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requirement and NO neighbor-notification under the current code (the 2019 700-sf / owner-occupancy ordinance is superseded).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 5–7 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