically include building and plan review fees, Austin Water tap or capacity fees if new services are required, impact fees, and meter charges for electric service. After completion, your property may be reassessed for taxes, which can raise your annual bill.
Design moves that work in Brentwood
Brentwood is an established central Austin neighborhood with mature trees, alley patterns on some blocks, and a mix of architectural styles. A thoughtful ADU design can fit right in and support privacy and comfort for you and your neighbors.
Consider these design choices:
- Massing and materials that complement the main house without copying it.
- Window placement that protects privacy for both homes.
- Landscape buffers and fencing to define outdoor areas for each household.
- Tree preservation strategies that work around protected or beloved shade trees.
If your lot falls near a floodplain, check both FEMA and local maps. Extra elevation or drainage measures may be required and will influence cost and layout.
Budget and financing considerations
ADUs add value and livability, but you should plan for both upfront and ongoing costs. Construction, design, permits, utility fees, and potential site work can add up. After completion, Travis County appraisal may reflect the improvement, which can increase your property taxes.
Homeowners commonly use a mix of cash, a home equity loan or line of credit, a cash-out refinance, or a construction loan to fund an ADU. Ask lenders about products that support renovation or accessory unit projects. If you plan to rent, build a conservative pro forma that includes maintenance, insurance, utilities, vacancy, and management.
Quick checklist for Brentwood homeowners
- Confirm property status
- Look up your zoning category and any overlays. Note floodplain, drainage, and tree constraints.
- Review your deed and any HOA covenants for restrictions on additional structures or rentals.
- Contact agencies early
- Connect with Development Services for permitting basics and process.
- Ask Austin Water about sewer and water capacity, tap fees, and meter options.
- Ask Austin Energy about electrical service capacity and meter requirements.
- Check with transportation staff if you need a new driveway or curb cut.
- Preliminary design and costs
- Hire an architect or designer experienced with Austin ADUs for a site plan and feasibility review.
- Request contractor pricing and a rough timeline so you can align scope and budget.
- Permits and approvals
- Submit complete plans and respond quickly to review comments.
- Construction and inspections
- Coordinate inspections to keep your schedule on track.
- Rental or occupancy plan
- For long-term leases, follow Texas Property Code. For short-term use, verify STR eligibility and registration requirements.
Your next step
An ADU can unlock space for family or create steady income, but every Brentwood lot is different. The smartest first move is to confirm your zoning and constraints, then build a plan that fits your goals and budget. If you want local guidance on feasibility, resale impact, and rental demand, reach out to Olivia Osborne. We can talk through your timeline, review neighborhood precedents, and connect you with designers and contractors who know Austin ADUs. Get your instant home valuation to understand how improvements could influence your equity.
FAQs
Can any Brentwood lot add an ADU?
- Not always. Eligibility depends on your zoning, overlays, site constraints, and any private deed restrictions or HOA covenants.
Do I need separate water or electric meters for an ADU in Austin?
- It depends on utility policies and your design. Confirm requirements and fees with Austin Water and Austin Energy before planning.
Will I need to provide extra off-street parking for an ADU?
- Possibly. Austin’s parking standards have evolved, and some lots qualify for exceptions. Verify current rules for your address.
Can I convert my detached garage into an ADU?
- Often yes, if the structure can meet building, fire separation, egress, and energy code requirements. Placement and parking rules still apply.
Can I rent my ADU short term on platforms like Airbnb?
- Maybe. The City of Austin regulates short-term rentals. Check whether your ADU is eligible and what registration and occupancy rules apply.
How long does ADU permitting take in Austin?
- Timelines vary by scope. Interior conversions can be faster, while detached builds with utility upgrades often take longer due to reviews and inspections.
