Pima County mapDefinition: A tiny house is a single family dwelling of maximum 400 square feet

Zoning Code Requirements

Tiny houses built on permanent foundations are permitted in any zones allowing detached single family dwellings.

Tiny houses built on a chassis where the suspension/axle components have been removed and the chassis permanently attached on a permanent foundation will be treated as factory-built buildings allowable only in the following zones: CR-3, CR-4, CR-5, TR, ML, SP, CB-1 and CB-2.

Tiny houses on mobile chassis are considered trailers and are only permitted in the following zones: RH, GR-1, SH, MU, CMH1, CMH2 and IR.

Tiny houses regulated by the State of Arizona shall be permitted in zones in accordance with the Arizona defined housing category.

Building Code Requirements

Tiny houses shall be built and inspected in accordance with the Pima County adopted building code.

The house can be partially or entirely built on-site or off-site. If built off-site, it needs to have been permitted by a recognized agency (jurisdiction with a code approval process similar to that of Pima County), or by an approved fabricator accredited by the International Accreditation Services, Inc., to build tiny houses.

The County will waive certain building code minimum standards to accommodate tiny houses in accordance with performance criteria in the ICC Performance Code. The reasoning is that certain minimum standards in the code exist to abate slum housing and to provide safe egress and ingress by fire-fighting personnel for multiple-room larger conventional structures. As these homes are tiny, they provide quicker exiting and occupants are more aware of the physical configuration of the space thereby alleviating fall and means of egress risks. As such, the following code adjustments are provided:

  • Minimum dwelling/room/ceiling height/windows/door/fixture/accessibility dimensions do not apply
  • Ladders may replace stairways to loft areas
  • Loft areas may have reduced fall protection
  • Number of electrical circuits may be reduced to reflect loads
  • Alternative compliance with NFPA 501 for mechanical/electrical systems is recognized

Source – http://webcms.pima.gov/cms/One.aspx?portalId=169&pageId=259596

Read more – http://tucson.com/business/tucson/roomy-enough-tiny-home-movement-takes-first-steps-in-tucson/article_a623fbad-86c5-5e73-a010-cd41a0105955.html

Please note that the city of Phoenix may have requirements that are different from the county’s.