How much did the ADU Cost to build?

Short answer: About $300K. Because cottage was built as an “owner builder,” and I and my amazing my dad (a licensed a general contractor for 35+ years) committed a ton of time to this project, I saved at least 100K. I’m very grateful for my Dad and his time.
I’ll probably write a post summarizing my 350+ row spreadsheet detailing every expense sometime in the future.

How long did it take to build?

From the time we officially paid for plans to the finished completion was two years (much of this was waiting on WC permitting) . The actual building process took almost almost exactly one year.
I kept an incredible log that details what was done every day of the project. I might publish it later if there’s interest.

Am I able to build an ADU?

The rules for building ADU's are regional to your area (State, county, city). That said, if you own a single family home in California, you can likely build an ADU, even if you think you don’t have space. Check out my Resources to learn more.

What would I do differently?

This should probably be a whole post, but I’d summarize into a few areas:

1. Minor tweaks to the plans

2. Pushed harder on Walnut creek with permitting and inspections

3. In wake of SB9, maybe I would have split my lot and built 2 houses

4. Work with a different HVAC subcontractor, he was awful

5. Had earlier conversations with my Neighbors, some of which were incredibly upset

6. In hindsight, maybe I should have taken out a loan, since interest rates were ~3% in 2021. I could have leveraged my money and invested the rest elsewhere.
   

What was the best and worst part of building the cottage?

The best parts were:

1. Spending time with my dad and learning to appreciate his knowledge, craft, and skill.

2. The sense of pride and accomplishment every time we passed a major hurdle (permitting, foundation and frame, final inspection), and especially when I look back at the finished product.

3. Sharing the cottage and the building process with other people who are curious about it.

The worst parts were:

1. Dealing with Walnut Creek permitting office and our inspector was the worst experience ever. My dad has never dealt with anything worse in his 35 years of building.

2. The financial stress of unplanned for skyrocketing expenses since I didn’t have a contract. The price of lumber and most building materials soared to an all time high in 2021 and quality labor was hard to find.

3. Living in a construction zone (torn up driveway turned into a mud pit when it rained) with a newborn baby and a very patient wife being pushed to her wit’s end. All this while working a full time job in tech and putting in 10-20 hours a week on the cottage definitely tested me.

Where can I learn more about building ADUs?

Check out my Resources page for everything I have compiled on ADU’s