When I lift my sheet cake to put it in the box the buttercream cracks HELP!!!!

double board it or at least put it on a board that doesn't flex at all -- if it flexes the icing will crack -- you could just buy and cut foam core boards to place under the boards you already use -- the foam core can even be cut a bit smaller -- i adhere with hot glue -- tape works too

We might need more info. What is the cake resting on ? Is it crusting B/C? I personally would have ensured the cake bird was able to support the weight before decorating .

I used Indydebi buttercream, I used Wilton half sheet cake board just one, I'll use 2 next time, thanks

It's definitely the board, bending make cracks.