Prefab / modular ADU Cost
A factory-built unit delivered and installed on a prepared site. Faster and more price-predictable than site-built; the range includes delivery, crane and site work.
Nationally a prefab / modular ADU runs $180–$300/sq ft turnkey. Below is a 600 sq ft example for every state, adjusted for local construction costs.
| State | 600 sq ft estimate | $/sq ft |
|---|---|---|
| Mississippi | $89,500–$149,500 | $149–$249 |
| Arkansas | $90,500–$151,000 | $151–$252 |
| Alabama | $92,000–$153,000 | $153–$255 |
| Oklahoma | $93,000–$155,000 | $155–$258 |
| South Carolina | $94,000–$156,500 | $157–$261 |
| North Carolina | $95,000–$158,500 | $158–$264 |
| Tennessee | $95,000–$158,500 | $158–$264 |
| Kansas | $95,000–$158,500 | $158–$264 |
| Louisiana | $95,000–$158,500 | $158–$264 |
| Georgia | $97,000–$162,000 | $162–$270 |
| Kentucky | $97,000–$162,000 | $162–$270 |
| Nebraska | $97,000–$162,000 | $162–$270 |
| New Mexico | $97,000–$162,000 | $162–$270 |
| South Dakota | $97,000–$162,000 | $162–$270 |
| West Virginia | $97,000–$162,000 | $162–$270 |
| Texas | $99,500–$165,500 | $166–$276 |
| Indiana | $99,500–$165,500 | $166–$276 |
| Iowa | $99,500–$165,500 | $166–$276 |
| Missouri | $99,500–$165,500 | $166–$276 |
| Florida | $102,500–$171,000 | $171–$285 |
| Ohio | $102,500–$171,000 | $171–$285 |
| Michigan | $102,500–$171,000 | $171–$285 |
| Idaho | $102,500–$171,000 | $171–$285 |
| North Dakota | $102,500–$171,000 | $171–$285 |
| Wyoming | $102,500–$171,000 | $171–$285 |
| Montana | $106,000–$176,500 | $176–$294 |
| Utah | $106,000–$176,500 | $176–$294 |
| Arizona | $106,000–$176,500 | $176–$294 |
| Virginia | $106,000–$176,500 | $176–$294 |
| Delaware | $108,000–$180,000 | $180–$300 |
| Wisconsin | $108,000–$180,000 | $180–$300 |
| Maine | $110,000–$183,500 | $184–$306 |
| Pennsylvania | $110,000–$183,500 | $184–$306 |
| Nevada | $110,000–$183,500 | $184–$306 |
| New Hampshire | $113,500–$189,000 | $189–$315 |
| Vermont | $113,500–$189,000 | $189–$315 |
| Colorado | $113,500–$189,000 | $189–$315 |
| Minnesota | $113,500–$189,000 | $189–$315 |
| Maryland | $113,500–$189,000 | $189–$315 |
| Oregon | $116,500–$194,500 | $194–$324 |
| Washington | $119,000–$198,000 | $198–$330 |
| Illinois | $119,000–$198,000 | $198–$330 |
| Rhode Island | $121,000–$201,500 | $202–$336 |
| Connecticut | $124,000–$207,000 | $207–$345 |
| New Jersey | $124,000–$207,000 | $207–$345 |
| Massachusetts | $129,500–$216,000 | $216–$360 |
| New York | $129,500–$216,000 | $216–$360 |
| Washington DC | $129,500–$216,000 | $216–$360 |
| California | $135,000–$225,000 | $225–$375 |
| Alaska | $140,500–$234,000 | $234–$390 |
| Hawaii | $146,000–$243,000 | $243–$405 |
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Other ADU types
Estimates are for planning only and are based on regional construction-cost indices and published statewide ADU statutes. Local ordinances, lot conditions and contractor pricing vary — always confirm with your city planning department and a licensed contractor.