As for the extension, consult an architect about the specific zoning rules in your town. Different Nassau towns have different zoning/regulations.
Lynn Pisani GRI, PSC, CBR
Prudential Douglas Elliman Real Estate/Garden City
Your question may sound easy and straight forward but actually can get very complicated. The answers given below are all correct and incorrect at the same time. Without knowing your local zoning, size of your property, legal status of your property(legal vs. non-conforming) what you intend to put in the addition and who you intend to put in the addition there is no way of accurately answering your question. As an appraiser I have seen many times, additions that were done without the advice of a true expert and the problems created. I urge you to speak to an architect familiar with the zoning and building codes for the Town of Hempstead instead of in this venue.
You can do some of the research yourself online. Go to the Town of Hempstead website and look up the zoning regulations. Before you do this you will need to know what your area zoning category is. I believe Levittown is LPRD but call the Town's real estate department to make sure. The zoning map is not on line.
Once you know your zoning you can look up the requirements for that designation. However as I mentioned earlier this can be complicated. You may not know all the questions that require an answer.
Your best bet is to make an appointment with a building department representative, tell him what you want to do and get the correct answers. Or you can consult a local architect and have all your questions answered by him if you are uncomfortable speaking with a Town official.
Century21 Yve R.E.
Licensed R.E. Agent
NYS Certified Residential Appraiser
It is your house you can have anyone living in you wish.
If you are putting in a second kitchen in your Single Family Residence then you have to file for a Mother/Daughter permit (for family members living together) or if you are a Senior Citizen you can file for an accesory apartment and rent to whomever you choose.