11 year olds pee the bed for a variety of reasons.
Sometimes 11 year olds have a weak bladder or the bladder is not growing as fast as the 11 year old.
Other causes of an 11 year old wetting the bed are being cold, having nightmares, bad dreams, being stressed or just a natural part of growing.
It's not usually anything to worry about when the kid is wetting the bed even at 11 years old.
To keep the 11 year old dry you should have them wear some pull ups or Goodnites or diapers.
Diapers would be much better as they are more absorbent and less prone to leak.
There are medications the 11 year old can take to slow urine production but personally I would avoid medications and just allow the child to grow out of the bed wetting.
It's normal to wet the bed as a kid and even up until 17 to 18 years of age.
They could wear pull ups but from my experience pull ups leak especially on heavy wetters at night.
But diapers hold the pee in much better.
It's normal for kids to continue to wet the bed even until they are 17 to 18 years old.
I personally wet the bed myself up until age 17 and then I finally quit.
I wish I had diapers for the bed wetting at the time as waking up in wet sheets and clothes every morning did not feel good at all.