Can I Trust the Setback Numbers on My Town's Website When Planning Where My ADU Goes?

By Buz Artiano, BuildX | August 2026

Watch: The Creighton Family Built an ADU in 98 Days, Here's the Full Story

You have walked your lot and you know where the ADU will go because you've been picturing it in that spot for months. You checked the town website, found your parcel, and measured the distance to the property line. According to the numbers you have room. Where to put the ADU seemed decided and the only left are the plan and the builder.

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 do the design, permitting, and construction. So we see every phase of a project from the first site visit up until you move in. We evaluate septic constraints, zoning issues, utility connections and the requirements for a permit from the city. We're the ones who deal with the zoning office when it comes to deciding where the ADU is allowed to sit.

Terry and Abby Creighton are BuildX clients and we built their 900-square-foot ADU above a garage in Plymouth for Abby and her partner, Raya. In the beginning of the project the town's website, the assessor's site, and three different mapping programs we use all gave us the same setback. But they were all wrong and the building moved.

You'd think a builder would talk about the projects where everything went according to plan. We are talking about this one because we got a number wrong on it and the Creightons had to deal with the consequences. Terry Creighton has said on the record that we didn't mislead them and that nobody was at fault. We take ownership anyway, because the entire problem could be avoided with one phone call.

Can I Trust the Setback Numbers on My Town's Website?

No. The published number that's published is just a starting point for planning, and it's not the number that determines your permit.

A setback is the distance a town says you must have between a structure and the property line. It shows the outer boundary of where a building can legally sit, which means it also determines the length of your driveway, your excavation, your utility runs, and how much of your lot must be cleared. GIS is the online geographic information system most Massachusetts towns use. GIS will put that requirement onto a map you can click through in about ninety seconds. The rendering is a convenience but the bylaw is a requirement.

On the Creighton lot, four different sources agreed with one another and all four were wrong. The correction was the result of a phone call to a person, not from a better map.

What Happened When We Believed the Mapping Software on a Plymouth Lot?

Terry Creighton wanted an on-site visit before any design work started, because she knew the lot was unusual. In her words: "I've got to get them at the house cause it's got such unique topography. And so I, it's quite a hill." We drove out that afternoon.

We drew up the initial plan with the location just off the existing driveway approach, where the ground was workable and the distance from the street was short. The town's website said the setback allowed it and the assessor's site said the same thing. Three separate mapping programs said the same.

Then we called the Plymouth zoning officer. He said 70 feet. That number is what the zoning officer told us for this specific project, and we aren't saying that it's a townwide rule. What's important for your property is how we got the information rather than the number itself. A person at the zoning office read the requirement that applies to that specific parcel and it didn't match what four other sources had told us.

We take responsibility for that. We were convinced it was 40 feet and Terry Creighton said "I was too." Four sources saying the same thing isn't confirmation of something. It's just one assumption given rendered four times.

What Moving the Building Added to the Creighton Project

The only location that worked with the correct setback was the back right corner of the lot, which the family had already decided against. "We had ruled out as a fantasy, the spot where it currently is," Terry Creighton said. "We're like, oh no, that's not even possible. It's so steep."

Everything that happened on this project goes back to that one relocation: a longer driveway going across the front of the property, tree clearing on ground that the family never planned, the relocation of a mature vegetable garden, and a gap in the financing once savings ran out. Those four consequences are the total cost story, and they're what to expect anywhere a building has to be moved after the plan is already drawn.

Here is what each one costs. The tree work is just an estimate of what a service would have charged, because the family did the labor themselves.

We can't give you the cost of the relocation as a single dollar figure, because the added work wasn't added to the total project. Abby Creighton described the effect plainly: "We had like emptied out our savings. So we had to find an additional loan." That's the honest version. A setback correction isn't an item on the budget, but it's there as a longer driveway, more excavation, more clearing, and a budget that isn't enough for the project.

Terry Creighton's description of the ground the building landed on was, "In the most difficult, spatially, terrain wise spot." The finished ADU sits there today, and we think it looks better than the original location. Terry Creighton agrees: "It looks great there." None of that changes however, what it cost to get there.

How Do I Get the Real Setback Number Before I Spend Money?

Call the zoning office and ask. That's the entire answer.

Give them your address and parcel identification, and ask what the setback is for an ADU on that specific lot. You should do that before you pay for a design, and before you decide on a location, and before you make a budget for a specific size. A zoning officer can answer a direct question about one better than any map you can pull up.

Massachusetts allows one ADU by right in single-family zoning districts under the Affordable Homes Act, and homeowners think that means the placement of the ADU is settled. By-right only deals with the use. The dimensions, building code and health code still decide where the structure can be built, and those are dealt with at the city level. You can review the state requirements at mass.gov.

Online parcel maps only show a bylaw, they aren't that bylaw. A map doesn't tell you which specific figures and conditions apply to your lot. We now always check the setback with the zoning office before anything is drawn up because the setback isn't a design preference. It's the number everything on the project gets measured from. Driveway length, excavation depth, utility runs, clearing volume are not independent numbers. They are all related to the placement and that is why placement is the first thing we check and the last thing we want the homeowner to have to guess at.

When Does the Real Number End the Project?

There are lots where the setback doesn't leave any space for building at all, and we'd rather tell you that at the first than after you've paid for a design.

We build detached ADUs, so you'd expect us to push you toward one. On a property where the real setback doesn't leave a usable space, a detached ADU is the wrong answer, and the best options are to build an attached addition, convert your existing home, or make a request to your town that we don't control. On the Creighton lot the space was there but it was on the worst ground on the property, and the family decided to accept the terrain, the driveway, and roughly 100 trees of their own labor to get it. That was their choice to make, knowing what the real costs were, which is the only way anyone should be making it.

If you are looking at a certain location you've already committed to emotionally, that's exactly where this goes wrong. The Creightons had walked their lot enough times to rule out the one place where their ADU now stands and the number decided it.

Find Out Where Your ADU Can Actually Go Before You Pay for a Design

One phone call to your town's zoning officer, made before you start the design process, is the cheapest way to control your risk on an ADU project. The Creightons discovered their real number early enough that the ADU was still built, and the costs were as result of driveway length, clearing, and a budget that had to stretch.

Always verify the setback for your parcel and then decide where the building will go.