Make sure the proposed space is actually a JADU.
Confirm that the proposed space fits the current state definition and City process before calling it a JADU. Size, location within the residence, facilities, and other conditions distinguish it from an attached ADU.
Bring a sketch of the existing bedrooms, bathrooms, kitchen, halls, exterior doors, and any area proposed for shared use.
Map every room the work will touch.
Map the rooms and systems that will change. A JADU may affect hallways, bedrooms, kitchens, bathrooms, laundry, storage, ventilation, electrical work, plumbing, and the way the main household moves through the home.
Because the project sits inside the house, small plan changes can move plumbing or electrical work into another room. Follow the route before approving the layout.
Plan for two households under one roof.
Discuss privacy honestly. Entries, locks, sound, mail, deliveries, outdoor access, and shared facilities should work for the actual occupants rather than only satisfying a diagram.
Talk through locks, sound, laundry, mail, storage, and outdoor access with the future occupants. Privacy is easier to plan than to add after construction.
Check the current rules at the time of design.
Ask the City and qualified advisers about current owner-occupancy, deed restriction, rental, and permitting questions for the specific proposal. Website summaries can become outdated as California law changes.
Price the work inside the existing home.
A contractor proposal should name the existing-condition work, protection, system modifications, finish scope, inspections, and restoration. Compare that complete work with other ADU choices.
If a JADU may fit the household, gather the existing floor plan and mark the shared and private areas. Call (949) 503-8004 or compare the attached ADU construction.
Where to confirm information about a junior ADU.
A junior ADU should be checked against current City and state pages; record the address, drawing, and date covered by the answer. For a junior ADU, check the City of Costa Mesa ADU page, California HCD, and CSLB hiring guidance. For a junior ADU, our Costa Mesa ADU Contractor homepage shows how it connects with the rest of the project.