Meridian accessory dwelling unit (ADU) rules under the UDC — where ADUs are permitted, maximum size, setbacks, parking, and owner-occupancy requirements.
ADU rules evolve. Verify at the City of Meridian Planning Division before permitting.
Applicable code
Code references active as of publication. Verify current standards at the official source before any development decision.
Accessory dwelling units are permitted as an accessory use in R-4, R-8, R-15, R-40, and TN-O (Old Town) zoning districts, subject to district-specific standards.
Investor implication: ADUs are NOT permitted in R-2 (estate residential) districts. Most master-planned communities (Paramount, Bridgetower) sit in R-4 but carry HOA covenants that prohibit ADUs regardless of zoning allowance.
Verify at Meridian Unified Development Code →An ADU shall not exceed 900 square feet or 50% of the gross floor area of the primary dwelling, whichever is less.
Investor implication: On a 1,600 sq ft primary dwelling, the ADU caps at 800 sq ft (50% rule). On a 2,000+ sq ft primary, the ADU caps at 900 sq ft (absolute maximum).
Verify at Meridian Unified Development Code →In R-2 and R-4 districts, either the primary dwelling or the ADU must be owner-occupied. In R-8, R-15, R-40, and TN-O districts, owner-occupancy is not required.
Investor implication: Out-of-state investors cannot rent both units in R-4 districts (Paramount, Bridgetower, most suburban Meridian). Downtown Meridian (TN-O) and R-8+ districts allow dual rental.
Verify at Meridian Unified Development Code →ADUs must meet the same setback requirements as the primary dwelling for the applicable zoning district, unless the ADU is located above an existing detached garage, in which case the existing garage setbacks apply.
Investor implication: Detached ADUs require full district setbacks (typically 5–10 feet side, 20–25 feet rear in R-4). Garage conversions or above-garage ADUs can use existing nonconforming setbacks.
Verify at Meridian Unified Development Code →One off-street parking space is required for the ADU, in addition to the parking required for the primary dwelling.
Investor implication: ADU adds one parking space requirement. On-street parking does not satisfy this requirement. Driveway expansion or garage conversion must accommodate the additional space.
Verify at Meridian Unified Development Code →Cities with populations over 10,000 must allow at least one ADU per single-family lot. Cities may not impose owner-occupancy requirements or blanket square-footage bans. HOAs may not adopt NEW ADU restrictions without written consent of all members; existing restrictions remain enforceable.
Investor implication: Meridian's R-4 owner-occupancy requirement may be preempted by SB 1354 after July 1, 2026. Existing HOA ADU bans (Paramount, Bridgetower) remain enforceable. New subdivisions platted after July 1, 2026 cannot add ADU bans without unanimous consent.
Verify at Idaho Legislature SB 1354 →HOAs may not adopt NEW ADU restrictions without written consent of all members. Existing restrictions remain enforceable.
Investor implication: Paramount and Bridgetower ADU bans are existing restrictions. SB 1354 does not invalidate them.
Verify at Idaho Legislature SB 1354 →One off-street parking space is required for the ADU.
Investor implication: Driveway expansion or garage conversion must accommodate the additional parking space.
Verify at Meridian Unified Development Code →An ADU shall not exceed 900 square feet or 50% of the gross floor area of the primary dwelling, whichever is less.
Investor implication: Primary dwelling size determines ADU size cap on smaller homes.
Verify at Meridian Unified Development Code →Renew analysis