House Addition

I am looking for someone to draft plans to submit to the county to add about 17 feet or so onto the back of my two story home in Placer County California (just a continuation of the existing roof line). The addition would add two bathrooms and a closet on the second floor (basically creating two master bathrooms since we currently just have one bathroom upstairs). The space on the first floor would be a storage/exercise/multi-purpose room and would likely only be accessible from the outside. Our house was built in 1920 and is on a raised foundation, but I would probably like to pour a cement slab for the addition.