First and most importantly, ask if you city has a handout for additions or new construction. Many cities who have made the time to put together their own ordinances have compiled a handout for you. This will list many important requirements. If they do not have a handout or some information is not clear be sure to ask:
Are the utilities required to go underground?
Are fire sprinklers required? (This is generally more for larger metropolitan areas)
What are the permitting fees? Such as plan check fees or school fees – this last one is usually a surprise to people when they first build and this fee can be quite significant.
Is there a design review for your area? Sometimes there are additional fees for this process but the architect or designer will be responsible for more drawings and meetings so they will charge a fee for this additional service.
Are utility upgrades required? When adding plumbing fixtures or a fire sprinkler system you might be required to upgrade the pipe from the cities main water pipe to your home.
Also, be sure you ask the city general questions about what you want to do to see if it is allowed in your area. Ask if there are restrictions on number of bedrooms, if there is a minimum car space requirement. All this should be listed in your general handout if your city has additional requirements.
Many times general information can be obtained from city websites. Your project address will need to be asked about specifically in case in falls into a specific city plan or if it has restrictions.
An architect or designer can go to the city and retrieve this information for you and in general they will want to ask some of their own questions also. But having the information up front will keep you informed.