Home addition contractors in New England
An addition is new construction attached to an existing building, which means it carries every trade at once plus the hardest part — tying new structure, roof, and systems into old ones that were never built to current code.
Mid-range cost by metro
A 400 sq ft scope at a mid-range finish, with each metro's cost factor applied and a 10% contingency included. Estimates for budgeting, not quotes.
| Metro | Low | Likely | High |
|---|---|---|---|
| Boston, MA1.12× metro factor | $178k | $242k | $323k |
| Worcester, MA0.94× metro factor | $136k | $186k | $248k |
| Providence, RI1.02× metro factor | $139k | $190k | $254k |
| Hartford, CT0.98× metro factor | $138k | $188k | $250k |
| Manchester, NH1.00× metro factor | $128k | $175k | $233k |
| Portland, ME1.06× metro factor | $131k | $178k | $238k |
| Cambridge, MA1.14× metro factor | $181k | $246k | $329k |
| Lowell, MA0.96× metro factor | $152k | $208k | $277k |
| Springfield, MA0.90× metro factor | $124k | $169k | $226k |
| Stamford, CT1.10× metro factor | $157k | $214k | $286k |
| New Haven, CT0.99× metro factor | $137k | $186k | $248k |
| Portsmouth, NH1.05× metro factor | $131k | $178k | $238k |
| Nashua, NH1.01× metro factor | $130k | $177k | $236k |
| Bangor, ME0.93× metro factor | $110k | $150k | $201k |
| Burlington, VT1.03× metro factor | $127k | $173k | $231k |
| South Portland, ME1.03× metro factor | $127k | $173k | $231k |
| Westbrook, ME1.00× metro factor | $123k | $168k | $224k |
| Scarborough, ME1.04× metro factor | $128k | $175k | $233k |
| Falmouth, ME1.07× metro factor | $132k | $180k | $240k |
| Cape Elizabeth, ME1.08× metro factor | $133k | $182k | $242k |
| Biddeford, ME0.98× metro factor | $121k | $165k | $220k |
| Saco, ME0.99× metro factor | $122k | $167k | $222k |
| Brunswick, ME0.99× metro factor | $122k | $167k | $222k |
| Gorham, ME0.99× metro factor | $122k | $167k | $222k |
| Windham, ME0.98× metro factor | $121k | $165k | $220k |
| Yarmouth, ME1.05× metro factor | $130k | $177k | $236k |
| Freeport, ME1.02× metro factor | $126k | $172k | $229k |
Estimated range — based on BLS OEWS national average wages and BLS PPI material indexes applied to Our Haus baseline unit costs, as of June 2026. Estimates are shown as a range and help set expectations. They are not a quote, a verified price, or an appraisal of what a contractor will charge.
City guides
- Home addition in Boston, MA
- Home addition in Worcester, MA
- Home addition in Providence, RI
- Home addition in Hartford, CT
- Home addition in Manchester, NH
- Home addition in Portland, ME
- Home addition in Cambridge, MA
- Home addition in Lowell, MA
- Home addition in Springfield, MA
- Home addition in Stamford, CT
- Home addition in New Haven, CT
- Home addition in Portsmouth, NH
- Home addition in Nashua, NH
- Home addition in Bangor, ME
- Home addition in Burlington, VT
- Home addition in South Portland, ME
- Home addition in Westbrook, ME
- Home addition in Scarborough, ME
- Home addition in Falmouth, ME
- Home addition in Cape Elizabeth, ME
- Home addition in Biddeford, ME
- Home addition in Saco, ME
- Home addition in Brunswick, ME
- Home addition in Gorham, ME
- Home addition in Windham, ME
- Home addition in Yarmouth, ME
- Home addition in Freeport, ME
What a complete estimate spells out
- • Whether design and engineering fees are inside or outside the price
- • Foundation type and an allowance or unit price for ledge and unsuitable soils
- • Who is responsible for zoning approvals and what happens if they are denied
- • Window and door schedule with manufacturer and series
- • How HVAC load was calculated and whether existing equipment can carry it
- • A payment schedule tied to inspected milestones, not calendar dates
- • Weather-protection responsibility during framing
Frequently asked questions
Is an addition cheaper than moving?
Sometimes. Compare the all-in addition cost — design, permits, construction, and the months of disruption — against transaction costs on a move, which typically run 8 to 10 percent of a sale price plus the price difference on the new house. In tight New England markets the addition often wins; in a soft market it often does not.
Do I need an architect?
For anything structural or anything requiring zoning relief, yes — and most municipalities will require stamped drawings for the permit anyway. A design-build contractor can supply this, but confirm who holds the stamp.