The British spelling is “storey”
The American spelling is “story”
When you are talking about the level of a house, in Canada, it’s “storey”. The Canadian spelling recognized as correct at the present time in universities is “storey”. American spellings are oftentimes shorter.
However, if we go back a bit historically, you will find that both spellings were correct around Shakespeare’s time. Then again, no one knew how to spell anything, since most people were illiterate.
Brian Madigan LL.B., Broker