Does anyone know of a way to get buttercream not to crack? every time I cover a sheet cake with my buttercream, when I lift it up to box it or deliver it, it always cracks. Is there a way to prevent this? Does anyone know what causes it to do it in the first place?

Maybe your cake board isn't strong enough to support the cake. I have had that happen before and now I use several if wilton or buy foam board which is much stronger and cut to the size you need.

Yup.......you need a stronger board. And....maybe a bit more fat (butter or shortening) in the recipe.

It's all about the board

Stronger board. You can use a 1/2 foam core board, or double up on cake boards under it, or use a cake base, which is several boards glued together and covered.