Residential drafting in Tempe, Arizona
Tempe has a longer residential chronology than most of the East Valley. Roughly 42 percent of its housing was built before 1980. The city's historic records cover adobe buildings, early bungalows, prewar subdivisions, postwar ranch houses, and later infill, and a remodel here can land on any of them.
Each era brings its own problem. Adobe and early masonry need careful wall thickness measurement and honest skepticism about hidden lintels and foundations. Bungalows tend to have crawlspaces, low slope porch roofs, and additions built in stages. Postwar ranch houses are slab on grade with low roof pitches, carports or converted garages, and bearing walls that are not obvious from the current layout.
Near downtown and the university, infill puts taller construction next to older single story houses, so privacy, upper story massing, and access carry more weight than they would in a subdivision.
ADU standards
Setback, size, and parking rules for an accessory dwelling unit in Tempe.
| Maximum size | 75 percent of the house or 1,000 sq ft, whichever is less (3-402(C)(2)(A)) |
|---|---|
| On lots of an acre or more | 75 percent of the house or 2,000 sq ft, whichever is less (3-402(C)(2)(B)) |
| Side, rear, and street side setback | 5 ft, or 3 ft at nine feet tall or under, or 4 ft up to ten feet tall (3-402(C)(5)(B), Table 3-401 C1) |
| Alley setback | Measured from the middle of the alley, not the property line (3-402(C)(5)(C)) |
| Height | The zoning district limit, commonly 30 ft. Two stories requires a use permit (3-402(C)(6), 3-420(B)) |
| How many | One attached and one detached. One more on a lot of an acre or more if one is restricted affordable (3-402(C)(1)) |
| Lot coverage | Counts toward the district maximum (3-402(C)(7)) |
| Parking | No additional space required, but displaced spaces for the house must be replaced (3-402(C)(3)) |
If your lot backs an alley, the setback is measured from the middle of the alley rather than from your property line (3-402(C)(5)(C)). That is a Tempe rule and it catches people out, because it means the buildable area is not where a survey alone would suggest.
The five foot setback everyone quotes is a ceiling, not the only option. A detached unit nine feet tall or under can sit three feet from the line, and one up to ten feet tall can sit four feet (Table 3-401 C1). On a tight lot that difference decides whether the project works.
A two story unit requires a use permit, following a Board of Adjustment decision in December 2025 (3-420(B)). That is a separate approval before the building permit, so it belongs in the schedule from day one.
Tempe runs a standard plan program. A licensed plan shortens building review but never replaces the site work: your plot plan, zoning review, foundation and grading adaptation, and utility coordination still have to be drawn for your lot.
Planning office: Tempe Community Development
Sources: Tempe Zoning and Development Code 3-402. Ordinance O2024.51, adopted November 2024. A.R.S. 9-461.18. Last checked August 2026.
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