ball hits top of bb in or out

[StevenW]

when the ball hits the top of the backoard is it in or out?

[Mark Padgett]

When it hits, it's still in. Whether it stays in or not depends on what it does after it hits. If it goes over toward the OOB area, it's out. If it goes back toward the playing court, it's in. If it comes to rest on the top (yeah, right), it's a jump ball.

[Nevadaref]

StevenW,
In addition to what Mark said, just remember that only one side of the backboard is out-of-bounds--the BACK. If the ball hits the board anywhere else, just keep playing.

[rainmaker]

also remember that these rules only apply to rectangular backboards. The fan shaped ones have different rules.

Also, if the ball hits the top edge of the backboard, and then bounces up and hits a wire or brace, it's out.

If it flies over the top and goes out of bounds, be sure to yell, "Over the back!" when you signal. This will confuse everyone who thinks that "over the back" is a foul.

[Camron Rust]

Additionally, if the ball hits at a corner of the board, it is simple physics to determine whether it hit the back or the side/top/bottom. If it bounces in any way back from whence it came, it hit part of the board facing that direction.

For example...a throwin from the endline hits the bottom/back corner of the board. It is deflected downwards but still towards the middle of the court...legal...it hit the bottom. Now, if it is deflected down to the floor or OOB behind the board, it it the back. Onlly the rear surface can redirect it back towards the thrower.