ADUs & In-Law Units Built for the Long Term.
Detached ADUs, garage conversions, and backyard cottages from a Rhode Island contractor who handles design coordination, permits, and construction.
ADUs / Accessory Dwelling Units across Southern New England.
J-One Construction builds accessory dwelling units across Rhode Island, Massachusetts, and Connecticut. Detached ADUs, in-law suites, garage conversions, and backyard cottages — planned around how your family actually needs to use the space, whether that's aging parents, adult children, or long-term rental potential.
ADU projects live and die on planning: town zoning, setbacks, utility routing, and layout have to line up before framing starts. We help you evaluate feasibility, coordinate with designers and surveyors, and then build the unit itself.
Every ADU we build is treated like a small custom home — real foundation, proper insulation, a functional kitchen and bath, and finishes that match your primary house.
Related services
What we handle on adus / accessory dwelling units projects.
Why homeowners choose J-One Construction.
Owner-run, locally accountable, and organized enough to keep projects on schedule without cutting corners on the finish.
- Clear communication start to finishYou'll know what's happening, when, and why — every step.
- Detailed written estimatesScope, materials, and price in writing before we start.
- Reliable schedulingRealistic timelines you can plan around.
- Clean, respectful job sitesDaily cleanup and property protection are standard.
- Quality materialsProducts we'd install in our own homes.
- Professional crewsExperienced tradesmen, not day labor.
- Local accountabilityOwner-run out of Rhode Island. We're not going anywhere.
- Final walkthrough before completionNothing gets called done until you sign off.
How your adus / accessory dwelling units project comes together.
Quick call to understand what you're planning.
On-site walk-through with photos and measurements.
Written scope, materials, and pricing.
Choose finishes and lock in the plan.
Confirmed start date and project schedule.
Our crew executes the plan.
You review every detail before we call it done.
Finishes and upgrades we recommend.
Every project is different. During the estimate we walk through the material options that best fit your budget, timeline, and how you'll use the space.
- Slab or full foundation options
- Utility coordination (water, sewer/septic, electrical)
- Compact kitchenette layouts
- Efficient bathroom layouts
- Accessibility upgrades (zero-step, grab bars, wider doors)
- Compact storage systems
- Exterior finishes to match the primary home
- Privacy-focused layouts and window placement
Your family needs more flexible space — aging parents, adult kids returning home, a home office, or rental income — but adding on to the main house isn't the right answer.
A purpose-built ADU or in-law unit that adds long-term property value, keeps family close, and stays independent from the main home.
Not sure if it's time?
If one or more of these sounds familiar, it's worth a free on-site consultation.
- You need space for aging parents
- You want proper guest quarters
- You're exploring long-term rental income
- Adult children are moving home
- You need a detached workspace
- You want flexible, future-proof square footage
- You have an existing garage or backyard with potential
Straight talk on cost.
Every project is priced individually. These are the biggest factors that move the number up or down.
Serving Southern New England's most prestigious communities.
Rhode Island
Warwick Neck
Waterfront Peninsula Homes
East Greenwich
Colonial Renovations
South Kingstown
Coastal Farmhouses
Narragansett
Oceanfront Estates
Newport
Coastal Estates
Jamestown
Island Retreats
Westerly
Watch Hill Beach Homes
Providence East Side
Historic Restorations
Massachusetts
Cape Cod
Shingle-Style Cape Homes
Newton
Victorian Restorations
Connecticut
Groton
Thames River Waterfront
Mystic
Historic Village Homes
Stonington
Coastal Borough Estates
Have a project in our service area?
Tell us what you're planning and we'll let you know if your project is a good fit for our schedule.
Questions about adus / accessory dwelling units?
Plan the ADU that fits your family and your property.
Tell us about your adus / accessory dwelling units project and we'll follow up within one business day to schedule your free on-site consultation.
- (888) 401-5136
- Rhode Island · Massachusetts · Connecticut