Home Addition Cost in Boston (2026): Average Price & Estimate

Home Addition Cost in Boston

Estimated home addition cost in Boston

$52,000–$156,000

Roughly about 30% above the national average.

High Northeast labor rates and historic-home rules raise costs.

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Addition type

Finish level

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Based on Boston, MA pricing.

Estimated cost range

$52,000–$156,000

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An estimate for planning, not a quote. Get written quotes from local pros below.

Estimate, not a quote. Local prices vary by contractor and project. These are 2026 estimates for Boston, MA. Get written quotes from licensed Boston contractors before you budget.

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What to know about home addition in Boston

Frost heave and freeze-thaw in Boston can stress foundations, so good drainage and proper footing depth matter for a lasting result.

What affects home addition cost in Boston

Beyond the local market, the same factors that drive home addition cost everywhere apply in Boston:

Addition size in square feet.
Type: a bump-out is cheapest, a second-story addition the most expensive.
Whether it includes a kitchen or bathroom (plumbing).
Foundation, framing, roof, and tie-in to the existing structure.

Home Addition cost by addition type in Boston

These figures are adjusted for Boston pricing (about 1.30x the national average), so they reflect what local homeowners actually pay.

Estimated home addition cost by addition type in Boston (2026)

Addition type	Cost in Boston	Typical total
Bump-out (a few feet)	$104 to $312 /sq ft	About $41,600 to $124,800
Sunroom	$117 to $351 /sq ft	About $46,800 to $140,400
Single room addition	$130 to $390 /sq ft	About $52,000 to $156,000
In-law / suite with bath	$156 to $468 /sq ft	About $62,400 to $187,200
Second-story addition	$182 to $546 /sq ft	About $72,800 to $218,400

Frequently asked questions

How much does home addition cost in Boston?

In Boston, MA, home addition typically costs $52,000 to $156,000 in 2026 for a standard project, about 30% above the national average. Your exact price depends on size, materials, and scope.

Why does home addition cost more or less in Boston?

High Northeast labor rates and historic-home rules raise costs. Labor rates, permit costs, and local demand are the main reasons Boston prices differ from the national average.

Do I need a permit for home addition in Boston?

Most home addition projects require a permit. Requirements vary by city and Massachusetts jurisdiction, so confirm with your local building department. A licensed contractor usually pulls the permit for you.

When is the best time of year for home addition in Boston?

In Boston, exterior work is easiest from late spring through early fall. Winter weather can delay roofing, siding, concrete, and foundation jobs, and some crews book up fast once the weather breaks.

Is home addition cheaper outside Boston?

Sometimes. Boston runs about 30% above the national average. Nearby smaller towns with lower labor costs can come in cheaper, while denser urban areas often cost more. Always compare quotes from contractors who serve your specific area.