Complete 2026 cost breakdown: construction, permits, financing, and expected rental ROI.
Calculate your Frisco ADU cost →Building an ADU in Frisco costs between $140,000-$350,000 for new construction, with per-square-foot costs averaging $250-$400. These figures include design, permitting, site preparation, and construction. The most affordable option is a garage conversion at $30,000-$100,000, while prefab/modular ADUs fall in between at $150,000-$300,000.
| Cost Category | Estimated Range |
|---|---|
| Architectural Plans | $3,000 – $15,000 |
| Permits & Fees | Building permit $150 for the first 300 sq ft plus $0.50 per added sq ft ($400 for 800 sq ft), plus a $300 application fee and $50-per-trade electrical, mechanical and plumbing permits, per the FY26 Comprehensive Fee Ordinance 2025-09-48 (effective Oct 1, 2025); FY27 figures apply from Oct 1, 2026. |
| Impact Fees | Frisco's impact fees are assessed per water meter and per new dwelling unit under Ordinance 19-04-29: water $2,120 and wastewater $2,344 for a 1-inch single-family meter (Exhibits B and C), and a roadway fee of $1,935-$4,257 per single-family dwelling unit depending on service area. Whether a garage apartment served by the existing meter is assessed is not stated in the schedule — confirm with Development Services (972-292-5301) before pricing the project |
| 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. We pass your request to up to 5 local builders serving Frisco, where we have them — free, no obligation.
Get Frisco builder quotes →Permit fees in Frisco are Building permit $150 for the first 300 sq ft plus $0.50 per added sq ft ($400 for 800 sq ft), plus a $300 application fee and $50-per-trade electrical, mechanical and plumbing permits, per the FY26 Comprehensive Fee Ordinance 2025-09-48 (effective Oct 1, 2025); FY27 figures apply from Oct 1, 2026.. The review timeline is Not published. Frisco's Residential Permits page lists the steps (electronic application, fees assigned by email, pre-screen, Department Review, permit download) but no review-time target — confirm current turnaround with Plans & Permits (972-292-5301)., with plan check: Standard residential plan review through the electronic permit portal; plan revisions are billed at $50 per hour (Ordinance 2025-09-48). Budget for the facade rule: the exterior of an accessory structure must use the same exterior material as the main building and meet or exceed §4.07.09 Exterior Construction of Main Buildings (100% masonry), with fiber cement siding allowed only on a structure of 200 sq ft or less in a single-family or two-family district, or where the main house is itself all wood or vinyl siding (§4.06.05). Impact fees are Frisco's impact fees are assessed per water meter and per new dwelling unit under Ordinance 19-04-29: water $2,120 and wastewater $2,344 for a 1-inch single-family meter (Exhibits B and C), and a roadway fee of $1,935-$4,257 per single-family dwelling unit depending on service area. Whether a garage apartment served by the existing meter is assessed is not stated in the schedule — confirm with Development Services (972-292-5301) before pricing the project. Pre-approved plans: None. No city pre-approved garage apartment or ADU plan library appears on Frisco's Residential Permits page or in the fee ordinance — confirm with Development Services (972-292-5301).
| 1-Bedroom Rent | $1,500-$2,100/month |
| 2-Bedroom Rent | $2,000-$2,600/month |
| Annual Rental Income (est.) | $21,600/year |
| Payback Period (est.) | 11.3 years |
| Short-Term Rental | Allowed with a city short-term rental permit. |
| Overall ROI Estimate | 5-12% gross rent yield |
A typical ADU in Frisco generates approximately $21,600 per year in rental income based on average 1-bedroom rents. At an average construction cost of $245,000, the estimated payback period is 11.3 years — before accounting for the resale value the ADU adds, which an appraiser determines from comparable sales in Frisco 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 Frisco: $30,000-$100,000.
2. Prefab/modular ADUs offer predictable pricing and faster timelines. Average: $150,000-$300,000.
3. Pre-approved plans — available in Frisco, which can save $3,000-$10,000 in design costs and 2-3 months in review time. 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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