An ADU builder in Gilbert 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 Gilbert's permit process and utility connections. Not every general contractor has built one, so the right builder is one with ADU-specific experience in Arizona.
What ADU Builders Cost in Gilbert [6]
Based on our Gilbert 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) | $130,000-$260,000 |
| Cost per Sq Ft | $150-$280 |
| Garage Conversion | $60,000-$140,000 |
| Prefab / Modular ADU (installed) | $90,000-$210,000 |
| City Permit & Plan Review | Building permit and plan review fees based on valuation — Confirm with Gilbert Development Services |
| Impact Fees | System development fees apply to new dwelling units — Confirm with Gilbert Development Services |
For a full line-item breakdown, see our Gilbert ADU cost guide. To confirm what you're allowed to build before you hire, review the Gilbert ADU rules (max detached size: 75% of the primary residence's gross square footage (state law guarantees at least the lesser of 1,000 sq ft or 75%); owner-occupancy: Not required for long-term rentals; no familial or pre-existing-relationship test allowed).
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How to Vet an ADU Builder in Gilbert
- License: Confirm a current contractor's license in Arizona 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 Gilbert 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 (Building permit and plan review fees based on valuation — Confirm with Gilbert Development Services), plan check (Full construction plan review required — Confirm with Gilbert Development Services), and impact fees (System development fees apply to new dwelling units — Confirm with Gilbert Development Services) are included.
- Permit handling: Confirm they manage Gilbert's permit process ("By-right building permit with construction plan review through Gilbert's One Stop Shop (no use permit or hearing)", typically Confirm with Gilbert Development Services (480-503-6700)) 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 Gilbert 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 (Confirm with Gilbert Development Services (480-503-6700)) 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 Arizona 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.
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