Serving the Bay Area
ADU Construction in Concord, CA: Add a Legal Unit Without the Guesswork
Bayside Home Builders handles permits, design, and build for accessory dwelling units in Concord, so you get a finished, rent-ready unit without the contractor shuffle.
adu project · ConcordConcord Lots Have the Space. Getting the ADU Built Is the Hard Part.
Concord's postwar ranch neighborhoods were built for single families, not for adding a second unit. The lots are often wide enough, but the path from idea to finished ADU involves utility upgrades, permit submittals, subcontractor coordination, and a construction timeline that most homeowners underestimate.
What you are living with
Homeowners who try to piece the project together, hiring a separate designer, then a permit expediter, then a general contractor, often find that nobody owns the full process. Delays stack up between handoffs, costs climb past initial quotes, and the project drags on while the lot sits empty. Concord's free pre-approved plans can help on design cost, but they still require a contractor who knows how to execute on your specific site conditions.
What you get instead
We run the full project as one team. We assess your lot, handle design or adapt a pre-approved plan to your site, pull the permits, and build. One contract, one point of contact, and a budget built around what your property actually needs, not a generic starting number.
Our Recent Work
Accessory Dwelling Units Built to Code, Start to Finish
An ADU adds a fully independent living space to your property, a detached backyard cottage, an attached unit, or a converted garage. We handle every piece of it: design, permits, foundation, framing, MEP rough-ins, finishes, and final inspection. One contractor accountable for the whole project.
Site Assessment and Feasibility Review
Before you spend money on drawings, we walk the property, check setbacks, utility access, and lot coverage limits so you know what is actually buildable on your specific parcel.
Custom Design and Construction Documents
Our in-house design team produces permit-ready architectural and structural drawings sized to your lot and matched to your goals, whether that is a rental unit, space for family, or a home office.
Permit Procurement
We prepare and submit the full permit package and manage agency responses, corrections, and resubmittals. You do not have to track down planners or decode comment letters.
Foundation and Structural Work
Depending on the ADU type, this means a new concrete foundation, reinforced slab, or engineered upgrades to an existing structure. All work is inspected and documented.
Full MEP Systems
Electrical panel upgrade or sub-panel, new plumbing supply and waste lines, HVAC or mini-split installation, and smoke and CO detection, all pulled under separate trade permits and signed off by inspectors.
Interior Finishes and Final Inspection
Kitchen, bath, flooring, doors, and trim completed to a livable, rentable standard. We walk the unit with the building inspector and hand you a passed final inspection card before we close out the job.
Why Homeowners Choose Bayside Home Builders for Their ADU
A lot of contractors will frame an ADU. Fewer can carry it from raw dirt to a certificate of occupancy without the homeowner having to manage three separate companies. Here is what sets our process apart.
Licensed Design-Build Under One Roof
We are a CA CSLB licensed, bonded, and insured contractor with in-house design staff. Your architect and your builder are on the same team from day one, which eliminates the finger-pointing that derails projects when design and construction are separate contracts.
Permit Experience Across Multiple Jurisdictions
ADU permit requirements vary significantly from one municipality to the next. We have worked through the planning and building departments in multiple cities and know how to prepare packages that move through review without unnecessary back-and-forth.
Family-Owned with Direct Superintendent Oversight
As a family-owned company, the people who sold you the project are the same people managing it in the field. You reach a decision-maker directly, not a call center, when you have a question mid-construction.
Transparent Scope Before You Sign
We provide a written scope of work that breaks out site work, structural, MEP, and finishes so you know what is included and what would constitute a change order. Vague contracts are the leading cause of ADU budget overruns.
What our clients say
We recently had our kitchen remodeled by Bayside Home Improvement, and overall, we’re really happy with how everything turned out. The kitchen looks completely refreshed, and the space is much more pleasing to walk into. The team was professional…
I had the pleasure of working with Samuel on my kitchen and home remodel and I am thrilled about how it came out. His team was great in getting the designs together and listening to our ideas and interests. We went with an open layout design which…
How an ADU Project Works With Us
ADUs involve more moving parts than a typical remodel. Here is the honest sequence of how we take a project from your first call to a finished, permitted unit.
Step 1: Site Visit and Feasibility Conversation
We schedule a visit to your property, review your parcel data, discuss what type of ADU fits your goals and your lot constraints, and give you a realistic picture of timeline and process before any money changes hands.
Step 2: Design, Pricing, and Contract
We produce a design that meets local zoning and building code requirements and prepare a fixed-scope proposal. Once you approve the design and sign the contract, we finalize construction documents and submit for permits.
Step 3: Permit Processing and Pre-Construction
We manage the permit queue and respond to any agency comments. While permits are in review, we lock in subcontractors and order long-lead materials so construction starts without delay once approvals are in hand.
Step 4: Construction, Inspections, and Closeout
We build to the approved plans with all required inspections scheduled and passed at each phase. At completion, we walk the unit with you, address any punch list items, and hand over your certificate of occupancy and all warranty documentation.
What Adu Costs
Concord ADU pricing depends on your lot, your existing structure, and which build path fits your property.
Attached ADU
Converting or adding living space within the existing footprint.
Garage conversion
Turning an existing garage into a permitted dwelling.
Detached DADU
A standalone backyard cottage, built to code and permitted.
Concord is one of the few Bay Area cities that offers free pre-approved ADU plans, which can cut design costs and speed up permit issuance if a standard floor plan works for your site. If you want a custom layout, plan for a standard City of Concord building department review cycle instead. Older Concord housing stock, ranch homes and postwar tract houses in particular, often needs electrical panel upgrades and foundation work that affects budget more than the ADU structure itself.
ADU Contractors Serving Concord, CA
Concord sits in Contra Costa County with a mix of postwar ranch homes and larger lots that often make good candidates for a detached backyard ADU. The city has also moved to offer free pre-approved ADU plans and an ADU rebate program, which can cut your upfront design and permit costs if the right plan fits your lot. We build ADUs across the Bay Area and serve Concord homeowners looking for a licensed design-build team who handles permits, construction, and finishes under one contract.
Permits & review
Concord follows California state ADU law and allows most single-family lots to add one detached ADU plus one Junior ADU. The city offers free standardized pre-approved ADU plans, which can speed up permit issuance and eliminate some design fees if a standard plan works for your site. Custom plans take longer and cost more, but give you more control over layout and finishes. Either way, you still need site-specific drawings for foundations, utilities, and setbacks. We prepare and submit your permit package and track it through the city's review process.
Housing stock
Much of Concord's single-family housing was built in the 1950s through 1980s, which means rear yards are often large enough for a detached unit, but the existing electrical panels, sewer laterals, and gas service may need upgrading to support a second dwelling. Garage conversions are also common here. Before committing to a budget, we walk your property and check utility capacity so the numbers you get reflect your actual site, not a best-case scenario.
Areas we serve
We serve Concord and the surrounding Contra Costa County communities. If your property is within reasonable distance of the Concord area, call us to confirm coverage before starting any planning.
Common questions
What does an ADU cost in Concord, California?
A detached ADU in Concord typically runs $200,000 to $400,000 depending on size, site conditions, and finishes. A garage conversion or attached ADU usually comes in lower, around $120,000 to $220,000, because you are reusing an existing structure. Prefab units are sometimes marketed as cheaper, but once you factor in site prep, foundation, utility connections, and permits, the savings are often smaller than the ads suggest. Get a line-item estimate so you can compare apples to apples.
Does Concord offer free pre-approved ADU plans, and should I use them?
Yes. The City of Concord offers free, standardized ADU plans through its pre-approved program, which can cut design costs and speed up permit issuance. That is a real benefit. The tradeoff is that the plans are fixed designs, so if your lot has unusual setbacks, slope, or utility placement, a pre-approved plan may need modifications anyway. We review whether a free city plan fits your site before you commit to it, so you do not spend time on a plan that will not work.
Can I get a $25,000 ADU grant in California?
CalHFA's ADU Grant Program has offered up to $40,000 in the past to cover predevelopment costs like plans, permits, and fees for income-qualified homeowners. Funding is limited and availability changes. Concord homeowners should check CalHFA's current program status and income limits before counting on this money. We can tell you what documentation lenders and grant programs typically ask for, but we do not administer the grants ourselves.
What are the real drawbacks of building an ADU?
The honest ones: upfront cost is significant and construction loans or HELOCs add carrying costs. Permitting in Contra Costa County adds time, typically 3 to 6 months before a shovel hits the ground. You will share your lot, utilities, and sometimes parking with a tenant or family member. If your property has a septic system, easements, or tight setbacks, costs go up. An ADU also adds assessed value to your property, which affects your property taxes.
What is the cheapest way to build an ADU in Concord?
A garage conversion is usually the lowest-cost path because the foundation and shell already exist. Junior ADUs carved out of existing living space are also cost-effective. Using Concord's free pre-approved plans can save $5,000 to $15,000 in design fees if the plan fits your site. The cheapest option is not always the fastest or the best fit for your lot, so it is worth a site review before deciding on a unit type.
How long does it take to build an ADU in Concord?
Plan for 12 to 18 months from the start of design to a finished, permitted unit. Concord's pre-approved plan program can shorten the permit phase. Construction itself on a standard detached ADU runs 4 to 6 months once permits are in hand. Site issues, utility upgrades, or design changes add time. Anyone promising you a completed ADU in 90 days is leaving something out.
How many ADUs can I build on my property in Concord?
Under current state law and Concord's local rules, most single-family lots can have one detached ADU and one Junior ADU, for a total of two units added to the property. Corner lots and larger parcels sometimes have more flexibility. Multifamily properties follow different rules. We do a zoning check on your specific parcel before quoting anything, because lot size, setbacks, and existing structures all affect what is actually buildable.
Keep exploring
Other services in Concord
Bathroom Remodeling→Kitchen Remodeling→Home Renovation→Home Addition→Home Builders→
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