How Tempe Handles Accessory Structures: A Practical Guide

Tempe maintains 149 local ordinances across all categories, and 4 of those deal specifically with accessory structures. Here is a breakdown of what the city actually requires, what is prohibited, and where Tempe falls on the strict-to-permissive spectrum compared to other cities.

Tiny Homes

Tempe's Zoning and Development Code lets homeowners build a tiny home as an accessory dwelling unit under Section 3-402(F)(4), as long as it sits on a permanent foundation and meets the city's adopted building code for tiny houses. That building code, at Section 8-300, caps a qualifying tiny house at 120 to 400 square feet.

Key details: Governing section: Zoning Code § 3-402(F)(4). Tiny house size range: 120 to 400 sq ft. Foundation requirement: Permanent foundation required. Max civil sanction: $1,000 (or misdemeanor). Applies in: All residential zoning districts.

Building or occupying a tiny-home ADU without meeting Section 3-402's foundation, size, setback or permit requirements is a Zoning and Development Code violation under Section 1-201. Penalties run from a civil sanction of $100 to $1,000, or a class 1 misdemeanor punishable by up to a $2,500 fine, three years of probation, or six months in jail, with each day of the violation charged as a separate offense.

ADU Rules

Tempe allows one attached and one detached ADU on any residential lot under an acre, capped at 1,000 square feet of habitable area or 75 percent of the main house, whichever is smaller. Larger lots get a bigger unit and a possible third ADU tied to affordability.

Key details: Density, lots under 1 acre: 1 attached + 1 detached ADU. Size cap, lots under 1 acre: 1,000 sq ft or 75% of house. Size cap, lots 1+ acre: 2,000 sq ft or 75% of house. Minimum setback (rear/side/street-side): 5 feet. Bedroom cap on 1,000 sq ft ADU: 3 bedrooms.

Building an ADU larger than the 1,000- or 2,000-square-foot cap, exceeding the density limit of one attached and one detached unit per sub-acre lot, or subdividing and selling an ADU separately from the main lot violates Section 3-402 and is enforced as a Zoning and Development Code violation under Section 1-201. The code also bars an owner from denying emergency responders or the public unencumbered access to an ADU.

ADU Rental Restrictions

A third ADU on a Tempe lot of an acre or more is allowed only if one of the three units is deed-restricted to renters earning up to 80 percent of area median income. The owner must record the restriction before permits issue and file an annual compliance report or face civil sanctions or forfeiture.

Key details: Trigger for 3rd ADU: Lot of 1 acre or more. Income limit for restricted unit: Up to 80% of area median income. Rent standard source: Arizona Dept. of Housing limits. Deed restriction: Recorded before permits issue. Reporting: Annual report required.

Renting the restricted-affordable ADU above the 80 percent area median income threshold, skipping the recorded deed restriction before building the third unit, or missing the annual compliance report deadline violates Section 3-402(G) and exposes the owner to a civil sanction under Section 1-201 and potential forfeiture of the unit.

Compared to other cities, Tempe takes a harder line on adu rental restrictions. The enforcement and penalty structure reflects that.

Shed & Carport Rules

Tempe draws the line between a permit-free accessory structure and a regulated accessory building at 200 square feet or 8 feet in height. Anything larger must sit at least 3 feet from side and rear lines, gain a foot of setback for every foot of height above 9 feet, and top out at 15 feet.

Key details: Accessory structure threshold: 200 sq ft / 8 ft or less. Above that = accessory building: Full setback rules apply. Minimum side/rear setback: 3 feet. Setback increase per foot of height: 1 extra foot above 9 ft. Maximum height, by right: 15 feet.

Building a shed or garage over 200 square feet or 8 feet tall without meeting the accessory-building setback and height standards in Section 3-401(C), or placing it in a required front or street-side setback without a Use Permit, is a Zoning and Development Code violation. Community Development can require removal, relocation or a retroactive Use Permit, and unresolved cases are enforced as violations under Section 1-201.

The Bottom Line

Tempe's accessory structures rules are a mixed bag. Some areas are strict, others are relaxed, and the details matter. The best approach is to check the specific rule that applies to your situation rather than assuming Tempe is broadly strict or permissive.

This guide is based on Tempe's current municipal code. Local rules can and do change, so check the individual ordinance pages for the latest details, penalties, and FAQs.