What is an in-law suite?
An in-law suite is an attached ADU: an addition joined to your house that works as a separate home, with its own entrance, kitchen and bathroom. It keeps a parent, adult child or caregiver close while giving both households a door that locks.
Is an in-law suite an ADU in Jacksonville?
It is when it is a complete unit. A bedroom and bath added to the house without a kitchen is simply an addition. Once it has its own kitchen and entry, it is reviewed as an ADU under the city's 2022 rules, including the requirement that the owner live on the property and the cap of one ADU per lot.
How big can it be?
The 2022 ordinance was reported to limit an ADU's footprint to 25% of the main home's gross floor area or 750 sq ft, whichever is less, and to keep it no taller than the main house. How that footprint is measured for an attached unit is a detail we confirm with the Zoning Section before design.
What changes when the addition joins the house?
- Roof tie-in. The new roof must connect to the old one and meet current wind design.
- Fire separation. A rated wall or floor between the two units.
- Utilities. Shared or separate service; we size the electrical panel for both.
- Flood rules. On a lot in a special flood hazard area, if the addition's cost reaches 50% of the house's market value, the whole house may have to meet current flood standards. We check that threshold before you commit.
Is an in-law suite cheaper than a backyard ADU?
Sometimes. It shares a wall, a foundation edge and sometimes utilities with the house, which can save money. It can also cost more if the existing roof, panel or flood status forces upgrades to the main home. It depends on the house, and we price both when both fit.
Related
As of October 2026. Sources: reporting on City of Jacksonville Ordinance 2022-0448; FEMA substantial improvement rules.