ADU Recommendations - prefab?


We are looking to add space via an ADU. Anyone have recommendations on a successful addition. Specifically, we’ve been attracted to the idea of a prefab ADU but have heard the point of friction is the installer. 

Would appreciate hearing recommendations and thoughts on the process. 
Thank you!

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We built an ADU after we found out that both of our jobs would be fully remote forever.  I highly recommend working with Inspired ADU  Carrie and her time are so helpful through the whole process and they have a large range of floor plans to choose from.  Our only regret was not going with the contractor they recommended.  We chose the cheapest bid and have had to manage the entire project ourselves. Inspired also offers a prefab version. 

Good luck!


Sorry to say that our ADU project wasn't successful, but we did extensively explore the prefab option and found that it didn't work with Berkeley city codes. We asked the manufacturer about moving a window that we knew the city wouldn't allow us to have and they told us it wasn't possible to make the change. We also found the actual installation costs to be much higher than advertised when we started contacting local companies. For our situation the structure would have needed to be craned into our yard and the actual cost was about 10x what the manufacturer estimated. I will also say that the process of building/getting plans approved is very long. It took us 9 months to get a property survey and it cost about $6500. The city has fees upon fees that didn't make a lot of sense to us. Be prepared to make adjustments. The good news is that the city tries to fast track ADU projects so the approval process might be shorter than a standard addition. 


We used a company called Type Five ( and are so happy with the outcome. They put it up in a few weeks and it looks great and matches our house! Aleksis, the co-founder, is wonderful and has been in the space for many years! Check them out!  


We sort of did this. Pick your gc very very carefully. If they lack online reviews, beware. If possible, you want to talk to someone who built and used an Adu they’ve built before. Did they do the electrical correctly? How did they handle the permitting process? Any surprises? These are all questions I wish I asked a former client instead of the gc, who I would never recommend


We didn’t do prefab, but here are my thoughts nonetheless. 

1. Would absolutely do it again

2. If you plan to rent it at all, ever, join BPOA 

3. It will end up costing more than you’d anticipated

4. Your property taxes *will* go up (this question is asked periodically here)

5. I wouldn’t recommend the contractor we used (who I understand does prefab now) but won’t mention their name here - just look at all reviews, everywhere (including Facebook) 

6. A fairly stressful process, but worth it in the end

Good luck!