I'm a primary teacher and really like one of me colleagues. Should i ask him out and risk it or stay friends?

We work in different year groups and we are both quite shy. I've seen he has a profile on match.com and dont have a clue if he is seeing anyone or not. I really like him but don't want to ruin our friendship or cause ripples at work. We get on very well and have been out for drinks on our own etc but I have never been able to pluck up the courage to ask him for a date. What should I do?