Boy can now play the ball off the roof as long it in above the field of play and does not cross the net 

12.5 Screening

• 12.5.1 - the players of the serving team must not prevent their opponent, through individual or collective screening, from seeing the service hit and the flight path of the ball.

• 12.5.2 - Any player of the serving team is forbidden to raise hands above the head during service, until the ball has passed beyond the net - to be clear, hands on heads to protect is fine, above is not.  Back row is not permitted to have hands raised at all.  

• The first referee is permitted to caution (advise) a team through the game captain, if he/she suspects that is is deliberately screening.  After the warning a fault will be administered on the next instance awarding the point from that rally to other team along with next serve.