Consider becoming an owner/builder for my project. Looking for tips.

[Raj Sidharthan]

Dear friends,
I am planning to build an ADU at my primary residence. I have an approved plan and I have been talking to general contractors. The price I am getting is way more than what I think the project should cost. I think that the markup that the general contractor takes is what makes the cost go up, so I am considering becoming an owner/builder to save some money.

Home improvement is not new to me. I own 5 properties and I have a lot of experience in hiring contractors for repairs and modifications. It's just that I have not done anything as big as this.

Any advice for becoming an owner/builder would be greatly appreciated. I dont know what I dont know :)
What should I get in terms of insurance?
How do you make sure that something that a contractor does meets the city's approval criteria. How would you write contracts in a way that I am covered against workmanship that the city does not approve, in case that happens.

Thanks in advance
Raj