ADU rules in Post Falls

A detached backyard ADU is a permitted use (P) in every residential district (R1S, R1, R2, R3) and in the Residential Mixed and Limited Commercial districts under the land use table at PFMC 18.20.030; it is not permitted in the CCS, I, TM, or CCM districts. PFMC 18.24.030.A.3 then attaches the operative conditions: only one ADU per lot, building materials consistent with the primary residence, no more than one ADU entrance visible from the street, and no separate drive approach unless it comes off a rear-loaded alley or a corner lot's side street. A detached ADU has to sit behind the front of the residence, except on a corner lot where it may go in the street-side yard. There is no lot-size gate and no hearing, so a conforming detached ADU is approved over the counter with a building permit.

The same PFMC 18.24.030.A.3 rules govern attached and internal ADUs: subsection (g) caps 'the Accessory Dwelling Unit (attached or detached),' and the city's ADU page and handout recognize four forms, a basement ADU, an attached ADU, a detached rear-yard ADU, and a detached side-yard ADU. Subsection (j) expressly contemplates converting an existing accessory building into an ADU, which then has to meet the currently adopted building codes. Whatever the form, the ADU needs its own electricity, kitchen, and sanitary facilities (subsection h), and only one ADU is allowed per lot.

PFMC 18.24.030.A.3.g: the ADU, attached or detached, 'can be no larger than fifty (50) percent of the living area of the primary residence and no more than one thousand (1,000) square feet.' The city's ADU handout reads the two limits together as 'whichever is smaller,' so a 1,600 sq ft house supports an 800 sq ft ADU and only a house of 2,000 sq ft or more reaches the 1,000 sq ft ceiling. There is no ADU-specific height or setback rule: the ADU takes the underlying district's bulk standards from PFMC 18.20.040, which allow 35 ft of height in R1S, R1, R2, and R3. Idaho Code 67-6541(2)(d) forbids a covered city from limiting an ADU to less than 1,000 sq ft or 75% of the primary dwelling, so the 50% multiplier has to be raised by February 1, 2027.

PFMC 18.24.030.A.3.b is one sentence: 'One of the residences must be owner-occupied.' It reads as an ongoing condition on the property rather than a test applied once at application, and it lets the owner live in either unit. Idaho Code 67-6541(2)(e), effective July 1, 2026, requires covered cities to prohibit an owner-occupancy requirement for either the primary dwelling or the ADU, and Post Falls (population well above the statute's 10,000 threshold) has to repeal this clause by February 1, 2027; until it does, the local rule is what the Community Development Department applies. Watch one trap: the city's ADU web page leaves owner occupancy out of its General Requirements bullets, but the code and the city's own ADU handout PDF both state it, so the page's silence is an omission, not a repeal.

PFMC 18.24.030.A.3.c: 'One additional off-street parking space must be provided.' That is on top of the two spaces PFMC 18.24.070.G requires for the single-family dwelling itself, and PFMC 18.24.020.H.1 requires residential access drives and parking areas to be surfaced with concrete or asphalt, which is why the city's handout calls it a paved space. Idaho Code 67-6541(2)(b) will end the unconditional version of this rule: by February 1, 2027 a covered city may require ADU parking only where the principal dwelling has no off-street parking, or the street is not paved and designed or constructed for on-street parking, or the principal dwelling is within a quarter mile of transit, an employment area, or commercial services. Post Falls has not amended the section yet.

The land use table at PFMC 18.20.030 marks 'Accessory Dwelling Unit' with a P in R1S, R1, R2, R3, LC, and RM, and PFMC 18.20.020.C provides that a P means the use 'is allowed in that classification, subject to the development and operational requirements of this title and other applicable titles.' No district that allows ADUs marks them S, so no special use permit and no discretionary hearing is involved. The path is a building permit with a detailed scaled site plan showing the proposed unit, setback lines, and ingress and egress routes (PFMC 18.24.030.A.3.i), with mechanical plans and truss sheets per the city's ADU page, followed by a certificate of occupancy or zoning compliance under PFMC 18.08.060. Idaho Code 67-6541(3), in force since July 1, 2026, independently requires conforming ADU projects to be approved administratively and as a matter of right.

Post Falls sets no minimum lease term and no rental registration, and the city's own ADU page names rental income as a reason to build one. The single constraint is PFMC 18.24.030.A.3.b, which requires one of the two residences to be owner-occupied, so an owner may rent out one unit but not both. A search of every title of the Post Falls Municipal Code turned up no short-term-rental ordinance at all, and Idaho Code 67-6539(5), as rewritten by H0583 (2026, ch. 22) effective July 1, 2026, now bars any city from requiring 'a license, fee, permit, certification, or registration to operate a short-term rental,' along with day limits, numeric caps, and conditional use permits in residential zones. The local owner-occupancy clause survives that statute because it applies to every ADU regardless of use and so is not a 'different restriction or obligation' under 67-6539(2)(a), but 67-6541(2)(e) still requires its repeal by February 1, 2027.