Legal Question in Real Estate Law in California

The parents are liable for the damages done and have to restore the door to the condition it was before the ball hit the window. If that requires work to the door itself, then they are responsible to pay for that, although they might be entitled to any improvement. For example, if someone throws a drink onto a wall in your house making it necessary to repaint that spot of discoloration, if the wall has not been painted for 3-4 years painting that spot will leave a noticeable area of difference in color, so the whole wall will need to be repainted, but there is some added value to you in having the entire wall painted so there needs to be some reduction of the costs that the drink thrower must pay.

I agree with the previous answer, and would only add that the child's act would probably be considered vandalism under Penal Code section 594. Civil Code section 1714.1 covers liability of parents and guardians for the "willful misconduct" of minors.