Attached Garage Conversion in San Bernardino, CA

Attached Garage Conversion in San Bernardino, CA

Our Garage Conversion ADU services in San Bernardino turn the attached garage that shares a wall with your living space into a permitted unit – typically a studio or one-bedroom – without excavating new foundations or running utilities from scratch. Because the space is already connected to your home’s electrical, plumbing, and structural envelope, the path from permit application to certificate of occupancy is shorter and less expensive than building detached. At Ellery ADU Studio San Bernardino, we handle drawings, permitting, and construction under a single written contract at a single written price before any work begins – call us at (909) 359-6463 to start the conversation, or read on to understand exactly what this process looks like.

Attached conversions are one of the most cost-effective ADU strategies in San Bernardino County, but they require careful coordination with the City’s development code – particularly around fire separation between the ADU and the main dwelling, egress window placement, and the owner-occupancy rules that still apply in some zones. Our full approach is documented on the Garage Conversion ADU in San Bernardino parent page; this page focuses specifically on the attached variant and what makes it different.

Nadia Ellery founded Ellery ADU Studio in 2015, the year California’s ADU law started its first significant expansion, and the studio has since taken more than 900 projects from permit set to final inspection – every one with a written price before a single stud was moved.

When You Need Attached Garage Conversion

• You want rental income but can’t lose parking entirely. In San Bernardino neighborhoods like Muscoy and the areas near Cal State San Bernardino where street parking is already strained, converting an attached garage and relocating one parking space on the driveway pad is often the only configuration the City will approve. We model that scenario in the feasibility drawing before you commit.
• A family member needs to live close but independently. An attached conversion shares a wall – and sometimes a corridor door – with the main house, which makes it the right fit for a parent who wants proximity but their own kitchen and bathroom. The interior connection can remain (with a proper fire door) or be sealed, depending on how you want to use the space.
• Your lot is too narrow for a detached ADU. San Bernardino’s 4-foot rear and side setback requirements eliminate detached ADU options on many of the long, narrow lots common in the Inland Empire’s older subdivisions. An attached conversion uses the existing footprint and sidesteps the setback problem entirely.
• You bought after 2015 and the garage is already partially finished. A lot of San Bernardino homes sold between 2015 and 2022 had insulated garages with drywall on the interior walls. That existing work may or may not meet current Title 24 energy standards, but it does reduce demo scope. We assess what’s usable before pricing the project.
• You want to avoid the design-versus-builder blame gap. Most homeowners who have tried to run a separate architect and a separate contractor on an ADU project have experienced scope disputes – the architect drew something the contractor said they couldn’t build, and neither refunded anything. A single design-build contract at Ellery eliminates that gap: one entity is responsible for the drawings and the finished unit.
• You need a realistic number before you talk to a lender. ADU financing – whether a HELOC, a renovation loan, or an ADU-specific product – requires a documented scope and price. Our written quote satisfies that requirement, and we can provide the permit drawings to your lender as part of the package.

Our Attached Garage Conversion Process

1. Site Assessment and Feasibility Drawing

   We visit the property to assess Carport Conversion or garage conversion feasibility, measure the footprint, check slab thickness, locate the existing electrical panel and plumbing stub-outs, and assess the shared wall’s current fire-rating status. In San Bernardino, the California Residential Code requires a one-hour fire separation between an ADU and an attached garage that connects to habitable space – the assessment tells us how much of that assembly already exists. You receive a written feasibility summary with a preliminary cost range before we quote the full project.

2. Written Price and Contract Signing

   Under Haven Standard Clause 1, the written price is delivered before any design work begins. This is not an estimate range with a disclaimer at the bottom – it is a fixed-scope price tied to a specific drawing set. If site conditions during construction reveal something we could not reasonably have seen – hidden plumbing, a non-standard footing – we document it in writing and discuss the impact before any additional cost is incurred. No door-side upsells, no scope creep added after signing.

3. Permit-Ready Drawing Set

   Our in-house design team produces the architectural, structural, mechanical, electrical, and plumbing drawings the City of San Bernardino’s Development Services Department requires. We include the Title 24 energy compliance report and the CalGreen checklist, which are mandatory for ADU permits in California as of 2023. Because we have processed permits in San Bernardino consistently since 2015, we know which plan-check comments are likely and pre-empt most of them in the first submission. Fewer rounds of comments means faster permit issuance – typically several weeks faster than a first-time submitter working with a separate architect.

4. Permit Issuance and Pre-Construction Planning

   Once the City issues the permit, we schedule the project in a specific sequence: demo and any hazardous-material testing first, then framing, rough mechanicals, insulation, and drywall. For attached conversions in San Bernardino’s hotter inland climate, the insulation specification matters more than people expect. The Inland Empire regularly sees summer temperatures that push into the 110s in exposed garage spaces, and an R-19 wall assembly with radiant barrier decking on the shared roof section is not optional – it is the difference between a livable unit and a space that requires the HVAC to run continuously. We specify the assembly in the permit drawings so there is no ambiguity on the job site.

5. Construction, Inspections, and Photo Record

   Every site visit during construction is documented with a photo record – framing before drywall covers it, rough plumbing before walls close, electrical panel work before the cover goes back on. You receive this documentation as the project progresses, not as a post-completion summary. City inspections are coordinated by us; you do not need to be present at each one, though you’re welcome to. Our crews are background-checked and uniformed, and our license number appears on every project document.

6. Certificate of Occupancy and 365-Day Done Right Promise

   The project is not complete until the City issues the certificate of occupancy and we have walked the finished unit with you. If anything in the finished ADU does not match the permitted drawings – a window in the wrong location, a ceiling height that differs from the spec, a finish that was substituted without your approval – the 365-Day Done Right Promise requires us to correct it, in writing, before the project closes. That promise is documented in the contract at signing, not offered verbally after a problem surfaces.

Attached Garage Conversion Pricing in San Bernardino

Attached garage conversions in San Bernardino typically run between $95,000 and $195,000 all-in, covering drawings, permit fees, and construction through final inspection – see How Much Does Garage Conversion ADU Cost? (2026 Price Guide) - San Bernardino, CA for a detailed breakdown. That range is wide because the variables are real – here is what moves the number in each direction.

A few things that consistently push projects toward the higher end in San Bernardino specifically: garages built before 1980 often have thinner slabs – sometimes 3 inches rather than 4 – that need reinforcement before the finished floor goes down. Homes in the Verdemont area and on hillside parcels near the San Bernardino National Forest sometimes have non-standard soil conditions that require a geotechnical report before the City will accept the structural drawings. And older homes near downtown San Bernardino frequently have 100-amp service panels that need a full upgrade to support a modern ADU’s electrical load, including EV charging if you’re planning ahead.

Every project at Ellery is quoted with a written price before work begins – Haven Standard Clause 1. The price you sign is the price you pay unless a documented, agreed-upon change is added in writing. To get your written quote, call (909) 359-6463. There is a live person on the line, not a voicemail queue.

FAQs – Attached Garage Conversion

How long does an attached garage conversion take in San Bernardino, from signed contract to certificate of occupancy?

Most attached garage conversions at Ellery ADU Studio take 5 to 9 months from signed contract to certificate of occupancy in San Bernardino. The design and permit phase typically runs 8 to 14 weeks, depending on the City’s plan-check queue and how many revision rounds the drawings require. Construction on a straightforward conversion – existing slab, no panel upgrade – generally runs 10 to 16 weeks from permit issuance. Projects with significant plumbing work, a panel upgrade, or soil conditions that require a geotechnical report will sit at the longer end. We give you a project-specific timeline in writing before you sign, not a generic estimate pulled from a brochure. Call (909) 359-6463 to discuss your specific site and get a documented schedule.

Does the attached garage conversion require a separate entrance in San Bernardino?

Yes – California’s ADU law requires the unit to have an independent exterior entrance, and the City of San Bernardino enforces this requirement at plan check. The ADU cannot rely solely on access through the main house. An interior connecting door between the main residence and the ADU is permitted (and often useful for multigenerational setups), but it must be a solid-core fire door that meets the one-hour separation requirement between garage-adjacent spaces. We show both the exterior entrance location and the fire door assembly in the permit drawings, so the inspector knows exactly what to look for at each rough-framing visit. This is a point where projects submitted by less experienced applicants often get flagged – we’ve pre-empted it in the drawing set since at least 2018.

Can I keep one parking space if I convert my attached garage in San Bernardino?

In many cases, yes. California law eliminated the replacement parking requirement for ADU conversions within a half-mile of public transit, and parts of San Bernardino – particularly near the Metrolink station and along major bus corridors – qualify. Outside those corridors, the City may still require you to document at least one off-street parking space on the parcel. A tandem space in the driveway often satisfies that requirement. We check the specific transit proximity and zoning conditions for your address during the feasibility phase and document the parking determination in writing before the project is scoped. Do not assume the exemption applies until it’s been verified for your parcel – we’ve seen applicants in San Bernardino lose time resubmitting because they assumed transit proximity and the City disagreed.

Is an attached garage conversion cheaper than building a new detached ADU in San Bernardino?

Generally, yes – by a meaningful margin. A Detached Garage Conversion or new detached ADU in San Bernardino typically starts around $180,000 and can run past $320,000 for a two-bedroom unit with site prep, utilities from the street, and a new foundation. An attached conversion starts with an existing slab, existing utility connections, and an existing roof, which eliminates three of the largest cost line items. The trade-off is flexibility: a detached ADU can be larger, can be positioned differently on the lot, and doesn’t share mechanical systems with the main house. For homeowners whose primary goal is affordable rental income or a multigenerational suite, the attached conversion usually wins on economics. For homeowners who want maximum separation or a larger unit, a new detached build may be the right answer. Our feasibility process covers both options in the same written summary so you can compare them directly before deciding. Call (909) 359-6463 to get that comparison for your specific property.

Why San Bernardino Homeowners Work With Ellery ADU Studio

San Bernardino’s development landscape is specific in ways that matter at the permit counter. The City uses a different fee schedule than Riverside or Ontario. The heat load calculations for an ADU in the Inland Empire require more rigorous HVAC sizing than the same unit would in coastal Los Angeles. And the older housing stock in neighborhoods like Muscoy, Del Rosa, and the Historic District means more pre-existing conditions – aging panels, shallow slabs, galvanized plumbing – that a less experienced design-build team will price optimistically and then change-order later.

Since 2015, Ellery ADU Studio has built its process around eliminating exactly that problem. The permit set is the core product. The written price comes before any work starts. The 365-Day Done Right Promise is documented in the contract, not mentioned in a sales conversation. And if you already have a written estimate from another firm, our Free Second Opinion will tell you what that estimate includes, what it likely excludes, and how it compares to what a full-scope, permit-ready project actually costs in San Bernardino today.

For homeowners researching the broader category, our home page covers the full range of ADU services Ellery offers in San Bernardino and the surrounding Inland Empire.

To get a written price for your attached garage conversion, call (909) 359-6463. A live person answers – no voicemail, no callback queue. If you want to understand the full scope of garage conversion options before you decide, the Garage Conversion ADU in San Bernardino page is the right next read.

Written by Nadia Ellery, Owner at Ellery ADU Studio San Bernardino, serving San Bernardino since 2015.