Guide
What homeowners need to know.
Ask what they actually do
Design, plans, permitting, engineering, prefab package, construction, and project management are different jobs.
Demand comparable scope
A lower bid with missing utility work is not a bargain. It is a future argument.
Match the city and ADU type
A provider good at prefab detached units may not be the right choice for a garage conversion in a tricky city.
Cost table
Use ranges until scope is real.
| Item | Planning range | Why it moves |
|---|---|---|
| Feasibility-first path | $1k-$5k+ | Good when budget and lot constraints are unclear. |
| Permit-plan path | $15k-$45k+ | Good before asking for construction bids. |
| Construction-ready bids | Project-specific | Only compare after scope is comparable. |
Mistakes
Avoid these expensive shortcuts.
- Hiring based on a cheap early number.
- Not asking who handles city comments.
- Ignoring utility and site-work exclusions.
- Treating fake badges or unverified rankings as evidence.
FAQ
Fast answers.
How many ADU builders should I compare?
Compare two to four serious fits after feasibility and scope are clear. Calling ten builders with vague requirements wastes everyone's time.
Sources