How to choose an ADU builder in Denver

The paperwork anyone can verify

1. Denver contractor license. Look the company up in Denver's contractor licensing records — confirm the license class covers residential new construction (for detached units), that it's current, and that it's held by the company quoting you, not a different entity.
2. Insurance certificates. Ask for current general liability and workers' comp certificates naming the builder, and confirm dates. A serious builder sends these within a day without friction.
3. Permit history. Denver's public permit records show what a company has actually permitted. A builder claiming "dozens of ADUs" with two permits on record has answered your question.
4. Complaint scan. BBB record, Google reviews read for patterns (not stars), and any public actions. One angry review means nothing; the same complaint three times is data.

Questions that expose real ADU experience

ADUs are a specialty hiding inside general construction — the failure points are Denver-specific. Ask these and listen for specifics, not confidence:

• "How many ADUs have you completed in Denver, and in which neighborhoods?" (Suburban or mountain-town experience doesn't transfer to Denver's bulk-plane and rear-35% rules.)
• "Who prepares and submits the permit set — you or me? Who handles the SUDP?" (The right answer: they do, it's in the price.)
• "What did your last project's utility trenching cost, and how do you price that risk?" (Tests honesty about the classic overrun.)
• "Have you taken a project through landmark review?" (Only matters in historic districts — but if you're in one, it's disqualifying if they haven't.)
• "What's your current start backlog and realistic construction duration?" (Compare their answer to the typical timelines; anyone promising half the normal duration is pricing a promise they won't keep.)

Reference calls that actually tell you something

Ask for two completed ADU clients and one current one — the current client knows what communication feels like mid-project. Three questions per call: Did the final price match the contract, and what caused any change orders? How did they handle the thing that went wrong? (Something always does — you're testing the response, not the absence of problems.) Would you use them for a second unit?

Contract terms that protect you

• Fixed scope with an allowances schedule — vague scope is where budgets die.
• Milestone payments — small deposit, payments tied to completed stages (foundation, framing, rough-in, final), never large sums ahead of work. Colorado law limits what can be demanded up front; be wary of anyone pushing hard against that.
• Named timeline with a start window, plus how delays are communicated.
• Lien waivers from subcontractors as payments are made.
• Warranty terms in writing — structure and systems, with durations.

Walk away when you see

• A price far below every other bid — in this market that's a scope you'll pay for later, not a bargain.
• Pressure to skip permits or "handle it as a remodel." Unpermitted ADUs can't be legally rented and surface at sale.
• License held by a different company name than the one contracting with you.
• Large upfront payment demands or cash-only terms.
• No physical project you can visit or drive past.