ADU rules in Hillsborough County

The accessory dwelling may be a detached structure (Sec. 6.11.02.D). Table 2.02.02 lists Accessory Dwellings as a Conditional Use (C) in agricultural districts (AM, A, AR, AS-0.4, AS-1, ASC-1), single-family districts RSC-2, RSC-3, RSC-4, RSC-6 and RSC-9, duplex district RDC-6, multi-family districts RMC-6, RMC-9, RMC-12 and RMC-16, and SPI-UC-1 and SPI-UC-3; blank (prohibited) elsewhere, including RSC-10, RDC-12, RMC-20 and commercial districts. Detached ADUs are subject to strict front-yard placement limits that shall not be varied, and an ADU above a detached garage or other accessory structure is allowed only where the principal dwelling has two or more stories (Sec. 6.11.02.F, G).

The accessory dwelling may be attached to the principal single-family dwelling on the lot (Sec. 6.11.02.D), in the same districts where Table 2.02.02 shows Accessory Dwellings as a Conditional Use. Attached ADUs applied for on or after January 1, 2021 must meet the district minimum front yard setback, a requirement that shall not be varied for front yards which function as front yards (Sec. 6.11.02.F.1).

Living space includes all areas used for living, sleeping, eating, cooking, bathing, washing, sanitation, laundry and storage, measured from the outside faces of exterior walls; unconditioned garages, attics used solely for parking and storage, and covered patios are excluded (Sec. 6.11.02.C). A minimum lot area of 7,000 sq ft is required unless otherwise expressly permitted in a Planned Development (Sec. 6.11.02.A).

The residential lot shall be occupied by a principal detached single-family dwelling that is owner occupied, and this requirement shall not be varied (Sec. 6.11.02.B). Table 2.02.02 footnote 15 repeats that in RDC-6, RMC-6 through RMC-16, SPI-UC-1 and SPI-UC-3 an ADU is allowed only if the parcel is developed with an owner-occupied single-family detached unit.

The Required Parking Spaces table lists residential ratios by housing type (multiple family efficiency 1.25, one bedroom 1.5, two or more bedrooms 2.0, single family conventional 2.0 per dwelling unit) but never mentions accessory dwellings, so no dedicated ADU ratio could be verified.

Table 2.02.02 designates Accessory Dwellings with a C in every district where they are allowed. Per the table key, C means Conditional Use, permitted pursuant to Article VI standards and the procedures of Section 10.01.00, with no public hearing required unless specified. Sec. 6.11.01.A adds that compliance with the Part 6.11.00 standards is determined during development review with no additional procedural steps, so review is administrative rather than a discretionary hearing.

Sec. 6.11.02 and the Accessory Dwelling definition are silent on renting the ADU, minimum lease terms, or short-term rental limits; the only occupancy rule verified is that the principal dwelling must be owner occupied. The definition states the ADU must be adequate for independent residential use and that occupancy by family members has no bearing on the definition.