How much does an ADU cost?
Our starting prices run from $129,000 for a 300 sq ft studio to $320,000 for a 1,200 sq ft three-bedroom, including our standard finishes. Plans, permits and utility connections are quoted after a site visit because they depend on your property and city. Try the calculator.
How big can my ADU be?
In California, a detached ADU can be up to 1,200 sq ft where local rules allow, and cities must allow at least 800 sq ft. Attached ADUs can be up to 50% of your home’s size, with at least 850 to 1,000 sq ft allowed. Check your property.
How long does it take?
Most projects take about 8 to 14 months from first visit to move-in: design 1 to 2 months, permits 2 to 4 months, and construction 4 to 6 months. See our process.
What’s included as standard?
9-foot ceilings, plywood-box cabinets with real wood doors, quartz countertops, fully tiled bathrooms, and concealed mini-split heating and cooling with no wall-mounted units. Upgrades are available.
Do you handle permits and design?
Yes. Core handles design, engineering, permits, utility applications and construction as one design-build team.
Can I rent out my ADU?
Yes. ADUs can be rented long-term. Many cities don’t allow ADUs to be rented for less than 30 days, so short-term rentals depend on where you live.
Do I have to live on the property?
Not for an ADU. California no longer requires owner occupancy for ADUs. Junior ADUs are different: the owner must live in the main home or the junior ADU.
Will my property taxes go up?
Only the value the ADU adds is assessed. Your main home is not reassessed because you built an ADU.
Are there impact fees?
ADUs under 750 sq ft pay no impact fees under state law. Larger ADUs can be charged fees proportional to the size of your home. Permit and plan-check fees still apply.
Can I sell the ADU separately?
Generally no. An ADU is sold along with the main home, except in cities that have adopted rules allowing ADUs to be sold separately as condominiums.
Will an ADU need its own utility meters?
Not always. Many ADUs share water, sewer and electrical service with the main home, while others need new service. We look at this on the site visit and include it in your estimate.
Can you change one of your plans?
Yes. Plans can be flipped, stretched or rearranged to fit your lot, and we also design fully custom ADUs.
Ready to see what fits your lot?
Book a free site visit. We’ll check what your property allows and give you a full estimate, including plans, permits and utility connections.