Home addition cost in Boston, MA
Local estimate from BLS wage data and BEA price levels. Reviewed Nov 4, 2026.
- Typical range (300 sq ft)
- $44,300 – $89,700
- Per sq ft
- $146 – $292
- before permit
- Versus US midpoint
- +16%
- US $57,500
- Rank of 300 metros
- #16
- 1 = most expensive
A home addition in Boston, MA usually costs $44,300 to $89,700 for 300 sq ft. That works out to about $146 to $292 per sq ft before permits. Compared with the national midpoint that is $9,500 more. Carpenters earn a median of $36.16 an hour in the Boston area, 24% above the US median of $29.12.
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Estimated cost for 300 sq ft in Boston, MA, standard level
$57,900 to $76,100
About $190 to $248 per sq ft before permits. Labor is about 71% of the bill.
| Part | Low | High |
|---|---|---|
| Materials | $15,500 | $20,300 |
| Labor | $41,300 | $54,100 |
| Permits and fees | $1,050 | $1,700 |
| Total | $57,900 | $76,100 |
Cost breakdown for 300 sq ft in Boston, MA
| Part of the job | Low | Midpoint | High | Share |
|---|---|---|---|---|
| Materials | $12,000 | $17,900 | $23,900 | 27% |
| Labor | $31,800 | $47,700 | $63,600 | 71% |
| Permits and fees | $540 | $1,350 | $2,150 | 2% |
| Total | $44,300 | $67,000 | $89,700 | 100% |
Where the Boston price comes from
The wage side of the estimate leans on carpenters, who do 50% of the hours on a typical job. Their local median is $36.16 an hour. Add the other trades involved and the blended wage index for Boston is 1.25 (US = 1.00), which puts labor at 71% of the total.
Materials are scaled with BEA's regional price parity for goods. Boston is at 99.7 against 100 for the US, so a materials line of $18,000 nationally becomes $17,900 here (midpoint, 300 sq ft). Permits follow the all-items index of 108.3: $540 to $2,150.
Data note: 10% of the labor weighting for this project uses a statewide median because BLS has no published metro figure for that trade in Boston. The wage table below marks each row.
What nearby projects cost in Boston
Jobs that often go together with home addition are priced below at their usual sizes, using the same Boston wage and price inputs. Compared with national midpoints, bathroom remodel comes out highest (+19%) and kitchen remodel lowest (+6%); the gap comes from the trades each job uses.
| Project | Size | Range | vs. US |
|---|---|---|---|
| Kitchen remodel | 120 sq ft | $19,600 – $33,400 | +6% |
| Bathroom remodel | 45 sq ft | $5,600 – $27,800 | +19% |
| Detached garage | 576 sq ft | $32,400 – $64,900 | +12% |
| Roof replacement | 2,000 sq ft of roof | $7,050 – $14,100 | +14% |
How Boston compares
Of the five closest metros, 4 are cheaper than Boston. Manchester is the lowest at about $58,100 (midpoint, 300 sq ft), 45 miles away.
| Area | Range | Midpoint | vs. here |
|---|---|---|---|
| Boston, MAthis page | $44,300 – $89,700 | $67,000 | |
| Manchester, NH45 miles | $38,400 – $77,800 | $58,100 | −13% |
| Worcester, MA50 miles | $45,000 – $91,100 | $68,100 | +2% |
| Providence, RI60 miles | $39,300 – $79,700 | $59,500 | −11% |
| Barnstable, MA70 miles | $42,400 – $85,800 | $64,100 | −4% |
| Portland, ME85 miles | $38,900 – $78,800 | $58,900 | −12% |
| Massachusetts (statewide) | $44,400 – $89,800 | $67,100 | level |
| United States | $38,000 – $77,000 | $57,500 | −14% |
Out of the 300 metros we cover, Boston ranks #16 for the cost of this job (#1 is the most expensive). Statewide, Boston is 0% below the Massachusetts figure.
Elsewhere in Massachusetts
| Metro | Size | Range | Midpoint | vs. here |
|---|---|---|---|---|
| Worcester, MA | 349,880 jobs | $45,000 – $91,100 | $68,100 | +2% |
| Springfield, MA | 201,240 jobs | $44,200 – $89,300 | $66,800 | level |
| Barnstable, MA | 94,110 jobs | $42,400 – $85,800 | $64,100 | −4% |
| Amherst, MA | 65,670 jobs | $41,700 – $84,300 | $63,000 | −6% |
| Pittsfield, MA | 56,810 jobs | $40,100 – $81,200 | $60,700 | −9% |
Metros of a similar size
Big cities and small ones price differently, so here is Boston against the 4 metros with the closest total employment.
| Metro | Size | Range | Midpoint | vs. here |
|---|---|---|---|---|
| Miami, FL | 2,819,940 jobs | $35,100 – $71,300 | $53,200 | −21% |
| Phoenix, AZ | 2,375,760 jobs | $36,700 – $74,500 | $55,600 | −17% |
| Atlanta, GA | 2,889,670 jobs | $34,900 – $70,700 | $52,800 | −21% |
| San Francisco, CA | 2,373,920 jobs | $49,600 – $100,500 | $75,000 | +12% |
What local crews earn in Boston
The labor line is built from BLS wage data, one trade at a time. This job draws on 6 trades. We compare each trade's local median with the US median, weight the ratios by how much of the job each trade does, and apply the blend to the national labor cost. For Boston the blend is 1.25.
Carpenters (47-2031), 50% of the weighting: a median of $36.16 an hour, 24% above the US median of $29.12. The middle half of them earn between $29.26 and $47.47 an hour. About 12,720 work in the metro. That is 47.0 per 10,000 jobs, compared with 43.1 nationally, so the supply of crews looks typical.
Cement masons and concrete finishers (47-2051), 10% of the weighting: a median of $30.23 an hour, 10% above the US median of $27.41. The middle half of them earn between $26.87 and $37.47 an hour. About 950 work in the metro. That is 3.5 per 10,000 jobs, compared with 13.3 nationally, so expect fewer local crews to bid.
For electricians (47-2111, weighted 10%) the local median is $38.42 an hour, which is 26% above the national $30.38. The middle half of them earn between $28.03 and $49.11 an hour. BLS counts 13,410 of them working in the area, 49.6 for every 10,000 jobs (US: 48.7), so the local bench is about average.
Plumbers, pipefitters and steamfitters (47-2152), 10% of the weighting: a median of $46.52 an hour, 52% above the US median of $30.67. The middle half of them earn between $30.12 and $56.68 an hour. About 9,200 work in the metro. That is 34.0 per 10,000 jobs, compared with 30.0 nationally, so the supply of crews looks typical.
Drywall and ceiling tile installers (47-2081) carry 10% of the labor weighting. BLS does not publish this trade for the Boston metro, so we used the Massachusetts statewide median: $33.42 an hour against $28.33 for the US. The middle half of them earn between $29.51 and $38.60 an hour.
Roofers (47-2181), 10% of the weighting: a median of $31.90 an hour, 20% above the US median of $26.65. The middle half of them earn between $28.87 and $37.61 an hour. About 1,120 work in the metro. That is 4.1 per 10,000 jobs, compared with 8.7 nationally, so expect fewer local crews to bid.
A quick sensitivity check: moving the lead trade (carpenters) from the median to the 75th percentile wage adds about $7,450 to the midpoint estimate; the 25th percentile takes off about $4,550. That is a swing of roughly 6.8% to 11.1% of the total, which is useful for judging whether a bid reflects wages or something else, such as scope or margin.
Boston-Cambridge-Newton has 2,703,890 jobs in total (BLS, May 2025), ranking 10th by size among the 300 metros on this site.
| Trade | Weight | 25th pct | Median | 75th pct | US median | Ratio | Level used |
|---|---|---|---|---|---|---|---|
| Carpenters (47-2031) | 50% | $29.26 | $36.16 | $47.47 | $29.12 | 1.24 | metro |
| Cement masons and concrete finishers (47-2051) | 10% | $26.87 | $30.23 | $37.47 | $27.41 | 1.10 | metro |
| Electricians (47-2111) | 10% | $28.03 | $38.42 | $49.11 | $30.38 | 1.26 | metro |
| Plumbers, pipefitters and steamfitters (47-2152) | 10% | $30.12 | $46.52 | $56.68 | $30.67 | 1.52 | metro |
| Drywall and ceiling tile installers (47-2081) | 10% | $29.51 | $33.42 | $38.60 | $28.33 | 1.18 | state |
| Roofers (47-2181) | 10% | $28.87 | $31.90 | $37.61 | $26.65 | 1.20 | metro |
| Blended | 100% | 1.25 | |||||
Boston: what basic, standard and premium work costs
The cited range is split into basic, standard and premium bands, then scaled to Boston. Bands overlap, because plenty of standard jobs cost as much as a light premium one. Sizes run from bump-out (100 sq ft) to large suite (600 sq ft).
Basic
$44,300 to $62,400
Bump-out or simple room without plumbing
Standard
$57,900 to $76,100
Standard room addition with HVAC and electrical
Premium
$71,500 to $89,700
Large addition with bath or kitchen and a new foundation
| Size | Basic | Standard | Premium |
|---|---|---|---|
| bump-out (100 sq ft) | $15,100 – $21,600 | $20,000 – $26,500 | $24,900 – $31,300 |
| 20x20 room (400 sq ft) | $58,900 – $82,900 | $76,900 – $101,000 | $94,900 – $119,000 |
| large suite (600 sq ft) | $88,100 – $123,500 | $115,000 – $150,500 | $141,500 – $177,000 |
Boston weather and the home addition calendar
Climate numbers on this page come from NOAA's 1991-2020 U.S. Climate Normals at the nearest suitable station, Boston Logan Intl Ap (5 miles from the city center). They are 30-year averages, so any one year can run hotter, colder or wetter.
For digging, grading and setting material in the ground, the comfortable months in Boston are April through November: 8 of 12. Outside them, January, February, March and December have an average overnight low at or below freezing (32°F).
In January, February, March and December the average low is at or below freezing, which means frozen ground and slower digging, compaction and sod or stone placement. NOAA counts about 92 days a year with a low at or below 32°F at this station.
Boston gets about 44 inches of precipitation in a normal year, including roughly 49 inches of snow. The wettest months are March, October and December (4.3 inches in December). Inside the workable window, May and August are the driest, at 3.3 and 3.2 inches. The station averages about 14 days a year at 90°F or above.
We do not adjust the estimate by month, because we have no reliable published data on seasonal pricing. It is still worth asking contractors whether an off-peak start date changes their bid.
| Month | Avg high °F | Avg low °F | Precip (in) | For this job |
|---|---|---|---|---|
| Jan | 37 | 23 | 3.4 | Cold |
| Feb | 39 | 25 | 3.2 | Cold |
| Mar | 46 | 31 | 4.2 | Cold |
| Apr | 56 | 41 | 3.6 | Workable |
| May | 67 | 50 | 3.3 | Workable |
| Jun | 76 | 60 | 3.9 | Workable |
| Jul | 82 | 66 | 3.3 | Workable |
| Aug | 80 | 65 | 3.2 | Workable |
| Sep | 73 | 58 | 3.6 | Workable |
| Oct | 62 | 48 | 4.0 | Workable |
| Nov | 52 | 38 | 3.7 | Workable |
| Dec | 42 | 29 | 4.3 | Cold |
Why two Boston quotes can differ
Foundation
A foundation, framing, roofing and matching exterior finishes all have to be built before the interior work starts.
Type of addition
A new room is $125-$250 per sq ft; a bump-out $85-$200; an attic conversion $50-$150; a garage conversion $50-$200 (HomeGuide).
Plumbing and fixtures
Adding a bathroom or kitchen drives the price up the most.
Get 3 local quotes
Tell us about the job and we will try to connect you with up to three local contractors for written quotes. It is free and you are under no obligation to hire. Your estimate of $57,900 to $76,100 for Boston, MA is attached.
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Home addition in Boston: your questions
+How much does it cost to build a home addition in Boston?
For 300 sq ft, expect $44,300 to $89,700 in the Boston area. A standard-spec job lands at $57,900 to $76,100. Small jobs usually cost more per sq ft and large ones less.
+What is the price per sq ft for home addition in Boston?
About $146 to $292 per sq ft for materials and labor, plus $540 to $2,150 for the permit if one is needed. The US range is $125 to $250.
+Is home addition cheaper in Boston or Manchester?
Manchester is 45 miles away. The midpoint for 300 sq ft there is $58,100, which is 13% less than Boston ($67,000). Wage and materials indexes both feed that gap.
+How much of the bill is labor in Boston?
About 71% at the midpoint, or $47,700 out of $67,000. Materials are 27% and permits 2%. Nationally, labor is 67%.
+What would 20x20 room (400 sq ft) cost in Boston?
$58,900 to $119,000. Pick a different size in the estimator above to get your own number.
+Does home addition need a permit in Boston?
Often, but rules are set by your city or county building office, so call before you hire. Budget $540 to $2,150 for fees in the Boston area (our national range of $500 to $2,000 scaled by the local price level).
+Is Boston expensive for home addition compared with the rest of Massachusetts?
Boston is 0% below the Massachusetts statewide estimate ($67,100 at the midpoint). We cover 6 metros in Massachusetts; see the state page to compare them.
+What do carpenters earn in Boston?
The BLS median is $36.16 an hour in the Boston area, compared with $29.12 nationally. The 25th to 75th percentile range is $29.26 to $47.47.
+What do basic and premium home addition work cost in Boston?
For 300 sq ft, basic work runs $44,300 to $62,400 and premium work $71,500 to $89,700. Basic means: bump-out or simple room without plumbing. Premium means: large addition with bath or kitchen and a new foundation.
+When is the best time to build a home addition in Boston?
Based on NOAA 1991-2020 normals, the comfortable months for this kind of work are April through November. May and August are typically the driest of those months. Local contractors' schedules matter as much as the weather, so book early for the busy months.
Home addition near Boston
Where these numbers come from
Base prices are national ranges from the sources below. We scale labor by local BLS wages, materials by BEA goods prices and permits by the BEA all-items price level. Full method on the methodology page.
- HomeGuide: How Much Does a Home Addition Cost? (2026) (accessed November 4, 2026)
- Cost to Renovate: Renovation Labor Report 2026: Where the Money Goes (accessed November 4, 2026)
- HomeGuide: 2026 Building Permit Costs | Fees & Cost Calculator (accessed November 4, 2026)
- BLS Occupational Employment and Wage Statistics, May 2025
- BEA Regional Price Parities, 2024
- NOAA NCEI U.S. Climate Normals, 1991-2020
Note on derived figures: Materials = 32% of the installed price, from Cost to Renovate's mid-range 'Structural' category split (56% labor, 32% materials, 11% permits and design). It is a category average rather than an addition-specific figure.