The Beginner's Guide to ADUs: What They Are and Why Everyone's Talking About Them
If you've spent any time on real estate forums, talked to a financial advisor, or scrolled through housing content recently, you've probably seen "ADU" come up more than once. Accessory dwelling units have gone from a niche concept to one of the most discussed topics in residential real estate — and for good reason. Here's everything a beginner needs to understand about them.
What exactly is an ADU?
An accessory dwelling unit is a secondary, self-contained living space located on the same parcel as a primary residence. It has its own entrance, kitchen, bathroom, and sleeping area — everything needed to function as a completely independent home. It just happens to share a lot with the main house.
ADUs go by a lot of different names depending on where you are: granny flat, in-law suite, backyard cottage, carriage house, secondary suite. They're all describing the same basic concept — a second, livable unit on a single-family parcel.
What are the different types?
Detached ADU — a completely separate structure on the same lot, not physically connected to the main home. This is the most flexible option and typically the highest-value addition to a property. A modular home placed on your parcel functions as a detached ADU.
Attached ADU — an addition built onto the existing home, sharing at least one wall but with a separate entrance and full amenities.
Interior ADU — a converted space inside the existing home, like a finished basement or converted garage with its own entrance.
For most landowners with enough lot size, a detached ADU is the most valuable and most versatile option — and the easiest to rent or use independently of the main house.
Why is everyone talking about them now?
A few things converged to make ADUs the conversation they are in 2026. First, the housing shortage across the West has created strong demand for rental units at every price point. Second, states including Utah, California, Arizona, and others have passed legislation making it significantly easier to permit and build ADUs than it was five years ago. Third, construction technology — particularly modular building — has made ADU development faster and more cost-predictable than traditional construction.
The result is that a move that used to be complicated, slow, and expensive has become genuinely accessible for a much broader range of property owners.
What does an ADU actually cost?
Cost varies significantly depending on type, size, location, and how the unit is built. A stick-built detached ADU in most western markets runs $150,000–$350,000+ when you factor in design, permits, site work, and construction. A modular ADU from Summit Luxury Dwellings is significantly more cost-predictable — the home is priced before it's built, site work runs concurrently, and the total timeline is under 90 days.
Permit and impact fees vary by city and are a real line item — in many Utah County municipalities, budget $15,000–$50,000 depending on the scope of the project and existing infrastructure on your parcel.
How do people use ADUs?
Rental income. The most common use. Rent the unit to a long-term tenant and offset your mortgage or generate pure cash flow. In Utah County, a well-finished detached ADU realistically commands $1,400–$2,000/month.
Multi-generational living. House a parent, adult child, or in-law on your property with genuine privacy — separate entrance, separate space, same lot.
Short-term rental. In areas with tourism or university demand, an ADU can generate significantly more income as a short-term rental than a long-term lease.
Future flexibility. Build now, use it however makes sense as your situation evolves. An ADU that starts as rental income can later become housing for a family member, a home office, or a guest suite.
The one number worth knowing: Studies show ADUs increase property values by up to 30%. In Utah's current market, that's a potential equity gain of $150,000+ — from an improvement that also generates income while you hold the property.
Is an ADU right for your property?
The key questions are: Does your lot size and zoning allow a detached ADU? Do you have utility access on the parcel? And does the income or lifestyle benefit justify the investment for your specific situation?
For most property owners in Utah and across the West with a reasonable lot size, the answer to the first two is yes — and the third question is worth a serious look. An ADU is not a small decision, but for the right property and the right owner, it's one of the most financially sound improvements available in today's market.
Wondering if an ADU makes sense for your property?
We help property owners across seven western states figure out ADU feasibility, model options, and timelines. Fill out our contact form to start the conversation.