Home / Deck building cost / Portsmouth, NH
Portsmouth · Rockingham County · labor +24.2%
Deck building cost in Portsmouth, NH
A 320 sq ft deck in pressure-treated pine deck comes to about $8,850 to $17,700 in Portsmouth once the national installed price is adjusted for what carpenters earn locally. The city's fee schedule has no separate line for it, but its general residential rate puts the permit at $110 for a job at the midpoint.
Figures checked October 20, 2026 · sources
- 1Pressure-treated, 320 sq ft $8,850–$17,700
- 2Labor index +24.2% vs US
- 3Portsmouth permit $110
Change size or material All Portsmouth projects
Deck building prices in Portsmouth by material
Each row starts from the installed price per square foot of deck published in a national cost guide, then moves only the labor part of that price by Portsmouth's labor index. For 320 sq ft:
| Material | National | Portsmouth | Midpoint |
|---|---|---|---|
| Pressure-treated pine deck | $8,000–$16,000 | $8,850–$17,700 | $13,300 |
| Cedar deck | $9,600–$15,050 | $10,450–$16,750 | $13,600 |
| Composite deck | $12,800–$25,600 | $13,650–$27,300 | $20,500 |
By size
| Deck area (sq ft) | Portsmouth estimate | Permit at midpoint |
|---|---|---|
| 144 sq ft | $4,000–$7,950 | $75 |
| 240 sq ft | $6,650–$13,300 | $80 |
| 320 sq ft | $8,850–$17,700 | $110 |
| 400 sq ft | $11,050–$22,150 | $135 |
Pressure-treated pine deck.
Permit fee in Portsmouth
General rate The fee schedule has no separate line for this work; the town's general residential building-permit rate is shown as what it would charge if the building department requires a permit for it.
“1 & 2 Family Detached - $8/$1000 cost per construction, minimum $75.00”
“All fees shall be rounded up to the nearest $5.00.”
Applied to a 320 sq ft deck estimated at $8,850 to $17,700, that gives $75 to $145, about 0.83% of the midpoint price. Among the 17 towns on this site whose schedules cover this work, Portsmouth ranks 4 from the cheapest; Goffstown is lowest at $40 and Merrimack highest at $252.60 for its own midpoint job.
Schedule: City of Portsmouth, Building Permits Fee Schedule (no effective date shown). The building department decides whether a permit is required and what valuation it accepts; the national guide puts deck permits at $50–$150.
Why Portsmouth differs from the national price
Portsmouth is in Rockingham County, which the Bureau of Labor Statistics counts in the Boston-Cambridge-Newton, MA-NH metropolitan area (mostly Massachusetts). The median wage there for carpenters is $36.16 an hour against $29.12 nationally, so the labor part of a national price is scaled by 1.242 (+24.2%). That area is mostly Massachusetts; the New Hampshire statewide median for the same trade is $29.42, so a Portsmouth quote may land nearer the low end of the range shown.
On this job the labor portion is $3,500 to $7,050 at national rates and $4,350 to $8,750 at Portsmouth rates, so the midpoint rises $1,300 above the national figure. Against the New Hampshire statewide wage it is $1,200 higher. Materials are priced at the national figure: shingle, lumber and equipment prices are set by distributors, not by a town.
A second published benchmark points the same way for the region: Remodeling's 2025 Cost vs Value report prices its “Deck Addition, Wood” job at $18,250 nationally and $20,600 in New England, and its “Deck Addition, Composite” job at $25,100 nationally and $25,800 in New England. Those are fixed specification jobs, not per-square-foot prices, so they are shown for comparison only.
Portsmouth at a glance
Portsmouth had 23,536 residents in the state's 2025 estimate, up 10.8% from 21,233 in 2010, faster than the state's 7.5% over the same years. At 1,487 people per square mile it is one of the most built-up places on this site (2 of 19 by density), so crews often work on tight lots with neighbours close by.
51.9% of Portsmouth's occupied homes are lived in by their owners, fewer than the 72.8% statewide, and the median owner-occupied home is valued at $688,500 (New Hampshire: $402,500). The midpoint estimate for this deck works out to 1.9% of that median value, a small share of what a typical house there is worth.
Before asking for quotes
- The Portsmouth building department can say for free whether this job needs a permit and what it will cost; the schedule linked above is its own published document.
- Written quotes that list the same scope (area, material line, removal, disposal, permit) can be compared line by line; the quote comparison guide walks through it with these numbers.
- A quote far below $8,850 or above $17,700 is not wrong in itself, but it is worth asking what it includes or leaves out.
Other projects in Portsmouth
Roof replacement cost in Portsmouth · Siding replacement cost in Portsmouth · Heat pump installation cost in Portsmouth
Deck building in nearby towns
| Town | Labor area | Estimate | Permit |
|---|---|---|---|
| Durham | Boston-Cambridge-Newton | $8,850–$17,700 | $142.94 |
| Exeter | Boston-Cambridge-Newton | $8,850–$17,700 | $116.38 |
| Londonderry | Boston-Cambridge-Newton | $8,850–$17,700 | $131.21 |
| Rochester | Boston-Cambridge-Newton | $8,850–$17,700 | $136 |
| Salem | Boston-Cambridge-Newton | $8,850–$17,700 | $128 |
More: all deck building town pages · permit fees by town · labor costs in New Hampshire
Sources
- Installed price: HomeGuide: Cost to build a deck (Feb 10, 2026) — “Pressure-treated pine $25 – $50 (installed, per sq ft)”.
- Labor portion: HomeGuide: Cost to build a deck (Feb 10, 2026) — “The labor cost to build a new deck is $11 to $22 per square foot.”.
- Labor index: O*NET OnLine, Carpenters (47-2031.00), New Hampshire local wages; area definitions: BLS, May 2025 Metropolitan and Nonmetropolitan Area Definitions.
- Permit: City of Portsmouth, Building Permits Fee Schedule.
- Population: NH Office of Planning and Development, 2025 Population Estimates of New Hampshire Cities and Towns (published July 17, 2026); housing: Census QuickFacts, Portsmouth.
All figures checked October 20, 2026. Estimates are ranges built from published averages, not quotes; a contractor's price depends on the house, access, the season and the scope written into the quote. Cost by Town does not perform or arrange work.