HABU pathway glossary

What is an accessory dwelling unit (ADU)?

An ADU is an additional home on the same property as an existing or proposed primary home. It may be attached, detached, or created within existing space, depending on the property and the rules that apply.

How to use this definition

Use it to understand the pathway named in your HABU report. A screen can identify a reason to investigate; only project-specific local and professional review can validate a development plan.

What this pathway means for a homeowner

What it could lead to

An ADU could create more living space, a long-term rental, or a home for family. Owners often evaluate two separate financial lenses: the contribution an ADU may make to a future sale price and the net rental income it may produce while the property is held. Neither lens is a guaranteed return.

What HABU screens

HABU uses available parcel, jurisdiction, zoning, site-constraint, market, and cost inputs to flag whether an ADU path appears worth closer study. It evaluates the stated preliminary unit program and shows a screening-level net-outcome range.

What still needs professional and local review

The local planning and building agencies and a qualified project team still need to confirm the allowed unit type and size, setbacks, access, fire and utility requirements, sewer or septic capacity, title conditions, and physical fit. Appraisal, rent, financing, insurance, and tax assumptions also need their own professional review.

Screening disclaimer: HABU does not determine legal eligibility or guarantee approval, physical fit, cost, rent, value, financing, timing, or return. Do not spend money or commit to a project based only on a screen; obtain local-agency and qualified professional review.

Questions about Accessory dwelling unit (ADU)

Does an ADU estimate assume I will sell or rent?

A useful screen keeps those as separate lenses. A resale scenario estimates a possible contribution to property value, while an income scenario considers market rent and project costs. Your report should identify which evidence supports the range.

Does an ADU screen confirm there is room to build?

No. Parcel records and map layers can identify obvious constraints, but a designer or other qualified professional must confirm dimensions, access, utilities, easements, and a buildable layout on site.

Why might 750 square feet and 800 square feet both appear in an ADU review?

They address different rules. Under current California law, a unit at or below 750 square feet can receive favorable treatment for certain local impact fees, while 800 square feet is important to the state protected-size standard. Neither number waives every permit, school, utility, or project charge, so HABU prices only the stated program until the local fee schedule and site are reviewed.

Check the source and compare pathways

Read the state source, then compare the other pathway definitions before treating one option as the answer for your property.

Authoritative source

California HCD: Accessory Dwelling Units

Ready for a property-specific screen?
Start with the available parcel data, then validate any promising path.
Run the Sacramento ADU screen