How Long Does ADU Permitting Take in Massachusetts?

By Buz Artiano, BuildX | February 2026

We have spent over 14 years dealing with the Massachusetts permitting process, and what we know is that questions about the timeline of a project are the ones that seem to keep people up at night. Not because the answer is bad, but because nobody seems to want to answer the question realistically and upfront.

Most people have no idea whether permitting will drag on for six months or whether it takes a quick two weeks for approval. Everything depends on your town and your property conditions. We've built dozens of ADUs across Massachusetts, so we know that once you understand the variables, it's not hard to plan around them.

At BuildX, we handle all the permitting for every ADU we build in the state of Massachusetts. We track the timelines, we know which towns move fast and which ones take longer and require some patience. We know exactly what causes delays and how to avoid them.

What Is the Typical ADU Permitting Timeline?

From a dead start to building permit in hand, expect 90 to 120 days. That includes getting your property surveyed, getting septic or sewer approvals, and waiting for the building department to process your application.

If your septic system is already approved and in good condition, you're only looking at 60 to 90 days. Getting an answer on septic usually takes the longest because it involves Board of Health scheduling, perc tests, and sometimes Title V inspections.

Once you actually file for a building permit, the building department usually has 30 days to respond. A lot of time you can see some back-and-forth on their online platform, like questions from the tax collector or other departments, and small changes. We've had permits come through in two weeks, and we have had them take the full 30 days or even longer.

Why Do Permitting Timelines Vary So Much Between Towns?

Massachusetts towns all interpret the building codes differently. The language in any code tends to be a bit vague and not always very specific. How we read that code and how the individual town's authority interprets it can be completely different. That means the same project can take two weeks in one town and several months in another.

Here's what we've seen from some of the towns we've worked with:

Freetown: Permit in two weeks once Board of Health was done. Permit fee was $410.

Plymouth: Very simple, everything is online. We filed for a zoning permit and they issued it in one day.

Hanover: Can be as quick as a week for the building permit once you have all the documents ready.

Marshfield: Somewhere in between. Not as fast as Hanover, not as slow as some of the more difficult towns.

Scituate: Can take months. Scituate has historically been one of the more challenging towns for ADU permits.

Permit fees also vary dramatically. The same permit that costs $410 in Freetown costs $3,000 in Kingston. The price is unrelated to how fast or slow the process moves, but it's good to always know what you're budgeting for.

What Steps Make Up the Permitting Process?

The permitting process has several phases, but a few of them you can be working on at the same time:

Property survey: This is your starting point. You need a licensed surveyor to document your lot lines, existing structures, setbacks, and any wetlands. Getting on a surveyor's schedule can take six to eight weeks depending on the season.

Septic or sewer determination: If you are on septic, you need approval from the Board of Health. They may need to do a perc test, Title V inspection, or septic design. If you are on sewer, you need to talk to the city and confirm sewer capacity and probably pay a connection fee. We did a project that required a $7,000 water connection fee before we could even file for the building permit.

Zoning permit: Some towns offer a separate zoning permit that locks in the location of the ADU. They're usually about $100 and good for one year. We try to get these first whenever they are available because they check another box. In Plymouth, the zoning permit is separate and very fast.

Building permit: Once you have your survey, septic approval, and final plans, you file for the building permit. The building department has 30 days to approve or deny. Most towns are using online portals for all this, which is nice because then there's a record of all communications.

What Causes Permitting Delays?

Wetlands are the most common cause of unexpected delays. If you have wetlands on your property, you need to deal with that before you do anything else. There's no way around it and no way to stay under the radar. You need to hire a professional surveyor, hire a botanist, have them flag the wetlands, have the surveyor pick it up, and then submit all that to the Conservation Commission. Waiting on wetland line approval can take weeks or even months.

Zoning Board of Appeals requirements: If your project needs ZBA approval, even if they decide in your favor, there's still a 21-day appeal period afterward. The decision gets certified by the town clerk about a week after the meeting, then you have to wait the 21 days. So that's a month of waiting you can't avoid if ZBA is involved.

Incomplete applications: Submitting an application without meeting with the building inspector, zoning officer, or Board of Health beforehand is a bad idea and will usually be the reason you have to re-do the whole application. The secret to good permitting is knowing the town's requirements and meeting with whoever you need to ahead of time and before you submit anything.

Town capacity: A lot of towns are working through all the changes the new state ADU law put in place. Some of them are getting in trouble with the Attorney General's office and having to go back and fix the wording in their zoning laws. When municipalities pass new zoning regulations, there's a 90-day review period by the AG's office. That's another thing that can slow you down as the towns adjust.

How Can You Speed Up Your Permitting Process?

The best way to speed up permitting is to do the homework before you file:

Meet with town officials early: Bring your site plan and preliminary set of plans to the building inspector, zoning officer, and Board of Health. Ask any questions you can think of. Ask for their input. Having this conversation can save you months of going back-and-forth with them later.

Start the survey immediately: Surveyors are very busy. You need to get on their calendar as early as possible. This makes sure everything else can move forward while you wait.

Address wetlands proactively: If your property is on wetlands, get them flagged and approved before you do anything else. That's the biggest wildcard you can deal with upfront that can affect your timeline.

Grab the zoning permit first: If your town offers a separate zoning permit, get it as soon as you know where you're going to put the ADU and you have the survey done. It's kind of like cheap insurance that locks in your approval for a year.

We can't control the permitting process. No builder can. If you live somewhere with a history of difficult permitting, or if your property has wetlands, variances, or other complications, you really need to plan for extra time. Some projects genuinely take longer than others, and a builder who promises fast permits regardless of your situation is a red flag because that's just not realistic. All we can control is how well we prepare, how well we understand the town's requirements, and if we deal with potential issues upfront before they slow us down.

Ready to Map Out Your ADU Timeline?

From a dead start, most Massachusetts homeowners should expect 9 months to a year from consult to move-in. Permitting is 90 to 120 days of that. Construction is another 100 days once we break ground. If it's going to take longer than 100 days for construction, we'll tell you upfront and explain the reasons why.

If you want to understand what the permitting timeline looks like for your specific property and town, that starts with understanding your site conditions. We can walk through the variables that apply to your situation and give you a realistic range based on what we've seen in your area.