Home · Process & costs
How an ADU project worksProcess, costs and California rules
Five stages, one team. Each stage has an owner, a clear deliverable and a pricing logic you understand before you commit.
Five stages, one team
Feasibility check (free)
We review your address, zoning and lot, then tell you clearly what is possible and what it involves.
Owner: Struct Builders · FreeDesign and budget
Layout, scope and phases, with the firm price written into your contract before construction.
You approve the design and pricePermits
We prepare and submit the package and respond to plan-check comments until approval.
Owner: Struct BuildersConstruction
One site team, regular updates and quality checks at key stages.
Single point of contactInspection and handover
Final inspection, documentation and the keys to your new space.
Walkthrough togetherStructure over improvisation
Compliance and regulation
Zoning, local rules, permit requirements and structural constraints are reviewed early to avoid delays and redesigns.
Documentation and transparency
Clear records and regular updates keep you, the city and the site team aligned at every step.
Risk management and accountability
Risks are identified early, constraints anticipated and responsibilities assigned clearly.
Standards, partners and oversight
We work with vetted professionals and keep oversight so the work stays aligned with your goals.
What drives the cost of an ADU
Six factors explain most of the difference between two ADU budgets. You get a realistic estimate after the free visit, and the firm price is written into your contract before construction starts.
Size and layout
Square footage, number of rooms and the complexity of the floor plan.
ADU type
Detached, garage conversion, junior ADU or second story each carry different work.
Site access
How easily crews and materials can reach the build area.
Utilities
Distance and capacity of water, sewer, gas and electrical connections.
Foundation and structure
Soil, slope and the condition of any existing structure.
Finishes
Cabinetry, flooring, fixtures and appliances, from essential to premium.
These factors help you plan; only a visit gives a realistic estimate for your property.
California ADU rules, in plain English
State law sets limits cities cannot exceed (California Government Code §§ 66310–66342 and the HCD ADU guidance). Local Los Angeles rules can add detail within those limits, so we check every address individually.
| Topic | What the state sets |
|---|---|
| Side and rear setbacks | A city cannot require more than 4 ft for a new ADU. |
| Minimum allowable size | Local limits cannot go below 850 sq ft, or 1,000 sq ft for more than one bedroom. |
| Impact fees | ADUs under 750 sq ft and all junior ADUs are exempt; larger ADUs are charged in proportion to the main home. |
| Parking | At most one space per unit; none for conversions of existing space, near transit or in historic districts; no replacement parking when a garage is converted. |
| Junior ADU | Up to 500 sq ft, within an existing or proposed single-family home, one per lot. |
Summary for information only, current as of 2026. Rules change; your feasibility check confirms what applies to your lot.
Process questions
What happens during the feasibility check?
We review your address, zoning, lot size, utilities, easements and hazard zones, then tell you which ADU types fit and what the next step is. It is free and without obligation.
When do I get a price?
A realistic estimate after the free visit, and a firm price written into your contract before construction starts.
Who submits the permits?
We prepare and submit the package, handle plan-check comments and schedule inspections.
What are the biggest cost drivers?
Size, ADU type, site access, utilities, foundation and structure, and finishes.
Do state rules override local rules?
State law sets limits cities cannot exceed, such as the 4 ft setback cap. Local rules still apply within those limits, which is why every address is checked.
Find out what your lot can hold.
Send your address. We check zoning and site constraints and reply with a clear next step.
Serving homeowners across Los Angeles
Los Angeles, the South Bay and Orange County, within about 40 miles of Paramount. Farther on request.
ADU rules, city by city
Permits, fire and coastal zones, pre-approved plans: see what applies in the 36 cities we serve.