Meridian ADU Feasibility Study

ADU Rules in Meridian (2026)

Meridian's ADU rules differ meaningfully from Boise's — the size cap is higher, parking IS required, and there's no free pre-approved plans program. The rules below reflect DSC's institutional knowledge from completed Meridian projects. Because Meridian's Unified Development Code is updated regularly, your free DSC feasibility study verifies the current rules for your specific property.

Size and Dimensional Standards

• Detached ADU max: typically ≤ 1,200 sq ft OR ≤ 50% of primary dwelling floor area (verify current code for your specific zone)
• Setbacks (typical): Front 20 ft, Side 5 ft, Rear 12 ft — varies by zone
• Allowed zones: R-2, R-4, R-8, R-15, R-40, TN-C, TN-R

Sources: Meridian Unified Development Code (Title 11), City of Meridian Planning.

Parking — Required in Meridian

1 off-street parking space is required per ADU in most Meridian residential zones. This is a key difference from Boise, which has no ADU parking requirement. The space must be on the same property as the ADU and meet Meridian's dimensional requirements for parking.

Your feasibility study confirms how the parking requirement applies to your lot and identifies whether existing site features (driveways, alley access) can satisfy it without expanding paved area.

Number Per Lot

1 ADU per lot. Verify the current code with the City of Meridian Planning division — ADU rules across the Treasure Valley are evolving and Meridian's UDC has been amended multiple times in recent years.

Owner-Occupancy

Meridian's current owner-occupancy rules vary by zone and have been updated in recent years. Your feasibility study confirms whether owner-occupancy applies to your specific zoning district.

Impact Fees

Meridian properties are within ACHD's service area. ACHD increased impact fees as of March 1, 2026 under Ordinance No. 254. ADU impact fees went up by approximately 68%. Plus City of Meridian permit fees and utility connection charges. Your feasibility study itemizes everything that applies.

What Affects the Cost of a Meridian ADU

ADU costs vary widely from project to project — sometimes by a factor of two or three on the same lot size. Rather than publish a generic dollar range that may or may not apply to your property, DSC delivers a specific cost range as part of your free, property-specific feasibility study. Below are the factors that drive that number up or down.

• ADU type and configuration. Detached, attached, above-garage, and garage-conversion ADUs each have different cost structures.
• Existing utility capacity. Often the single largest cost variable. Newer Meridian neighborhoods generally have more capacity than older ones, but every property is different.
• Site topography and soil conditions. Sloped lots add foundation, grading, and drainage cost.
• Finish level. Cabinet selections, countertops, flooring, lighting, fixtures, and trim move the number meaningfully.
• Structural complexity. Two-story ADUs and above-garage configurations cost more than single-story slab-on-grade.
• Required parking space construction. Meridian's parking requirement means budgeting for the additional paved area or carport — a cost item Boise projects don't carry.
• Permit, impact fee, and utility connection costs. City of Meridian permits, ACHD impact fees (up ~68% as of March 2026), and utility connection charges are real budget items separate from construction.

A Note on Pre-Approved ADU Plans

Unlike the City of Boise (which released 8 free pre-approved ADU plans in 2026), Meridian does not currently offer a free pre-approved ADU plans program. Meridian ADU projects require full custom architectural and engineering design.

If you're looking for cost-saving design options in Meridian, DSC offers our own library of efficient ADU designs developed over multiple completed projects — ask about it in your feasibility study.

How Long Does It Take to Build an ADU in Meridian?

Custom design path

• DSC feasibility study: 2–3 days
• Site review, 3D modeling, design contract: 2–4 weeks
• Design diligence, finish selection, structural engineering: 4–6 weeks
• Administrative planning review: 1–2 weeks
• Building permit review: 4–6 weeks
• Construction: 4–7 months
• Total: 7–12 months

Meridian's ADU permitting process is straightforward compared to Boise's HD-O properties — no historic overlay considerations to add time. DSC's design-build process compresses both timelines through milestone-driven scheduling.

Frequently Asked Questions — Meridian ADUs

Recent DSC ADU Projects

The ADU projects below are DSC builds with their owners' actual Google reviews. While these specific projects were Boise-area, the same DSC team, design-build process, and quality standards apply to every Meridian ADU build.

Brookman ADU (Fully Custom)

"Almost a full year, from concept to finished project, and it was all so worth it! It was a very collaborative process, and I'm so happy with my new space. It was especially great to know I was helping support so many small businesses, and families. Derek and all the subs were like extended family."

— Helen Brookman (Google review, 1 year ago)

View the Brookman ADU project →

Swift ADU

"Nothing but good things to share about Derek Sammons Construction. My wife and I originally met with him to discuss an ADU build on the back of our property. Derek was on time, professional, and used state of the art software to create renderings of the vision with video animation. Once we gave the go ahead, Derek handled all of the permitting and construction process and communicated often where we were at in the build. The end result was nothing short of amazing. The quality craftsmanship and close attention to detail were evident everywhere you look."

— Bryan Swift (Google review)

Majors ADU

"We used Derek Sammons for a backyard Accessory Dwelling build and we cannot recommend him enough. We worked closely with DSC during the entire process. From a complete demolition of our garage to creating a layout that worked with us, all while being honest and aware of our budget."

— Corey Majors (Google review)

Ullman ADU

"Derek did a fantastic job of managing our ADU build. He was professional, organized, and made sure that everything went smoothly. He used Builder Trend to keep everything organized, which was great for us to keep track as things moved along. I would highly recommend!"

— Shannon Ullman (Google review)

Four projects, one DSC process — applied identically to Meridian builds. The full set of DSC reviews is on our Google Business Profile — 5.0 stars across 11 reviews.