How Fast Can You Actually Build an ADU? (One Family's 84-Day Story)

By Buz Artiano, BuildX | March 2026

Watch: How She Built Her Dream Home in 84 Days | Massachusetts Design-Build Story

Every family who's thinking about building an ADU wants to know how long it will take. One of the biggest reasons that families hesitate to build is the fear of the dreaded construction project that drags on for months and disrupts everyone in the house. You worry that the project will just sail right on by all the projected deadlines. You hear stories about renovations that were supposed to take four months and ended up taking eighteen, and that really does happen, your fear is justified. In residential construction, missed timelines are just what is expected.

My name is Buz Artiano, and I am the founder of BuildX. We've built dozens of ADU projects across Massachusetts, mostly around the South Shore and Plymouth County areas. We are the only team you need, we handle design, permitting, and construction. So we see every phase of a project from the first site visit up until you move in. We deal with septic constraints, zoning issues, and the state's new ADU laws under the Affordable Homes Act.

Sherie and Michael Bartlet are BuildX clients. We built their ADU in Plympton, Massachusetts, in their daughter's backyard. We broke ground on May 19th and they moved in on August 11th. That's only 84 days from start to finish. That's not some marketing number we just threw out there, it's a documented timeline from a real family in a real Massachusetts town.

Of course we want to share stories from families who had a great experience with us, but there's a reason we are sharing the Bartlets' story in particular. They explored all kinds of options for their living situation before choosing BuildX. They met with us after other builders didn't call back or follow through, and they could see that this was how the construction process was going to go. Their story and perspective on our timeline is more useful to you than anything we could say about ourselves.

How Long Does ADU Construction Actually Take?

The honest answer is that the timelines vary based on your specific project, but an ADU built by a single design-build team can move way faster than most people think. The Bartlet family's ADU in Plympton went from excavation to move-in in 84 days. Patrick, our excavator, started the driveway on May 15th. We started digging the basement on May 19th and Sherie and Michael moved in on August 11th.

Sherie told us that the speed we moved was almost disorienting. One day the walls were up and then all of a sudden the roof was on, and then they were already moving furniture in. None of that just happens by accident. It comes from careful planning where one company controls every trade, all the materials, and every inspection. There's no waiting for subcontractors that are also working on multiple other jobs. You also won't be waiting two weeks between framing and rough-in because the HVAC crew is booked on another job.

To kind of put it in context, most ADU projects in Massachusetts take six months to over a year when the homeowner is the one coordinating things like permitting, architects, general contractors, and specialty trades. The difference has nothing to do with cutting corners, it's about not having that dead time between phases.

What Factors Determine How Fast Your ADU Gets Built?

Several different things will decide whether your project finishes in three months or goes on for over a year. If you know what those things are before you start, it's the difference between realistic expectations and major disappointment.

Foundation type. The Bartlets' ADU has a full basement, which added some time for the digging, but now they have a nice clean mechanical room downstairs. Slab-on-grade foundations are faster to pour but then you don't get that extra storage and mechanical space. A crawl space is somewhere in between. What you choose for your foundation will affect the timeline and also where your HVAC equipment lives and how easy it is to get to when you have to do maintenance in the future.

Site conditions. A flat, dry lot with easy truck access can move along quicker than a sloped lot with ledge, wetlands, or a long setback from the road. The Bartlets needed a new driveway before construction could even start, so we had Patrick handle that a few days before the basement dig started.

Permitting lead time. The 84-day number applies to the construction phase only. Before any construction can even start, your project needs a solid design, a building permit, and in most Massachusetts towns, a Board of Health review for septic capacity. Permitting can take anywhere from a few weeks to a few months depending on your town and whether or not you have to upgrade your septic.

Builder model. This is the one that most families underestimate. When one company handles design, permitting, and construction, the schedule is controlled by that team and that team only. When you hire an architect, then separately bid the project to a general contractor, then the general contractor has to coordinate and schedule a bunch of other subcontractors, that creates a ton of delays. People lose months of time just waiting on work to be done by different subcontractors.

Why Do Most ADU Projects Take So Much Longer Than Expected?

The number-one reason ADU projects drag isn't because of bad weather or running out of materials. It's all the scheduling being broken up into so many different pieces and waiting on so many different people. In a traditional type of construction, your general contractor is hiring and scheduling subcontractors who are also working on other projects. So when your electrician finishes up, the plumber can't start for another two weeks. Then when the plumber finishes, the insulation crew is still three weeks out. All of that time adds up fast.

The second reason things get delayed is making changes during construction. When a homeowner sees the framing go up and then wants the bedroom window to be six inches to the left, that change costs time and money. The framer then has to come back a second time and the window order changes. Then the siding crew has to adjust their schedule, so making one small change can escalate until you've lost over a week's time.

We build every ADU with nine-foot ceilings, which was exactly what we recommended to the Bartlets because their home is so small. But we decided that before construction started, not after the framing had already started. We've built enough of these to know that nine-foot ceilings in a smaller house makes the space feel a lot bigger. We make that call during the design phase and not mid-build. Deciding something like that during the build is what will keep a project from staying on schedule. Every design decision we make before breaking ground is just one more decision that can't slow us down.

The third reason things often get delayed is uncoordinated inspections. In Massachusetts, a building inspector, an electrical inspector, and a plumbing inspector all need to sign off at various stages. If you don't have those inspections scheduled way in advance you can end up waiting for weeks or even more just to get that sign off.

What Happens Before Groundbreaking That Most Families Forget to Plan For?

The 84-day construction timeline we keep talking about is the build phase only. Before Patrick started digging on May 15th, we had already finalized the project's design, engineering, and permitting. Most people tend to focus on the construction calendar and forget about the months of preparation that have to come first.

At BuildX, the typical pre-construction phase includes a site evaluation where we assess your lot for buildable area, septic capacity, utility access, and setback compliance. Then we start the design, where the floor plan, elevation, and specifications are all chosen and finalized. Then we turn in paperwork for a building permit and sometimes a Board of Health review. Then once we have the permits we go ahead and schedule the excavator.

For families planning the timeline for their ADU project, plan for a pre-construction phase of several weeks to a few months depending on how fast your town issues permits, and then a construction phase of roughly three to four months for a typical BuildX ADU. The Bartlets' ADU was done in only 84 days.

Is an 84-Day Build Realistic for Every ADU Project?

No. And we'd never tell you otherwise. The Bartlets' 84-day timeline is a real number from a real project, but their project had all the right conditions. A buildable lot, a quick permitting process, and a family who made design decisions early and stuck with them.

If your lot requires a septic system upgrade, that can add weeks to the pre-construction phase and potentially to the build itself. If your property is in a nitrogen-sensitive zone or requires a zoning variance, unfortunately it can take months just to get those permits. If you change the floor plan after framing is complete, that delays every single trade that has to come do work after that.

We're not trying to say that every BuildX project finishes in 84 days. We're just showing you what is possible when the process is controlled by a builder who manages every phase and design options are locked in. Some projects take longer. The question to ask any builder is not just "how fast" but "what controls your schedule, and what could slow it down?"

What Did the Bartlets Say About the BuildX Experience?

Sherie Bartlet said that the construction process went really fast once it started. She recalled watching the walls go up and the roof was up almost immediately after that. She couldn't believe the pace, but that wasn't the only thing she noticed.

Before choosing BuildX, the Bartlets had looked at all kinds of other options for their living situation. Sherie told us about other builders who didn't call back and didn't show up. But she said "Buz and BuildX were the first ones who didn't drop the ball, they met with us right away. It was just boom, boom, boom." The good communication didn't stop after they moved in either. Sherie mentioned that she can still text Buz or Stevie and get an immediate response for any small thing that comes up.

She also named the BuildX team members individually: Justin, Aaron, Jeff, Kevin, Stevie, and Patrick. "I feel like they're just part of our family now," she said. "It's weird that they're not here every day." You don't get that kind of builder-client relationship on a project where the crew rotates weekly and the homeowner never meets the same person twice.

If you are in a similar situation, exploring options for where and how to live, and feeling frustrated by builders who don't call you back, the Bartlets were in the same spot before they found us.

Your ADU Timeline Starts with a Conversation

The Bartlets went from first meeting to move-in within a single season. They didn't spend a year waiting for a place to live. They didn't have to coordinate a dozen contractors. They worked with one team that controlled the design, the permits, and the build. All of that put together is what made 84 days possible.

Your timeline depends on your lot, your town, and your design decisions. The fastest way to find out what is realistic for your property is to talk to us.