I have a 14 year old daughter that wets the bed. One of my Aunts wet the bed till she was teen, my brother wet the bed tail he was like 11. My son has accidents, and my current husband wet the bed tail he was about 12.
It happens. Don't worry a lot. Talk with a urologist. There might be other issues. If there aren't, they will help give you some advice as to what to do. Most children grow out of it. It is sometimes a deep sleep issue. A urologist will help you sort things out much better then I could.
I do have the children wash their sheets. Learning to be responsible for themselves isn't a punishment, but a fact of life. I don't scold them or rant-and-rave. We found out my daughter has other problems (emotionally). We work with it. Someday she'll stop. The accident's my son has are less and less (we are talking months in-between).
Everything will be fine. Just remember, consequences for something like this can lead to more problems. Work with him, not against him. Talk with your Dr. about seeing a urologist. It will all come together.