i was asked to make a cake that looks like a building but for it to feed 30. i have already made 6" cakes and am wondering how high i can stack it for it to be stable? and also have enough servings for 30.
i was planning on stacking 5" tall cake on top of another 5" tall cake. with dowels to support the top cake.
would 2 -5" high cakes be ok to stack? would that feed enough? my chart says a 6" cake feeds 12 but i figure since the cakes will be 5" high then it would ok.
An extra inch of cake height will not increase your number of servings since the cake is still going to be cut the same way. For many people, a 6 inch cake barely makes the 12 servings. Most I have seen have given 10 servings as the most realistic number of servings. Might want to bake a couple of cupcakes to make up the difference, especially if they are paying you for 30 servings.
That said, you can stack two 6 inch cakes (like a double barrel cake) as long as you provide internal supports for every 4 inches or so of cake.
I've re-read your post, but sorry, I find it hard to follow.
Each tier (that's 2, 2" tall cakes put together) will provide a certain # of servings.
If you want to stack 5" round cakes, I'd estimate one tier to serve 8, so to serve 30, you'd need 4 tiers (8 layers), with supports (cake board and dowels/straws) between each 2 layer tier.
For 6" cakes, you'd need 3 tiers with supports.
For 7" cakes, you'd need 2 tiers with supports.
With a board and supports every 4" tier, you can go to any height.