Home addition cost in Boulder, CO
Local estimate from BLS wage data and BEA price levels. Reviewed Nov 4, 2026.
- Typical range (300 sq ft)
- $37,800 – $76,600
- Per sq ft
- $124 – $248
- before permit
- Versus US midpoint
- −1%
- US $57,500
- Rank of 300 metros
- #119
- 1 = most expensive
A home addition in Boulder, CO usually costs $37,800 to $76,600 for 300 sq ft. That works out to about $124 to $248 per sq ft before permits. That is within a few percent of the national midpoint, so there is little local premium or discount. Building materials run about 4% below the US average here (BEA goods price index 96.1).
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Estimated cost for 300 sq ft in Boulder, CO, standard level
$49,400 to $64,900
About $161 to $211 per sq ft before permits. Labor is about 67% of the bill.
| Part | Low | High |
|---|---|---|
| Materials | $15,000 | $19,600 |
| Labor | $33,400 | $43,700 |
| Permits and fees | $1,000 | $1,650 |
| Total | $49,400 | $64,900 |
Cost breakdown for 300 sq ft in Boulder, CO
| Part of the job | Low | Midpoint | High | Share |
|---|---|---|---|---|
| Materials | $11,500 | $17,300 | $23,100 | 30% |
| Labor | $25,700 | $38,600 | $51,400 | 67% |
| Permits and fees | $530 | $1,300 | $2,100 | 2% |
| Total | $37,800 | $57,200 | $76,600 | 100% |
Why Boulder prices look the way they do
The wage side of the estimate leans on carpenters, who do 50% of the hours on a typical job. Their local median is $28.73 an hour. Add the other trades involved and the blended wage index for Boulder is 1.01 (US = 1.00), which puts labor at 67% of the total.
Materials are scaled with BEA's regional price parity for goods. Boulder is at 96.1 against 100 for the US, so a materials line of $18,000 nationally becomes $17,300 here (midpoint, 300 sq ft). Permits follow the all-items index of 105.2: $530 to $2,100.
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 Boulder. The wage table below marks each row.
What local crews earn in Boulder
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 Boulder the blend is 1.01.
Carpenters (47-2031), 50% of the weighting: a median of $28.73 an hour, in line with the US median of $29.12. The middle half of them earn between $23.92 and $35.50 an hour. About 540 work in the metro. That is 28.1 per 10,000 jobs, compared with 43.1 nationally, so expect fewer local crews to bid.
Cement masons and concrete finishers (47-2051), 10% of the weighting: a median of $29.00 an hour, 6% above the US median of $27.41. The middle half of them earn between $23.59 and $32.25 an hour. About 150 work in the metro. That is 7.8 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 $30.83 an hour, which is in line with the national $30.38. The middle half of them earn between $24.37 and $37.48 an hour. BLS counts 420 of them working in the area, 21.8 for every 10,000 jobs (US: 48.7), so the local bench is thinner than average.
Plumbers, pipefitters and steamfitters (47-2152), 10% of the weighting: a median of $31.20 an hour, in line with the US median of $30.67. The middle half of them earn between $28.30 and $38.49 an hour. About 420 work in the metro. That is 21.8 per 10,000 jobs, compared with 30.0 nationally, so expect fewer local crews to bid.
Drywall and ceiling tile installers (47-2081) carry 10% of the labor weighting. BLS does not publish this trade for the Boulder metro, so we used the Colorado statewide median: $29.70 an hour against $28.33 for the US. The middle half of them earn between $23.43 and $33.77 an hour.
Roofers (47-2181), 10% of the weighting: a median of $26.99 an hour, in line with the US median of $26.65. The middle half of them earn between $23.08 and $29.26 an hour. About 140 work in the metro. That is 7.3 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 $4,450 to the midpoint estimate; the 25th percentile takes off about $3,150. That is a swing of roughly 5.5% to 7.8% of the total, which is useful for judging whether a bid reflects wages or something else, such as scope or margin.
Boulder has 192,390 jobs in total (BLS, May 2025), ranking 119th 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% | $23.92 | $28.73 | $35.50 | $29.12 | 0.99 | metro |
| Cement masons and concrete finishers (47-2051) | 10% | $23.59 | $29.00 | $32.25 | $27.41 | 1.06 | metro |
| Electricians (47-2111) | 10% | $24.37 | $30.83 | $37.48 | $30.38 | 1.01 | metro |
| Plumbers, pipefitters and steamfitters (47-2152) | 10% | $28.30 | $31.20 | $38.49 | $30.67 | 1.02 | metro |
| Drywall and ceiling tile installers (47-2081) | 10% | $23.43 | $29.70 | $33.77 | $28.33 | 1.05 | state |
| Roofers (47-2181) | 10% | $23.08 | $26.99 | $29.26 | $26.65 | 1.01 | metro |
| Blended | 100% | 1.01 | |||||
Cost by quality level and size in Boulder
The cited range is split into basic, standard and premium bands, then scaled to Boulder. 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
$37,800 to $53,300
Bump-out or simple room without plumbing
Standard
$49,400 to $64,900
Standard room addition with HVAC and electrical
Premium
$61,100 to $76,600
Large addition with bath or kitchen and a new foundation
| Size | Basic | Standard | Premium |
|---|---|---|---|
| bump-out (100 sq ft) | $12,900 – $18,500 | $17,100 – $22,700 | $21,300 – $26,900 |
| 20x20 room (400 sq ft) | $50,200 – $70,700 | $65,600 – $86,000 | $80,900 – $101,500 |
| large suite (600 sq ft) | $75,000 – $105,500 | $97,800 – $128,500 | $120,500 – $151,000 |
Is Boulder cheap or dear? The local comparison
Contractors rarely work more than an hour or two from home, so the neighboring metros set a rough ceiling and floor for your quotes. Midpoints for 300 sq ft range from $54,400 to $59,800 across Boulder and its five closest metros.
| Area | Range | Midpoint | vs. here |
|---|---|---|---|
| Boulder, COthis page | $37,800 – $76,600 | $57,200 | |
| Fort Collins, CO40 miles | $36,700 – $74,500 | $55,600 | −3% |
| Denver, CO55 miles | $39,500 – $80,100 | $59,800 | +5% |
| Greeley, CO60 miles | $36,700 – $74,300 | $55,500 | −3% |
| Cheyenne, WY90 miles | $35,900 – $72,800 | $54,400 | −5% |
| Colorado Springs, CO95 miles | $36,400 – $73,700 | $55,100 | −4% |
| Colorado (statewide) | $38,400 – $77,800 | $58,100 | +2% |
| United States | $38,000 – $77,000 | $57,500 | +1% |
Out of the 300 metros we cover, Boulder ranks #119 for the cost of this job (#1 is the most expensive). Statewide, Boulder is 2% below the Colorado figure.
Elsewhere in Colorado
| Metro | Size | Range | Midpoint | vs. here |
|---|---|---|---|---|
| Denver, CO | 1,609,350 jobs | $39,500 – $80,100 | $59,800 | +5% |
| Colorado Springs, CO | 316,060 jobs | $36,400 – $73,700 | $55,100 | −4% |
| Fort Collins, CO | 169,430 jobs | $36,700 – $74,500 | $55,600 | −3% |
| Greeley, CO | 119,540 jobs | $36,700 – $74,300 | $55,500 | −3% |
| Grand Junction, CO | 67,170 jobs | $36,500 – $74,000 | $55,300 | −3% |
| Pueblo, CO | 61,780 jobs | $36,100 – $73,200 | $54,600 | −4% |
Metros of a similar size
Big cities and small ones price differently, so here is Boulder against the 4 metros with the closest total employment.
| Metro | Size | Range | Midpoint | vs. here |
|---|---|---|---|---|
| Corpus Christi, TX | 192,580 jobs | $32,400 – $65,800 | $49,100 | −14% |
| Wilmington, NC | 191,280 jobs | $33,900 – $68,800 | $51,400 | −10% |
| Modesto, CA | 195,230 jobs | $43,500 – $87,900 | $65,700 | +15% |
| Pensacola, FL | 190,480 jobs | $32,400 – $65,800 | $49,100 | −14% |
Boulder 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, Boulder (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 Boulder are April through October: 7 of 12. Outside them, January, February, March, November and December have an average overnight low at or below freezing (32°F).
In January, February, March, November 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 138 days a year with a low at or below 32°F at this station.
Boulder gets about 21 inches of precipitation in a normal year, including roughly 93 inches of snow. The wettest months are April, May and September (3.2 inches in May). Inside the workable window, August and October are the driest, at 1.7 and 1.6 inches. The station averages about 33 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 | 47 | 22 | 0.8 | Cold |
| Feb | 48 | 22 | 1.0 | Cold |
| Mar | 57 | 29 | 2.0 | Cold |
| Apr | 63 | 35 | 3.0 | Workable |
| May | 71 | 43 | 3.2 | Workable |
| Jun | 83 | 51 | 1.9 | Workable |
| Jul | 88 | 57 | 1.8 | Workable |
| Aug | 86 | 56 | 1.7 | Workable |
| Sep | 79 | 48 | 2.1 | Workable |
| Oct | 66 | 37 | 1.6 | Workable |
| Nov | 55 | 28 | 1.2 | Cold |
| Dec | 46 | 21 | 0.8 | Cold |
Why two Boulder 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.
Related projects, priced for Boulder
Jobs that often go together with home addition are priced below at their usual sizes, using the same Boulder wage and price inputs. Compared with national midpoints, bathroom remodel comes out highest (level) and kitchen remodel lowest (−3%); the gap comes from the trades each job uses.
| Project | Size | Range | vs. US |
|---|---|---|---|
| Kitchen remodel | 120 sq ft | $18,000 – $30,700 | −3% |
| Bathroom remodel | 45 sq ft | $4,700 – $23,200 | level |
| Detached garage | 576 sq ft | $28,500 – $57,200 | −1% |
| Roof replacement | 2,000 sq ft of roof | $6,100 – $12,400 | level |
Get 3 local quotes
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Home addition in Boulder: your questions
+How much does it cost to build a home addition in Boulder?
For 300 sq ft, expect $37,800 to $76,600 in the Boulder area. A standard-spec job lands at $49,400 to $64,900. Small jobs usually cost more per sq ft and large ones less.
+What is the price per sq ft for home addition in Boulder?
About $124 to $248 per sq ft for materials and labor, plus $530 to $2,100 for the permit if one is needed. The US range is $125 to $250.
+Is home addition cheaper in Boulder or Fort Collins?
Fort Collins is 40 miles away. The midpoint for 300 sq ft there is $55,600, which is 3% less than Boulder ($57,200). Wage and materials indexes both feed that gap.
+How much of the bill is labor in Boulder?
About 67% at the midpoint, or $38,600 out of $57,200. Materials are 30% and permits 2%. Nationally, labor is 67%.
+What would 20x20 room (400 sq ft) cost in Boulder?
$50,200 to $101,500. Pick a different size in the estimator above to get your own number.
+Does home addition need a permit in Boulder?
Often, but rules are set by your city or county building office, so call before you hire. Budget $530 to $2,100 for fees in the Boulder area (our national range of $500 to $2,000 scaled by the local price level).
+Is Boulder expensive for home addition compared with the rest of Colorado?
Boulder is 2% below the Colorado statewide estimate ($58,100 at the midpoint). We cover 7 metros in Colorado; see the state page to compare them.
+What do carpenters earn in Boulder?
The BLS median is $28.73 an hour in the Boulder area, compared with $29.12 nationally. The 25th to 75th percentile range is $23.92 to $35.50.
+What do basic and premium home addition work cost in Boulder?
For 300 sq ft, basic work runs $37,800 to $53,300 and premium work $61,100 to $76,600. 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 Boulder?
Based on NOAA 1991-2020 normals, the comfortable months for this kind of work are April through October. August and October 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 Boulder
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.