Habit for Humanity proof of volunteering?

If you volunteer on a construction site for Habitat for Humanity do you get any proof that you volunteered? I am asking because I am a construction management student and want to use it on my resume once I graduate since it represents service specific to my field. Are you given some sort of proof or is it just kind of on the honor system. I would like to be able to list the specific amount I have volunteered but if there isn't proof I would probably just have to say "volunteered for Habitat" right? Thanks for your help.