How to Vet an ADU Builder: Red Flags to Watch For

How to Vet a Tiny Home or ADU Builder: The Red Flags That Cost People Money

Buying a tiny home or ADU is a large purchase, and the hardest part isn't the money — it's telling which builders are actually solid from the ones that just look great online. Reputations lag reality in both directions, and a polished website tells you nothing about what happens after a company has your deposit.

We build these homes, so we know where the bodies are buried. Here are the red flags worth watching for before you put any money down — most of them are things builders know and buyers don't.

1. A large upfront deposit with a vague scope

This is the single biggest one. If a builder wants a big percentage up front and the contract doesn't spell out exactly what's included, walk away. Payments should be tied to completed build milestones, not collected as a lump sum before work starts. And the scope should itemize finishes, appliances, systems, delivery, and setup — so you're comparing apples to apples and you're protected if something goes sideways. Most horror stories start with a big deposit and a fuzzy scope.

2. No clear answer on certification

Ask exactly what standard the builder builds to. Park models are built to ANSI A119.5. Road-legal tiny homes on wheels often reference RVIA or NOAH. Some units are built to actual residential code. A solid builder answers this instantly and puts it in writing. Hesitation or hand-waving is a flag.

3. Vague answers on water intrusion

Leaks are the number-one long-term failure in tiny homes, so this deserves direct questions: How do you flash the windows and the wet wall? What roofing system do you use? Do you water-test units before delivery? The specificity of the answer tells you how much the builder actually sweats the details that matter five years in.

4. Insulation done on the cheap

Ask for actual R-values and the type of insulation (spray foam, batt, or rigid). This is invisible at delivery and miserable later — especially anywhere with real winters like Utah's. A builder cutting corners here is cutting them where you won't notice until your first cold snap or your first power bill.

5. A warranty that's vague or verbal

Get the warranty in writing: what's covered, for how long, and — critically — who honors it. Then go a step further and ask for two or three customers who took delivery in the last year. Call them, and ask specifically about the after-sale experience: warranty responsiveness, the punch list, how reachable the builder was once they had the money. That's where good builders and bad ones separate, and it's the single best signal you can get.

6. They won't let you see a finished unit in person

Photos hide an enormous amount. A builder confident in their build quality wants you to stand inside a finished unit — you'll learn more about craftsmanship in five minutes in person than in a week of online research. Reluctance to show you one is telling.

The throughline

Notice the pattern: almost every red flag comes down to specificity and accountability. Good builders give precise answers and put them in writing. They tie your money to completed work. They connect you with real recent customers. They show you their product. The risk isn't usually outright fraud — it's vagueness that turns into finger-pointing once you've paid.

Slow down, ask these questions, and weight the recent-customer phone calls over reviews and brand longevity. It's a big purchase and worth getting right.

If you're early in the process and figuring out the cost and rules side too, we've put together a couple of honest resources for Utah buyers: an ADU cost breakdown with a calculator and a city-by-city ordinance tracker covering the new SB284 rules. And if you'd like to see our build quality for yourself, our floor plans are a good place to start.