Currently, our home has a main floor and basement. I've noticed a few people adding a second floor to older homes.

While it makes sense to add a floor instead of buying another home, I wonder how easy this is when the home is an older Victorian.

Would a second floor require the foundation be extended? How long does it take to add another floor?

If the foundation can't be extended, due to property line limits, is there a way to fram the support for the second floor with a new outer wall, encasing the original first floor?

You're going to need to start with an architect and a structural engineer. Then you will need permits and a reputable contractor. Also, you may need to plan to live somewhere else for a while when they tear the roof off your house.

The permit process is very long, so don't do anything until you have a green light from the city. You don't want a cease and desist order while this is going on and you don't want a city inspector to come by later and put the brakes on your project.

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Tommy Bahama 

Good advice, do not take a project like this lightly. You need to make sure you have the right people for the job.