How long do Zebra Finches live?

I rescued 2 zebra finches that were kept in a fish tank with no perches and strong stench in the back of a pitch black closet. One of them has no feathers on the back of his head or neck - will they grow back? I was trying to find them a home but figured they will be safer with me and have all the necessities they need. I really don't have the room for them but after what they've been through it's hard to give them up. I wanted to know how long they live so i know how long my husband will be agitated by the continuous chirping - lol. Thank you for your time.