Any designer or draftsman can take care of it.
A structural engineer might need to be involved also.
Let me know if you need any help with this
Where is the property? Different cities and Counties have unique requirements.
Identify where you property is (Santa Clara County Pockeck, City of San Jose etc..) and head over to their planning department. They will be more than happy to go over the requirements with you.
City of San Jose is good to get back to you by phone.
If you have little time it is better to asked a general contractor to do it for you. Most have tons of experience
saving you lots of time.