Building a casita in Buckeye: the rules, fees and the math

The rules in Buckeye

Mobile homes, industrialized housing, RVs, travel trailers and wheeled structures may not be used as a unit. The unit is not required to have separate utility service unless the utility requires a separate meter for safety. The code is silent on rental and short-term rental, so the state's long-term rental right applies. Fee schedules could not be retrieved; fees are confirmed per address.

Source: City of Buckeye: Development Code Section 3.3.4.A, Accessory Dwelling Units; buckeyeaz.gov. Read October 7, 2026. Some items could not be confirmed from the city's published material and are left out above; we confirm them with the city during the property review.

Fees in Buckeye

Buckeye does not publish a simple ADU fee figure. Permit fees are set by valuation, impact fees depend on the fee district, and water and sewer fees depend on the provider; we pull the exact numbers for your parcel during the property review.

In June 2026 the state capped the development (impact) fees a city may charge an ADU for services other than water and sewer at the lesser of 25% of the single-family fee or the unit's proportionate share, and limited water and sewer fees to the unit's added demand (HB 2946, signed June 5, 2026). Most cities had not yet re-published schedules when we read them; Glendale's 25% ADU line is the first we found. Expect ADU impact fees to fall toward that cap. Governor's announcement.

What the state law guarantees here

Whatever the local code says, in Buckeye these points come from A.R.S. § 9-461.18 and the city cannot be stricter:

• At least one attached and one detached ADU on any lot with a single-family home, as a permitted use (no public hearing, no variance)
• A unit up to 75% of the main home's gross floor area or 1,000 sq ft, whichever is smaller (cities may allow larger)
• A third, detached unit on lots of one acre or more if one unit is deed-restricted affordable
• Separate long-term rental of either the house or the ADU (leases of 90 days or more, or month to month)

The math in Buckeye

Redfin's median sale price in Buckeye is $224 per square foot. A new casita builds for about $265 to $280 per finished foot and a garage conversion for about $120. That puts Buckeye in the "Conversion territory" tier: one square foot of new casita, at the typical $272 build cost, comes out −$104 at a 75% appraiser credit and −$48 at full credit. A conversion clears at either credit.

The target areas page explains the tiers and the math page has the calculator. Rent is the other half: see rental math.

Owners and investors in Buckeye

• Homeowners get a by-right unit for family, guests or long-term rent, with the same appraisal and lender rules as anywhere in the Valley.
• Investors can treat the casita as the piece that moves a house out of its neighborhood's price band at resale, as our two Maryvale sales show on the case studies, and as monthly income in the meantime. Buckeye's rental rules above say whether both units can be let separately.
• Either way the lot decides: setbacks, utilities, sewer depth and easements. Request a property review and we confirm the current Buckeye rules for your address.

Other city pages: Phoenix, Mesa, Chandler, Gilbert, Scottsdale, Tempe, Glendale, Peoria, Surprise, Goodyear.