Home addition cost in Idaho
Statewide estimate from BLS wages and BEA prices. Reviewed Nov 4, 2026.
- Statewide range (300 sq ft)
- $34,700 – $70,300
- Per sq ft
- $114 – $228
- before permit
- Versus US midpoint
- −9%
- US $57,500
- Metros covered
- 3
What does it cost to build a home addition in Idaho? Plan on $34,700 to $70,300 for 300 sq ft. Wages (0.89x the US blend), materials (price index 96.3) and permit costs (95.5) put the state below the national midpoint by 9%.
Inside Idaho, the metros we cover range from $52,200 (Idaho Falls) to $54,000 (Coeur d'Alene) at the midpoint. Pick your closest city in the table for a tighter number.
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Estimated cost for 300 sq ft in Idaho (statewide), standard level
$45,400 to $59,600
About $148 to $194 per sq ft before permits. Labor is about 65% of the bill.
| Part | Low | High |
|---|---|---|
| Materials | $15,000 | $19,600 |
| Labor | $29,500 | $38,500 |
| Permits and fees | $910 | $1,500 |
| Total | $45,400 | $59,600 |
Cost breakdown for 300 sq ft in Idaho
| Part of the job | Low | Midpoint | High | Share |
|---|---|---|---|---|
| Materials | $11,600 | $17,300 | $23,100 | 33% |
| Labor | $22,700 | $34,000 | $45,300 | 65% |
| Permits and fees | $480 | $1,200 | $1,900 | 2% |
| Total | $34,700 | $52,500 | $70,300 | 100% |
Other Idaho jobs that often go with home addition
The table prices neighboring jobs at their usual sizes using statewide Idaho wages and prices. Against national midpoints, roof replacement comes out highest (+1%) and bathroom remodel lowest (−9%), because each job leans on different trades.
| Project | Size | Range | vs. US |
|---|---|---|---|
| Kitchen remodel | 120 sq ft | $17,400 – $29,700 | −6% |
| Bathroom remodel | 45 sq ft | $4,250 – $21,100 | −9% |
| Detached garage | 576 sq ft | $27,500 – $55,200 | −5% |
| Roof replacement | 2,000 sq ft of roof | $6,200 – $12,500 | +1% |
Wages behind the Idaho number
Statewide wages come from BLS's state-level estimates, which blend big cities with small towns and rural areas. 6 trades drive the labor line for this job, and the weighted ratio against the national wage level is 0.89 for Idaho.
For carpenters (47-2031, weighted 50%) the local median is $25.00 an hour, which is 14% below the national $29.12. The middle half of them earn between $21.76 and $30.25 an hour. BLS counts 8,380 of them working in the state, 97.7 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 $27.12 an hour, which is in line with the national $27.41. The middle half of them earn between $22.92 and $29.35 an hour. BLS counts 2,540 of them working in the state, 29.6 for every 10,000 jobs (US: 13.3), so the local bench is deeper than average.
Electricians (47-2111), 10% of the weighting: a median of $30.29 an hour, in line with the US median of $30.38. The middle half of them earn between $23.26 and $39.44 an hour. About 5,690 work in the state. That is 66.4 per 10,000 jobs, compared with 48.7 nationally, which suggests plenty of local crews to bid.
For plumbers, pipefitters and steamfitters (47-2152, weighted 10%) the local median is $25.18 an hour, which is 18% below the national $30.67. The middle half of them earn between $22.21 and $33.48 an hour. BLS counts 3,090 of them working in the state, 36.0 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 $21.05 an hour, 26% below the US median of $28.33. The middle half of them earn between $17.11 and $27.68 an hour. About 920 work in the state. That is 10.7 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 $27.78 an hour, which is 4% above the national $26.65. The middle half of them earn between $19.92 and $30.57 an hour. BLS counts 1,190 of them working in the state, 13.9 for every 10,000 jobs (US: 8.7), so the local bench is deeper than average.
A crew paid at the 75th percentile for carpenters ($30.25 an hour) would add about $3,450 to the statewide midpoint; one at the 25th percentile ($21.76) would take off about $2,150. Use that as a rough guide to how far a bid can sit from our midpoint on wages alone.
BLS counts 857,440 jobs across Idaho (May 2025), which is 0.6% of US employment.
| Trade | Weight | 25th pct | Median | 75th pct | US median | Ratio | Level used |
|---|---|---|---|---|---|---|---|
| Carpenters (47-2031) | 50% | $21.76 | $25.00 | $30.25 | $29.12 | 0.86 | state |
| Cement masons and concrete finishers (47-2051) | 10% | $22.92 | $27.12 | $29.35 | $27.41 | 0.99 | state |
| Electricians (47-2111) | 10% | $23.26 | $30.29 | $39.44 | $30.38 | 1.00 | state |
| Plumbers, pipefitters and steamfitters (47-2152) | 10% | $22.21 | $25.18 | $33.48 | $30.67 | 0.82 | state |
| Drywall and ceiling tile installers (47-2081) | 10% | $17.11 | $21.05 | $27.68 | $28.33 | 0.74 | state |
| Roofers (47-2181) | 10% | $19.92 | $27.78 | $30.57 | $26.65 | 1.04 | state |
| Blended | 100% | 0.89 | |||||
How Idaho compares with nearby states
Idaho ranks 36 of 51 (the 50 states plus DC) for home addition, where 1 is the most expensive. The costliest is Hawaii at $76,300 and the cheapest Arkansas at $48,200, both for 300 sq ft at the midpoint. Idaho sits at $52,500. The five states closest by workforce center are listed below.
| State | Distance | Range | Midpoint | vs. here |
|---|---|---|---|---|
| Montana | 270 miles away | $38,700 – $78,400 | $58,600 | +12% |
| Utah | 280 miles away | $35,000 – $71,100 | $53,000 | +1% |
| Oregon | 350 miles away | $43,300 – $87,700 | $65,500 | +25% |
| Washington | 380 miles away | $45,200 – $91,400 | $68,300 | +30% |
| Nevada | 460 miles away | $38,000 – $76,900 | $57,400 | +9% |
Home addition: what moves the price in Idaho
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.
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.
Home addition cost by metro in Idaho
1 of the 3 metros sit above the statewide midpoint of $52,500, and the top-to-bottom gap is 3%. Each row prices the default size with that metro's own BLS wages and BEA price levels, so the gap between rows is real local variation rather than a flat markup.
| Metro | Range (300 sq ft) | Midpoint | vs. state |
|---|---|---|---|
| Coeur d'Alene, ID | $35,700 – $72,300 | $54,000 | +3% |
| Boise, ID | $34,700 – $70,400 | $52,500 | level |
| Idaho Falls, ID | $34,500 – $69,900 | $52,200 | −1% |
Quality levels and sizes in Idaho
The cited range is cut into three overlapping bands (basic, standard and premium) and scaled to statewide Idaho wages and prices. The grid prices the same bands at 3 common sizes.
Basic
$34,700 to $49,000
Bump-out or simple room without plumbing
Standard
$45,400 to $59,600
Standard room addition with HVAC and electrical
Premium
$56,100 to $70,300
Large addition with bath or kitchen and a new foundation
| Size | Basic | Standard | Premium |
|---|---|---|---|
| bump-out (100 sq ft) | $11,900 – $17,000 | $15,700 – $20,900 | $19,600 – $24,700 |
| 20x20 room (400 sq ft) | $46,100 – $64,900 | $60,200 – $79,000 | $74,300 – $93,200 |
| large suite (600 sq ft) | $68,900 – $96,900 | $89,900 – $118,000 | $111,000 – $139,000 |
When Idaho weather lets you build
Season matters for home addition. For each Idaho metro below we took NOAA's 1991-2020 monthly normals from the nearest suitable station and counted comfortable months for digging and ground work.
Coeur d'Alene has the longest comfortable season of the metros we cover in Idaho at 7 months (April through October); Idaho Falls has the shortest at 5 (May through September). Rainfall runs from 10 inches a year in Idaho Falls to 25 inches in Coeur d'Alene.
We do not adjust prices by month, because we have no reliable published data on seasonal pricing. Timing is still worth raising when you collect bids.
| Metro | Jan avg low °F | Jul avg high °F | Precip (in/yr) | Comfortable months |
|---|---|---|---|---|
| Boise | 26 | 93 | 12 | 6: March through June and September through October |
| Idaho Falls | 12 | 87 | 10 | 5: May through September |
| Coeur d'Alene | 26 | 83 | 25 | 7: April through October |
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Home addition in Idaho: your questions
+How much does it cost to build a home addition in Idaho?
$34,700 to $70,300 for 300 sq ft, using statewide wages and prices. Metro areas inside Idaho can sit above or below that.
+Which city in Idaho is cheapest for home addition?
Idaho Falls at about $52,200 (midpoint, 300 sq ft). The priciest is Coeur d'Alene at $54,000.
+Is home addition cheaper in Idaho than the US average?
It is 9% cheaper: $52,500 against $57,500 for 300 sq ft at the midpoint.
+What share of the price is labor in Idaho?
About 65% ($34,000). Materials are 33%. Statewide labor for this job is weighted 0.89x the national wage level.
+What do carpenters earn in Idaho?
The BLS statewide median is $25.00 an hour, against $29.12 for the US. The 25th to 75th percentile range is $21.76 to $30.25.
+Where does Idaho rank for home addition costs?
36th most expensive of 51 (the 50 states plus DC) at the midpoint, $52,500 for 300 sq ft. Rank 1 is the costliest.
+What do basic and premium home addition work cost in Idaho?
For 300 sq ft, basic work runs $34,700 to $49,000 and premium work $56,100 to $70,300. Basic means: bump-out or simple room without plumbing. Premium means: large addition with bath or kitchen and a new foundation.
+Does the season matter for home addition in Idaho?
Yes where winters or summers are hard. Of the Idaho metros we cover, Coeur d'Alene has the most comfortable months (7 of 12) based on NOAA 1991-2020 normals. Our prices do not change by month, so ask contractors whether they charge more or less in busy and slow seasons.
Home addition by city in Idaho
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.