It's ages since I did this but if you save it as a Sims3pack it should be in your Exports file.
A good way to share lots, and it's the way we do it on another site I am on, is to save it to your library (the bin). Make note of the time that you do it, then check your Library folder and sort it by date. The file that corresponds to the time you saved your house (or the top one) should be your house. Make a copy, rename it to whatever you want to call it, and then you can share it knowing that it will not include any custom or store content that may have crept into your house. When the person downloads it, they just put it into their library folder. It makes a much smaller file than a Sims3pack and is perfectly safe.