Complete 2026 cost breakdown: construction, permits, financing, and expected rental ROI.
Calculate your Plano ADU cost →Building an ADU in Plano costs between $130,000-$260,000 for new construction, with per-square-foot costs averaging $150-$275. These figures include design, permitting, site preparation, and construction. The most affordable option is a garage conversion at $60,000-$145,000, while prefab/modular ADUs fall in between at $90,000-$200,000.
| Cost Category | Estimated Range |
|---|---|
| Architectural Plans | $3,000 – $15,000 |
| Permits & Fees | Building permit and plan review fees are valuation-based — Confirm current amounts with Plano Building Inspections |
| Impact Fees | Confirm with Plano Engineering — no ADU-specific impact fee schedule found in a city source |
| 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 |
Quotes for the same ADU commonly vary 20–40% between builders. Get up to 5 free quotes from ADU builders serving Plano — no obligation.
Get Plano builder quotes →Permit fees in Plano are Building permit and plan review fees are valuation-based — Confirm current amounts with Plano Building Inspections. The review timeline is Confirm with Plano Building Inspections (972-941-7140) — no published review timeline for Backyard Cottages found in a city source, with plan check: Standard residential plan review — Confirm timing with Plano Building Inspections. Impact fees are Confirm with Plano Engineering — no ADU-specific impact fee schedule found in a city source. Pre-approved plans: No city pre-approved plan library found — Confirm with Plano Planning (972-941-7151).
| 1-Bedroom Rent | $1,250-$1,650/month |
| 2-Bedroom Rent | $1,650-$2,250/month |
| Annual Rental Income (est.) | $17,400/year |
| Payback Period (est.) | 11.2 years |
| Short-Term Rental | Effectively no in single-family neighborhoods — Plano's short-term rental ordinance treats a Backyard Cottage and the main dwelling as a single residence, and the two cannot be rented as separate Off-site Management STRs (Plano Zoning Ordinance §15.2300.8; Ord. No. 2024-4-13). Off-site Management STRs are permitted only in nonresidential districts and multifamily. Confirm your address with Plano Planning |
| Overall ROI Estimate | 5-8% annual return |
A typical ADU in Plano generates approximately $17,400 per year in rental income based on average 1-bedroom rents. At an average construction cost of $195,000, the estimated payback period is 11.2 years — before accounting for the resale value the ADU adds, which an appraiser determines from comparable sales in Plano and varies by market (often less than build cost).
1. Garage conversions save 40-60% vs new construction since the shell already exists. Average cost in Plano: $60,000-$145,000.
2. Prefab/modular ADUs offer predictable pricing and faster timelines. Average: $90,000-$200,000.
3. Pre-approved plans — Plano does not offer a pre-approved/standard ADU plan program yet, so budget for custom architectural plans (typically $3,000-$15,000). See which cities offer pre-approved ADU plans.
4. State grants — California's CalHFA ADU grant (up to $40K) is currently paused; check calhfa.ca.gov/adu for status and your state for active 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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