ADU Construction in Meridian, ID: Costs, Ideas & Options

It depends on what your CC&Rs said when you bought. Under Idaho Code § 55-3212, as amended with Idaho's 2026 ADU law (Senate Bill 1354), an HOA cannot add, amend, or enforce anti-ADU restrictions without the owner's written consent — but restrictions that already applied when you purchased remain enforceable, and HOAs may still adopt reasonable size, height, setback, parking, and bedroom rules. Your HOA can also still regulate ADU design, placement, exterior materials, roofline compatibility, and other architectural standards — and those regulations are enforceable. In practice, most Meridian HOAs will approve a well-designed ADU that matches the primary home's architectural character but may reject a design that does not comply with their specific guidelines. Iron Crest reviews your CC&Rs and design guidelines as part of our initial ADU consultation and prepares architectural committee submissions designed to move through approval on first submission. If your HOA tries to enforce a restriction adopted after you bought, you have legal recourse under the statute — but the better outcome is a design that is approved without a dispute.

Meridian impact fees for a new ADU typically total $10,000–$18,000 depending on the unit's square footage and the specific fee categories applicable — transportation, water, sewer, fire, and parks. These fees are assessed per dwelling unit and are collected at the time of building permit issuance, before construction begins. They are not negotiable and cannot be reduced through project design choices, though the specific fee amount scales with ADU size. Iron Crest calculates the applicable impact fees for your specific project during the budgeting phase so there are no surprises at permit issuance. Omitting impact fees from an ADU quote is one of the most common ways contractors present misleading project costs in Meridian — always confirm whether the number you are comparing explicitly includes impact fees.

A full two-car garage conversion may create a parking deficiency under Meridian's current code (Ordinance 25-2102 requires ADU parking by bedroom count and allows a garage conversion only if the required parking is provided elsewhere — rules Idaho Code § 67-6541 overrides by February 1, 2027) and under your HOA's parking requirements. The most practical solution is a partial conversion — converting one bay of a two-car garage to the ADU while maintaining the other bay as a garage — which satisfies parking requirements while still creating a 300-to-400-square-foot ADU footprint. Alternatively, adding a paved parking pad in the side yard replaces the eliminated garage parking. Iron Crest assesses both the city code and HOA parking requirements for your specific lot as part of the pre-design review and designs conversions that satisfy both. This is a solvable constraint for most North Meridian properties — the specific solutions vary by site configuration and HOA guidelines.

A realistic Meridian ADU timeline must account for the HOA review layer, which is the most common source of schedule extension. For projects requiring HOA architectural committee approval — the majority of Meridian ADU projects — the total timeline from initial design to certificate of occupancy is typically 22–36 weeks. The HOA architectural review process alone takes 4–8 weeks, City of Meridian building permit review adds another 6–10 weeks after a complete application is submitted, and design and pre-permit preparation adds 4–6 weeks. Construction after permit issuance runs 10–16 weeks for a garage conversion and 14–22 weeks for a new detached unit. Projects that take significantly longer than expected are almost always delayed by HOA review complications — an initial denial requiring redesign, or a committee that meets infrequently. Iron Crest structures our Meridian ADU projects to move through the HOA process as efficiently as possible from the beginning.

We do not publish rent figures for Meridian, and you should be skeptical of any contractor who does. Rents move, they vary between subdivisions that are a mile apart, and a number in a marketing page is not something you can take to a lender or build a budget on. What we can tell you is which variables move it: bedroom count matters more in Meridian than in Boise because West Ada School District access is what drives family renter demand and families need two bedrooms; a private entrance, dedicated parking, and a full kitchen rather than a kitchenette separate a unit that competes with small homes from one that competes with apartments; and finish level shows up in both the rent and the turnover rate. The right way to get the number is a written rent opinion from a property manager who actively leases in your part of Meridian, on the specific configuration you are considering. Get that before you finalize the scope — it costs you nothing and it is the single input that most determines whether the project works.

Yes. ADU projects require building permits, plan review, and multiple inspections. In most Boise-area jurisdictions, ADUs also require zoning compliance review to confirm lot size, setbacks, and parking requirements are met. We handle the entire permitting process.

Most Boise ADUs cost $95,000–$320,000, with a typical project near $165,000. A garage conversion typically runs $95,000–$145,000, and a new 600 sq ft one-bedroom detached ADU $145,000–$220,000; utility connection costs vary with distance to existing services and are one of the most variable line items. Our 600 sq ft detached North End ADU ran $120,000–$150,000.

From start of design to move-in, a typical ADU project takes 6 to 12 months. This includes design (4-8 weeks), permitting (4-8 weeks), and construction (3-5 months). Garage conversions are faster; detached new construction takes longer.

In most Boise-area jurisdictions, yes. ADUs can be rented as long-term rentals. Short-term rental rules (Airbnb, VRBO) vary by city and may have additional restrictions. Check local regulations before planning a short-term rental strategy.

It depends on location, size, finish level, and market conditions — check current listings for comparable units. Our 600 sq ft North End one-bedroom ADU has a recorded rental potential of $1,400–$1,600 per month.

Maximum ADU size varies by jurisdiction. In Boise, an ADU can be up to 900 square feet or 70% of the primary structure's floor area, whichever is smaller, with no more than two bedrooms. Idaho's 2026 ADU law (Senate Bill 1354) requires every city over 10,000 residents to allow at least 1,000 square feet or 75% of the primary home by February 1, 2027, so local limits are changing. We confirm the specific rules for your property during the feasibility phase.

No. Idaho's 2026 ADU law (Senate Bill 1354, Idaho Code § 67-6541, in force since July 1, 2026) prohibits every city over 10,000 residents from requiring owner-occupancy of either the primary home or the ADU, so you can live in one unit and rent the other, or rent both. Boise had already dropped its owner-occupancy rule in the 2023 Modern Zoning Code. Cities of 10,000 or fewer residents (such as Emmett, Fruitland, Payette, Homedale, Parma, or New Plymouth) still set their own rules, and lenders or HOA covenants that existed when you bought may have their own conditions — we confirm all of it during the feasibility review.