Casita builder in the Catalina Foothills

In the Foothills, a casita is a Pima County guest house

The Catalina Foothills is not a city or town. It is unincorporated Pima County, so your casita is permitted by Pima County Development Services, not the City of Tucson. Arizona's 2024 ADU law applies to large cities, not to unincorporated county land, so the county's own guest house rules are what matter here.

Pima County's guest house rules

From the county's guest house page and zoning code Section 18.09.020:

• A guest house is a detached building with at least two rooms and a bathroom. It may have a kitchen.
• The lot must be at least 4,000 sq ft, and only one guest house per lot is allowed.
• Setbacks and lot coverage follow the accessory building standards for your zone, and the guest house must be at least 3 feet from the main home.
• It must use the same access as the main home. No new driveway.
• No separate utility meter.
• Occupancy is limited to family members and their non-paying guests.
• The submittal follows the county's custom home process. If a setback can't be met, a modification or variance may be possible.

That last occupancy point is the big difference from the City of Tucson, where state law requires that a casita can be rented long term. In the Foothills, a guest house is for family and guests. If you want an attached suite instead, our casita vs home addition guide compares the two.

Slopes, native plants and washes

Foothills lots are rarely flat, and three county rules often come up:

• Hillside development. Pima County's hillside chapter (18.61) applies where a lot has slopes of 15% or more that run longer than 50 feet horizontally and rise more than 7.5 feet. It aims to keep grading to a minimum and restore disturbed areas.
• Native plants. The native plant preservation rules (18.72) apply when grading reaches 14,000 sq ft or a grading plan is required, with exemptions for some existing lots. A casita alone rarely gets there, but a new driveway or pad on a big lot can.
• Floodplains. Nearly any structure in a regulatory floodplain or erosion hazard area needs a Floodplain Use Permit from the county's Regional Flood Control District before construction.

On a sloped lot, the best spot for a casita is usually where it needs the least cut and fill, keeps the view from the main house and stays clear of a wash. We work that out on the site walk.

Utilities on an older Foothills lot

Because a county guest house can't have its own meter, its power and water come from the main house. On older Foothills homes that often means checking whether the electrical panel has room for a mini-split, a water heater and a kitchen, and how far the lines have to run across rock and slope to reach the casita. If the house is on septic rather than sewer, adding a bathroom can mean the system has to be reviewed by Pima County first. These are the items that most often move a Foothills casita budget, so we price them up front rather than finding them mid-build.

Matching an older Foothills home

Many Foothills homes have flat roofs with parapets, smooth or sand-finish stucco and deep window reveals. A guest house looks right when it repeats those details. Our own crew does the stucco and roofing, so the texture, color and roof line can match the house rather than look added on.

How we build a casita in the Foothills

1. Site walk. Slope, access, utilities, washes and where the casita fits best.
2. County check. Zone, accessory setbacks, hillside, native plant and floodplain items for your parcel.
3. Plans. Drawings and a site plan for the county's custom home process.
4. Permit. We submit and answer review comments.
5. Build. Foundation, framing, structural work, roofing and stucco by our crew, then interiors.
6. Inspections and final. We schedule inspections and walk the finished guest house with you.

For costs, see the casita cost guide. For how rules change across the metro, read building a casita in Tucson. More Foothills work is on our Catalina Foothills contractor page.