I'm am stacking a 9x13 sheet on top of a 12x18 sheet. Do I need to dowel at all? Do I need to have a cardboard under the 9x13 or just sit it right on top? This cake is for birthday party tomorrow. Please help quick....
Yes and Yes!! I would put cardboard under the 9X13 and I would put dowels in to support it. Better safe that sorry!
I personally would be fine with no cardboard and no dowels. I've done these before and they were fine. If you made a 2-layer 10" round cake, you probably wouldn't carboard and dowel it. This is the same thing except they are rectangle.
But you need to do whatever is best for your comfort level.
I'm with Indy Debi, no dowels or cardboard. 2 layer is normal for round, why not square, rectangle etc. any taller than two layers yes and maybe if torted with whipping cream I might dowel. I quite often dowel my double layer rounds if torted or filled with rasp. I put one single straw or dowel right in the middle.
If both cakes are torted and filled than yes I would put the dowels and place the smaller cake on a cakeboard.
If you are just treating it as another layer than no I would not, but remember for serving purposes it would be less messy if the top cake were on it's own board.