An ADU builder in Richardson is a licensed contractor who designs and constructs accessory dwelling units — detached backyard units, garage conversions, attached additions, and junior ADUs (JADUs). Because an ADU is a complete second dwelling, the builder coordinates foundation, framing, plumbing, electrical, and HVAC work and pulls it through Richardson's permit process and utility connections. Not every general contractor has built one, so the right builder is one with ADU-specific experience in Texas.
What ADU Builders Cost in Richardson [10][11][12]
Based on our Richardson cost data, expect the following ranges from local ADU builders. Quotes for the same scope typically vary 20-40% between contractors, so getting at least three bids is the single best way to control cost.
| New Detached ADU (all-in) | $140,000-$350,000 |
| Cost per Sq Ft | $250-$400 |
| Garage Conversion | $30,000-$100,000 |
| Prefab / Modular ADU (installed) | $150,000-$300,000 |
| City Permit & Plan Review | Accessory building permit: $100 for a structure of 150 sq ft or less, $200 for one larger than 150 sq ft; a room addition is $200 up to 500 sq ft, then $200 plus $0.10/sq ft (Appendix B, Master Fee Schedule, Ord. 4559, Sept. 15, 2025). |
| Impact Fees | None found. The Master Fee Schedule (Appendix B, as amended through Ord. 4560, Oct. 13, 2025) lists no development impact fee for residential work; the only impact-related charges are traffic impact analysis reviews filed with a zoning request ($500 without modelling, $1,500 with). Water and sewer connection charges are billed per the schedule; confirm with Development Services |
For a full line-item breakdown, see our Richardson ADU cost guide. To confirm what you're allowed to build before you hire, review the Richardson ADU rules (max detached size: N/A: a detached second dwelling is not a permitted use. Detached accessory buildings are capped instead: all detached structures together, garages included, may occupy no more than 8% of the lot area and may not exceed 40% of the floor area of the principal dwelling (Art. IV, Sec. 4(d)(2); Art. VII, Sec. 4(d)(2)). Servants' quarters, the only accessory living space allowed, may not have kitchen facilities or separate utility connections (Art. I, Sec. 2); owner-occupancy: Moot for ADUs, since none may be built. Servants' quarters must be occupied by persons employed full-time on the premises as domestic help by the occupant, and may not be rented (Art. I, Sec. 2). Renting rooms inside the house is allowed to a maximum of two individual renters or tenants (Art. IV, Sec. 1(j); Art. VII, Sec. 1(j))).
Get Free ADU Quotes in Richardson
Tell us about your project and we'll pass it to ADU builders serving Richardson. Free, no obligation — you choose who to work with. We don't have builders in every area yet; if nobody covers yours, we'll email you to say so.
Takes about a minute.
Up to 5 independent local ADU builders — never more, and we tell them nothing you don't submit here.
Compare quotes, verify license & insurance, hire (or don't). No spam either way.
🔒 Your info is secure. We share it only with contractors quoting your project. No spam, no obligation.
Just browsing? Search ADU builders near you by ZIP code.
How to Vet an ADU Builder in Richardson
- License: Confirm a current contractor's license in Texas and that it's in good standing. Ask for the license number and verify it with the state board.
- ADU-specific experience: Ask how many ADUs they've completed in or near Richardson and request addresses or photos. ADU permitting and setbacks differ from a kitchen remodel.
- Portfolio & references: Get references from recent ADU clients and, if possible, visit a finished unit.
- Insurance: Verify general liability and workers' compensation coverage. Ask for a certificate of insurance.
- Written, detailed bid: Insist on an itemized, fixed-price or clearly-scoped bid — not a verbal estimate. It should state whether permits (Accessory building permit: $100 for a structure of 150 sq ft or less, $200 for one larger than 150 sq ft; a room addition is $200 up to 500 sq ft, then $200 plus $0.10/sq ft (Appendix B, Master Fee Schedule, Ord. 4559, Sept. 15, 2025).), plan check (Scaled drawings are required for any accessory building over 150 sq ft, and each exterior wall of a building over 150 sq ft must be at least 35% masonry (Art. IV, Sec. 2(b)(2)); 150 sq ft or less may be wood or metal. The building must be permanently anchored, and the approved permit must be posted on site before work starts. Richardson has adopted the 2021 International Codes and the 2020 National Electrical Code, and every contractor must be registered with the city ($100, Sec. 6-116)), and impact fees (None found. The Master Fee Schedule (Appendix B, as amended through Ord. 4560, Oct. 13, 2025) lists no development impact fee for residential work; the only impact-related charges are traffic impact analysis reviews filed with a zoning request ($500 without modelling, $1,500 with). Water and sewer connection charges are billed per the schedule; confirm with Development Services) are included.
- Permit handling: Confirm they manage Richardson's permit process ("There is no ADU permit in Richardson because there is no ADU use to permit. A second unit would need a zoning change, realistically a PD planned development district whose uses and standards are written for the individual tract (Art. II, Sec. 1; Art. XXI-C): a City Plan Commission and City Council process, filing fee $2,500 (Appendix B), not a counter application. For an ordinary accessory building, Building Inspection requires a permit for any structure over 40 sq ft; 150 sq ft or less needs an application with a location sketch, anything larger needs scaled drawings. Submit by email to permits@cor.gov or at 2360 Campbell Creek Blvd, Suite 550", typically Not published. Building Inspection (972-744-4180) posts no review time for accessory-building permits, and no ADU timeline exists because no ADU use exists.) and who is responsible if revisions are required.
- Payment schedule: Avoid large upfront payments. A reasonable schedule ties payments to completed milestones.
Questions to Ask Before You Hire
- How many ADUs have you built in Richardson in the last two years?
- Is your bid fixed-price, and what would trigger a change order?
- Are permits, plan check, and utility connection fees included?
- What's a realistic timeline, including permit review (Not published. Building Inspection (972-744-4180) posts no review time for accessory-building permits, and no ADU timeline exists because no ADU use exists.) and construction?
- Who is my point of contact and how are delays communicated?
- What warranty do you provide on workmanship?
- Can you share three recent Texas ADU client references?
Finance Your ADU Project
Most ADU projects are funded through HELOCs, construction loans, or cash-out refinancing. Compare rates from top lenders.
Some links on this page are affiliate links. We may earn a commission at no extra cost to you. Learn more
Are you an ADU builder? Get Richardson leads
Homeowners on this page submit real ADU project requests in Richardson. Each one goes to up to five local builders — that is what the homeowner agrees to — so claiming never takes it from anyone and there is no bidding. In practice far fewer ever make contact, which is why the number is five rather than three. A flat $50 only on the leads you accept: no subscription, no contract, and you deal with the homeowner directly.
Get Richardson ADU Leads →Frequently Asked Questions
How much do ADU builders charge in Richardson?
How do I find a good ADU builder in Richardson?
Do ADU builders in Richardson handle permits?
How long does it take to build an ADU in Richardson?
Get Free ADU Builder Quotes in Richardson
Compare bids from experienced local Richardson ADU builders. Free, no obligation.
Get Free Quotes →