Prefab or site-built ADU?
Compare the installed, permitted project rather than the factory price against a contractor’s complete bid.
Compare equal scope
- For prefab, ask whether the quote includes foundation, delivery, crane placement, utility hookups, permits and final inspections.
- For site-built, identify site access, material storage, weather exposure and trade scheduling.
- Confirm which design changes are possible, their lead times and their effect on price.
Check delivery before ordering
- Measure street access, turning space, overhead lines and the route to the foundation.
- Ask the supplier and installer to verify crane setup and delivery permissions.
- Confirm storage costs and responsibility if the site or foundation is not ready on the delivery date.
Confirm approvals and handoff
- Ask the city which approvals apply to the specific construction system and site.
- Identify who resolves damage or defects at the factory/installer boundary.
- Get one written list of exclusions and an accountable contact for the finished project.
Turn the checklist into a project plan
Record each open question, the person responsible, evidence needed and target date. Confirm requirements with the city and your licensed design/build professionals.
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Planning guidance. Requirements depend on the property, design and adopted local codes; this guide does not certify compliance. How our guidance is prepared