Symbium
Checks permit eligibility and helps homeowners, contractors and cities prepare code-compliant applications.
Order is editorial. Descriptions come from each company's own website, last checked October 2026. A listing is not an endorsement. How we work.
Maxable
ADU plans, designs and education, including a free ADU starter kit.
Casita Coalition
Nonprofit that advocates for ADUs and other small-scale housing.
Hello Housing
Nonprofit housing organization that designs ADU programs and other missing-middle housing strategies.
No matches. Try another filter.
Is this your company? Correct or update your listing.
Read before you call
All guides →
Costs
Five real ADU projects, broken down line by line
A public housing agency built five ADUs and published every cost. Here is what they paid for permits, surveys, design and construction.
3 min read · 2 sources
Design and build
JADU, attached or detached
A junior unit inside your house costs a fraction of a backyard cottage. Here is what each type allows and what it gives up.
3 min read · 3 sources
Rules and permits
How long ADU permits really take
State deadlines say 60 days in California. Real projects take longer. Here is what to expect and how to keep yours moving.
3 min read · 4 sourcesNewsletter
The Backyard Letter
One short email when we publish something new: a guide, a rule change in your state, or a public cost report worth reading. Every item links to its source. Free, unsubscribe any time.