ADU rules in Manhattan

Manhattan has no accessory dwelling unit use: the Manhattan Development Code defines an ADU but Table 26-2C-3.1 never lists one, and Sec. 26-2A-1 C says uses not listed as permitted are prohibited. A detached backyard home is possible only as a second principal single-family detached dwelling (SFR-D) in the RL-A and RM districts, where more than one principal building is allowed and the lot has 3,000 sq ft per dwelling unit (so at least 6,000 sq ft for two). In the RL district, the city's largest single-family district, only one principal building is allowed per lot, so no detached second home can be added; RH and RC do not permit SFR-D at all. Planning staff told the Planning Board on 8-3-2026 that second units 'would be allowed in RL-A and above', and the Board's 3-7-2026 letter asking the City Commission to authorize a by-right ADU framework is still unanswered with a draft.

There is no attached or internal ADU use either; adding a second unit to a house turns it into a two-unit single-family attached building (SFR-A, the code's duplex category). A two-unit SFR-A is permitted by right in RL-A, RM and RH but not in RL or RC (RC starts at three units), and the lot needs 1,500 sq ft per unit in RL-A, 750 in RM and 700 in RH. In the Established Neighborhood overlay (O-EN), SFR-A in RL-A is capped at three units and the overlay's own bulk table applies. Owners in RL have no route to an internal second unit short of rezoning.

Because Manhattan regulates a second home as a full principal dwelling, there is no floor-area or percent-of-house cap. Detached SFR-D units in RL-A and RM are limited by density (3,000 sq ft of lot per unit), 35 ft height and 45% building coverage, with principal-building setbacks (RL-A: 15 ft front, 6 ft interior side, 10 ft rear), not the 3 ft side and 5 ft rear allowed for accessory structures. Attached SFR-A units allow 60% coverage at 1,500 sq ft (RL-A), 750 (RM) or 700 (RH) of lot per unit. In the O-EN overlay, Table 26-4A-1.1 replaces these with 35% coverage in RL-A (40% in RM), a 35 ft height cap and a 10 ft rear setback (25 ft rear in RL).

Nothing in the Manhattan Development Code requires an owner to live on a lot with two dwellings; 'owner-occupied' appears only in the bed-and-breakfast home definition and standards. The only occupancy rule is that no more than one family may live in each dwelling unit. The city's rental registration ordinance exempts owner-occupied units (an owner living there more than 275 days a year) but imposes no residency requirement. Kansas has no statute on ADU owner occupancy either way.

Table 26-7B-3.1 requires 2 spaces per single-family detached dwelling and, for SFR-A, 1 per dwelling unit or 0.75 per bedroom, whichever is less. Residential requirements within 1,000 feet of the CD, CA and UC districts are halved, but not below 1 space per unit or 0.5 per bedroom, whichever is less. On existing RL-A lots inside the core infill area, Table 26-2C-5.1 allows 1 space per detached unit instead. The same table also lists 'Accessory Dwelling: 1 per dwelling unit' under residential accessory uses, a line added in the January 2025 infill package that has no operative use behind it until the city adopts an ADU use.

Where a second unit is possible, it is a by-right use ('P', permitted by right) handled through building permit and zoning review with no hearing. Since 7-1-2026, Kansas SB 418 also deems a complete application for a single-family home, townhouse or ADU that meets the zoning code approved unless denied within 30 days, a rule the 8-26-2026 staff memo behind Ord. No. 7841 says fits the city's existing processing times. An owner seeking an actual ADU (a subordinate unit in RL, for example) has only the Sec. 26-2A-1 D route of asking the Zoning Administrator to find it similar to an allowed use; absent that finding it stays prohibited.

Each unit rented for 30 or more days must be registered with the city under the Rental Dwelling Unit Registration Program (in force since 7-1-2017), with a local agent required for owners living more than 60 miles away; owner-occupied units are exempt. Each dwelling unit may house one family, defined as related persons or no more than four unrelated persons, with a rebuttable presumption that five or more are not a family, a rule that matters in Manhattan's Kansas State University rental market. Short-term rentals (under 30 days) are a limited use in every residential district: one family per booking, the unit must be a legally established dwelling, keep a residential appearance, hold any state and city licenses, and host no events. Selling a unit separately requires a replat that gives it its own lot (Sec. 26-5B-2 minimums for new lots: 3,000 sq ft per SFR-D, 1,500 per SFR-A unit).