Accessory Dwelling Unit Code Requirements

• Each unit must have its own HVAC system that meets heating requirements.
• Each unit must be able to control its own HVAC system.
• Units cannot share air transfer systems.

Important Notes:

• If converting an existing structure to an ADU, all existing fuel-fired equipment (like furnaces or water heaters) must have enough combustion air.
• Gas pipes must be sized correctly, and you might need to increase the size of the gas line depending on demand.

Both the ADU and the main house need proper plumbing systems:

Water Supply:

For shared water supply:

1. Each fixture must have a shut-off valve, or there must be a whole-house shut-off valve accessible to both units.
2. New constructions must have a control valve accessible for each unit.
3. Shared water heaters must have individual shut offs.
4. The water supply line might need to be larger if adding more fixtures.

Sewer:

1. If the ADU’s floor is lower than the next upstream manhole cover, a backwater valve is needed for each new plumbing fixture. NOTE: if you are unsure if your ADU floor is lower than the next upstream manhole cover it is recommended to consult a design professional or licensed plumber to help make this determination.
2. For basement conversions, the drain piping above the backflow protection level must connect to the building sewer downstream from the new basement fixtures.
3. Backwater valves must be accessible for maintenance.

Important Note:

For detached ADUs, the water supply and sewer systems must be separate from other buildings and not installed under them. Building sewers must be at least 5 feet away from any other building. If rerouting is impractical, an application for an Alternate Means and Methods may be needed.

Occupant Designation:

• Drawings for ADU permits must clearly label rooms to show who will occupy the space (e.g., ADU Tenant, Primary Dwelling).

Attached ADUs:

• Dwellings must be separated by walls and floors with at least a one-hour fire-resistance rating.
• New construction and remodels must comply with the Oregon Residential Specialty Code for two-family dwellings.
• Doors between units must be fire-resistant, self-closing, and smoke gasketed.
• Smoke alarms must be upgraded to meet the current Oregon Residential Specialty Code.  

Detached ADUs:

• There must be at least 6 feet of separation between units unless exceptions apply.
• Smoke alarms must be updated to meet the Oregon Residential Specialty Code.