ADU resale value in Utah: what appraisers and buyers see

A permitted ADU is part of your real property, so it can show up in an appraisal — usually through comparable sales or rental income, not as a flat add-on to your home's value. Appraisers look for permits, legal conforming status, separate utilities, and real comps. A tiny home on wheels is personal property on a chassis and is valued like a vehicle, separately from the land.

How appraisers actually treat an ADU

An appraiser does not add the cost of your ADU to the value of your house. They look for evidence in the market: recent sales of comparable properties that also had an accessory unit, and in some cases the income the unit produces. If three similar homes with legal ADUs sold nearby in the last year, the appraiser has something to work with. If none did, the adjustment gets harder to support and tends to come in conservative.

That comp problem is real along the Wasatch Front. Accessory units are becoming more common in Salt Lake, Utah, and Davis counties, but in many neighborhoods they are still rare enough that an appraiser has to reach for comps a few miles away or lean on rental data. It does not mean the unit has no value — it means the number on the report may lag what the market would actually pay.

The single biggest factor is whether the unit is permitted and legal under the city's ordinance. An unpermitted basement apartment or a backyard cottage built without a permit is usually described as unpermitted space, given little or no value, and occasionally flagged as something the buyer will have to resolve. Permits, inspections, and a certificate of occupancy are the paperwork that turns square footage into appraisable square footage.

What lenders look at when an ADU is in the picture

Lenders care about three things: is the unit legal, does it still read as a single-family property, and can any rental income be documented. Most conventional lending on a house with an accessory unit expects the property to remain a single-family home with an accessory — not a duplex. That usually means one address, one tax parcel, and a unit that is clearly subordinate in size to the main house.

Whether rental income counts toward qualifying depends on the loan program and the underwriter, and it generally requires a lease, documented history, or a market rent study. Do not assume the income will offset the payment until someone in lending says so in writing for your specific file.

Appraisers and underwriters also notice utility setup. Separate electric and water meters, an independent entrance, and a kitchen that meets the city's definition of one all support the case that the unit is a true dwelling. Shared everything and a hot plate in a finished basement does not. If you are weighing a conversion, our comparison of an ADU versus a garage conversion in Utah walks through where conversions tend to fall short on exactly these details.

Why a tiny home on wheels is valued differently

A tiny home on wheels sits on a trailer chassis. In most Utah jurisdictions that makes it personal property — closer to a vehicle than to a house — and it is almost never included in the appraised value of the land it sits on. Sell the property and the home can leave with you, which is part of the appeal, but it also means you are selling two assets, not one.

Resale for a tiny home on wheels works more like the RV and specialty vehicle market: condition, build quality, age, certification, and how easily a buyer can finance and insure it. Units with third-party RV certification or documented residential-standard construction generally find buyers faster than units built to neither standard. We cover how that classification works in our piece on tiny homes on wheels compared with park models.

None of that makes a tiny home on wheels a bad decision. It makes it a different decision. You are buying mobility, a faster timeline, and no foundation, and you are trading away the appraisal treatment that comes with permanent construction.

Marketability is not the same as appraised value

Two homes can appraise the same and sell very differently. An ADU widens the buyer pool: multigenerational families looking for a place for aging parents, buyers who want rental income to help with the payment, people who work from home and want a separate office. In a market where payments are tight, a property that comes with a second income stream gets attention.

It can narrow the pool too. Some buyers do not want a tenant on their lot, and in cities with owner-occupancy requirements the next owner inherits the obligation to live there. That is worth knowing before you build if investment is your main motive — our article on putting an ADU on a rental property in Utah covers how those clauses follow the title.

Design matters more here than most people expect. A detached unit with its own yard access, parking, and visual privacy reads as a separate home. An addition carved awkwardly out of the main house can read as a compromise. The tradeoffs between those approaches are laid out in our guide to detached versus attached ADUs in Utah.

Build choices that tend to hold value

Keep the permits clean and keep the records. A folder with approved plans, inspection sign-offs, and the final occupancy approval answers most of what an appraiser, a lender, and a buyer's agent will ask. Rebuilding that history years later, after a city has rewritten its ordinance, is painful.

Build it like a house you would live in. Full-height ceilings, real insulation for a Utah winter, code egress windows, a proper kitchen and bath, and separate metering where the city allows it. Shortcuts in those areas are the first things a buyer's inspector finds. A separate entrance that does not require walking through the main home is close to non-negotiable for rental appeal.

Finally, be honest about why you are building. Most of the families we work with in Lehi and the surrounding cities build for a parent, an adult child, or their own downsizing plan, and treat any effect on resale as a secondary benefit. No builder, appraiser, or agent can promise what the market will do — but a legal, well-built, well-documented unit gives you the strongest position whenever you decide to sell.

Frequently asked questions

Does an ADU increase property taxes in Utah?

Generally yes. A permitted accessory dwelling unit adds improved value to the parcel, and the county assessor reassesses accordingly. How much depends on the county's valuation of the added space and whether it is treated as owner-occupied residential. Your county assessor's office can explain how they handle accessory units at your address before you build.

Will an appraiser count an unpermitted basement apartment?

Usually not as a dwelling unit. Unpermitted space is typically noted as such and given little or no value, and some lenders will require that it be removed or legalized before closing. If the space was finished without a permit, talk to the city about what retroactive permitting would involve — the answer varies by city and by how the work was done.

Does a tiny home on wheels add value to my land?

Not in the appraisal sense. Because it sits on a chassis, it is normally personal property and valued separately from the real estate, much like a vehicle or an RV. The land may gain value from improvements you make around it — a pad, utility connections, a driveway — but the unit itself is a separate asset you can sell or take with you.

Can I sell a house with an ADU to any buyer?

You can list it to anyone, but financing and local rules shape who can actually close. Conventional lending usually expects the property to remain a single-family home with an accessory unit, and cities with owner-occupancy requirements expect the new owner to live on site. Disclose the permit status and any recorded deed restriction early so it does not surface during the inspection period.

How long does it take to build an ADU in Utah?

Plan on roughly four to six months from start to finish, covering architecture, city permitting, and construction. Permitting timelines vary the most, since every city reviews on its own schedule. Site conditions — slope, soil, and how far utilities have to be trenched — account for most of the rest of the variation.

If you are weighing an ADU or a tiny home on wheels for your lot, come walk our model homes in Lehi and we will talk through how it would sit on your property. See more at mycocoonhomes.com.