Design, permits and construction managed by one accountable team
Build a custom accessory dwelling unit around your property, budget and reason for adding space. Eco Home Builders manages the process from the first site evaluation and floor plan through permitting, construction and final walkthrough.
Trust strip
- ✓California General Building Contractor License #1074166
- ✓Full-service design-build process
- ✓Project communication and documentation in Buildertrend
- ✓300+ five-star reviews across Google, Yelp and Houzz
- ✓BBB Accredited with an A+ rating
A San Diego ADU should start with the property—and the purpose
An ADU intended for rental income should not be planned the same way as a home for aging parents, an independent space for an adult child or a private guest suite. The purpose affects the entrance, bedroom count, privacy, storage, accessibility, sound separation, utility strategy, finishes and total investment.
The property matters just as much. Two lots with similar square footage can have very different possibilities because of setbacks, slope, access, easements, utility locations, coastal restrictions, fire requirements or the condition of an existing garage.
That is why our process starts with feasibility, not a generic floor plan or an unrealistic price based only on square footage. We first work to understand what can be built, what it will take to build it and whether the plan supports your goals.
Eco Home Builders is a San Diego ADU contractor and design-build company serving homeowners who want one team to coordinate the major parts of an ADU project: property evaluation, design, plans, permitting and construction.
Whether you are comparing ADU companies in San Diego for a backyard rental unit or looking for a design-build team to handle full ADU construction from permits through move-in, the property evaluation is where every accurate plan and price starts.
CTA: Tell Us About Your Property
ADU options we can evaluate for your property
The right ADU type depends on your available space, existing structures, privacy needs and budget.
Detached ADUs
A detached ADU is a separate backyard residence with its own living area, kitchen, bathroom and entrance. It can provide the greatest privacy for tenants or family members and gives you more freedom to design the unit around its intended use.
Detached construction may also require more site work, utility trenching, foundation work and planning for access between the street and the build area. Early evaluation is especially important on sloped lots, tight urban properties and sites with limited equipment access.
Attached ADUs
An attached ADU connects to the primary home while functioning as an independent residence. It may be a strong option when the yard cannot comfortably accommodate a separate structure or when extending the existing building creates a better layout.
The design needs to account for how the new and existing structures connect, including rooflines, foundations, utilities, privacy, sound and the flow around the property.
Garage conversion ADUs
Converting an existing garage may allow you to use space that is already part of the property. However, a garage is not automatically ready to become a legal dwelling.
The slab, foundation, ceiling height, framing, waterproofing, ventilation, insulation, windows, fire separation, electrical capacity, plumbing route and sewer connection all need to be evaluated. A conversion can be efficient when the existing structure is suitable, but assumptions made before inspection can lead to major budget changes later.
Above-garage and second-story ADUs
Building above a garage or adding a second level can preserve more of the yard, but it introduces structural, engineering, access and construction-complexity questions. We evaluate whether the existing structure can support the concept or whether substantial reinforcement or rebuilding would be required.
Interior conversions and JADUs
In some homes, existing interior space may be converted into an ADU or junior ADU. These options are highly property-specific and may involve different size, kitchen, owner-occupancy and access requirements. We can help determine which path is worth exploring before design begins.
What do you want the ADU to accomplish?
Create a long-term rental
For a rental-focused ADU, we consider privacy from the main home, a practical bedroom count, durable materials, storage, laundry, utility access and a layout that uses every square foot efficiently. We do not project or guarantee rental income; homeowners should evaluate rents, financing, taxes and operating expenses independently.
Build for parents or multigenerational living
An ADU for a parent may need fewer barriers, comfortable circulation, a step-free entrance, an accessible bathroom layout and close proximity to the main home without giving up independence. Planning these features during design is more effective than trying to add them after construction.
Give adult children an independent home
A private entrance, usable kitchen, laundry, sound separation and enough storage can make the space feel like a real home rather than a temporary room behind the house.
Add flexible space for changing needs
Some owners want a guest suite, office or future living space. If the project is intended to qualify as an ADU, it still needs to be designed, permitted and built as a legal independent dwelling—not simply finished as an extra room.
Is your San Diego property a good fit for an ADU?
Online zoning maps and standard plans can provide a starting point, but they do not show every condition that can affect feasibility or cost. Before recommending a direction, the project team may need to review:
- ✓Property jurisdiction and zoning
- ✓Lot size, shape and usable building area
- ✓Setbacks and separation from existing structures
- ✓Easements and recorded property constraints
- ✓Slope, grading, drainage and retaining conditions
- ✓Street-to-yard construction access
- ✓Existing garage condition, when applicable
- ✓Electrical service and potential panel upgrades
- ✓Water, sewer and gas routing
- ✓Fire access and applicable fire-safety requirements
- ✓Coastal, historic or other overlay zones
- ✓Parking requirements or available exemptions
- ✓Solar and current energy-code requirements
- ✓The location and condition of the primary home
San Diego County contains multiple cities and unincorporated communities, each with its own review process and local standards layered over California ADU law. A property in the City of San Diego may not follow the same local path as a property in Carlsbad, Encinitas, Del Mar or Oceanside.
Our job during early planning is to identify the issues that could change the design, budget or schedule before construction starts.
CTA: Request an ADU Property Review
Our San Diego ADU design-build process
1Initial phone consultation
We start with the property address, your goals, desired size, intended use, budget expectations and timing. This gives both sides a clear picture of the project before scheduling the next step.
2Property meeting and site review
We walk the property to look at the proposed ADU location, access, slope, existing structures and visible utility conditions. If you are considering a garage conversion, we also review the existing space and discuss the investigations that may be needed.
3Feasibility and concept planning
The team evaluates the concept against the property and applicable requirements. We discuss possible ADU types, layout priorities and the major conditions likely to influence cost. The goal is to select a direction that works for the homeowner and can realistically move into design.
4Architectural design and engineering
The selected concept is developed into plans. Depending on the project, the plan set may require architectural drawings, structural engineering, energy documentation and other technical work needed for permit submittal. Our ADU architect and engineering partners work directly with the construction team rather than handing off a finished set with no context.
Design and construction decisions are coordinated early so the plans do not develop in isolation from the build.
5Permit preparation and plan check
We prepare and coordinate the permit-submittal process for the agreed scope. The reviewing agency may issue corrections or request additional information; those comments are addressed until the permit can be issued.
Permit timing is controlled by the jurisdiction and may also be affected by project complexity, outside-agency approvals and the completeness of required information.
6Preconstruction and selections
Before work begins, we align the construction scope, schedule, material selections, site logistics and project documentation. Early decisions help reduce avoidable interruptions once crews are working on the property.
7ADU construction
Construction may include site preparation, foundation, framing, roofing, windows and doors, rough plumbing, electrical, HVAC, insulation, drywall, cabinetry, tile, flooring, fixtures, finish work and required inspections. The exact sequence depends on the ADU type and site.
Project information, photos, schedules and documented decisions are organized in Buildertrend so there is one place to follow the job rather than relying on scattered text messages.
8Final inspections and walkthrough
The project moves through the required final inspections. We then complete the final walkthrough, address agreed completion items and turn over the finished space.
How much does it cost to build an ADU in San Diego?
Construction typically runs $375–$600 per square foot, plus design fees of $8,000–$25,000 and permit costs of $6,000–$20,000 depending on jurisdiction. These are general ranges, not a quote — every property is different, and the real driver of where you land is the property itself, not a square-footage formula.
The largest cost drivers usually include:
- ✓Detached construction versus an attached or conversion ADU
- ✓Total size, bedroom count and number of bathrooms
- ✓Site access, demolition, grading and foundation conditions
- ✓Distance to sewer, water and electrical connections
- ✓Electrical service or panel-upgrade requirements
- ✓Structural reinforcement for conversions or second-story units
- ✓Roof design and connection to the existing home
- ✓Window, door, cabinet, countertop, tile and fixture selections
- ✓Energy, solar and fire-code requirements
- ✓Permit, plan-check, engineering and consultant costs
- ✓Coastal or other location-specific review
We use the early design and feasibility phase to replace assumptions with a property-specific scope. Before signing a construction agreement, homeowners should understand what is included, what is excluded, which selections are allowances and which site conditions could require additional work.
For the full breakdown by size, what drives the range, and a permit-fee walkthrough for the City of San Diego specifically, see our complete ADU cost guide for San Diego.
How long does an ADU project take?
An ADU schedule has three major parts: design and engineering, permit review and construction. The total timeline depends on the jurisdiction, project type, correction cycles, owner decisions, utility coordination, site conditions and inspection availability.
A detached custom ADU generally involves more ground-up work than an interior conversion, while a second-story ADU can require additional structural design and a more complex build sequence. Coastal or technically difficult properties may need additional review.
We establish the project schedule after the scope and permitting path are better understood. Buildertrend is used during the construction stage to keep the working schedule and project updates documented.
Why homeowners choose Eco Home Builders
One team, not six separate hires
A typical ADU project means coordinating an architect, a structural engineer, an interior designer, a permit expediter, a general contractor and a project manager — six different relationships and six different places for something to fall through the cracks. Eco bundles architectural design, engineering coordination, permit management, interior design and construction into one team and one point of contact.
A licensed San Diego ADU contractor
Eco Home Builders holds California General Building Contractor License #1074166 and is licensed and insured for ADU construction throughout San Diego County.
Documented project communication
Schedules, project photos and decisions are organized in Buildertrend. Important information has a defined place instead of being spread across individual calls and text-message threads.
A record homeowners can review
Eco Home Builders has more than 300 five-star reviews across Google, Yelp and Houzz and is BBB Accredited with an A+ rating.
Design that reflects the ADU’s real use
The layout is developed around who will live there and how the unit needs to perform—not around a one-size-fits-all rendering.
What to compare when interviewing San Diego ADU contractors
An ADU is a complete residence, even when the footprint is small. Before choosing a contractor, ask each company:
- 1Who is responsible for feasibility, design, engineering, permits and construction?
- 2Is the contractor’s California license active and appropriate for the work?
- 3What exactly is included and excluded from the proposal?
- 4Are finish materials fixed, selected separately or carried as allowances?
- 5How are utility work, panel upgrades, grading and unforeseen site conditions handled?
- 6Who responds to plan-check corrections and coordinates inspections?
- 7How will schedules, photos, approvals and changes be documented?
- 8Can the contractor show completed projects and verified reviews?
- 9Does the agreement clearly explain change orders and payment milestones?
- 10Who remains accountable from the first design meeting through final inspection?
The lowest preliminary number is not always the lowest completed cost. A useful proposal should make the scope understandable enough to compare.
ADU construction across San Diego County
Eco Home Builders serves homeowners in San Diego and surrounding communities as an ADU builder in La Jolla, an ADU contractor in Carlsbad, and a design-build partner for ADU projects in Del Mar, Encinitas and Oceanside.
Because zoning, plan-check procedures and site conditions differ by address, every project begins with the property—not a generic countywide assumption.
San Diego ADU FAQs
What is an ADU?
An accessory dwelling unit is an independent residential unit located on the same property as a primary residence or residential building. Depending on the property and local rules, it may be detached, attached, created from existing space or built as a garage conversion. A junior ADU is a separate category with different requirements.
Can I build an ADU on my property?
Many California residential properties can accommodate an ADU, but the workable design is address-specific. Zoning, existing development, lot constraints, utilities, access, easements and overlay zones can all affect the plan. A property review is the best starting point.
How large can an ADU be in San Diego?
Size rules depend on the jurisdiction, property, ADU type and applicable state protections. In the City of San Diego, current guidance states that attached and detached ADUs may range from 150 to 1,200 square feet, subject to the complete rules and site conditions. Properties outside the City of San Diego must be checked under their local jurisdiction.
Do I need a permit for an ADU?
Yes. A legal ADU requires the applicable permits and inspections. The City of San Diego states that a building permit is required to create an ADU or JADU. Other approvals may apply depending on the address and project.
Can I convert my garage into an ADU?
Possibly. The first question is not only whether a conversion is allowed, but whether the existing garage can be upgraded into a safe, code-compliant residence at a sensible cost. The structure, slab, ceiling height, moisture conditions, utilities, fire separation, windows and parking implications should be reviewed before committing to the concept.
Will I need additional parking?
Parking rules and exemptions depend on the property, jurisdiction, ADU type and location. Do not assume parking is required—or exempt—without reviewing the current rules for the address.
Does an ADU need separate utilities?
The best utility approach depends on the project and local provider requirements. Water, sewer, electrical capacity, metering and gas or all-electric design should be evaluated early because utility work can materially affect the scope, schedule and cost.
Is an ADU better than a room addition?
They solve different needs. An ADU is designed as an independent dwelling with living, sleeping, cooking and sanitation facilities. A room addition expands the primary home. If privacy, independent living or long-term rental use is the goal, an ADU may be the better path. If the family simply needs a larger kitchen, bedroom or living area connected to the home, an addition may make more sense.
Do you handle ADU plans and permits?
Yes. Eco Home Builders offers a design-build process that coordinates feasibility, plans, permitting and construction for the agreed project scope.
Can you guarantee that my ADU will increase property value or produce rental income?
No contractor should guarantee a specific increase in value, rent or return. Those results depend on the property, market, financing, taxes, operating costs and final project. We focus on designing and building the agreed ADU; homeowners should review investment assumptions with qualified real estate, tax and financial professionals.
Start with an ADU property consultation
The first decision is not the cabinet color or the exterior style. It is whether the ADU concept fits the property, supports your goals and makes sense within the investment you are prepared to make.
Schedule a consultation with Eco Home Builders to discuss your San Diego property, the type of ADU you are considering and the next step toward design and construction. As an ADU construction company with dedicated ADU contractors on staff, we can walk you through what’s realistic for your property before you commit to a direction.
California General Building Contractor License #1074166
