Sahuarita and Green Valley follow different rules
Sahuarita is an incorporated town with its own zoning code and permit office. Green Valley, right next door, is not a town at all. It is unincorporated Pima County. So the same casita can be allowed on one side of the line and need a different design on the other. Your parcel record on the Pima County Assessor site tells you which applies, or we can check for you.
Sahuarita's ADU rules
Sahuarita is under the 75,000-person threshold in Arizona's 2024 ADU law, but the town adopted its own accessory dwelling unit standards in Section 18.12.030 of its zoning code (Ordinance 2023-167, amended by Ordinance 2024-177). The key points:
- One ADU per lot, allowed in the RH through R-5 residential zones.
- Minimum lot size of 11,000 sq ft. Many newer subdivision lots are smaller than that, so check yours first.
- Maximum size of 1,000 sq ft.
- Height. An ADU that meets the main house setbacks can be as tall as the house. Any part that sits closer, inside the ADU setback, is limited to 16 feet.
- Parking. One extra parking space is required on top of the main home's parking.
- Setbacks by zone. ADU side setbacks run from 5 feet in the R-4 and R-5 zones up to 20 feet in RH, and rear setbacks from 10 feet up to 50 feet.
- Manufactured and tiny homes can serve as an ADU in RH and GR-1 on a foundation, and in SR, R-1 and R-2 only with a conditional use permit, behind the house and screened by an opaque wall.
Some neighborhoods sit under their own specific plans. The town lists plans for Rancho Sahuarita, Quail Creek, Madera Highlands and others on its zoning and specific plans page, and Rancho Sahuarita has its own zoning code. HOA rules apply on top of all of this.
Check your lot size before anything else
The 11,000 sq ft minimum is the rule that rules out the most Sahuarita lots, so it is worth checking first. Your lot area is on your parcel record with the Pima County Assessor. If the lot is too small for an ADU, you still have options. A bedroom suite with a bathroom built onto the house is a home addition rather than a separate dwelling, and it is permitted as an addition. For a parent who needs to be close, that is often the better layout anyway. Our home addition cost guide covers what drives that price.
Green Valley guest houses
In Green Valley, a detached casita is a Pima County guest house. Per the county's guest house rules: one per lot on lots of at least 4,000 sq ft, at least two rooms and a bathroom, a kitchen allowed, accessory building setbacks, 3 feet from the main home, shared driveway, no separate utility meter, and occupancy limited to family and non-paying guests. Many Green Valley homes are also in HOAs with their own review.
Because a Green Valley guest house shares the main home's meter and driveway and isn't set up as a rental, it works best as family space: a place for visiting children and grandchildren, or for a parent who wants independence close by. Designing it that way from the start keeps the plans simple and the review straightforward.
Designing a casita for visiting family
A lot of casitas here are for parents, grandparents or long visits from family. That points to single-level layouts, a low-threshold walk-in shower, wider doorways and blocking in the walls for grab bars later. Our bathroom team builds those showers every week, and our mother-in-law suite guide covers layouts. On a smaller lot, an attached suite may be the better fit. See casita vs home addition.
How we build a casita here
- Site walk. Lot size, zone, HOA, utilities and where the casita fits.
- Jurisdiction check. Sahuarita ADU standards, a specific plan, or Pima County guest house rules.
- Plans. Drawings and a site plan that meet the right setbacks and parking.
- Permits. HOA approval where needed, then the town or county permit.
- Build. Our crew handles framing, structural work, roofing and stucco in house.
- Inspections and final. We schedule inspections and walk the finished casita with you.
For budgets, see the casita cost guide. For other work in the area, visit our Sahuarita and Green Valley contractor page.