Destructive step son

[eyeofthetiger1979]

I need some advice on how to deal with my step son. I noticed over the last couple of months some holes appearing in the plastic cladding in the bathroom. After researching I asked my husband to question his 12 years old son. He admitted that he had been pushing the end of his toothbrush into the cladding and causing the holes. My husband told him to stop and my step son agreed. This conversation happened last night. Tonight I have just noticed 3 new holes have appeared!
I am so angry at this blatantly destructive behaviour. We live in a rented house and will be moving out of next year. My husband is military and so have to pay for any damages and usually at a hugely inflated cost. At rate we will be paying to re-clad the entire bathroom!
How do we deal with this behaviour?

Has your husband spoken to his son again re the new holes?

Not yet, I only noticed them about an hour ago and he is asleep.

Supervise him brushing his teeth. Time him, make it annoying for him. Tell him he can't brush unsupervised til he can be trusted.

I would like to take money out of his monthly allowance to pay for the damage. Plus stop with the money he gets here and there for McDonald’s etc with his friends for a couple of months. My husband thinks this is a bit harsh.

Why is he doing it ? Does he know you will have to pay to have it repaired?

When we asked him why he was doing it he shrugged his shoulders and said he didn’t know. We told him last night when we spoke to him about the first holes we would have to pay for the damage so he is aware.