The Post Falls ADU build tracker

AnsweredDoes Idaho's new ADU law apply to this property?

Yes. Post Falls has more than 10,000 residents, so Idaho Code § 67-6541 (SB 1354) applies. It took effect July 1, 2026.

Source: Idaho Code § 67-6541, checked July 4, 2026.

AnsweredDoes Post Falls allow an ADU on my lot without a public hearing?

Yes. The city permits one ADU per single-family lot (attached, detached, or basement) through an ADU permit plus a building permit. No hearing, no conditional use process.

Source: City of Post Falls ADU page and its ADU information handout, checked July 3, 2026.

PartialCan I rely on the state law's protections before Post Falls updates its own code?

The city is still using city code. Post Falls Planning Manager Jon Manley, by email on July 30, 2026: "we are currently reviewing against the adopted City Code. We will be amending our code to be concurrent with Idaho's new SB 1354 by February 1, 2027." So an application filed today is measured against city code, and the city plans to take until the statutory deadline to change it. What that answer does not settle is whether a homeowner can require the state limits be applied before then. That is still a question for an attorney, not more reading.

Source: Email from Jon Manley, Planning Manager, City of Post Falls, July 30, 2026.

PartialHow big can it be?

The rules conflict. The city code caps an ADU at the smaller of 50% of the main house or 1,000 square feet. The state law bars caps below 1,000 square feet or 75% of the main house. Which one governs today is the open legal question above. I wrote up the full conflict here.

Source: PFMC 18.20.190 vs. § 67-6541(2)(d), checked July 4, 2026.

PartialDo I have to live in one of the two units?

The rules conflict. The city code says yes, one of the residences must be owner-occupied. The state law bars cities from requiring that. Same conflict, same unresolved question about which rule governs today.

Source: PFMC 18.20.190 vs. § 67-6541, checked July 4, 2026.

PartialDo I have to add a parking space?

The rules conflict. The city code requires one additional off-street space. The state law bars that requirement, with limited exceptions. Third conflict, same question.

Source: PFMC 18.20.190 vs. § 67-6541, checked July 4, 2026.

PartialWhat setbacks, height limit, and lot coverage apply to my zone?

The table is public. My zone is the missing piece. The numbers live in PFMC Table 18.20.040, and the city publishes it as a one-page PDF (revised August 1, 2023). In R-1, the most common single-family district, it's 35 ft max height, 15 ft front, 10 ft rear, 5 ft interior side, 15 ft street side, and 40% max lot coverage. Two details that catch people: setbacks are measured to the foundation or the face of a covered porch, not to the wall, and a garage gets its own 20 ft front setback. What I still have to confirm is which district my own lot is in.

Source: PFMC Table 18.20.040, Official Bulk and Placement Regulations, revised August 1, 2023.

AnsweredHow many ADUs can one lot have?

One. Every Idaho jurisdiction I've researched so far says the same thing.

Source: Post Falls ADU handout, checked July 3, 2026.

AnsweredDo I need to pay for plans?

Probably not. Four free, pre-approved plan sets are published by the Housing Solutions Partnership and reviewed by building departments across Kootenai County. I broke down all four here. I'm looking hard at using one of them.

Source: Housing Solutions Partnership plan page, checked July 8, 2026.

AnsweredDoes the ADU need its own water/sewer hookup, with its own capitalization fee?

No, but you're allowed to. The ADU can share the main house's existing water and sewer service, and then owes no capitalization fee at all. That takes the fee schedule's roughly $10,900 new-service charge off the table. It can also take its own service instead, which costs about $11,000 (a water capitalization fee plus a meter, and a $7,621 sewer capitalization fee) and needs extra approval from City Planning based on lot size, orientation and zoning. Water and sewer go together: separate one and you have to separate both. I asked this in July and was told sharing was required; in August the city checked with Building, Engineering and Planning and corrected it to a choice. I'm sharing. One thing I don't know yet: that $11,000 is the price of a separate service, and the city's fee schedule prices a water meter as its own line item. Whether the ADU can have its own meter without its own service, for less money, is a question I've asked and haven't had answered.

Source: City of Post Falls permit desk, email, July 7, 2026, corrected by the same desk on August 5, 2026 after consulting the Building, Engineering and Planning departments. No public link; compare the published fee schedule for the new-service numbers.

AnsweredWhat city fees does the project actually owe?

$1,000 to $2,000. The same permits as a house remodel: building permit with plan review, plumbing permits for the ADU and the underground line (about $51), an electrical permit, and a mechanical permit. That range is the city's own estimate, "on the high side." Inspections are included; the city can charge a $100 reinspection fee per incident if you repeatedly schedule inspections before the work is ready.

Source: City of Post Falls permit desk, email, July 8, 2026. No public link; the underlying rates are on the published fee schedule.

PartialDoes the electrical service have capacity for a second dwelling, and what will Avista charge?

Yes, with a trench and a city sign-off first. Avista walked the property on paper. The electric wire from the house to the corner of the lot has to be upgraded, which means trenching across the property to an underground "hand hole" by the street light. Their planner's ballpark for that trenching is $1,000 to $2,000, and he hedged it as a rough number. The result would be two 200-amp services. Gas and electric would share the same trench out to the ADU. What I don't have yet is a firm written quote. New complication, August 10: the city confirmed this exact arrangement, one incoming line split into two meters, triggers a Planning Department review, and the city might not issue permits for the new lines or meters even if Avista is ready to install them. I'm checking with Planning before I spend anything with Avista.

Source: Phone call with an Avista service planner for Post Falls and Rathdrum, August 4, 2026 (Avista construction case #00394233). Planning-review requirement: Post Falls permit desk, email, August 10, 2026.

OpenDoes the existing water line or meter need upsizing for the combined load?

Not asked yet. The no-capitalization-fee answer covers fees, not whether the physical line and meter can carry both units.

PartialIs the ADU billed on its own utility account, or through the main house?

My choice, and now a Planning review too. For Avista gas and electric it's a choice, not a rule: both units can run off one meter if code allows. Coeur d'Alene requires an ADU to have its own address and its own meters. Post Falls confirmed on August 10 that it doesn't require separate gas/electric meters, but the arrangement I'm actually planning, one incoming line split into two meters, still triggers a Planning Department review, and the city might not permit those meters without it even if Avista installs them. I'm going to meter separately regardless, so a renter can pay their own actual bill instead of me estimating it. The cost of that choice is a $20 per month basic charge on every meter, per fuel, whether it's used or not (Avista's published Idaho rate sheets: electric Schedule 1, effective May 1, 2026; gas Schedule 101, effective January 1, 2026) about $40 a month, $480 a year, before any energy at all. That's the Avista side. City water and sewer looks more promising. The city confirmed on August 5 that a fully separate water/sewer service costs about $11,000 up front. But on August 10 the same office described a third option: a "deduct meter," a private meter installed downstream of the city's main one. It's still one city meter and one bill, but I could read the second meter myself and see the ADU's actual usage, and no additional sewer capitalization fee applies to that setup. What I still don't know is what a deduct meter costs to install, or whether the city will actually approve the Avista arrangement once Planning reviews it.

Source: Phone call with an Avista service planner for Post Falls and Rathdrum, August 4, 2026 (Avista construction case #00394233). Basic charge verified against Avista's published Idaho rate schedules, August 4, 2026. City separate-service confirmation: Post Falls permit desk, email, August 5, 2026. Deduct-meter option and Planning-review requirement: Post Falls permit desk, email, August 10, 2026.

AnsweredDoes the ADU need its own street address?

Yes, as "Unit A." The city confirmed the ADU will get a street address: the same number as the main house, with "Unit A" added.

Source: Post Falls permit desk, email, August 10, 2026.

OpenHow long does city plan review take?

Unknown. Not researched for Post Falls yet. Using a pre-approved plan set should shorten it; by how much is one of the things this build will find out.

OpenWhat's the realistic start-to-occupancy timeline?

Unknown. Nobody publishes this end to end. Documenting the real one is half the point of this page.

OpenHow do people finance an ADU in Idaho?

Unresearched. Cash, HELOC, construction loan, renovation loan, and whether Idaho has any ADU-specific program are all still on the list.

OpenWhat happens to my property taxes after the ADU is assessed?

Unresearched.

OpenWhat happens to my homeowner's insurance?

Unresearched.