Complete 2026 cost breakdown: construction, permits, financing, and expected rental ROI.
Building an ADU in Henderson costs between $130,000-$250,000 for new construction, with per-square-foot costs averaging $140-$280. These figures include design, permitting, site preparation, and construction. The most affordable option is a garage conversion at $60,000-$140,000, while prefab/modular ADUs fall in between at $90,000-$200,000.
| Cost Category | Estimated Range |
|---|---|
| Architectural Plans | $3,000 – $15,000 |
| Permits & Fees | Confirm with Henderson Development Services Center |
| Impact Fees | Confirm with Henderson Development Services Center |
| Site Prep & Foundation | $10,000 – $35,000 |
| Framing & Structure | $15,000 – $45,000 |
| Plumbing | $8,000 – $20,000 |
| Electrical | $5,000 – $15,000 |
| HVAC | $3,000 – $8,000 |
| Interior Finishes | $15,000 – $40,000 |
Permit fees in Henderson are Confirm with Henderson Development Services Center. The review timeline is Confirm with Henderson Development Services Center, with plan check taking approximately Confirm with Henderson Development Services Center. Impact fees are Confirm with Henderson Development Services Center. Pre-approved plans: No city pre-approved ADU plan program identified as of June 2026.
| 1-Bedroom Rent | $1,300-$1,650/mo/month |
| 2-Bedroom Rent | $1,550-$1,900/mo/month |
| Annual Rental Income (est.) | $17,700/year |
| Payback Period (est.) | 10.7 years |
| Short-Term Rental | No — accessory dwelling rental agreements must exceed 30 days (per Review-Journal reporting); Henderson's separate short-term rental licensing rules apply to other property types |
| Overall ROI Estimate | 5-8% annual return |
A typical ADU in Henderson generates approximately $17,700 per year in rental income based on average 1-bedroom rents. At an average construction cost of $190,000, the estimated payback period is 10.7 years — before accounting for property value appreciation, which typically adds 20-35% to home value.
1. Garage conversions save 40-60% vs new construction since the shell already exists. Average cost in Henderson: $60,000-$140,000.
2. Prefab/modular ADUs offer predictable pricing and faster timelines. Average: $90,000-$200,000.
3. Pre-approved plans (No city pre-approved ADU plan program identified as of June 2026) can save $3,000-$10,000 in design costs and 2-3 months in review time.
4. State grants — California's CalHFA program offers up to $40K. Check your state for available programs.
5. Get multiple bids — ADU contractor pricing varies 20-40% for the same project. We recommend getting at least 3 quotes.
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