Finding a contractor who says they can build an ADU is easy. Finding one who actually knows what they're doing is a different story. Here are eight questions to ask any builder before you sign anything — and what good answers look like.
Why ADU work is different from general contracting
An ADU isn't just a room addition. It involves zoning compliance, separate utility connections, permitting under Massachusetts' new ADU law, and design work that has to hold up to inspection. A contractor who's great at kitchen remodels but has never pulled an ADU permit is starting from scratch on your project.
That's not a risk worth taking on a $150,000–$300,000 build.
The questions below aren't meant to trip anyone up. They're meant to help you quickly figure out who knows this work and who's figuring it out as they go.
The 8 questions to ask any ADU builder
1. How many ADUs have you completed — and can I see finished ones?
Not in-progress. Not framed up. Finished. You want to see completed units with photos, finishes, and ideally a walkthrough. A builder who can't show you finished ADU work from the last couple of years is not an ADU specialist — they're a general contractor who's willing to try.
2. Are you licensed and insured in Massachusetts?
Non-negotiable. ADU construction in Massachusetts requires a licensed general contractor. Before any other conversation, verify they hold a valid Construction Supervisor License (CSL) and Home Improvement Contractor (HIC) registration — both verifiable through the Massachusetts Division of Professional Licensure. They should also carry general liability insurance and workers' comp. If they hesitate on any of this, stop there.
3. Do you handle design and permitting, or do I need to hire separately?
This one matters more than most people realize. A lot of contractors build to plans — meaning you're responsible for hiring an architect, getting designs stamped, and coordinating permits yourself. That adds cost, time, and a whole lot of back-and-forth.
When design and build are handled by separate teams, things get lost in the handoff. Your vision gets diluted. Timelines slip because one party is waiting on the other. A design-build firm that handles everything under one roof is a fundamentally different — and smoother — experience.
4. Do you know Massachusetts ADU zoning — including the new 2025 law?
Since February 2025, ADUs are legal by right in single-family zoning districts across the state. But "by right" doesn't mean no rules. Setbacks, size limits, utility requirements, and short-term rental restrictions still apply town by town. Your builder needs to know the law and know your specific town. If they're vague about local zoning or can't speak to the Affordable Homes Act, that's a gap you'll eventually pay for.
5. What does your feasibility process look like?
A good builder doesn't jump straight to design. Before anything gets drawn, they should be assessing your lot — zoning compliance, setbacks, utility capacity, realistic budget. If a contractor skips this step and goes straight to drawings, you're at risk of designing something your lot can't support.
Anyone who will start designing your ADU without first checking whether your property can actually handle one is a red flag.
6. Who's actually doing the work — your crew or subcontractors?
Both models can work, but you deserve a straight answer. If they're using subs, ask how they're managed and whether they've worked together on ADU projects before. A patchwork of subcontractors who've never coordinated on this kind of build increases your chances of miscommunication, delays, and inconsistent quality.
7. How do you handle delays — and how do you communicate when things come up?
Delays happen. Permits take longer than expected, materials get backordered, inspections get rescheduled. What separates good builders from frustrating ones isn't whether delays happen — it's how they handle it when they do. Ask specifically: who contacts you, how often, and through what channel. The answer should be simple and direct. If it's not, that's your preview of what communication looks like mid-project.
8. What does your warranty cover?
Get specifics. Workmanship warranties typically range from one to ten years depending on the contractor and what's covered — structural, plumbing, electrical, finishes. A builder who's vague about warranty coverage or buries it in fine print is one who doesn't want to be held accountable after the job is done.
One thing to check before any conversation even starts
Before you book a single consultation, look the contractor up and read their reviews — not just on their own site. Check Google, Thumbtack, Houzz, and the BBB. Pay attention to how they respond to any negative reviews. A contractor who gets defensive or dismissive when something goes wrong tells you everything you need to know about what it's like to work with them mid-project.
Word of mouth still matters too. Ask around. A builder who does good work in a community tends to be known in that community.
What to look for in Massachusetts specifically
ADU work in Massachusetts has its own wrinkles. The new state law opened the door, but local towns still have their own interpretations of setbacks, parking, and short-term rental rules. You want a builder who has pulled ADU permits in your county — not just someone who's done general construction somewhere in the state.
Ask them directly: Have you built ADUs in my town or nearby? Do you have relationships with local inspectors? Experienced builders know local inspectors, and that relationship matters when it comes to keeping your project on schedule.
The right ADU builder asks as many questions as you do. They check your lot before they pitch you a design. They give you a real timeline, a real budget, and one person to call when you have questions. If you're a Massachusetts homeowner exploring what's possible on your property, we're happy to be one of the builders you talk to.
What's possible on your property?
Tell us about your project and we'll schedule your free consultation.