Boise ADU permit requirements
Last reviewed: June 22, 2026
Quick answer
Permitting an accessory dwelling unit (ADU) in Boise, Idaho means pulling a building permit from the local authority that issues it. ArchPermit tracks 15 source-cited requirements (11 required, the rest conditional) for this jurisdiction. Submittals go through Accela Citizen Access (Planning) + PDS Online ePlanReview (building). These requirements were last reviewed June 22, 2026; confirm the exact forms and fees with the local permitting authority.
A source-cited checklist of what an ADU (accessory dwelling unit) permit package needs in City of Boise. Every item links to its authoritative source; items that vary are flagged to confirm locally.
ADUs are a permitted / by-right use (Modern Zoning Code Table 11-03.1 marks ADU 'A*' = Allowed subject to use-specific standards, NOT conditional) in R-1A/R-1B/R-1C/R-2/R-3/MX-1/MX-2/MX-3/MX-U/A-1/A-2. Current standards (§ 11-03-03.2.B, eff Dec 1 2023): ≤900 sf or 70% of the primary building, whichever smaller; ≤2 bedrooms; ≤2 stories; one ADU per lot. There is NO owner-occupancy requirement and NO neighbor-notification under the current code (the 2019 700-sf / owner-occupancy ordinance is superseded). The process is two-track: begin a Planning (PLN) case in Accela for administrative zoning review, then submit the building-permit package.
- ACCA Report (Manual J)required
Required for any heating/cooling system serving a new ADU.
source · reviewed 2026-06-22 - Building Elevations (Planning, to scale)required
All external materials/colors with % of each material per façade; scale + height callouts.
source · reviewed 2026-06-22 - Building Floor Plans (existing & proposed)required
Room uses, window/door size & type, hard-wired interconnected smoke/CO detectors, fixtures (~¼"=1').
source · reviewed 2026-06-22 - Building Permit Site Planrequired
Existing + proposed structures, decks/driveways, dimensions/distances to property lines, lot dimensions per recorded plat, easements (scale ~1"=10' or ⅛"=1').
source · reviewed 2026-06-22 - Detailed Landscape Planrequired
Existing/proposed plant materials & ground cover; existing trees with species/caliper/condition + mitigation; structure footprints (may combine with the site plan).
source · reviewed 2026-06-22 - Detailed Site Plan (Planning)required
Title block; scale + north arrow; parcel size; property lines + setbacks; all structures with size & use; ROW/easements/drainage; adjacent sidewalks.
source · reviewed 2026-06-22 - Fire Flow Information Letterrequired
City form: contact Veolia re: adjacent hydrants and water volume (allow 5 to 7 days).
source · reviewed 2026-06-22 - Floor Plans (Planning, to scale)required
Labeled, dimensioned rooms + total gross square-footage calc.
source · reviewed 2026-06-22 - Planning Application + Letter of Explanationrequired
Completed planning (PLN) application for the ADU plus a detailed letter of explanation (scope, design intent, approval findings per § 11-05-05.2).
source · reviewed 2026-06-22 - Site Photosrequired
Colored, labeled photos of the site and surrounding area.
source · reviewed 2026-06-22 - Statement of Legal Interestrequired
City form completed and signed by the legal owner of record.
source · reviewed 2026-06-22 - Building Envelope Energy Code Complianceconditional
REScheck / ERI / Simulated Performance report, or prescriptive info shown in the section views.
source · reviewed 2026-06-22 - Certificate of Appropriateness (Historic District)conditional
Required prior to the ADU application if the property is in a Historic District.
source · reviewed 2026-06-22 - Foundation, Framing & Section Viewsconditional
Foundation plan, floor/roof framing plans (joists/trusses/beams + wall bracing), and a footing-to-roof wall cross-section, for a detached/new ADU.
source · reviewed 2026-06-22 - Stamped Structural Calculationsconditional
An Idaho-licensed-engineer stamp for non-prescriptive framing/bracing, beams, tall/retaining walls, or Hillside footings.
source · reviewed 2026-06-22
Boise ADU permit questions
- Do I need a permit to build an ADU in Boise?
- Yes. An accessory dwelling unit (ADU) in Boise requires a building permit. ArchPermit tracks 15 cited requirements for this jurisdiction (11 required, the rest conditional). Always confirm the exact forms, fees, and code edition with the local permitting authority that issues the permit.
- What does an ADU permit package require in Boise?
- Core required items include: ACCA Report (Manual J); Building Elevations (Planning, to scale); Building Floor Plans (existing & proposed); Building Permit Site Plan; Detailed Landscape Plan; Detailed Site Plan (Planning), plus 5 more. Each requirement links to its authoritative source, and nothing is permit-ready until an independent licensed professional reviews and seals it.
- How are ADU permits submitted in Boise?
- Boise accepts permit submittals via Accela Citizen Access (Planning) + PDS Online ePlanReview (building). ArchPermit prepares a draft package you can submit there after a licensed architect reviews and seals it.