ACCESSORY DWELLING UNIT COST CALCULATOR

Estimate your construction cost, calculate your monthly payment, and see what it could take to build your ADU - all in about 30 seconds.

Capricorn Concepts Construction

How much could an ADU cost on your property?

Use our free 30-second calculator to get a preliminary planning range.

1,000 sq. ft.
5001,500 sq. ft.
Bedrooms
Bathrooms
Finish level
Septic
Site conditions
Planning estimate only. This build cost estimator is intended for preliminary planning purposes and is based on the information provided. Actual construction costs may vary based on property access, utilities, septic, engineering, permitting, material selections, market pricing, site conditions and other project-specific factors. This is not a formal proposal or construction contract. Monthly payment estimates include principal and interest only and do not include taxes, insurance, lender fees or other financing costs.

An ADU isn't just a construction project - it can be an investment that pays you back. Building a home for aging parents may cost far less over time than years of assisted living or senior housing. For other homeowners, an ADU can generate rental income that helps offset - or even cover - a portion of the construction loan. Whether you're planning for family, retirement, or additional income, a well-designed ADU can continue creating value long after it's built.

FREQUENTLY ASKED QUESTIONS

Do I need a permit to build a detached casita or guest house in Texas?

In almost every case, yes. A detached guest house with plumbing, electrical, HVAC, or living space requires permits and inspections. Requirements vary depending on your city, county, HOA, septic system, floodplain restrictions, and other site-specific factors.

How long does it take to build a custom guest house?

Every project is unique, but most custom casitas take several months from design through final completion. The timeline depends on permitting, engineering, weather, utility work, and the complexity of the project. Because Capricorn Concepts Construction intentionally limits the number of projects we take on, you'll work directly with Luke and Mary Claire throughout the process and receive realistic timelines instead of overly optimistic promises.

What's the difference between a casita, guest house, and ADU?

The terms are often used interchangeably, but they can mean different things depending on local regulations. In Texas, homeowners commonly refer to detached living spaces as casitas or guest houses, while Accessory Dwelling Unit (ADU) is the planning and permitting term used by many municipalities. No matter what you call it, we design and build fully custom detached living spaces tailored to your property, your family's needs, and your local jurisdiction's requirements.

Can I rent out my guest house in Texas?

It depends on where your property is located. Texas does not have a statewide law that allows or prohibits renting a detached guest house. Instead, rules are determined by your city, county, HOA, deed restrictions, and any applicable short-term rental regulations. If you plan to use your guest house as a long-term rental, Airbnb, or vacation rental, it's important to verify local requirements before designing or building your project. We're happy to discuss your goals early in the planning process so your guest house is designed with your intended use in mind.

Can I convert my garage into an ADU or guest house?

In many cases, yes. An existing garage can often be converted into a comfortable guest suite (or, if it’s detached, a guest house, casita, or accessory dwelling unit), but the feasibility depends on your home's structure, ceiling height, foundation, utilities, parking requirements, and local building codes. We'll evaluate your existing garage and help you determine whether a conversion is the best option or if building a new detached guest house would provide greater long-term value and functionality.