Home addition cost in Kahului, HI
Local estimate from BLS wage data and BEA price levels. Reviewed Nov 4, 2026.
- Typical range (300 sq ft)
- $49,400 – $99,900
- Per sq ft
- $163 – $326
- before permit
- Versus US midpoint
- +30%
- US $57,500
- Rank of 300 metros
- #3
- 1 = most expensive
Kahului homeowners pay roughly $49,400 to $99,900 to build a home addition at 300 sq ft, or $163 to $326 per sq ft (permit not included). Against the US midpoint, Kahului is 30% higher. Carpenters earn a median of $39.47 an hour in the Kahului area, 36% above the US median of $29.12.
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Estimated cost for 300 sq ft in Kahului, HI, standard level
$64,500 to $84,700
About $212 to $277 per sq ft before permits. Labor is about 71% of the bill.
| Part | Low | High |
|---|---|---|
| Materials | $17,400 | $22,800 |
| Labor | $46,100 | $60,300 |
| Permits and fees | $1,050 | $1,700 |
| Total | $64,500 | $84,700 |
Cost breakdown for 300 sq ft in Kahului, HI
| Part of the job | Low | Midpoint | High | Share |
|---|---|---|---|---|
| Materials | $13,400 | $20,100 | $26,800 | 27% |
| Labor | $35,500 | $53,200 | $70,900 | 71% |
| Permits and fees | $550 | $1,350 | $2,200 | 2% |
| Total | $49,400 | $74,600 | $99,900 | 100% |
Where the Kahului price comes from
Labor is 71% of the midpoint bill here, against 67% nationally. The mix of trades behind this job is carpenters (50%), cement masons and concrete finishers (10%), electricians (10%), plumbers, pipefitters and steamfitters (10%), drywall and ceiling tile installers (10%), roofers (10%). We weight each trade's local median wage by that share and compare it with the national median. In Kahului the blended ratio comes out at 1.39.
On the materials line, the BEA goods price index for the Kahului metro is 111.6 (US = 100). The midpoint materials bill for 300 sq ft comes to $20,100, compared with $18,000 at national prices. Permit and inspection fees are scaled by the broader index (109.4) and land at $550 to $2,200.
How Kahului compares
Same job, same size (300 sq ft), priced for the nearest metros. Honolulu is the priciest of the group at $79,600. Santa Cruz is the cheapest at $66,700.
| Area | Range | Midpoint | vs. here |
|---|---|---|---|
| Kahului, HIthis page | $49,400 – $99,900 | $74,600 | |
| Honolulu, HI110 miles | $52,700 – $106,500 | $79,600 | +7% |
| Santa Rosa, CA2340 miles | $45,100 – $91,300 | $68,200 | −9% |
| Santa Cruz, CA2350 miles | $44,100 – $89,300 | $66,700 | −11% |
| San Francisco, CA2355 miles | $49,600 – $100,500 | $75,000 | level |
| Napa, CA2370 miles | $45,800 – $92,700 | $69,300 | −7% |
| Hawaii (statewide) | $50,500 – $102,000 | $76,300 | +2% |
| United States | $38,000 – $77,000 | $57,500 | −23% |
Across 300 US metros, Kahului comes in at #3 from the top. The priciest is Honolulu, HI at $79,600; the cheapest is Brownsville, TX at $44,300 (midpoints, 300 sq ft). Statewide, Kahului is 2% below the Hawaii figure.
Other Hawaii metros
| Metro | Size | Range | Midpoint | vs. here |
|---|---|---|---|---|
| Honolulu, HI | 446,380 jobs | $52,700 – $106,500 | $79,600 | +7% |
Cities with a workforce like Kahului's
Big cities and small ones price differently, so here is Kahului against the 4 metros with the closest total employment.
| Metro | Size | Range | Midpoint | vs. here |
|---|---|---|---|---|
| Rapid City, SD | 73,820 jobs | $33,200 – $67,300 | $50,300 | −33% |
| Bloomington, IN | 73,240 jobs | $38,600 – $78,200 | $58,400 | −22% |
| Blacksburg, VA | 74,070 jobs | $33,400 – $67,800 | $50,600 | −32% |
| Auburn, AL | 72,710 jobs | $32,400 – $65,800 | $49,100 | −34% |
When to schedule home addition in Kahului
We use NOAA's 1991-2020 climate normals for Kahului Ap (5 miles from the city center). These are 30-year monthly averages, not forecasts.
October through July is the stretch where digging, grading and setting material in the ground runs into the fewest weather problems in Kahului (10 of 12 months). August and September have an average daytime high of 90°F or more.
Kahului gets about 16 inches of precipitation in a normal year. The wettest months are January, March and December (2.8 inches in December). Inside the workable window, June and July are the driest, at 0.2 and 0.5 inches. The station averages about 39 days a year at 90°F or above.
Does the season change the price? Probably, but we do not have a sourced seasonal price curve, so the estimator shows a year-round figure and does not adjust by month. When you collect quotes, ask whether scheduling in a slower month gets a better rate.
| Month | Avg high °F | Avg low °F | Precip (in) | For this job |
|---|---|---|---|---|
| Jan | 82 | 64 | 2.4 | Workable |
| Feb | 82 | 64 | 2.0 | Workable |
| Mar | 83 | 65 | 2.6 | Workable |
| Apr | 85 | 67 | 1.3 | Workable |
| May | 87 | 68 | 0.7 | Workable |
| Jun | 88 | 70 | 0.2 | Workable |
| Jul | 89 | 72 | 0.5 | Workable |
| Aug | 90 | 72 | 0.5 | Hot |
| Sep | 90 | 71 | 0.5 | Hot |
| Oct | 89 | 70 | 0.8 | Workable |
| Nov | 86 | 68 | 1.8 | Workable |
| Dec | 83 | 66 | 2.8 | Workable |
Kahului: what basic, standard and premium work costs
Three bands are cut from the same cited range and localized for Kahului wages and prices. They overlap on purpose: a good standard job and a modest premium job can cost the same. The grid below prices the same bands at 3 common sizes.
Basic
$49,400 to $69,600
Bump-out or simple room without plumbing
Standard
$64,500 to $84,700
Standard room addition with HVAC and electrical
Premium
$79,700 to $99,900
Large addition with bath or kitchen and a new foundation
| Size | Basic | Standard | Premium |
|---|---|---|---|
| bump-out (100 sq ft) | $16,800 – $24,000 | $22,200 – $29,400 | $27,600 – $34,700 |
| 20x20 room (400 sq ft) | $65,700 – $92,400 | $85,700 – $112,500 | $105,500 – $132,500 |
| large suite (600 sq ft) | $98,200 – $138,000 | $128,000 – $168,000 | $158,000 – $197,500 |
Local wages behind the labor line
Wages are the part of this estimate that changes most from town to town. 6 trades carry the job here, and each is compared with its US median. The weighted result for Kahului is 1.39 times the national level.
For carpenters (47-2031, weighted 50%) the local median is $39.47 an hour, which is 36% above the national $29.12. The middle half of them earn between $30.77 and $48.89 an hour. BLS counts 700 of them working in the area, 94.9 for every 10,000 jobs (US: 43.1), so the local bench is deeper than average.
For cement masons and concrete finishers (47-2051, weighted 10%) the local median is $50.22 an hour, which is 83% above the national $27.41. The middle half of them earn between $36.41 and $54.26 an hour. BLS counts 60 of them working in the area, 8.1 for every 10,000 jobs (US: 13.3), so the local bench is thinner than average.
Electricians (47-2111), 10% of the weighting: a median of $47.34 an hour, 56% above the US median of $30.38. The middle half of them earn between $29.05 and $57.68 an hour. About 310 work in the metro. That is 42.0 per 10,000 jobs, compared with 48.7 nationally, so the supply of crews looks typical.
For plumbers, pipefitters and steamfitters (47-2152, weighted 10%) the local median is $37.31 an hour, which is 22% above the national $30.67. The middle half of them earn between $28.92 and $50.02 an hour. BLS counts 310 of them working in the area, 42.0 for every 10,000 jobs (US: 30.0), so the local bench is deeper than average.
Drywall and ceiling tile installers (47-2081), 10% of the weighting: a median of $40.00 an hour, 41% above the US median of $28.33. The middle half of them earn between $36.58 and $56.15 an hour. About 60 work in the metro. That is 8.1 per 10,000 jobs, compared with 5.3 nationally, which suggests plenty of local crews to bid.
For roofers (47-2181, weighted 10%) the local median is $29.52 an hour, which is 11% above the national $26.65. The middle half of them earn between $22.97 and $37.64 an hour. BLS counts 100 of them working in the area, 13.6 for every 10,000 jobs (US: 8.7), so the local bench is deeper than average.
Quotes come from real crews, not medians. If the carpenters on your job are paid at the 75th percentile ($48.89 an hour) instead of the median, the labor line grows by about $6,200. At the 25th percentile ($30.77) it shrinks by about $5,700. The total moves by 8.3% or 7.7%, so wages alone rarely explain a quote that is far outside our range.
For context on the local economy, BLS counts 73,750 jobs in the Kahului-Wailuku area. That makes it the 250th largest of the 300 metros we cover, with 0.05% of US employment.
| Trade | Weight | 25th pct | Median | 75th pct | US median | Ratio | Level used |
|---|---|---|---|---|---|---|---|
| Carpenters (47-2031) | 50% | $30.77 | $39.47 | $48.89 | $29.12 | 1.36 | metro |
| Cement masons and concrete finishers (47-2051) | 10% | $36.41 | $50.22 | $54.26 | $27.41 | 1.83 | metro |
| Electricians (47-2111) | 10% | $29.05 | $47.34 | $57.68 | $30.38 | 1.56 | metro |
| Plumbers, pipefitters and steamfitters (47-2152) | 10% | $28.92 | $37.31 | $50.02 | $30.67 | 1.22 | metro |
| Drywall and ceiling tile installers (47-2081) | 10% | $36.58 | $40.00 | $56.15 | $28.33 | 1.41 | metro |
| Roofers (47-2181) | 10% | $22.97 | $29.52 | $37.64 | $26.65 | 1.11 | metro |
| Blended | 100% | 1.39 | |||||
Why two Kahului quotes can differ
Plumbing and fixtures
Adding a bathroom or kitchen drives the price up the most.
Permits
Construction permits run $500-$2,000, or $5-$21 per $1,000 of project cost (HomeGuide).
Foundation
A foundation, framing, roofing and matching exterior finishes all have to be built before the interior work starts.
Planning more than one job in Kahului?
Because every project leans on different trades, Kahului's wage level does not move all prices equally. Against the US midpoint, detached garage runs +30% and kitchen remodel +16%.
| Project | Size | Range | vs. US |
|---|---|---|---|
| Kitchen remodel | 120 sq ft | $21,500 – $36,600 | +16% |
| Bathroom remodel | 45 sq ft | $5,700 – $28,400 | +22% |
| Detached garage | 576 sq ft | $37,700 – $75,600 | +30% |
| Roof replacement | 2,000 sq ft of roof | $7,150 – $14,500 | +16% |
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 $64,500 to $84,700 for Kahului, HI is attached.
Detailed home addition report for Kahului, HI, $9
The report lays out the home addition numbers for Kahului, HI line by line, with the local wage and price inputs, permit and timing notes, a quote comparison sheet and the full method. Save your estimate above, preview page 1 free, and unlock the full report for $9 one-time, or get every report with CostLocal Pro.
Home addition in Kahului: your questions
+How much does it cost to build a home addition in Kahului?
For 300 sq ft, expect $49,400 to $99,900 in the Kahului area. A standard-spec job lands at $64,500 to $84,700. Small jobs usually cost more per sq ft and large ones less.
+What is the price per sq ft for home addition in Kahului?
About $163 to $326 per sq ft for materials and labor, plus $550 to $2,200 for the permit if one is needed. The US range is $125 to $250.
+Is home addition cheaper in Kahului or Honolulu?
Honolulu is 110 miles away. The midpoint for 300 sq ft there is $79,600, which is 7% more than Kahului ($74,600). Wage and materials indexes both feed that gap.
+How much of the bill is labor in Kahului?
About 71% at the midpoint, or $53,200 out of $74,600. Materials are 27% and permits 2%. Nationally, labor is 67%.
+What would 20x20 room (400 sq ft) cost in Kahului?
$65,700 to $132,500. Pick a different size in the estimator above to get your own number.
+Does home addition need a permit in Kahului?
Often, but rules are set by your city or county building office, so call before you hire. Budget $550 to $2,200 for fees in the Kahului area (our national range of $500 to $2,000 scaled by the local price level).
+Is Kahului expensive for home addition compared with the rest of Hawaii?
Kahului is 2% below the Hawaii statewide estimate ($76,300 at the midpoint). We cover 2 metros in Hawaii; see the state page to compare them.
+What do carpenters earn in Kahului?
The BLS median is $39.47 an hour in the Kahului area, compared with $29.12 nationally. The 25th to 75th percentile range is $30.77 to $48.89.
+What do basic and premium home addition work cost in Kahului?
For 300 sq ft, basic work runs $49,400 to $69,600 and premium work $79,700 to $99,900. 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 Kahului?
Based on NOAA 1991-2020 normals, the comfortable months for this kind of work are October through July. June and July 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 Kahului
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.