Room Addition/Re-designing Business

I want to start a business adding rooms to a home, but most importantly specialize in designing "escape" rooms for people who want a get away inside their home. Sorta like man caves but it can have several different features

What do I need to do to get in business with this idea ?

How much will the initial start up cost be ?


I want to be the guy who designs the layouts, deal with the financial expenses and hire contractors to preform the work

Suggestions ?