Building permits for unincorporated Ada County are issued by Ada County Development Services through its Building Division, at the Ada County Courthouse, second floor, 200 W Front St, Boise (208-287-7900). Ada is Idaho’s most populous county, with 546,141 people in the Census Bureau’s 2025 estimate. Boise, Meridian, Eagle, Kuna and Garden City lie in it, as does most of Star; each of those cities takes building permits for its own limits, and the county building code applies only in the unincorporated areas (Ada County Code 7-2-1).
This guide covers the department and how to reach it, the local conditions that shape a filing here, what permits cost and who may pull them, and how inspections are booked. Rules that apply everywhere in Idaho are summarized in each section, with a link to the full statewide explanation.
This guide covers unincorporated Ada County. Boise, Meridian, Eagle, Kuna, Garden City and Star each permit separately.
In this county the building permit and the road approval come from different governments — even inside the cities. The Ada County Highway District (ACHD) runs the public roads throughout Ada County, so access, driveway approaches and work in the public right-of-way need ACHD approval while the building permit comes from the city or the county. Establish the road approval path at the same time as the building one.
What requires a building permit in Ada County?
Where a city or county enforces building codes, a permit is required under its ordinance before construction, alteration or repair (Idaho Code 39-4111).
Permit required
- New residential and commercial construction, additions, remodels and tenant improvements
- Structural and load-bearing work, foundations, decks, porches, stairs, garages and accessory buildings
- Electrical service changes, panel work, generators, solar, EV chargers and most wiring
- Plumbing, water heaters, sewer and water connections, gas piping, backflow and fixture relocations
- HVAC installation and replacement, ductwork, ventilation, combustion air and fuel-gas appliances
- Roofing, siding, windows, signs, pools, demolition, grading, erosion control and right-of-way work where regulated
Typically exempt
- Painting, wallpaper, flooring, trim, cabinets and countertops
- Minor repairs replacing existing materials in kind with no structural or system change
- Small detached accessory structures below the local threshold, without utilities, where zoning allows
- Portable equipment or temporary work the adopted code specifically exempts
Short on time to read all of this?
Get a free quote →Which work is exempt is set by the adopted codes (IBC and IRC Section 105.2) and the local ordinance, and an exemption from a building permit is not an exemption from zoning, setbacks, floodplain rules, utility approval or a fire authority review. Confirm scope with the department before work starts rather than after.
Which code edition applies
For unincorporated areas Ada County adopts the 2018 International Building, Existing Building, Residential, Mechanical, Fuel Gas, Energy Conservation, Wildland-Urban Interface and Swimming Pool and Spa codes, each with county amendments (Ada County Code 7-2-3 to 7-2-11). The base codes are the state’s, but each city adopts its own amendments, so check those of the government that issues the permit.
Idaho’s building codes are set statewide and enforced by the cities and counties that run a building program: the 2018 International Building Code and the Idaho Residential Code (based on the 2018 IRC), the 2018 Idaho Energy Conservation Code, the 2023 National Electrical Code, and a state plumbing code based on the 2015 Uniform Plumbing Code rather than the International Plumbing Code. Idaho’s adopted codes
Who handles permitting in Ada County?
The county issues building permits only in unincorporated territory; each city permits its own limits. Ada County Code Title 9 sets an area of city impact around each of the six cities. That land stays under the county: Ada County’s zoning ordinance applies there, with the city’s comprehensive plan as adopted by the county, and the county issues the building permit (Idaho Code 67-6526).
| Detail | Information |
|---|---|
| Authority | Ada County Development Services, Building Division |
| Apply | Development Services Client Portal for building, manufactured home and mechanical permits; inspections requested online or by phone |
| Jurisdiction | Unincorporated Ada County only |
| Cities inside | Boise, Meridian, Eagle, Kuna, Garden City and most of Star |
| Roads | Ada County Highway District (ACHD), separate from the building authority |
| Boundary to check | City limits; in an area of city impact the county still issues permits, under county zoning |
| Code | Idaho adopted codes — 2018 I-Codes with Idaho amendments, 2023 NEC |
| Contractor credentials | State contractor registration (Idaho Code 54-5204); state electrical, plumbing and HVAC licences |
The county’s engineering and surveying division reviews hillside applications, drainage plans, private roads and floodplain permits in unincorporated Ada County, and the county has adopted the International Wildland-Urban Interface Code with its own amendments (Ada County Code 7-2-9).
Not sure this scope needs a permit?
Get a free quote →In 2025, building permits issued in unincorporated Ada County authorized 201 new privately owned housing units, all of them single-family homes, according to the U.S. Census Bureau Building Permits Survey.
Electrical, plumbing and HVAC permits come from the state’s Division of Occupational and Professional Licenses unless the city or county runs its own program by ordinance. Septic systems need a health district installation permit, a highway district controls the roads in its system, and since 2024 the county’s zoning applies in a city’s area of impact. Who issues permits in Idaho
Permit types
Residential permits
For houses, Ada County does not require rebar in footings and foundations unless it is part of an engineered design or a subdivision-wide geotechnical report. On parcels without public sewer, the septic installation permit comes from Central District Health, which covers Ada, Boise, Elmore and Valley counties (IDAPA 58.01.03).
Snow, seismic and wildland exposure
Design loads are site-specific. Idaho law lets each city and county set the design criteria in Section R301 of the Idaho Residential Code, including ground snow load, by local ordinance (Idaho Code 39-4116), so design to the figure the issuing department sets for the site.
The seismic design category is also set by the site under the adopted codes, and wildland-urban interface rules apply where the city, county or fire district has adopted them. Confirm the design criteria for the parcel with Ada County Development Services at the start of design.
Commercial permits
Commercial work in unincorporated Ada County follows the 2018 International Building Code with county amendments (Ada County Code 7-2-4). Access and work in the public right-of-way need an ACHD right-of-way permit, and the county charges a separate grading and drainage fee ($1,500 for a commercial project).
A local government must say within 10 business days (residential) or 20 (commercial) whether an application is complete, and if an inspection is not made within 48 business hours the permit holder may hire a third-party inspector and is refunded the fee (Idaho Code 39-4117, 39-4118). Deadlines on Idaho permits
Rather talk it over?
Call 1-855-478-4290 →Ada County permit costs and fees
Ada County building permit fees are calculated from the total valuation of the work, using the square-foot costs in the latest ICC Building Valuation Data or the applicant’s value, whichever is higher. Plan review is 50 percent of the permit fee under the International Residential Code and 65 percent under the International Building Code. Electrical and plumbing permits and their fees are the state’s (DOPL), and ACHD and Central District Health charge their own fees.
| Fee component | How it works |
|---|---|
| Residential building permit | From valuation: for example $743 for the first $100,000 plus $4.15 for each additional $1,000, up to $1,000,000 |
| Commercial building permit | The same valuation table, plus a $1,500 grading and drainage fee on a commercial project |
| Plan review | 50% of the permit fee (IRC) or 65% (IBC); on IBC work, accessibility and energy review add 25% each of the plan review fee |
| Trade permits | Mechanical from the county: $35 base on homes, or $35 plus 2% of the job value on commercial work. Electrical and plumbing from DOPL |
| Outside agency reviews | ACHD and Central District Health fees are separate (a new septic permit is $1,070) |
| Re-inspections and revisions | $100 per reinspection after the first; plan revisions from $100 |
Need a real number for a specific Ada County project? Send us the scope, address and valuation and we will identify the filing path, the reviews it will trigger and the fee categories that will apply.
Fee schedules are revised on each jurisdiction’s own cycle, so ask the issuing department for the schedule in force on your filing date, and ask separately about plan review, trade, re-inspection and revision charges. How Idaho permit fees work
Rather not deal with the Ada County building department?
Get a free quote →Trade permits and who may pull them
Permit required
- Service upgrades, panels, new circuits, solar PV, EV chargers and generators
- New plumbing, fixture relocations, water heaters, sewer and water connections and gas piping
- Furnaces, boilers, heat pumps, ductwork, ventilation and commercial kitchen exhaust
- Fire alarm, sprinkler and suppression systems on commercial work
Typically exempt
- Replacing a fixture, switch, receptacle or light with no alteration to wiring or piping
- Clearing a stoppage without replacing or rearranging concealed piping
- Filter, thermostat and routine component service
- Appliance repair that does not alter the gas, electrical or venting connection
Contractors must register with the state, and electrical, plumbing and HVAC contractors are licensed by the state; a city or county may not require an extra licence or fee for HVAC work. Contractor registration in Idaho
How to apply for an Ada County building permit
Inside the area of impact the county’s zoning applies (Idaho Code 67-6526).
Roads here are a separate government from the building authority.
ACHD, Central District Health, the fire authority and the county’s floodplain review each give their own approval.
Cities and counties set the design criteria, including snow load, by ordinance (Idaho Code 39-4116).
Slope, access and drainage decide the buildable footprint.
Electrical and plumbing permits come from DOPL; mechanical permits come from the county.
Under Section 105.5 of the adopted codes a permit becomes invalid if work does not start within 180 days or stops for 180 days; check whether the local ordinance amends that. How long Idaho permits last
Inspections in Ada County
Request an inspection the day before it is needed: by 4:30 PM by phone, or by midnight by email, or online. Footing inspections are always required. Do not cover work before the required inspection is approved.
Do not cover work before the required inspection has been approved. The approved construction documents must be kept at the site (IBC 107.3.1, IRC R106.3.1).
Want this handled start to finish?
Get a free quote →Ada County permit search and official resources
Permit records sit with the authority that issued them, which in Idaho means the record may be split. A property can have records with several bodies: the building department, the state where it issued trade permits, a highway district for access and the health district for a septic system. If you are buying, refinancing or renovating, ask Ada County Development Services what it holds for the parcel, and ask separately about the septic and access records where those apply.
Where a property has been annexed, permits issued before annexation may still be held by the county.
Confirm the code edition against Idaho’s adopted list. Idaho enforces the 2018 International Building Code and the Idaho Residential Code (based on the 2018 IRC), the 2023 National Electrical Code and a plumbing code based on the 2015 Uniform Plumbing Code. A new edition takes effect on January 1 after the Idaho Building Code Board adopts it (Idaho Code 39-4109), so check the codes and local amendments in force on your filing date.
These are the primary sources behind this guide. Codes, fee schedules and portal procedures change. Confirm the position for your filing date.
- Ada County Development Services
- Idaho DOPL — adopted building codes
- Idaho DOPL — plan review and permits
- Idaho Contractors Board — contractor registration
Frequently asked questions
Does Ada County issue permits inside Boise or Meridian?
No. Boise, Meridian, Eagle, Kuna, Garden City and Star each take permits for their own limits. The county covers unincorporated land, including the areas of city impact, where county zoning applies.
Why is a highway district involved in my building project?
Where a highway district exists, its commissioners have exclusive jurisdiction over the highways and public rights-of-way in its system (Idaho Code 40-1310). Access, driveway approaches and right-of-way work on those roads are approved by the district, which is separate from the authority issuing the building permit.
Inspections are where schedules slip.
Get a free quote →Which code edition applies in Idaho?
Idaho enforces the 2018 International Building Code with Idaho amendments and the 2021 IBC mass timber provisions, the Idaho Residential Code based on the 2018 IRC, the 2018 Idaho Energy Conservation Code and the 2023 National Electrical Code (IDAPA 24.39.30; Idaho Code 54-1001).
Does the International Plumbing Code apply?
No. Idaho has adopted the Idaho State Plumbing Code, based on the 2015 Uniform Plumbing Code with Idaho amendments (IDAPA 24.39.20).
What does the health district do?
Installing, modifying, repairing or expanding a septic system needs an installation permit, which the public health district finalizes (IDAPA 58.01.03).
Does my contractor need a licence?
Contractors must register with the state unless an exemption applies (Idaho Code 54-5204, 54-5205). Electrical, plumbing and HVAC contractors are licensed by the state, and a city or county may not require an extra licence or fee for HVAC work (Idaho Code 54-5015).
Simplify Ada County permitting with Alliance Permitting
In unincorporated Ada County the building and mechanical permits come from the county, electrical and plumbing permits from DOPL, and road approvals from ACHD. We start those approvals together so none of them holds up the project.
Trusted by leading builders, developers, and national contractors — 21+ years of filing in the jurisdictions we write about.
Contractors and builders choose Alliance for Ada County because the work is done by people who have stood at the counter:
- We verify jurisdiction against city limits and the area of city impact.
- We start highway district access approval alongside the building submittal.
- We identify fire, health, floodplain and utility reviews before filing.
- We get site-specific snow, seismic and wildland criteria before design.
- We check contractor registration and trade credentials against the scope.
Alliance Permitting is a permit documentation and submission company in Idaho. We prepare your paperwork, file it correctly and coordinate with the building department through issuance. We are not a contractor and we do not perform licensed plan review or inspections; that work stays with your licensed team and the jurisdiction.
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More Idaho permitting guides
This guide is provided by Alliance Permitting for general information about Ada County permitting. Requirements, fees, and procedures change; confirm details with the permitting authority before relying on them.