Junior ADU construction inside a Fullerton home.

01 · Program fit

Begin with the rules and the household plan.

Confirm the current state and City definition, allowed size, required facilities, owner-occupancy rules when applicable, and where the unit sits within the home.

Then test whether the space can provide a workable entrance, bathroom arrangement, food-preparation area, storage, daylight, and privacy.

02 · Existing house

Opening walls can reveal the real scope.

Framing direction, plumbing locations, electrical capacity, heating and cooling, ventilation, insulation, windows, and prior alterations affect the work.

Plans and permit records help establish a baseline. Selective investigation may still be needed when the existing construction is unclear.

03 · Occupied construction

Protect the rest of the home.

The scope should address dust containment, temporary access, noise, work hours, security, and planned interruptions to water or power.

A clear sequence is especially important when the household remains in place throughout the conversion.

04 · Compare options

A JADU works only when it fits the household.

Some owners value the smaller footprint and use of existing space. Others need greater independence, more rooms, or a separate backyard building.

Compare the impact on the main home, cost categories, privacy, long-term use, and construction disruption before choosing.

Continue the research

Use the next guide when the question changes.

These pages cover the parts of a Fullerton ADU job that connect directly to this topic.