ADU Design & Permitting in Montclair - Plans, Permits & Build, One Fixed Price

Fast, Reliable ADU Design & Permitting Across Montclair

ADU design and permitting in Montclair, CA typically runs $8,500-$18,000 for the full design-build package, drawings through final inspection, with most garage conversion ADUs permitted in 90-120 days. We’re Ellery ADU Studio Ontario, and our crews serve Montclair from our Inland Empire office, dispatching to the Pomona Valley with the same written pricing and documented process we’ve used on 900-plus ADUs since 2015. Call (951) 577-3472 to schedule your free estimate.

Call (951) 577-3472

Why Ellery ADU Studio Ontario Is Montclair’s Preferred ADU Design & Permitting Company

Montclair homeowners know the difference between a contractor who treats ADU permitting as paperwork and one who treats the permit set as the product. We’ve built our reputation in this city by documenting every finding, pricing every allowance in writing before work starts, and backing the finished ADU with our 365-Day Done Right Promise.

Our Montclair clients leave reviews that mention specifics: the photo record they received after each site visit, the written scope that didn’t change once signed, the permit that passed on first submittal. We don’t chase stars; we chase documentation that holds up in a city building department.

Response time to Montclair is same-day for site assessments scheduled through our Inland Empire dispatch. We know the Montclair Transcenter transit-stop boundary, the San Bernardino County fire setback overlays, and the difference between a 1958 ranch slab and a 1972 one when it comes to conversion viability.

Our ADU Design & Permitting team has walked enough Montclair side-driveway garages to know that the cosmetic quote and the permit-ready quote are rarely the same number. We tell you which one you’re getting.

Our ADU Design & Permitting Services in Montclair

Site Assessment

Every Montclair project starts with a site assessment that produces a documented photo record, not a verbal summary. On a typical 5,000-7,500 sq ft lot in the city’s post-WWII neighborhoods, we’re measuring setbacks to the inch, checking the garage’s original slab against current code, and mapping your address against the Montclair Transcenter half-mile transit-stop line. That line determines whether your ADU faces owner-occupancy and parking-replacement requirements, or skips them entirely. We find the 100-amp panels, the termite-damaged sill plates, and the slab edges wicking water from decades of failed waterproofing. You get photos of each finding and a written allowance for anything that affects the final price.

ADU Design & Blueprints

Our permit sets are drawn for Montclair’s specific conditions: garage conversions that must account for existing slab elevations, detached structures accessed from side driveways, and the 100°F-plus Pomona Valley summers that make mini-split HVAC sizing non-negotiable. We design for family-quarters privacy, not market-rate tenant appeal, because Montclair’s ADU demand is driven by multigenerational household need. Every set includes Title 24 energy compliance documentation, structural calculations for any framing sistering, and electrical load sheets that prove the panel can carry the ADU. No permit set leaves our studio without a named engineer’s stamp where required.

Permit Application

Montclair permits through San Bernardino County, and we’ve submitted enough sets to know the common kickbacks: incomplete Title 24 forms, missing fire-setback variances, and electrical load sheets that don’t account for the ADU’s full demand. We prepare the application package to pass on first review, including the transit-stop exemption documentation that eliminates owner-occupancy and parking requirements for qualifying addresses. Our permit application includes the full construction set, energy compliance, and any variance requests with supporting justification. We track submittal status and respond to corrections in writing, with copies to you.

HOA & Zoning Compliance

Montclair’s older neighborhoods include homeowners associations with CC&Rs written before ADUs were common. We review governing documents for ADU restrictions, parking requirements, and architectural review triggers that could delay your permit. For properties without HOA oversight, we verify zoning against the city’s general plan, checking lot coverage, height limits, and the rear-yard setback calculations that often kill detached new-construction ADUs on Montclair’s tight lots. Our zoning compliance report is included in every site assessment.

Title 24 Energy Compliance

Every Montclair ADU must meet California’s Title 24 energy standards, and garage conversions face particular scrutiny: existing walls must meet insulation requirements, windows must meet U-factor and SHGC limits, and HVAC must be properly sized and ducted. Window units do not comply. We specify ducted mini-split systems with HERS verification, size mechanical systems for the Pomona Valley’s 100°F-plus summer peaks, and document every envelope upgrade in the permit set. Our Title 24 compliance is included in the design fee, not billed as an add-on.

Trusted Brands We Service in Montclair

Ellery ADU Studio specifies and coordinates prefab and modular systems from Abodu, Cover, and Mighty Buildings within the same single-contract design-build model we use for site-built work. For Montclair’s tight lots where detached new-construction ADUs often fail setback math, these systems can make sense when delivered as panelized or modular garage replacements. We coordinate factory specifications with local foundation and utility connections, pulling permits and managing inspections under the same written price. Our crews are fluent in each manufacturer’s connection details, so the builder can’t blame the designer and the designer can’t blame the builder. One contract. One written price. One party responsible.

Common ADU Design & Permitting Problems We See in Montclair Homes

• The 100-amp panel that won’t carry the ADU load. Most Montclair garages from the 1950s-1970s were fed by the home’s original 100-amp service, adequate for a washer and a work light but not for a kitchen, bath, and mini-split. The permit forces the upgrade, and contractors who don’t inspect the panel before quoting leave clients with mid-project change orders.
• Termite-damaged sill plates on the shared stem wall. Our climate, with wet winters and dry summers, creates conditions where garage slab edges and stem walls deteriorate. Opening the walls for permit-required insulation often reveals framing that needs sistering or replacement, scoped and priced before we touch it.
• Failed waterproofing wicking moisture through the slab edge. Decades of splash-back from Montclair’s occasional heavy rains and irrigation runoff degrade garage slab edges. We find it during site assessment, document it with photos, and write the repair into the contract allowance.
• Window-unit HVAC that bakes occupants and fails inspection. Montclair’s 100°F-plus summers and significant diurnal temperature swings mean Title 24-compliant mini-split systems are mandatory, not optional. Contractors who skip proper mechanical sizing deliver ADUs that draw comfort complaints and fail final inspection.

Pricing for ADU Design & Permitting in Montclair, CA

We Also Serve Cities Near Montclair

Our crews work throughout the Pomona Valley and western San Bernardino County, including Montclair, Claremont, Ontario, Pomona, and La Verne. Each city has distinct zoning, setback, and transit-stop exemptions; we map every address individually rather than applying a regional template.

FAQs - ADU Design & Permitting in Montclair