How much does construction cost?

Construction costs (also called “hard costs”) for your ADU will vary significantly depending on personal preferences, site conditions, location, and many other factors. Hard costs typically total around 85% of your total project budget. 

See the Budgeting and Finance page for more details and visit our Stories to see real-world cost examples for ADUs built in San Mateo County. Also check out our ADU Calculator to create a construction cost estimate based on your location.