ADU 101
New to accessory dwelling units? Start here. In a few minutes you'll understand what an ADU is, the types, what they're for, what they cost, and how one gets built.
The basics
An accessory dwelling unit is a second, fully independent home on the same lot as an existing house. It has its own kitchen, bathroom, and private entrance, everything a standalone home has, at a smaller scale.
You'll hear them called many things: granny flats, in-law units, backyard cottages, casitas, or secondary suites. They're all the same idea, a flexible, self-contained living space that adds room, income, and value without moving.
The four types
A standalone home in your yard, fully separate from the main house. The most private and flexible option, and ADU Nation Builders's specialty.
A new unit joined to your existing home, sharing one wall. A smart way to add a self-contained living space while keeping a smaller footprint.
An existing garage transformed into a legal dwelling. Because the structure already exists, it often needs no extra yard space.
A compact unit created inside the walls of your current home, often with its own entrance and kitchenette. Size caps and whether it's recognized as its own category vary by city.
Why build one
Long-term rentals are the most common reason homeowners build, a backyard home can generate meaningful monthly income for decades.
Give aging parents or adult children their own independent space while keeping everyone close. Privacy and proximity at once.
A quiet, dedicated workspace steps from your door, no commute, no distractions, and a clean separation from home life.
A permitted, well-built ADU adds flexible square footage and can meaningfully increase your property's resale value.
What it costs
ADU Nation Builders is a fixed-price builder, our models start at $139,000 for a 400 sq ft Studio, $189,000 for a 600 sq ft One Bedroom, and $249,000 for an 800 sq ft Two Bedroom. From there, five things move your final number:
The clearest way to see your real number is to configure a unit in our studio, every option's price updates live as you choose.
How it works
Pick a model and configure your exterior, interior, and upgrades in our online studio, with live pricing at every step.
We confirm your lot qualifies and prepare permit-ready plans. In Colorado, qualifying ADUs clear administrative review in weeks; in New Braunfels, TX your ADU follows the city's local zoning ordinance and permit process.
Your unit is stick-built on site. A typical ADU Nation Builders home is constructed in about 10–12 weeks once permitted.
Final inspections, walkthrough, and keys. Your new home is ready for family, tenants, or whatever comes next.
Want to see it in motion? Watch our step-by-step build simulator →
Find out if your lot qualifies, or start designing your ADU right now.