Commission workshop considers tighter ADU setbacks, ending story step‑backs and raising impervious‑area minimums

City planning staff presented possible code amendments for accessory structures, accessory dwelling units (ADUs) and impervious‑surface standards at a June 10 workshop of the Coeur d'Alene Planning and Zoning Commission. Commissioners provided preliminary direction: increase setbacks for rear/side yards to simplify administration, consider removing the ADU "story step‑back" requirement, limit taller accessory structures to those attached to principal dwellings, and study raising pervious/impervious thresholds for single‑family lots. No ordinance or formal code amendment was adopted at the meeting.

Staff said the conversation continues a joint March workshop with the Historic Preservation Commission and framed the discussion as focused on two administrative problems: the difficulty of administrating the existing ADU story step‑back and growing neighborhood concerns about large accessory structures and runoff from increased hardscape. Virginia Loustalow and Barbara Barker were introduced as planning staff in the audience; city engineer Chris Bosley and building official Ted Lancey participated in the discussion.

Key items discussed

- Story step‑back and height limits: Staff described the current approach that allows taller accessory structures in the principal building envelope—up to 32 feet in some configurations—while ADUs built over garages are capped at 24 feet and other accessory roofs have limits of 18 feet (pitched) or 14 feet (low‑slope/flat). Staff proposed eliminating the complex 45‑degree "story step‑back" verification and instead using clearer rear and side setback measurements (examples discussed included 10‑foot side yards and 10‑foot rear yards where no alley exists; narrower 5‑foot rear setbacks could remain where a rear alley provides separation). Commissioners broadly favored increased setbacks and a move away from the step‑back verification because the latter is time‑consuming for applicants and staff to measure on irregular lots.

- Attachment and height relationship: Staff proposed restricting the ability to exceed standard accessory heights within the principal building envelope only to ADUs and accessory structures that are physically attached to the principal dwelling. Commissioners expressed support for limiting free‑standing tall accessory structures on narrow lots; several suggested historic overlay areas could consider stricter limits.

- Windows and privacy: Commissioners discussed whether windows should be restricted on ADU walls that face neighboring residential lots. Opinions varied; some commissioners recommended sensitivity to adjacency and minimizing privacy impacts but did not adopt a blanket prohibition on windows. Commissioners noted that building and fire code requirements for egress and safety still apply.

- Impervious/pervious surfaces and stormwater: Staff noted the current ADU rule requires 30 percent pervious surface on lots with ADUs, and that a prior, more detailed impervious‑surface table had been repealed. Staff proposed returning to an impervious‑area standard for residential lots and suggested a simpler citywide threshold (staff cited a potential move from 30 percent pervious to 40 percent pervious as an example). City engineer Chris Bosley cautioned that soils and lot sizes vary and that commercial/multifamily projects require more detailed stormwater plans; he supported a pragmatic approach—raise the pervious minimum where problems are most likely and require a more detailed drainage plan only where a project exceeds a reasonable threshold.

- Practical administration: Staff said the story step‑back requirement burdens plan reviewers because verifying the 45‑degree plane and eave encroachments on sloped lots requires field measurement and repeated plan corrections. Commissioners and staff agreed that a simple, consistent setback standard would be easier for property owners and staff, though PUDs and planned developments would still be able to request reduced setbacks through the PUD process.

- Access, decks and stairs: The commission discussed whether small landings, stairs and code‑required entries should be permitted to encroach into a new 10‑foot setback. Building official Ted Lancey (not present at the start) indicated the building department would likely allow typical stair and landing encroachments by code standard (for example, a 3‑foot stair width and minimal landing) but urged clarity in the code to reduce later disputes.

- Compliance and enforcement: Commissioners noted that many problems arise after construction—residents adding hardscape or converting yard area—and discussed options such as a checklist requirement for permits or a threshold that would trigger a more detailed drainage plan. Bosley suggested a tiered approach: a straightforward pervious/impervious threshold for most single‑family lots and a required engineering/stormwater plan for projects above that threshold or for PUDs.

What commissioners asked staff to do

Commissioners generally directed staff to: (1) pursue simpler, consistent setbacks (10 feet side yards and 10 feet rear yards where feasible) and remove the story step‑back requirement; (2) limit taller accessory structures within the principal building envelope to units attached to the principal dwelling; (3) study a revised impervious/pervious threshold (staff discussed 30% pervious increasing toward 40% pervious as an example) and develop a simple, tiered review approach so only projects over a set threshold require full engineering analysis; and (4) coordinate with building and engineering staff on clarifying stair/deck encroachments and snow/snow‑shedding mitigation (building staff indicated an intent to require snow retention devices on metal roofs within 5 feet of property lines when warranted).

No formal vote was taken; staff will draft proposed code language and thresholds for future review by the commission and the City Council as appropriate.