You may only need a structural engineer ($1200), and not an architect($2500+), which could you save you some money. A good structural engineer can draw up the plan views for the floorplan along with the elevation views for the foundation and stamp them. If you’re the home owner, the DCRA home center will help you figure out what you need. I drew up the electrical and plumbing for my work, using a couple of books I bought from home depot. It’s rather easy. You may just need a licensed electrician and plumber to do the work. You’ll probably need a structural engineer for the underpinning anyway, b/c I don’t know any architects who can stamp that type of work. I could be wrong though… my wife tells me it happens. I think otherwise. Good luck!!