Accessory Dwelling Unit (ADU) Permit in Post Falls, Idaho
VerifiedPost Falls permits Accessory Dwelling Units (attached, detached, or basement conversions) as secondary dwellings on single-family lots under Post Falls Municipal Code Sections 18.24.020, 18.24.030, and 18.20.040. ADUs are processed through the standard Residential Building Permit, priced under the same per-square-foot valuation categories as other residential construction (new living space, addition, interior finish, or basement finish, depending on the ADU type).
Verified 2026-07-03 · Source
When you need this permit
- ADU may be detached, attached, or a basement conversion; must have its own electricity, kitchen, and sanitary facilities
- Size limited to 50% of the primary residence's living area or 1,000 sq ft, whichever is smaller
- Only one ADU allowed per lot; one of the two dwelling units on the lot must be owner-occupied
- Detached ADUs must be set back behind the front of the primary residence (corner lots may place the ADU on the street-side yard)
- One additional paved off-street parking space required
- No separate driveway approach permitted unless from a rear-loaded alley, or a side street on a corner lot
- Building materials must be consistent with the primary residence; no more than one entrance visible from the street; primary residence entrance must remain clearly visible and street-facing
- An existing accessory structure may be converted to an ADU if it is brought up to all currently adopted building code requirements
- Detailed site plan required, drawn to scale, showing full property extents, setbacks, and all existing/proposed structures with square footage
- ADU must comply with lot coverage, height limitations, and setback requirements for its underlying zoning district
- Apply through the Community Development Portal using the standard Residential Building Permit application
Required documents
- Required
Building Permit Application
Submitted online through the Community Development Portal; ADUs use the standard Residential Building Permit application, not a separate ADU-specific form
- Required
Post Falls Accessory Dwelling Units General Information
City handout summarizing ADU type diagrams (basement, attached, detached rear-yard, detached side-yard), placement/size/parking standards, and Municipal Code citations
- Required
Site Plan
Detailed, to-scale site plan showing property extents, setbacks, and all existing/proposed structures with square footage of floor area and footprint
Fee schedule
| Fee type | Amount | Notes |
|---|---|---|
| New detached ADU (new living space) | $96.83 per sq ft (use Valuation Chart to calculate Building Permit and plan-review fee) | City of Post Falls Fee Schedule, rev 10-1-2025; no separate ADU fee category is published — new ADU square footage is billed under the same Residential Living Space rate as other new construction |
| Basement-conversion ADU (finished basement) | $96.83 per sq ft (use Valuation Chart to calculate Building Permit and plan-review fee) | City of Post Falls Fee Schedule, rev 10-1-2025 |
| Attached ADU built as an addition | $72.62 per sq ft (use Valuation Chart to calculate Building Permit and plan-review fee) | City of Post Falls Fee Schedule, rev 10-1-2025 |
| Residential Plan Review (Building Plan Check) | 25% of the Building Permit fee | City of Post Falls Fee Schedule, rev 10-1-2025 |
Review timeline
10–10 business days
Post Falls’s published plan-review target
Inspection process
- 1
Foundation
Before concrete pour, per standard Residential Building Permit inspection sequence
- 2
Framing
Structural framing per approved plans
- 3
Mechanical/Electrical/Plumbing Rough-In
Verifies the ADU's independent electrical, kitchen, and sanitary facilities are properly roughed in
- 4
Final
Confirms independent electricity, kitchen, and sanitary facilities; parking space; setback and lot-coverage compliance; and only one street-visible entrance
Tips
- There is no separate ADU permit application or ADU-specific fee line — ADUs are permitted and fee'd as standard Residential Building Permits (new construction, addition, or basement-finish valuation rate depending on ADU type).
- Only one entrance to the ADU may be visible from the street, and the primary residence's entrance must remain clearly oriented toward the public street.
- An existing accessory structure (e.g., a shop or garage) may be converted into an ADU, but must be brought up to all currently adopted building codes.
- Contact the Community Development Department at (208) 773-8708 for zoning-district-specific setback verification before finalizing an ADU site plan.
Frequently asked questions
- How big can an ADU be in Post Falls?
- An ADU cannot exceed 50% of the primary residence's living area, or 1,000 square feet, whichever is smaller. Source: City of Post Falls Accessory Dwelling Units General Information.
- Is there a separate ADU permit fee in Post Falls?
- No. Post Falls has not published a distinct ADU permit fee category — ADU construction is permitted under the standard Residential Building Permit and billed at the applicable per-square-foot valuation rate (new living space, addition, or basement finish) from the City's Fee Schedule.
Sources & verification
Verified against official sources. Last reviewed 2026-07-03.
- City of Post Falls Community Development Department, Building Division — official building department
- Accessory Dwelling Units (ADUs) | Post Falls, ID
- Post Falls Accessory Dwelling Units General Information (PDF)
- Fee Schedule (PDF) | City of Post Falls
- Residential Site Plan Requirements / Bulk and Placement Table | City of Post Falls
- Idaho Code § 39-4117 — Processing Building Permits — Timely Review (Idaho State Legislature)
Fees, timelines, and adopted codes are researched from each jurisdiction's published records — see how we verify. Requirements change and vary by project, so always confirm the current details with the Post Falls building department before you submit. PermitBase is an independent reference and is not affiliated with any government agency.
Other permits in Post Falls
Accessory Dwelling Unit (ADU) Permit in other cities
Compare accessory dwelling unit (adu) permit fees across Idaho →
Project checklist — coming soon
Describe your project once and get every permit, document, and fee it triggers in Post Falls — in one checklist. Leave your email and we'll tell you when it's ready.
We only use your email to send permit updates. No spam, unsubscribe anytime. Privacy.