Bolthole Index

Ada County, Idaho

Building permits, zoning and septic rules in Ada County, Idaho

39Index Score / 100
#39 of 44 in Idaho

Unincorporated Ada County, Idaho requires a building permit before construction, enforced by Ada County Development Services1. The county also zones unincorporated land through Ada County Code Title 82. Septic permits for any Ada County address come from Central District Health, not the building office3. Owner-builders are exempt from contractor registration only, not from permits4.

At a glance

Building permit
Required for building work in unincorporated Ada County, subject to listed exemptions1
Zoning
Yes, unincorporated Ada County is zoned under the Ada County Zoning Code, Title 82
Septic permits
Required through Central District Health; new permits are listed at $1,070, or $535 without a test hole or site visit56
Owner-builder
Contractor-registration exemption when owners work on their own land and do not intend to sell within 12 months; permits still apply4
Manufactured homes
Need a state installation permit and tag before installation, plus a pre-occupancy inspection, in areas without an approved local building program78
Wells
A drilling permit from the Idaho Department of Water Resources is required before any well is drilled9
RV street parking
Motor homes, travel trailers and camp trailers may park on residential streets in unincorporated Ada County for up to 72 hours10
Septic soil difficulty
Only 10.1% of county soils are free of severe limits for a conventional drain field11

Who to call

Building permits

Ada County Development Services, Building Division

Building permits, plan review and inspections for unincorporated Ada County

208-287-7900

Ada County Courthouse, Second Floor, 200 W Front St., Boise, ID 83702

Planning & zoning

Ada County Development Services, Community Planning Division

Zoning administration, land-use permits and the Ada County Comprehensive Plan for unincorporated Ada County

208-287-7900

Ada County Courthouse, Second Floor, 200 W Front St., Boise, ID 83702

Septic permits

Central District Health, Boise Office (Environmental Health)

Individual/subsurface sewage disposal (septic) permits, site evaluations and inspections for Ada County

208-375-5211

707 N Armstrong Pl., Boise, ID 83704

Contact details are copied from each office’s official page and were checked against it on October 12, 2026.

Off-grid gear

Going off-grid in Ada County means bringing your own water and power. The kit we’d start with:

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Do you need a building permit in Ada County, Idaho?

Yes. Anyone who intends to construct, enlarge, alter, repair, move, demolish or change the occupancy of a building in unincorporated Ada County must first apply to the building official and obtain the required permit1. Listed exemptions include certain small accessory structures, fences, retaining walls, sidewalks, driveways and finish work, and agricultural buildings that fall under the code's agricultural-building exception are excluded from the county building chapter1. Idaho's adopted code set includes the 2018 International Building Code and parts of the 2018 International Residential Code, with Idaho amendments12. Electrical, plumbing and HVAC work also requires permits, although the administering jurisdiction varies by location13. New manufactured-home installations need an installation permit and tag before work begins where no approved local building program exists, and every installation must be inspected and approved before occupancy78. Idaho's owner-builder exemption covers contractor registration when owners do their own work on their own land and do not intend to sell within 12 months; it does not waive building or trade permits4.

Who issues building permits and zoning approval in Ada County, and how do you reach them?

For unincorporated Ada County, contact Development Services at the Ada County Courthouse, Second Floor, 200 W Front St., Boise, ID 83702, phone 208-287-790014. The department's online client portal accepts building, manufactured-home and mechanical permit applications14. Community Planning shares that address and phone line; ask that division to confirm the parcel's zoning district15. Inside Kuna, the city issues building permits16. Septic permits remain with Central District Health for Ada County addresses inside and outside city limits3.

Does unincorporated Ada County have zoning, and what are the lot sizes and setbacks?

Unincorporated Ada County has district-specific zoning; confirm the parcel's district before applying these standards2. Rural Preservation (RP) has a 40-acre base minimum lot; Rural Residential (RR) has a 10-acre base minimum, and both list a separate rural-residence range of 1–2.5 acres1718. Estate Residential (R1) requires 1 acre and 100 feet of street frontage19.

RP and RR front setbacks are 50 feet from arterial, collector or section-line streets, 30 feet from other roadways, and 25 feet from property lines not fronting a roadway2021. Both require 25-foot interior side and rear setbacks, with a 10-foot side allowance for rural residences adjacent to other rural residences2021. RR side-street setbacks are 30 feet for base development and 25 feet for rural residences21. R1 requires 10-foot interior side and 20-foot rear setbacks22.

City zoning applies inside Boise City23, Meridian24, Eagle25, Kuna26, Star27, Garden City28. Septic permits stay with Central District Health3.

How do septic permits work in Ada County?

A property owner must obtain a septic permit from a public health district before installing a system, and Central District Health administers that program in Ada County53. Septic applications, inspection applications and inspection results are available through Central District Health's Accela portal29. The published sewage fee schedule lists a new permit at $1,070, or $535 for the option without a test hole or site visit; a repair permit is $535 without a test hole and $1,070 with one6. Central District Health's Boise office is at 707 N Armstrong Pl., Boise, ID 83704, phone 208-375-521130. A system cannot receive wastewater until the final installation inspection, and inspection preparation requires at least 48 hours' notice, excluding weekends and holidays31. Only 10.1% of Ada County soils are free of severe limitations for a conventional drain field, so arrange the site evaluation before committing to a rural parcel11.

Can you live in an RV or tiny home on your land in Ada County?

We could not confirm a general private-land RV or tiny-home occupancy rule outside Ada County's planned-community districts; ask Community Planning about the parcel's district and proposed use15. In those planned-community districts, including Spring Rock, RVs and tiny homes are prohibited outside an approved RV or tiny-home park3233. The unincorporated county's 72-hour street-parking allowance for motor homes, travel trailers and camp trailers does not authorize private-land occupancy10.

A secondary dwelling in unincorporated Ada County needs at least 6,000 square feet of parcel area, continuous owner occupancy of either dwelling, a foundation and compliance with district dimensions34. Its floor area must be at least 350 square feet and no greater than 1,200 square feet or 60% of the principal home's above-ground living space, whichever is less34. Idaho treats an accessory dwelling as a single-family dwelling for septic capacity, so include it in wastewater planning35.

Building a home in Ada County: the steps, in order

  1. Confirm the parcel's zoning district, lot size and setbacks with Ada County Community Planning152. If the project subdivides land, also account for Central District Health's sanitary-restriction review36.
  1. Apply to Central District Health for the required septic permit; only 10.1% of Ada County soils are rated without severe limits for a conventional drain field511.
  1. If the site needs a well, obtain the Idaho Department of Water Resources drilling permit before drilling begins9.
  1. If access meets a state highway, obtain an Idaho Transportation Department encroachment permit before work in the right-of-way37.
  1. Submit the residential building-permit application to Ada County Development Services114.
  1. Arrange the required electrical, plumbing and HVAC permits with the authority serving the location13.
  1. If acting as owner-builder, remember that the contractor-registration exemption requires no intent to sell within 12 months and does not waive permits4.

What to check before you buy land in Ada County

Terrain is gentle overall, with 83.2% of the county at 15% slope or less38. Federal land makes up 46.3% of the county, which reduces what is privately available in remote areas and makes legal access worth checking carefully39. Annual precipitation is about 12 inches, and severe drought occurs in 6.7% of years4041. The effective property-tax rate is about 0.6%, with a median annual bill near $2,643 and a typical home value around $530,977424344.

Watch-outs

  • Ada County's 72-hour allowance for motor homes, travel trailers and camp trailers on residential streets in unincorporated areas is a parking rule, not permission to live in an RV on private land10.
  • Only 10.1% of Ada County's soils are free of severe limitations for a conventional septic drain field, so budget for a site evaluation, and possibly an engineered system, before you count on a standard drain field11.
  • Idaho's health district can deny a septic permit when public or central wastewater treatment is reasonably accessible, so don't assume an onsite system is automatic near Boise's sewer service area45.
  • Idaho's owner-builder exemption applies only when owners work on their own land without intending to sell within 12 months, and it does not remove permit requirements4.
  • Dimensional standards such as the 40-acre base lot in Rural Preservation were amended by ordinance in October 2025, so confirm current numbers with Community Planning before you design1715.

Sources

  1. Ada County Code § 7-2-4: Amendments to the 2018 International Building Code, quoted and re-checked
  2. Ada County Code § 8-2-23: Use Table, quoted and re-checked
  3. Septic, Subdivisions & Water, quoted and re-checked
  4. dopl.idaho.gov, quoted and re-checked
  5. Septic, Subdivisions & Water, quoted and re-checked
  6. cdh.idaho.gov, quoted and re-checked
  7. Building Archives - Division of Occupational and Professional Licenses (Idaho statewide rule), quoted and re-checked
  8. Building Archives - Division of Occupational and Professional Licenses (Idaho statewide rule), quoted and re-checked
  9. Wells Overview (Idaho statewide rule), quoted and re-checked
  10. Ada County Code § 6-5-3: Parking of Vehicles in Residential Areas, quoted and re-checked
  11. Share of soils USDA rates "not limited" for a conventional septic drain field (SSURGO). A strict rating: the median county is about 6% and a tenth of counties are 0%, so a low figure means most lots need a site evaluation or an engineered system, not that septic is impossible. Cite it only with that caveat: Bolthole Index county data
  12. Idaho Adopted Codes, quoted and re-checked
  13. Frequently Asked Questions (FAQs) - Division of Occupational and Professional Licenses (Idaho statewide rule), quoted and re-checked
  14. Ada County Development Services, Building Division (adacounty.id.gov)
  15. Ada County Development Services, Community Planning Division (adacounty.id.gov)
  16. Kuna: Kuna City Code § 4-1-3, Building Permit Required; Fees (Ada County), quoted and re-checked
  17. Ada County Code § 8-2-5: Rural Preservation (RP), quoted and re-checked
  18. Ada County Code § 8-2-6: Rural Residential (RR), quoted and re-checked
  19. Ada County Code § 8-2-9: Estate Residential (R1), quoted and re-checked
  20. Ada County Code § 8-2-5: Rural Preservation (RP), quoted and re-checked
  21. Ada County Code § 8-2-6: Rural Residential (RR), quoted and re-checked
  22. Ada County Code § 8-2-9: Estate Residential (R1), quoted and re-checked
  23. Boise City: Boise, ID Laws (Ada County), quoted and re-checked
  24. Meridian: Unified Development Code (Ada County), quoted and re-checked
  25. Eagle: 8-1-1: Interpretation, Scope of Regulations (Ada County), quoted and re-checked
  26. Kuna: Kuna City Code § 5-8-501, Zoning Districts Established; Purpose (Ada County), quoted and re-checked
  27. Star: Planning & Zoning (Ada County), quoted and re-checked
  28. Garden City: Table of Contents - Garden City, ID (Ada County), quoted and re-checked
  29. Septic, Subdivisions & Water, quoted and re-checked
  30. Central District Health, Boise Office (Environmental Health) (cdh.idaho.gov)
  31. IDAPA 58.01.03 Individual/Subsurface Sewage Disposal Rules (Idaho statewide rule), quoted and re-checked
  32. Ada County Code § 8-21B-3: Allowed Uses, quoted and re-checked
  33. Ada County Code § 8-21B-3: Allowed Uses, quoted and re-checked
  34. Ada County Code § 8-4-23: Dwelling, Secondary Attached or Detached, quoted and re-checked
  35. Idaho DEQ - Uncommon Wastewater Flows (Idaho statewide rule), quoted and re-checked
  36. Septic, Subdivisions & Water - Central District Health, quoted and re-checked
  37. Types of Right-of-Way Encroachment Permits (Idaho statewide rule), quoted and re-checked
  38. Share of land at 15% slope or less: Bolthole Index county data
  39. Federal land share: Bolthole Index county data
  40. Annual precipitation: Bolthole Index county data
  41. Share of years in severe drought: Bolthole Index county data
  42. Effective property tax rate: Bolthole Index county data
  43. Median property tax bill: Bolthole Index county data
  44. Typical home value (Zillow): Bolthole Index county data
  45. IDAPA 58.01.03 Individual/Subsurface Sewage Disposal Rules (Idaho statewide rule), quoted and re-checked

Written October 12, 2026 from the rules quoted below, each taken from an official source and re-checked by an independent reviewer. This is research, not legal advice: rules change, so confirm with the office before you buy or build.

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Compared with neighboring counties

Like all 6 of its neighbors, Ada County requires a building permit for a home.

RuleAda CountyCanyon CountyElmore CountyBoise CountyPayette CountyOwyhee CountyGem County
Building permitRequiredRequiredRequiredRequiredRequiredRequiredRequired
County zoningYesYesYesYesYesYesYes
Septic permitsCentral District HealthSouthwest District HealthCentral District HealthCentral District HealthSouthwest District HealthSWDHSouthwest District Health

County locator

Ada County in Idaho

39
County map
Ada County highlighted among the Idaho counties · colored by Index score

How Ada County scores

Seclusion25100% ev.
Self-Sufficiency22100% ev.
Admin Boringness42100% ev.
Durability61100% ev.
Property Autonomy90100% ev.
Carry Cost50100% ev.

Evidence strength: 100%. This reports direct-source completeness and fallback use; it is separate from the score and is not a confidence interval. How it works →

$531kTypical home
0.6%Property tax
$13,084Land / acre
12"Annual rain
6.7% of yrsSevere drought
21.1 / yr (+16.7)Mid-century 100°F days
43 daysMid-century dry spell
0.66" (+7.1%)Mid-century 1-day rain
1.11×Wildfire change factor
100%Forward climate coverage
$1,052Home insurance / yr
4.6% / yrInsurance growth
0.59%Nonrenewal rate
county median (2+ published ZIPs)Insurance basis
357,241People within 30 min
924,493People within 2 hr
488,213Radius comparison (15 mi)
498.7People / sq mi
46.3%Federal land
83.2%Land at 15% slope or less
10.1%Soils rated "not limited" for septic (strict USDA rating)
64,473 acWorkable land screen
8.3%Wooded land
15.2 tonsBiomass / forest ac
52°FAvg temp

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Cities and towns in Ada County

Inside a city or town, that city usually issues building permits and sets zoning; the county’s rules above cover unincorporated land. Septic, wells and floodplain rules usually stay with the county or state everywhere.

Answers from the rulebook for Ada County

What the ordinances and state agencies actually say — one answer per question, each quoted from the official source and independently re-checked.

Ada County rules

  • Building permitRequired

    Construction, enlargement, alteration, repair, movement, demolition, or occupancy changes involving buildings or structures in unincorporated Ada County.

    • The owner or authorized agent must apply to the building official and obtain the required permit before the work.
    • Building work exemptions include listed items such as certain small accessory structures, fences, retaining walls, sidewalks and driveways, and finish work.
    • Agricultural buildings covered by the code's agricultural-building exception are excluded from Title 7, Chapter 2.
    “Any owner or owner's authorized agent who intends to construct, enlarge, alter, repair, move, demolish, or change the occupancy of a building or structure [...] shall first make application to the building official and obtain the required permit.”
  • County-wide zoningPresent (with conditions)

    Ada County zoning districts and their permitted, conditional, accessory, and temporary uses in unincorporated Ada County.

    • Uses are governed by the applicable zoning district and associated use standards.
    • This claim does not extend Ada County zoning administration into incorporated municipalities.
    “The Use Table found in Table 8-2-23-2 of this Chapter establishes principal, conditional, accessory, and temporary uses permitted within each zoning district, and how they are permitted.”
  • Local zoningVaries (with conditions)

    Aggregate of Ada County zoning districts and the separate Spring Rock planned-community zoning regime within unincorporated Ada County; this is an aggregate conclusion and does not assert that Ada County administers incorporated-municipality ordinances.

    • Ada County's ordinary zoning rules differ by base district, including RP, RR, and R1 dimensional standards.
    • Spring Rock has separate standards that control when they conflict with the ordinary Ada County zoning ordinance.
    • Incorporated municipalities require separate jurisdiction-specific research.
    “Any contradiction, inconsistency, or ambiguity between the requirements of this article and any other provision of the Ada County zoning ordinance will be governed and controlled by this article.”
  • Minimum dwelling sizeSpecified

    Secondary attached or detached dwellings in Ada County zoning districts.

    • The subject property must have at least 6,000 square feet.
    • Either the principal dwelling or secondary dwelling must be continuously occupied by an owner.
    • The secondary dwelling must meet applicable zoning-district dimensional standards.
    • The secondary dwelling is limited to a maximum of three bedrooms and must be placed on a foundation.
    • The size is 350 square feet minimum and no more than 1,200 square feet or 60% of the principal dwelling's above-ground living space, whichever is less.

    minimum secondary dwelling area: >= 350 square feet · maximum secondary dwelling area: <= 1200 square feet (Also limited to 60% of above-ground living space of the principal dwelling, whichever is less)

    “A secondary dwelling may be between three hundred fifty (350) square feet up to a maximum of one thousand two hundred (1,200) square feet or sixty percent (60%) of the square footage of above-ground living space of the principal dwelling, whichever is less.”
  • Minimum lot sizeDistrict specific (with conditions)

    Rural Preservation (RP) zoning district.

    • The table distinguishes base RP development from rural-residence development.
    • Only one dwelling unit is generally allowed per property, subject to listed approved additional-dwelling exceptions.
    • The cited section states the ordinance was amended by Ordinance 1002 on October 28, 2025.

    base minimum lot size: >= 40 acres · rural residence minimum lot size: >= 1 acre (Rural residence range extends to 2.5 acres maximum)

    “Lot Size (min) | 40 acres | 1 acre (min) to 2.5 acres (max)”
    2 more reviewed findings on this topic
  • SetbacksDistrict specific (with conditions)

    Development in the Estate Residential (R1) zoning district.

    • Front setback is 30 feet from an arterial or collector street and 25 feet from a local street or private road.
    • With alley access, a side-loaded garage, or rear garage, the local/private-road front setback may be 20 feet.
    • Interior side setback is 10 feet.
    • Side setback from a local street or private road is 20 feet, but 15 feet is permitted if vehicle access is restricted on that street or road.
    • Rear setback is 20 feet.
    • The cited section was amended by Ordinance 1002 on October 28, 2025.

    front setback from arterial or collector street: >= 30 feet · front setback from local street or private road: >= 25 feet (20 feet if alley access, side-loaded garage, or rear garage) · interior side setback: >= 10 feet · side setback from local street or private road: >= 20 feet (15 feet if vehicle access is restricted) · rear setback: >= 20 feet

    “Arterial or Collector Street | 30' [...] Local Street or Private Road | 25' [...] If providing alley access, a side loaded garage, or rear garage | 20' [...] Interior Side Setback (min) | 10' [...] Side Setback from Local Street or Private Road (min) (if vehicle access is restricted on the local street or private road, a setback of 15' is permitted) | 20' [...] Rear Setback (min) | 20'”
    2 more reviewed findings on this topic
    • District specific (with conditions) — Development in the Rural Preservation (RP) zoning district.
      “Arterial, collector, or section line street | 50' | 50' [...] Other roadway | 30' | 30' [...] Property line not fronting a roadway | 25' | 25' [...] Side Setback (min) (for rural residences, side property line setback of 10' is allowed adjacent to other rural residences) | 25' | 25' [...] Rear Setback (min) | 25' | 25'”
    • District specific (with conditions) — Development in the Rural Residential (RR) zoning district.
      “Arterial, collector, or section line street | 50' | 50' [...] Other roadway | 30' | 30' [...] Property line not fronting a roadway | 25' | 25' [...] Side Street Setback (min) | 30' | 25' [...] Interior Side Setback (min) (for rural residences, side property line setback of 10' is allowed adjacent to other rural residences) | 25' | 25' [...] Rear Setback (min) | 25' | 25'”
  • Living in an RVLimited

    Parking of recreational vehicles on streets in residential areas within unincorporated Ada County.

    • A recreational vehicle may not be parked on a residential street for more than two hours, except that motor homes, travel trailers, and camp trailers may be parked for up to 72 hours.
    • The 72-hour limit applies whether or not the recreational vehicle is attached to a motorized vehicle.
    • No vehicle may be parked upon the streets in a residential area within unincorporated Ada County for a continuous period exceeding seven days.

    ordinary residential-street parking limit for recreational vehicles: <= 2 hours (motor homes, travel trailers, and camp trailers may be parked for up to 72 hours) · motor home, travel trailer, or camp trailer street-parking limit: <= 72 hours (applies irrespective of attachment to a motorized vehicle) · continuous street-parking limit for any vehicle in a residential area: <= 7 days

    “No person shall park the following, whether attended or unattended, upon the streets in any residential area within unincorporated Ada County for a period in excess of two (2) hours: [...] Any recreational vehicle: [...] Notwithstanding anything to the contrary in this section, motor homes, travel trailers and camp trailers may be parked on the street for a period not to exceed seventy two (72) hours; [...] The seventy two (72) hour period applies irrespective of whether they are attached to a motorized vehicle. [...] No person shall park any vehicle upon the streets in any residential area within unincorporated Ada County for a continuous period in excess of seven (7) days.”
    One more reviewed finding on this topic
    • Prohibited — Recreational vehicles used as dwelling units or occupied on property in Ada County planned community districts governed by Chapter 21B
      “Recreational vehicles and tiny homes are not considered dwelling units and are a prohibited use in all districts unless located within an approved recreational vehicle or tiny home park as set forth in section 8-21B-4 G.”
  • Tiny homesProhibited

    Tiny-home occupancy within the Spring Rock planned community in unincorporated Ada County.

    • Tiny homes may be located only within an approved recreational vehicle or tiny home park under § 8-21B-4(G).
    • The rule is specific to the Spring Rock planned community and should not be generalized to every Ada County zoning district.
    “Recreational vehicles and tiny homes are not considered dwelling units and are a prohibited use in all districts unless located within an approved recreational vehicle or tiny home park as set forth in section 8-21B-4 G.”
  • Who permits septicLocal

    Septic programs serving Ada County within Central District Health's service area.

    • Central District Health oversees programs within Ada, Boise, Elmore, and Valley counties.
    • Idaho remains responsible for monitoring and dealing with environmental concerns and hazards.
    “Central District Health’s (CDH) Environmental Health Division oversees a number of programs relating to the health and the environment within Ada, Boise, Elmore and Valley counties. Environmental Health Specialists at Central District Health (CDH) permit septic systems, review land development applications and verify location of shallow injection wells to ensure reliable and safe water resources for the community.”
  • Septic permitRequired

    Septic systems in Ada County within Central District Health’s service area.

    • Central District Health Environmental Health Specialists administer the septic permitting program.
    • Specific permit requirements and exceptions were not established from the opened page.
    “To have a septic system installed, the property owner must obtain a permit from a public health district.”
  • Subdividing landLimited

    Land-development and subdivision proposals in Ada County insofar as Central District Health reviews sanitary restrictions.

    • This claim is limited to Central District Health’s sanitary-restriction and environmental-health review; it is not a complete statement of Ada County subdivision approval requirements.
    “CDH reviews land development proposals for the release of sanitary restrictions.”
  • Permit feesPublished (with conditions)

    Central District Health sewage-program permit fees applicable to Ada County.

    • The page labels the schedule 'Sewage Program Fees – Jul 2026'.
    • Listed fees include new permits, expansions, repairs, central/LSAS, accessory-use reviews, tank-only permits, vault privies, speculative site evaluations, and additional test holes.

    new septic permit: 1070 USD (No test hole/site visit option listed at $535.) · repair permit with test hole: 1070 USD · repair permit without test hole: 535 USD

    “Sewage Program Fees – Jul 2026 Permit – New – $1070 Permit – New – No test hole/Site Visit – $535 Permit – Expansion (no test hole) – $535 Permit – Repair (no test hole) – $535 Permit – Repair (with test hole) – $1070”
  • Permit processPublished (with conditions)

    CDH septic and environmental-health permit processing for Ada County.

    • CDH states that all license and permit services are available through the Accela portal.
    • The page specifically identifies permit applications and inspection applications/results.
    • Questions are directed to CDH at (208) 375-5211.
    “All license and permit services are now available through the Accela portal: Permit applications Inspection applications and results.”

Idaho rules that apply here

  • Owner-builder exemptionConditional

    Homeowners personally performing plumbing work on their own residential premises in Idaho.

    • The homeowner must own the residential property and personally perform the permitted work.
    • The homeowner permit is valid only for a primary or secondary residence and associated outbuildings.
    • Associated outbuildings must not be used for commercial purposes or rented by a tenant.
    • The homeowner must accept responsibility for all work performed.
    • All work must be inspected by the Division of Occupational and Professional Licensing.
    • A plumbing permit must be obtained by application to the Division.
    • The application must be submitted with payment.
    • The application form states that an additional $65 fee may be assessed if the location is not clearly provided by directions or an attached map.
    • The application was revised 8/17/2022; this revision date is not treated as an effective date.

    unclear-location fee: 65 USD (May be assessed if the location is not clearly given by directions or an attached map.)

    “I certify that I am the owner of the residential property and will personally perform the work covered by this permit.”
    5 more reviewed findings on this topic
    • Conditional — Owner-performed construction on the owner's own land in Idaho, including Ada County.
      “Owners: Owners who do their own work on their own land and do not intend to sell the property within 12 months are exempt from registration.”
    • Available — An owner performing their own construction work on the owner's own land in Idaho.
      “A: Any person who engages in a construction job with a dollar amount exceeding $2000.00 (materials & labor) and is not otherwise exempt (The exemptions are listed below); [...] Owners: Owners who do their own work on their own land and do not intend to sell the property within 12 months are exempt from registration.”
    • Conditional — An Idaho homeowner undertaking construction or trade work for which a state-administered permit process applies.
      “Public (Homeowners Only) [...] *Public: “Homeowner” is pre-selected. [...] Once payment is processed, you may choose “Request Inspection” and/or “Print Permit””
    • Conditional — Owners performing construction work on their own land in Idaho under the state contractor-registration system.
      “Owners who do their own work on their own land and do not intend to sell the property within 12 months are exempt from registration.”
    • Conditional — Homeowners personally performing electrical work on a primary or secondary residence and related outbuildings in Idaho.
      “Homeowners may purchase a permit only when they themselves are doing electrical work on their primary or secondary residence and/or related outbuildings.”
  • Building code adoptedAdopted (with conditions)

    Building construction in Idaho subject to the Idaho Building Code Act and the Idaho Division of Occupational and Professional Licenses building-code program.

    • The adopted codes include amendments identified by Idaho; local-government application is subject to the Idaho Building Code Act.
    • The reference to the 2020 Edition is an identifier to the legislative session in which amendments were adopted.
    • Amendments can be made in any legislative cycle regardless of code cycle.
    • The cited DOPL page states that existing rules remain in effect for 2026–2027.

    International Building Code: 2018 edition, with amendments · International Residential Code: 2018 edition, parts I, II, III and IX, with Idaho amendments; collectively named Idaho Residential Code (2020 Edition) · International Energy Conservation Code: 2018 edition, with amendments; collectively named Idaho Energy Conservation Code (2020 Edition) · International Existing Building Code: 2018 edition

    “Building Codes: 2018 International Building Code, with amendments 2018 International Residential Code (parts I, II, III and IX), with Idaho amendments collectively named the Idaho Residential Code (2020 Edition) 2018 International Energy Conservation Code, with amendments collectively named the Idaho Energy Conservation Code (2020 Edition) 2018 International Existing Building Code”
    2 more reviewed findings on this topic
    • Adopted (with conditions) — Statewide Idaho building-code adoption applicable to building work in Ada County, subject to the adopted code provisions and amendments.
      “Building Codes: 2018 International Building Code, with amendments 2018 International Residential Code (parts I, II, III and IX), with Idaho amendments collectively named the Idaho Residential Code (2020 Edition)”
    • Adopted — Statewide Idaho building-code adoption framework applicable to local governments, including counties that enforce building codes.
      “The following codes are hereby adopted for the state of Idaho division of building safety”
  • InspectionsRequired

    All manufactured-home installations in Idaho before the manufactured home is occupied.

    • The inspection and approval are performed by DOPL or the authority having jurisdiction.
    • Inspection and approval must occur before occupancy.
    “All installations must be inspected and approved by the Idaho Division of Occupational and Professional Licenses or the authority having jurisdiction before the manufactured home is occupied.”
  • Camping on your landLimited

    Camping or parking a vehicle or trailer on Idaho Fish and Game Wildlife Management Areas and access sites separate from a WMA.

    • The restriction applies in areas posted against camping or parking.
    • Leaving an unattended camp, vehicle, or trailer for more than 48 hours is prohibited without authorization.
    • Camping or parking for more than 10 days during any 30-day period on one WMA or one separate access site is prohibited without authorization.
    • The rule permits authorization by the Commission, Director, Regional Supervisor, or designee.

    unattended duration: > 48 hours (Unless specifically authorized by the Commission, Director, Regional Supervisor, or designee.) · camping or parking duration: > 10 days during any 30-day period per WMA or separate access site (Unless specifically authorized by the Commission, Director, Regional Supervisor, or designee.)

    “camp or park a vehicle or trailer for more than ten (10) days during any thirty (30) day period”
  • Manufactured homesLimited

    Occupancy of manufactured homes installed in Idaho.

    • For new homes in areas without an approved local building program, an installation permit and installation tag are required before installation begins.
    • All installations must be inspected and approved by DOPL or the authority having jurisdiction before the manufactured home is occupied.
    • Manufactured homes are for residential use only and are regulated under federal manufactured-housing standards plus state and local requirements.
    “An installation permit and installation tag (required only for new homes) is required by Idaho Division of Occupational and Professional Licenses prior to starting the installation in areas where there is not an approved local building program. All installations must be inspected and approved by the Idaho Division of Occupational and Professional Licenses or the authority having jurisdiction before the manufactured home is occupied.”
  • Accessory dwellingsLimited

    Accessory dwelling units for Idaho DEQ wastewater-flow and septic-system sizing purposes; this claim does not establish statewide zoning permission.

    • An ADU is sized as a single-family dwelling for the cited wastewater-flow guidance.
    • An ADU may combine flows with another structure into one system.
    • Any common septic tank must be large enough to hold the required capacity from both structures.
    • Local land-use, building, and septic authorities may impose additional requirements.

    wastewater flow basis: single-family dwelling

    “Size as a single family dwelling. Can combine with another structure's flows into one system”
  • Septic inspectionRequired

    Individual and subsurface sewage disposal systems constructed or installed under Idaho’s onsite wastewater rules.

    • The Director requires one or more inspections necessary to determine compliance.
    • The permittee must uncover or make available for inspection any portion covered or concealed in violation of the rules.
    • If preparation is required, the applicant or permittee must provide at least 48 hours’ advance notice, excluding weekends and holidays.
    • For individual systems, the public health district inspects the installation.
    • Large soil absorption systems are inspected by the public health district and DEQ.

    advance inspection notice: >= 48 hours (Excludes weekends and holidays.)

    “No system may receive wastewater until the Director conducts a final installation inspection”
  • Well permitRequired

    Construction or drilling of wells in Idaho, including domestic wells.

    • Before drilling, the well owner or driller must obtain a drilling permit from IDWR.
    • All wells must be constructed by a well driller with a valid IDWR license.
    • The separate water-right permit exemption for domestic purposes does not eliminate the drilling-permit requirement.
    • For new diversions in qualifying subdivisions filed on or after July 1, 2025, a water-right permit is required in a moratorium area, critical groundwater area, or groundwater management area, except for in-home uses and watering livestock.
    • Well construction rules apply to wells and other artificial openings more than 18 vertical feet below land surface.

    well depth threshold: > 18 vertical feet below land surface (The cited well-construction rules describe covered wells and artificial openings.) · subdivision application date: >= 2025-07-01 (Applies to qualifying new diversions described in Idaho Code § 42-227(4).)

    “Prior to drilling a well, the well owner or well driller must first obtain a drilling permit from IDWR.”
  • Mandatory utility hookupConditional

    Proposed individual or subsurface sewage disposal systems where public or central wastewater treatment facilities may be available.

    • The Director may deny a septic permit when public or central wastewater treatment facilities are reasonably accessible.
    • The cited rule does not establish a universal statewide requirement to connect every property to public sewer.
    • Subsurface septic discharge remains an identified onsite disposal method.
    “Public or central wastewater treatment facilities are reasonably accessible.”
  • Driveway accessRequired

    Private and public driveways or streets connecting to Idaho state highway right-of-way.

    • An ITD encroachment permit is required for private and public approaches, including driveways and streets.
    • No activity may occur on state highway rights-of-way until the Department or a delegated local highway agency issues an approved permit, except emergency approval affecting highway operations and motorist safety may precede processing.
    • A Traffic Impact Study may be required for new or expanded development seeking direct access to a state highway when the stated thresholds are met, unless waived by the District Engineer.

    peak-hour trips for possible TIS requirement: >= 100 new trips (unless waived by the District Engineer) · daily traffic for possible TIS requirement: >= 1000 vehicles per day (unless waived by the District Engineer)

    “Encroachment permits approved by the Department are required for private and public approaches (driveways and streets), utilities and other miscellaneous encroachments.”
  • Campground & park staysLimited

    Temporary camping in Idaho State Parks administered by the Idaho Department of Parks and Recreation.

    • Camping is permitted only in designated areas.
    • Stays are limited to 14 nights in a 30-day period; the same page's FAQ separately states a 15-day limit, creating an unresolved internal discrepancy.
    • Individual-site occupancy is limited to one family unit or no more than 8 persons unless otherwise specified; companion-site and site-design restrictions apply.
    • Camping is not permitted on beaches, parking lots, or day-use facilities.
    • Check-in is at 2 p.m. for campsites and checkout is at 1 p.m.; late checkouts may incur additional fees unless prior arrangements have been made.

    state-park stay limit: 14 nights in 30 days (FAQ on the same page states 15 days in any 30-day period) · individual-site people limit: <= 8 people (one family unit or site-specific limits may apply)

    “Camping is permitted only in designated areas. [...] Stays are limited to 14 nights in a 30-day period.”
  • county zoning authorityGeneral

    Idaho counties adopting zoning for unincorporated areas through their boards of county commissioners.

    • A board of county commissioners is a governing board and may exercise the powers authorized by the Local Land Use Planning Act.
    • The county board's powers under the chapter apply to the unincorporated area of the county.
    • Zoning must be adopted, amended, or repealed by ordinance using the notice and hearing procedures in Idaho Code § 67-6509.
    • Zoning districts must conform to the adopted comprehensive plan.
    • Within zoning districts, standards may regulate or restrict building height, number of stories, size, construction, reconstruction, alteration, repair or use of buildings and structures; lot occupancy; courts, yards and open spaces; population density; and building and structure location and use.
    • Standards must be uniform for each class or kind of building throughout each district, but may differ between districts.
    • Overlay zoning districts require clear and objective standards and must not constitute a regulatory taking under Idaho or federal law.
    “The powers of the board of county commissioners conferred by this chapter shall apply to the unincorporated area of the county.”
  • county building authorityGeneral

    Idaho counties' authority to adopt and enforce building codes and require permits for residential construction in unincorporated areas when the county operates a building-code enforcement program.

    • The statute defines local government as any city or county of Idaho.
    • A local government that had not previously implemented a code-enforcement program may elect to implement one by ordinance evidencing its intent to do so.
    • Construction in a local-government jurisdiction enforcing building codes requires a permit under the applicable local ordinance.
    • A local government issuing permits and performing enforcement must adopt the specified state-adopted codes and may amend them only within the limits stated in Idaho Code § 39-4116(4).
    • Local amendments must generally provide at least an equivalent level of protection; accessibility amendments are restricted, and additional residential-code amendments require the statutory good-cause, necessity, ordinance, public-hearing, publication, and notice procedures.
    • Single-family homes and multiple-family dwellings up to two units are exempt from automatic fire-sprinkler requirements in the enumerated codes.
    • Agricultural buildings must be exempted; a county may issue farm-building permits only for road setbacks and utility easements, at no more than actual issuance cost.
    • Permits are governed by the laws in effect when the application is received.
    • The state division retains jurisdiction for in-plant inspections and installation standards for manufactured or mobile homes and for in-plant inspections and enforcement of modular-building and commercial-coach construction standards.
    “"Local government" means any city or county of this state.”

Still unanswered

We looked and could not find an official answer yet. Silence is not permission — ask the county directly.

  • Certificate of occupancy — Certificates of occupancy for buildings in unincorporated Ada County.
  • Zoning districts — Published zoning districts and maps for unincorporated Ada County.
  • Lot coverage — Lot-coverage rules in unincorporated Ada County.
  • Building height — Building-height rules in unincorporated Ada County.
  • Off-grid sanitation — Off-grid sanitation systems in Ada County.
3 more unanswered
  • Agricultural exemption
  • Building in a floodplain
  • Short-term rentals

Each answer was extracted from an official source and independently re-checked against that source by a second reviewer. That is an evidence check, not legal advice. Rules change; confirm with the authority before you buy or build.

Water rights & wells in Ada County

Whether a new home can legally get its own water here — the sub-state groundwater regime, from Idaho’s water agency.

Over-appropriated / declining

The aquifer here is over-appropriated and declining. A domestic well is usually still permit-exempt, but long-term supply is a genuine risk.

Household wellExempt — no permit or water right

Groundwater for domestic purposes up to 13,000 gpd is exempt from permitting; critical-area and moratorium closures generally target new PERMITTED (non-exempt) appropriations, so a household can still drill a domestic-exempt well even inside a critical groundwater area.

Limit: 13,000 gpd (homes, stockwater, irrigation of ≤0.5 acre) under Idaho Code 42-227

Idaho Dept of Water Resources — Domestic Exemption ↗

Prior-appropriation state (first in time, first in right). Groundwater rules change and basin boundaries follow the aquifer, not the county line — confirm current well and appropriation rules with the Idaho state water agency before you buy or drill.Groundwater governance as of Jul 2026, cited to each administering agency.

Living off-grid in Ada County, Idaho

Is Ada County a good place to live off-grid or homestead?

Ada County scores 39/100 on the Bolthole Index, a marginal county profile. Its strengths: a stronger property-autonomy legal backdrop and elevated mid-century heat, water, rain, or wildfire exposure. Watch-outs: weak self-sufficiency basics: only 12″ of rain a year and about 357,241 people within a 30-minute drive.

Do you need a building permit in Ada County, Idaho?

Ada County generally requires a residential building permit, and it enforces county zoning. Onsite septic is permitted by Central District Health (Ada & Boise Counties). Owner-builders may act as their own contractor to build their home. These answers are quoted from official sources and independently re-checked. Rules change and cities within the county differ — always confirm with the county before you buy or build.

Can you live in an RV or tiny home on your land in Ada County?

Living in an RV on your own land in Ada County is limited to specific cases: Parking of recreational vehicles on streets in residential areas within unincorporated Ada County. A recreational vehicle may not be parked on a residential street for more than two hours, except that motor homes, travel trailers, and camp trailers may be parked for up to 72 hours. The 72-hour limit applies whether or not the recreational vehicle is attached to a motorized vehicle. Confirm with the county before relying on it.

How much does land cost in Ada County, Idaho?

Land in Ada County runs about $13,084 per acre, based on the latest county data.

What is the water situation in Ada County?

Ada County gets about 12" of rain a year, with severe drought in roughly 6.7% of years. On water rights, Ada County lies in the Cinder Cone Butte Critical Ground Water Area — Mountain Home Plateau; designated critical (1981); new permitted groundwater appropriations not allowed; domestic-exempt wells excepted..

How remote is Ada County?

A representative private-land location has about 357,241 people within a 30-minute drive and 924,493 within two hours. The road-network catchments count population across county lines and clusters of smaller cities; straight-line radius values remain available as a comparison.

How Ada compares in Idaho

Compare side-by-side →See all 44 Idaho counties ranked →