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How much does a 400 sq ft deck cost in South Boston, MA?

A pressure-treated deck build in South Boston, MA
$14,929
400 ft² of deck · typical range $11,310 – $22,620
Typical total$37 per ft² of deck$14,929
Range you should see in bidsthree bids on the same scope normally land inside this$11,310 – $22,620
Labor portion55% of the job — this is the part that moves by city$8,211
Material portion45% — bought at national prices$6,718
Carpenters pay near South Bostonabout $39/hr · Boston-Cambridge-Newton, MA-NH metro$81,260/yr
U.S. mean for the same tradeSOC 47-2031$65,630/yr
Versus the national pricetrade pay here runs +23.8% against the U.S. mean+$1,729

Notes

  • Where the number comes from. The national price for a pressure-treated deck build is $33 per ft² of deck — pressure-treated deck pricing published for 2026, $25–$50 per ft² installed. Labor is about 55% of that. Carpenters near South Boston, MA average $81,260 a year against a U.S. mean of $65,630 — a factor of 1.238 — so the labor half is scaled by that and the material half is not. Source: BLS OEWS May 2025 for the Boston-Cambridge-Newton, MA-NH metro area, SOC 47-2031.
  • Why the city matters, not just the state. Trade pay moves inside a state as much as it does between states. Crews do not commute across a state to bid a job, and materials ship at national prices either way — so a metro wage is the honest input here and a state average quietly rounds four different cities into one number.
  • What is in the price: footings, framing, pressure-treated decking, fasteners, a code-compliant railing, and labor.
  • What is not: stairs beyond two steps, permits, ledger repair on the house, and any grading work. These are the lines that turn a $14,929 quote into a $18,661 invoice, so ask about each one before signing.
  • Use this as a bid check, not a quote. It prices an average job in average condition. Difficult access, the state of what is being replaced, the season, and a crew booked out three months all move the real number, and none of them are in a per-unit average.

a pressure-treated deck build in South Boston, MA

$14,929 is the typical number, and three bids on the same scope normally land between $11,310 and $22,620.

That is $1,729 more than the same job priced at the national average.

Why the city changes the number

About 55% of this job is labor — $8,211 of the $14,929 above. Labor is the only part that moves locally; a bundle of material costs what it costs wherever it is nailed down.

Carpenters near South Boston average $81,260 a year, against a U.S. mean of $65,630. That is a factor of 1.238, so the labor half is scaled by it and the material half is not.

Source: BLS OEWS May 2025 for the Boston-Cambridge-Newton, MA-NH metro area, SOC 47-2031.

What the quote should include

The lines that turn a quote into an invoice

Ask about each of them before you sign. On a job this size they are the difference between $14,929 and something a quarter higher.

Use it as a bid check, not a quote

This prices an average job in average condition. Access, the state of what is being replaced, the season, and a crew booked out three months all move the real number, and none of them are in a national average.

If a bid lands outside $11,310 – $22,620, that is not automatically wrong — but it is the question worth asking out loud.

Nearby sizes

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