Building permits, zoning and land rules in Pima County, Arizona

At a glance

Building permit

Required unless a listed exemption applies¹

Zoning

Yes; county zoning applies to unincorporated land²

Septic

County-issued Construction and Discharge Authorizations³

Owner-builder exemption

Allowed if building solely for your own occupancy⁴

Tiny homes

Allowed up to 400 sq ft; allowed zone depends on construction type⁵

Accessory dwelling units

Allowed in all residential zones as of Jan. 1, 2026⁶

Soils suitable for conventional septic

33.3% of the county's soils have no severe limits⁷

Who to call

Contact details are copied from each office’s official page and were checked against it on September 28, 2026.

Do you need a building permit in Pima County, Arizona?

Yes. Pima County requires a building permit for construction of new buildings or structures, remodeling, and manufactured building placement or relocation, unless the specific project falls within one of the county's listed exemption examples⁸. The county is explicit that its exemption list is only a set of examples and warns a permit may still be required even for listed project types, so don't assume a small project is exempt without checking⁸. Two of the plainer exemptions: a non-retaining wall or fence up to 7 feet high, and flat work like a patio up to 30 inches above adjacent grade that isn't over a basement or story below⁸. Two overlays can add requirements on top of the base rule: Native Plant Preservation Ordinance compliance and the Buffer Overlay Zone Ordinance, plus extra permitting if the project sits in a floodplain⁸. Arizona law backs this up statewide: outside cities and towns with their own permitting ordinance, a county must require a permit for construction or additions over $1,000⁹.

Who is the Pima County building department and how do you reach them?

Pima County Development Services issues building permits and runs plan review and inspections for unincorporated Pima County, with its public office at 115 N Church Avenue, 2nd Floor, Suite 231, Tucson, AZ 85701, phone 520-724-9999¹⁰. The county's adopted building codes are available for inspection at its Development Services location on Stone Avenue, and currently list the 2024 Building Codes and 2023 National Electric Code, both effective January 1, 2026¹¹. Applications go through the online Pima County Permit Gateway rather than paper submittal; Development Services assigns an activity number, routes the project for review, and emails you if anything is incomplete or needs correction¹²¹⁰. Permit fees are built from three pieces - the building fee itself, a sewer-connection fee, and a transportation impact fee - each calculated separately¹³. Inspections can be done in the field or remotely depending on the project, but if you're building in Ajo, Why, Lukeville, Arivaca, Sasabe, or on Mt. Lemmon, on-site inspections in those areas are limited to one day a week, so plan your schedule around that¹⁴.

Does Pima County have zoning?

Yes. Every parcel in unincorporated Pima County carries a zoning designation that lists permitted uses and development standards such as minimum lot size, building setbacks and height, and lot coverage¹⁵. The county doesn't administer every jurisdiction's rules, though: Pima County's own GIS data shows base zoning for both incorporated and unincorporated areas, and several cities and towns inside the county run their own separate zoning¹⁶¹⁷. As one real example rather than a countywide rule, the county's CR-1 Single Residence Zone sets a minimum lot area of 36,000 square feet, a minimum lot width of 100 feet, front/side/rear setbacks of 30, 10 and 40 feet, and a maximum height of 34 feet or two stories¹⁸¹⁹²⁰; your own parcel's district sets its own numbers under that same state zoning authority²¹. Arizona law also protects grazing and general agricultural use on tracts of five or more contiguous commercial acres from county zoning restrictions, which matters if you're buying acreage with any agricultural use in mind²². Two more zoning-driven answers worth knowing before you buy: as of January 1, 2026, accessory dwelling units are allowed in every residential zone in the county unless your HOA or plat map says otherwise, capped at the smaller of 1,250 square feet or 75% of the main home's living area⁶; and a tiny house up to 400 square feet is allowed as a single-family dwelling, though whether it sits on a permanent foundation, a fixed chassis, or a mobile chassis determines which zones allow it⁵.

How do septic permits work in Pima County?

Pima County, not a separate district, issues septic permits here: Development Services and Environmental Quality run onsite wastewater treatment facility permitting under the county's program³. Before you can build or replace a system, Pima County must issue a Construction Authorization, and after the finished system passes a final field inspection, the county must issue a Discharge Authorization before it can be buried and used²³. If you're buying a property that already has a septic system, know the transfer rule: the seller must have a qualified inspector check the system within six months before the sale and hand you the report before closing, and you as the buyer must submit a Notice of Transfer within 15 calendar days after the transfer, with a $50 fee for the inspection submittal but none for the notice itself²⁴. Septic inspectors can be reached directly at 520-724-7400²⁵. Soils are the honest caution here: only 33.3% of Pima County's soils have no severe limits for a conventional septic drain field, so budget for a site evaluation and the real chance of an engineered or alternative system on many lots⁷. A portable or chemical toilet can supplement a bathroom during peak use, but it can't replace a required permanent wastewater connection, and human waste can only go into an approved wastewater system²⁶.

Can you live in an RV or tiny home in Pima County?

It depends heavily on the zone, not just the county as a whole. A tiny house up to 400 square feet is allowed as a single-family dwelling on a permanent foundation in any zone that allows detached single-family homes, but a tiny house still on a mobile chassis is treated as a trailer and only permitted in a specific list of zones such as RH, GR-1, SH, MU, CMH1, CMH2 and IR⁵. Living in an RV is narrower still: in the county's RVC Rural Village Center Zone, a recreational vehicle can be used as temporary housing for up to one year while you build a residence on the same property, with a possible 180-day extension once you hold a valid building permit for that residence and notify neighbors within 100 feet²⁷. The separate TH Trailer Homesite Zone exists for seasonal or temporary occupancy of travel trailers, motor homes and campers, but it's a distinct zone typically sited near highways, not a countywide right to camp on any rural parcel²⁸. Outside these specific zones, nothing in this Index's research confirms a general right to live in an RV on ordinary residential or rural-zoned land in Pima County, so confirm your parcel's zone and its rules with Pima County Development Services before you plan around it²⁹.

Building a home in Pima County: the steps, in order

1. Check the parcel's zoning district and floodplain status; search the county's floodplain map or call the Regional Flood Control District at 520-724-4600³⁰.
2. Confirm whether Native Plant Preservation or Buffer Overlay Zone rules apply to the site⁸.
3. If the lot isn't on public sewer, get a septic Construction Authorization from Pima County before finalizing house plans, and budget for a site evaluation given the county's soils²⁵²³.
4. Decide whether to use Arizona's owner-builder exemption or hire a licensed contractor; the exemption only covers a home built solely for your own occupancy, not one intended for sale or rent within a year of completion⁴³¹.
5. Submit your application through the online Pima County Permit Gateway¹²¹⁰.
6. Pay the building, sewer-connection and transportation-impact fees once the application is approved¹³.
7. Schedule inspections, remote or in person; in Ajo, Why, Lukeville, Arivaca, Sasabe, or on Mt. Lemmon, on-site inspection days are limited, so plan ahead¹⁴.
8. Get your Discharge Authorization on the septic system, if you have one, before it's buried and put to use²³.

What to check before you buy land in Pima County

Run the practical numbers before you commit to a parcel. Only 33.3% of Pima County's soils carry no severe limits for a conventional septic drain field⁷. About 75.5% of the county's land sits at 15% slope or less³², and 5.5% is wooded³³, but parcel-level slope, vegetation and access still need a site check. Federal land covers 30.7% of the county³⁴, so verify legal access and boundaries where private land meets public land. About 27.5% of years bring severe drought³⁵, and mid-century projections estimate roughly 86.8 days a year at or above 100°F³⁶. If you plan to split a larger tract, creating six or more lots generally triggers Arizona's subdivision-notification law³⁷. Farmland averages about $504 an acre³⁸, a typical home value is around $343,106³⁹, and the median property tax bill is $2,248 a year at an effective rate near 0.8%⁴⁰⁴¹. From the county's center, the nearest city of 100,000 or more is about 49 miles away⁴².

Watch-outs

• Pima County's own exemption list for building permits is described as examples only, and the county explicitly warns a permit may still be required even for listed project types, so confirm with Pima County Development Services before skipping a permit on a borderline project⁸¹⁰.
• This Index's research did not find an official Pima County land-use rule on short-term rental use, only rules for assessor classification and registration, so confirm current zoning treatment of short-term rentals directly with Pima County Development Services before buying with that use in mind²⁹.
• A minimum interior dwelling floor area doesn't appear in the county zoning provisions this Index reviewed, which set lot size and area-per-unit instead, so confirm any minimum square footage requirement with Pima County Development Services before designing a very small home¹⁰.

Sources

1. Do I Need a Permit? (2026 county census)
2. Land Planning & Regulation (2026 county census)
3. Onsite Wastewater Treatment Facilities (2026 county census)
4. Persons not required to be licensed; penalties; applicability (2026 county census)
5. Permitting Regulation for Tiny Houses, quoted and re-checked
6. Accessory Dwelling Units (ADU), quoted and re-checked
7. Share of soils without severe limits for a conventional septic drain field (USDA SSURGO): Bolthole Index county data
8. Do I Need a Permit?, quoted and re-checked
9. 11-321 - Building permits; issuance; state preemption; utilities; distribution of copies; subsequent owner; limitation; definition (Arizona statewide rule), quoted and re-checked
10. Pima County Development Services (pima.gov)
11. Policies, Ordinances & Procedures, quoted and re-checked
12. Online Building Permits, quoted and re-checked
13. Development Services Fees, quoted and re-checked
14. Building Inspection Portal, quoted and re-checked
15. Land Planning & Regulation, quoted and re-checked
16. Land Planning & Regulation, quoted and re-checked
17. Zoning - All Jurisdictions, quoted and re-checked
18. 18.21.030 Development standards—General, quoted and re-checked
19. 18.21.030 Development standards—General, quoted and re-checked
20. 18.21.030 Development standards—General, quoted and re-checked
21. 11-831 - Review of land divisions; definitions (Arizona statewide rule), quoted and re-checked
22. 11-801 - Definitions (Arizona statewide rule), quoted and re-checked
23. Onsite Wastewater Treatment Facilities, quoted and re-checked
24. Onsite Wastewater Treatment Facilities, quoted and re-checked
25. Pima County Onsite Wastewater Treatment Facilities (pima.gov)
26. Onsite Wastewater Treatment Facilities, quoted and re-checked
27. Pima County Code § 18.41.030, RVC Rural Village Center Zone, quoted and re-checked
28. Pima County Code § 18.11.010, TH Trailer Homesite Zone, quoted and re-checked
29. Pima County Development Services — Land Planning & Regulation (pima.gov)
30. Pima County Regional Flood Control District (pima.gov)
31. A.R.S. § 32-1121 — Persons not required to be licensed; penalties; applicability, quoted and re-checked
32. Share of land at 15% slope or less: Bolthole Index county data
33. Wooded share of land: Bolthole Index county data
34. Federal land share: Bolthole Index county data
35. Share of years in severe drought: Bolthole Index county data
36. Projected mid-century days at or above 100°F: Bolthole Index county data
37. 32-2181 - Notice to commissioner of intention to subdivide lands; unlawful acting in concert; exceptions; deed restrictions; definition (Arizona statewide rule), quoted and re-checked
38. Farmland value per acre (USDA census): Bolthole Index county data
39. Typical home value (Zillow): Bolthole Index county data
40. Effective property tax rate: Bolthole Index county data
41. Median property tax bill: Bolthole Index county data
42. Distance to the nearest metro area: Bolthole Index county data

Written September 28, 2026 from the rules quoted below, each taken from an official source and re-checked by an independent reviewer. This is research, not legal advice: rules change, so confirm with the office before you buy or build.