Second story on a half house

Hi All
Weighing up a few options for home.
Currently live in art deco half house in Malvern area in Melbourne. Was thinking of selling and buying larger home in same area but house prices are very expensive now and associated buying/selling associated costs would likely be over $100k. We then thought that perhaps it may be worth considering building a second story to the home instead.

Does anyone have any experience on building a second story on a half house? Not sure if it ends up being very expensive to re-enforce bottom and how much space we can fit up there once heritage frontage is maintained etc...

Any thoughts or insights would be appreciated. Where is a good place to start research?

Sorry for basic question but hoping others have some experience too. thanks