Facebook her? ...or wait?

Hey guys, so i was out tonight and spent some of the evening speaking to a lovely girl. The weird thing is she lives two houses down from me, has done for the last semester, but we have never met. Speaking tonight i wanted to ask her if she wanted to go out some time (I'm a firm believer of strike while the iron is hot) but once i had worked up the courage to ask her she had already left the club with her house mates. Talking to one of my friends, he knows her from lectures and is her facebook friend, he said to add her on facebook. However i don't really want to ask a girl out over facebook, i don't want to add her and ...become just a friend. I went a whole semester without meeting her so the chances of coincidentally meeting her again may not be in my favor. Should i add her and ask her out on facebook (seems a little fast and furious to me) add her and chat and get to know her? (seems like a single ticket to friendzone) Or this is what i was thinking, ask my mate to either give her my number, or ask her if she would be willing to let me have hers? what do you guy AND girls at TSR think? Girls, which would your preferred way be for a guy who knows you through friends to ask you out?

Put the internet to work for you. via Personal Recipe 2629979