Hooper planning commission backs bigger 'oversized structures' and larger ADUs, sends recommendation to council

The Hooper City Planning Commission on July 10 recommended that city council increase the allowable size for oversized accessory structures and raise the permissible size of accessory dwelling units (ADUs) contained within or detached from those structures.

Commissioners voted to recommend changing the maximum square footage for accessory buildings in R-1 (single-family) lots to 5,000 square feet, R-7.5 lots to 3,000 square feet, and R-2 lots to 2,500 square feet. The commission also recommended allowing an ADU equal to up to 50% of the accessory structure’s square footage when the ADU is contained inside that structure. For detached ADUs the commission recommended maximums of 2,500 square feet (R-1), 1,500 square feet (R-7.5), and 1,250 square feet (R-2). The recommendation includes a limit of one ADU per property (one internal plus one detached not to exceed the combined limit) and asks staff to add parking requirements to any ordinance draft.

Why it matters: commissioners said the proposed changes would reduce the number of conditional use permit requests for modestly larger structures, give property owners more flexibility on large lots and could support Hooper’s moderate‑income housing strategies by increasing ADU availability. Staff analysis presented historical CUP data to show how different thresholds would have affected past applications.

Overview and discussion

Planning staff summarized data on recent years of conditional use permits for oversized structures and presented options for a square‑foot cap or a percentage of rear‑yard area. Staff said most nearby cities use a 25% rear‑yard rule; the commission discussed tradeoffs between a percentage standard (which scales to lot size) and a fixed square‑foot maximum (which is simpler to apply). Commissioners and staff ran through examples for typical half‑acre and full‑acre lots and how various caps (2,200, 2,500, 4,000, 5,000) would have changed the number of CUPs required in prior years.

Commissioners emphasized practical safeguards already in place, such as the city’s impervious‑surface limits, and noted that larger accessory buildings remain subject to building permits and other infrastructure reviews. Staff and commissioners also discussed how setbacks and the location of the primary dwelling (setback from the road / "drip edge") affect whether an accessory structure counts as a rear‑yard structure or would require case‑by‑case review.

ADUs and housing strategy

Members raised the ADU size cap (currently 960 square feet for detached ADUs) as a constraint for families and as a component of the city’s moderate‑income housing progress reporting. Commissioners proposed tying the ADU maximum to the allowed accessory structure (50% of the accessory structure cap) to expand legal, on‑site living options without increasing the building footprint beyond what the accessory structure allows. They also added a recommendation to allow only one ADU per parcel to avoid converting large lots into multiple rental units.

Motion and next steps

Commissioner Prince moved that the commission recommend ordinance revisions reflecting the size caps described above and the ADU provisions; Commissioner Greener seconded. The commission approved the recommendation and directed staff to draft ordinance amendments for the council, including recommended parking and application language to implement the limits discussed.

Votes at a glance

- Motion: Recommend ordinance revision to increase allowable oversized structure sizes and ADU square footage (detailed caps as described). Mover: Commissioner Prince. Second: Commissioner Greener. Outcome: approved (motion passed).

What staff will do next

Staff said it will prepare drafted ordinance language and bring it back to the commission for review before forwarding a final recommendation to city council. The commission requested the draft show clear definitions (parcel vs. owner, rear‑yard measurement method, ADU counting rules) and to include a proposed approach to parking so city reviewers can assess infrastructure impacts when applications are submitted.

Ending

Commissioners framed the recommendation as reversible: they said the city can revisit the caps if they lead to unexpected issues. The commission referred the specific ordinance text to staff to prepare for a future meeting and for formal submittal to the city council.