ADU rules in Cedar Falls

Cedar Falls allows one ADU per lot with a detached single-unit dwelling, including a detached ADU in a building accessory to the house (for example above a detached garage), set back 5 ft from the side and rear lot lines in the rear yard. The current text of Sec. 26-142(b)(1) was rewritten by Ord. No. 3126 (adopted 11-3-2025) to conform to Iowa Code 364.3(23); the same rules apply in the downtown character districts through Sec. 26-193.1 G. The state floor independently requires the city to allow a detached ADU wherever a single-family residence is an allowed principal use.

An internal or attached ADU (basement, upper story or a building addition) is allowed "within or attached to the principal dwelling, provided all setbacks applicable to the principal dwelling are met". Ord. No. 3126 added building additions as an allowed form; the pre-2025 rule allowed only rear-yard units or units inside the existing building envelope. A basement ADU needs one egress window per bedroom, and an internal ADU needs walled separation and its own entrance.

Sec. 26-142(b)(1)d caps an ADU at 50 percent of the principal dwelling's floor area (excluding any attached garage) or 1,000 sq ft, whichever is larger, matching the state floor, and limits it to two bedrooms and a 125 sq ft minimum. Height may reach the principal dwelling's allowance in the underlying zone (35 ft in most single-unit zones per the city's 2025 staff memo). A detached ADU's footprint is still tied to the general accessory-structure footprint limit in Sec. 26-126(2) (1,024 sq ft or 45 percent of the required rear yard, whichever is less); because 364.3(23)(b)(1) bars placement and coverage rules stricter than those for the house, that footprint cap is open to challenge where it would hold an ADU below the state minimum. From 7-1-2026 SF 2369 also excludes unfinished basements from the ADU's size and measures the house by gross living area excluding garages, decks and unheated porches; the city text has not been updated for that, so the statute governs where it is more generous.

Ord. No. 3126 deleted the owner-occupancy requirement from Sec. 26-142; the code now requires only that "The ADU and the principal dwelling must be under the same ownership", which is a common-ownership rule rather than a residency test. Iowa Code 364.3(23)(b)(4) bars any requirement that the owner live on the property. One stale clause survives: Sec. 26-193.5 E.2 (neighborhood small frontage in the downtown character districts, not amended by Ord. 3126) still says ADUs are "Permitted for owner-occupied rowhouses and detached houses"; that clause is void under 364.3(23)(d).

Sec. 26-142(b)(1)f.10 states "No additional parking is required for an ADU", but the lot must still carry the spaces required for the principal dwelling under Sec. 26-220: two spaces per single-unit dwelling, plus one more for each adult occupant beyond two when the house is renter-occupied. This matches 364.3(23)(b)(3), which bars parking beyond the single-family requirement or a fee in lieu. New rentals under the rental code must also have paved parking (Sec. 11-179).

An ADU needs a site plan approved administratively by the zoning administrator under Sec. 26-37 ("submitted to the city for administrative review and approval"), followed by building permits; there is no hearing. Before approval the owner signs an acknowledgement that the ADU does not create rights to use or sell the property as a duplex. Iowa Code 364.3(23)(c) requires approval without discretionary review on the single-family timeline. In the College Hill Neighborhood (CHN) overlay, Sec. 26-181 still sends any new detached accessory structure over 300 sq ft to Planning and Zoning Commission and City Council review with architectural-matching standards, which conflicts with 364.3(23)(b)(1) and (c) for a detached ADU (see caveats).

Either the house or the ADU (or both) may be rented: Ord. No. 3126 removed the old one-rental-licence-per-lot and owner-occupancy rules. Every non-owner-occupied dwelling unit needs a minimum rental housing occupancy permit, inspection and registration under Chapter 11, Article II (fees at extraction: $250 base for a newly registered rental), and newly registered single-unit and two-unit rentals default to two adult occupants unless a group rental permit is granted (Sec. 11-335). Sec. 26-142(b)(1)b caps an ADU's rental occupancy at two adults (children are not precluded); that ADU-specific cap is arguably more restrictive than 364.3(23)(b)(2) allows, but it remains in the code. The code contains no short-term-rental regulation, and Iowa Code 414.1(1)(e) bars one, including any short-term-rental licence or fee. The signed acknowledgement means the ADU cannot be sold separately or treated as a duplex.