How Much Does a Home Addition Cost in Massachusetts? (2026)
A home addition in Massachusetts costs about $60,000 to $300,000 or more as of 2026, depending on whether you build out or build up. A single-story addition (400 to 600 sq ft) runs $60,000 to $160,000. A second-story addition (800 to 1,000 sq ft) runs $200,000 to $280,000 or more. The biggest cost driver is whether your existing frame and foundation can carry the new work without reinforcement.
How much does a home addition cost in Massachusetts in 2026?
Massachusetts addition costs vary by type and size. That data comes from Schlickmann Construction's Massachusetts cost guide, published May 6, 2026.
| Addition type | Massachusetts cost range |
|---|---|
| Bump-out | $20,000 to $60,000 |
| Single-story addition (400 to 600 sq ft) | $60,000 to $160,000 |
| Second-story addition (800 to 1,000 sq ft) | $200,000 to $280,000 |
| In-law suite or ADU | $80,000 to $180,000 |
These numbers are a Massachusetts market snapshot, not a Walbridge Construction quote. Michael walks your actual home before any number goes on paper.
Every job starts with a free, no-obligation estimate. Request a free estimate and get a real number for your project, not a statewide average.
A bump-out or single-story addition works well when you have side or rear yard space and do not need to touch the roofline. A second story or an in-law suite fits a small or narrow lot with nowhere left to build out. Which one fits your home depends on your lot, your local zoning setbacks, and what your foundation can carry.
Why does a second-story addition cost more than building out?
A second story runs $200,000 to $280,000 for 800 to 1,000 square feet. That is far more per square foot than a single-story addition. The reason is what is already there, not what you are adding.
The median Braintree home was built in 1957. About 55 percent of the town's 15,163 homes were built before 1960. A home that age was framed to carry its original roof, not a new floor on top of it. Adding a second story usually means reinforcing the walls and foundation below it first. That reinforcement work, not the new square footage itself, is what pushes the price up.
Massachusetts renovation costs also run about 25 percent above the national average overall. Build up or build out, expect your project to land above a generic national number.
Why do South Shore homeowners add on instead of moving?
Only 14 percent of Braintree's homes were built in 2000 or later. Across the built-out inner South Shore towns, there is not much open land left to build on. So homeowners grow their square footage where they already live instead of buying a new lot.
That is why second stories, garage conversions, and rear family-room additions are the standard project shape here, not the exception. We see the same pattern across homes in Braintree and the surrounding South Shore.
Do you need a permit for a home addition in Massachusetts?
Yes, always. Massachusetts building code Section R105.1 makes it unlawful to construct, add on, or alter a structure without a permit first. There is no small-project exemption for an addition the way there is for a small deck.
Many South Shore towns, including Braintree, run their permitting through one Building Division that reviews building, electrical, plumbing, and gas permits together, often with online submittal. Michael Walbridge holds a Massachusetts Unrestricted Construction Supervisor License, so he pulls the permit under his own license and schedules the required inspections. That paperwork sits on us, not on you.
If you also want the deck-specific permit rules for the same building code, our Massachusetts deck permit guide covers footing depth and inspection timing in detail.
What else drives the price up or down on your addition?
Five things move a Massachusetts home addition price more than anything else. We quote against all of them on every home remodeling job.
Size and scope. A small bump-out has less new framing, roofing, and finish work than a full second story, so it costs less.
Layout changes that move walls, plumbing, or wiring. Tying a new room into the existing floor plan without moving pipes or circuits keeps cost down. Rerouting them adds labor fast.
Material and finish grade. Standard trim and flooring cost less than custom millwork and high-end finishes.
What we find once walls are open in older South Shore homes. Older framing, wiring, and plumbing behind the walls are common in a house built before 1960. A clean tie-in keeps the estimate on target. A hidden problem adds a real repair cost. If we find rot, undersized framing, or old wiring once a wall opens, we show you what we found before we fix it, not after.
Permit and inspection requirements. Any new footing for a ground-level addition has to go below 48 inches, the frost line depth set statewide by the Massachusetts building code. Pour a footing too shallow, and a New England winter can freeze the ground under it and crack it. Getting the depth right the first time is one thing the permit inspector checks.
A garage conversion is a lower-cost way to add living space, since the walls, roof, and foundation already exist. It typically runs $80 to $150 per square foot in Massachusetts, well under the cost of framing a brand-new addition from scratch.
Get a free estimate from Walbridge Construction
We are a veteran-owned general contractor based in Hull, MA. Michael has more than 20 years of hands-on building experience. He holds a Massachusetts Construction Supervisor License. He is also a registered Massachusetts Home Improvement Contractor. We build additions across Hull and the surrounding South Shore, including Hingham, Cohasset, Scituate, Quincy, Weymouth, Braintree, Norwell, and Marshfield.
We respond within 30 minutes of your call or message, and financing is available if you want to spread the project cost over time. Every estimate is written and clear before work begins, so you know the real cost for your addition, not just a statewide range. Call (857) 326-7157 or request a free estimate.
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FAQ
Related questions
Does a small bump-out still need a permit in Massachusetts?
Yes. Section R105.1 of the Massachusetts building code makes it unlawful to build, add on, or alter a structure without a permit. Unlike a small deck, there is no size exemption for an addition. Even a modest bump-out needs a permit before work starts.
How long does a home addition take?
Most Massachusetts home additions take 12 to 24 weeks from start to finish, based on 2026 market data. Michael gives you a clear, written timeline for your specific project before any work begins, so you know what to expect.
Is a garage conversion cheaper than building a new addition?
Often, yes. A garage conversion typically runs $80 to $150 per square foot in Massachusetts, well under the $60,000 to $160,000 total cost of a new single-story addition, because the walls, roof, and foundation already exist. The tradeoff is losing covered parking and storage space.