Dilemma with an ADU Conversion

[Gadiel Del Orbe]

I own a Duplex in Los Angeles and I want to convert the back storage unit into an ADU. I'm planning to demolish the storage and build the ADU from the ground up. The ADU is going to end up being 552 sqft and a one-bedroom. I've never done anything like this before, but I'm looking to learn from this. My plan is get a home improvement loan and hire subcontractors myself. I'm afraid of spending too much money on this conversion, a contractor quoted me at 100,000 and it scared the living daylights out of me. I heard if I do it myself I would save half of that. Do you guys think this is a good idea? or should I hire a contractor to do the work?

How much does it cost to build an ADU? Also, do you know any home improvement lenders you could recommend me?