Pre ADU Questions - Talk to an appraiser or contractor first?

[Kevin King]

Hey guys, 

I'm looking to build an ADU in the back of my primary residence in LA. I don't have any real life experience with building or developing, so excuse my lack of knowledge.

Before I build of course, I want to make sure it's worth it - I want to make sure the cash flow and equity will be worth the investment. 

Should I talk to a contractor first to see what it would cost, or an appraiser to see what they would think it would add in value to the home? 

And does anyone know anyone or recommend an ADU contractor or appraiser in my area (90031).

Or if there are any reliable "coaches" I can consult with on the matter. 

I hope I'm asking the right questions :)

Thanks!