600 Sq Ft ADU Cost: Price Guide for U.S. Homes 2026
The typical 600 sq ft ADU price range reflects factors like land prep, foundation, utilities, and finishing quality. The main cost drivers are site access, local permitting, and the level of interior finish. This guide presents practical cost estimates in USD with clear low–average–high ranges to help buyers budget effectively.
| Item | Low | Average | High | Notes |
|---|---|---|---|---|
| Total project cost | $120,000 | $210,000 | $330,000 | Assumes full foundation, utilities, and mid-range finishes |
| Cost per sq ft | $200 | $350 | $550 | Depends on region and material choices |
| Permits & design | $6,000 | $15,000 | $30,000 | Includes fees, plan review, and impact studies |
| Foundation & framing | $40,000 | $70,000 | $120,000 | Slab vs crawlspace vs full basement; structural complexity matters |
| Utilities (water, sewer, electric, gas) | $20,000 | $40,000 | $70,000 | Connection to main lines, trenching, meters |
| Interior finishes | $25,000 | $50,000 | $90,000 | Includes cabinets, appliances, flooring, fixtures |
| Site work & drive/yard access | $8,000 | $18,000 | $40,000 | Grading, drainage, paving or gravel |
| Delivery, disposal & contingencies | $6,000 | $14,000 | $28,000 | contingency for unforeseen issues |
Overview Of Costs
Key takeaway: a 600 sq ft ADU often totals $120,000–$330,000, with per‑unit ranges of roughly $200–$550 per square foot. Factors include foundation type, finishes, lot preparation, and local permitting costs. Assumptions: region, specs, labor hours.
Cost Breakdown
The following table consolidates major cost categories and typical ranges for a 600 sq ft ADU where mid-range finishes are desired. Assumptions: standard foundation, full utilities, and normal site access.
| Category | Low | Average | High | Notes |
|---|---|---|---|---|
| Materials | $25,000 | $60,000 | $120,000 | Framing, insulation, drywall, fixtures |
| Labor | $60,000 | $110,000 | $180,000 | Skilled trades for framing, electrical, plumbing |
| Equipment | $5,000 | $15,000 | $25,000 | Tools, lifts, temporary power, generators |
| Permits | $6,000 | $15,000 | $30,000 | Planning, design review, impact fees |
| Delivery/Disposal | $4,000 | $10,000 | $18,000 | Material transport and debris removal |
| Warranty | $2,000 | $6,000 | $12,000 | Structural and appliance warranties |
| Overhead & Profit | $6,000 | $14,000 | $28,000 | Contractor markup |
| Taxes | $4,000 | $10,000 | $20,000 | State/local sales and use tax |
What Drives Price
Regional variation: costs vary by state and metro area, with higher rates in coastal cities and tight labor markets. Assumptions: typical urban/Surburban mix.
Labor, Hours & Rates
Labor costs reflect crew size and duration. A 600 sq ft ADU often requires a small crew for 8–14 weeks, depending on weather and inspections. Typical hourly rates range from $60–$120 for carpentry and $75–$150 for licensed trades combined with permit timelines.
Regional Price Differences
Comparing regions, the urban West and Northeast tend to be higher, followed by the Midwest, with rural areas usually lowest. Expect ±15–35% deltas across regions depending on labor markets and permit stringency. Prime drivers include permit complexity and utility trenching costs.
Real-World Pricing Examples
Three scenario cards illustrate how design choices affect total cost. Assumptions: 600 sq ft footprint, compliant foundation, standard interior finishes.
Basic Scenario
Specs: slab foundation, basic exterior, mid-range interior. Labor: 8 weeks. Per‑unit price: $180–$230/sq ft. Total: $108,000–$138,000.
Mid-Range Scenario
Specs: crawlspace foundation, mid-range siding, upgraded kitchen. Labor: 10–12 weeks. Per‑unit price: $230–$360/sq ft. Total: $138,000–$216,000.
Premium Scenario
Specs: full basement or deeper crawl, high-end fixtures, custom cabinetry. Labor: 12–16 weeks. Per‑unit price: $350–$550/sq ft. Total: $210,000–$330,000.
Permits, Codes & Rebates
Permit fees vary by jurisdiction; some locales offer rebates for energy efficiency upgrades or ADU-friendly zoning. Budget for plan reviews, inspections, and potential impact fees.
Additional & Hidden Costs
Hidden items may include soil tests, grading, drainage improvements, and utility upgrades. Assumptions: standard site, no major environmental constraints.
Ways To Save
Strategies include choosing a simpler design, opting for prefab components, and scheduling work in off-peak seasons. Careful permitting research can reduce wait times and costs.
Pricing FAQ
Q: Do foundations differ by region? A: Yes, slab, crawlspace, and basement choices impact cost significantly. Q: Are there ongoing ownership costs? A: Yes, utilities, maintenance, and potential property tax adjustments. Accurate estimation requires a local bid with site-specific details.