Home addition cost in Illinois
Statewide estimate from BLS wages and BEA prices. Reviewed Nov 4, 2026.
- Statewide range (300 sq ft)
- $47,400 – $95,800
- Per sq ft
- $156 – $313
- before permit
- Versus US midpoint
- +25%
- US $57,500
- Metros covered
- 6
Illinois prices for home addition: $47,400 to $95,800 for 300 sq ft, or $156 to $313 per sq ft without the permit. The state midpoint is 25% above the national one. Local wages for carpenters are $37.98 an hour.
Inside Illinois, the metros we cover range from $64,200 (Champaign) to $74,000 (Chicago) 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 Illinois (statewide), standard level
$61,900 to $81,300
About $203 to $266 per sq ft before permits. Labor is about 72% of the bill.
| Part | Low | High |
|---|---|---|
| Materials | $16,200 | $21,200 |
| Labor | $44,800 | $58,600 |
| Permits and fees | $950 | $1,550 |
| Total | $61,900 | $81,300 |
Cost breakdown for 300 sq ft in Illinois
| Part of the job | Low | Midpoint | High | Share |
|---|---|---|---|---|
| Materials | $12,500 | $18,700 | $24,900 | 26% |
| Labor | $34,500 | $51,700 | $68,900 | 72% |
| Permits and fees | $500 | $1,250 | $2,000 | 2% |
| Total | $47,400 | $71,600 | $95,800 | 100% |
Quality levels and sizes in Illinois
The cited range is cut into three overlapping bands (basic, standard and premium) and scaled to statewide Illinois wages and prices. The grid prices the same bands at 3 common sizes.
Basic
$47,400 to $66,800
Bump-out or simple room without plumbing
Standard
$61,900 to $81,300
Standard room addition with HVAC and electrical
Premium
$76,500 to $95,800
Large addition with bath or kitchen and a new foundation
| Size | Basic | Standard | Premium |
|---|---|---|---|
| bump-out (100 sq ft) | $16,100 – $23,000 | $21,300 – $28,100 | $26,400 – $33,300 |
| 20x20 room (400 sq ft) | $63,100 – $88,700 | $82,300 – $108,000 | $101,500 – $127,000 |
| large suite (600 sq ft) | $94,300 – $132,500 | $123,000 – $161,000 | $151,500 – $189,500 |
What carpenters and the other trades earn in Illinois
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 1.35 for Illinois.
For carpenters (47-2031, weighted 50%) the local median is $37.98 an hour, which is 30% above the national $29.12. The middle half of them earn between $27.00 and $51.42 an hour. BLS counts 19,570 of them working in the state, 32.1 for every 10,000 jobs (US: 43.1), so the local bench is thinner than average.
For cement masons and concrete finishers (47-2051, weighted 10%) the local median is $37.58 an hour, which is 37% above the national $27.41. The middle half of them earn between $27.82 and $47.56 an hour. BLS counts 5,890 of them working in the state, 9.7 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 $47.87 an hour, 58% above the US median of $30.38. The middle half of them earn between $35.35 and $56.47 an hour. About 23,120 work in the state. That is 37.9 per 10,000 jobs, compared with 48.7 nationally, so expect fewer local crews to bid.
For plumbers, pipefitters and steamfitters (47-2152, weighted 10%) the local median is $48.05 an hour, which is 57% above the national $30.67. The middle half of them earn between $34.65 and $57.72 an hour. BLS counts 16,750 of them working in the state, 27.5 for every 10,000 jobs (US: 30.0), so the local bench is about average.
Drywall and ceiling tile installers (47-2081), 10% of the weighting: a median of $30.38 an hour, 7% above the US median of $28.33. The middle half of them earn between $24.78 and $49.27 an hour. About 740 work in the state. That is 1.2 per 10,000 jobs, compared with 5.3 nationally, so expect fewer local crews to bid.
For roofers (47-2181, weighted 10%) the local median is $37.45 an hour, which is 41% above the national $26.65. The middle half of them earn between $27.81 and $49.54 an hour. BLS counts 5,300 of them working in the state, 8.7 for every 10,000 jobs (US: 8.7), so the local bench is about average.
A crew paid at the 75th percentile for carpenters ($51.42 an hour) would add about $8,850 to the statewide midpoint; one at the 25th percentile ($27.00) would take off about $7,200. Use that as a rough guide to how far a bid can sit from our midpoint on wages alone.
BLS counts 6,098,130 jobs across Illinois (May 2025), which is 3.9% of US employment.
| Trade | Weight | 25th pct | Median | 75th pct | US median | Ratio | Level used |
|---|---|---|---|---|---|---|---|
| Carpenters (47-2031) | 50% | $27.00 | $37.98 | $51.42 | $29.12 | 1.30 | state |
| Cement masons and concrete finishers (47-2051) | 10% | $27.82 | $37.58 | $47.56 | $27.41 | 1.37 | state |
| Electricians (47-2111) | 10% | $35.35 | $47.87 | $56.47 | $30.38 | 1.58 | state |
| Plumbers, pipefitters and steamfitters (47-2152) | 10% | $34.65 | $48.05 | $57.72 | $30.67 | 1.57 | state |
| Drywall and ceiling tile installers (47-2081) | 10% | $24.78 | $30.38 | $49.27 | $28.33 | 1.07 | state |
| Roofers (47-2181) | 10% | $27.81 | $37.45 | $49.54 | $26.65 | 1.41 | state |
| Blended | 100% | 1.35 | |||||
Home addition: what moves the price in Illinois
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.
Illinois against its neighbors
Illinois ranks 2 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. Illinois sits at $71,600. The five states closest by workforce center are listed below.
| State | Distance | Range | Midpoint | vs. here |
|---|---|---|---|---|
| Wisconsin | 120 miles away | $39,300 – $79,500 | $59,400 | −17% |
| Indiana | 140 miles away | $38,500 – $78,000 | $58,300 | −19% |
| Michigan | 220 miles away | $39,200 – $79,400 | $59,300 | −17% |
| Iowa | 240 miles away | $35,900 – $72,700 | $54,300 | −24% |
| Kentucky | 280 miles away | $34,500 – $70,000 | $52,200 | −27% |
Which Illinois city is cheapest for home addition?
1 of the 6 metros sit above the statewide midpoint of $71,600, and the top-to-bottom gap is 15%. 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 |
|---|---|---|---|
| Chicago, IL | $49,000 – $99,000 | $74,000 | +3% |
| Springfield, IL | $44,200 – $89,400 | $66,800 | −7% |
| Peoria, IL | $43,700 – $88,300 | $66,000 | −8% |
| Rockford, IL | $43,600 – $88,200 | $65,900 | −8% |
| Bloomington, IL | $43,000 – $86,900 | $64,900 | −9% |
| Champaign, IL | $42,500 – $85,900 | $64,200 | −10% |
If you are planning more than one job in Illinois
The table prices neighboring jobs at their usual sizes using statewide Illinois wages and prices. Against national midpoints, roof replacement comes out highest (+25%) and kitchen remodel lowest (+10%), because each job leans on different trades.
| Project | Size | Range | vs. US |
|---|---|---|---|
| Kitchen remodel | 120 sq ft | $20,300 – $34,600 | +10% |
| Bathroom remodel | 45 sq ft | $5,650 – $27,900 | +20% |
| Detached garage | 576 sq ft | $34,500 – $69,200 | +19% |
| Roof replacement | 2,000 sq ft of roof | $7,850 – $15,400 | +25% |
Illinois seasons and home addition
Season matters for home addition. For each Illinois metro below we took NOAA's 1991-2020 monthly normals from the nearest suitable station and counted comfortable months for digging and ground work.
Chicago has the longest comfortable season of the metros we cover in Illinois at 8 months (April through November); Bloomington has the shortest at 7 (April through October). Rainfall runs from 34 inches a year in Chicago to 40 inches in Springfield.
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 |
|---|---|---|---|---|
| Chicago | 19 | 85 | 34 | 8: April through November |
| Peoria | 18 | 86 | 38 | 8: April through November |
| Rockford | 15 | 84 | 37 | 7: April through October |
| Champaign | 18 | 85 | 37 | 7: April through October |
| Springfield | 19 | 86 | 40 | 8: April through November |
| Bloomington | 16 | 86 | 39 | 7: April through October |
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Home addition in Illinois: your questions
+How much does it cost to build a home addition in Illinois?
$47,400 to $95,800 for 300 sq ft, using statewide wages and prices. Metro areas inside Illinois can sit above or below that.
+Which city in Illinois is cheapest for home addition?
Champaign at about $64,200 (midpoint, 300 sq ft). The priciest is Chicago at $74,000.
+Is home addition cheaper in Illinois than the US average?
It is 25% more expensive: $71,600 against $57,500 for 300 sq ft at the midpoint.
+What share of the price is labor in Illinois?
About 72% ($51,700). Materials are 26%. Statewide labor for this job is weighted 1.35x the national wage level.
+What do carpenters earn in Illinois?
The BLS statewide median is $37.98 an hour, against $29.12 for the US. The 25th to 75th percentile range is $27.00 to $51.42.
+Where does Illinois rank for home addition costs?
2nd most expensive of 51 (the 50 states plus DC) at the midpoint, $71,600 for 300 sq ft. Rank 1 is the costliest.
+What do basic and premium home addition work cost in Illinois?
For 300 sq ft, basic work runs $47,400 to $66,800 and premium work $76,500 to $95,800. 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 Illinois?
Yes where winters or summers are hard. Of the Illinois metros we cover, Chicago has the most comfortable months (8 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 Illinois
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.