I have a request for a 5 tier wedding cake similar to the one below.  I am not sure how to construct this cake!!  Do I need to use dummy layers??  How do I keep the larger layer from having gravity take hold of the outside edges??  The customer wants this in buttercream.   I have been racking my brain, HELP!!

Let's see some of your butter cream work, and I'll give you my opinion on whether you're up for the task. Cause unless you've got mad skills with BC, and can put that together without dinging it, you're better off using fondant, which this is clearly done in, so that you get the most accurate look.

And before any feathers get ruffled, I wouldn't do it in BC, so there's that. :D

I agree with AZ. I wouldn't do it in buttercream. If the serving requirements allow it, I would do the smaller middle tiers as dummies.

AIt sounds as though you haven't built a tiered cake before. Correct?

I'd make the smaller cakes dummy's out of styrofoam and treat them as if they were pillars between my tiers. Put my larger cakes on square card boards on top of square cake plates as you'd do any cake stacked with pillars. I'd run a dowel up the center to help anchor the styro layers, place dowels in my real cake layers under the styro as usual as supports. Replace the lost servings where the styro tiers are with cakes in the kitchen.

As others said, I wouldn't do this out of butter cream (that would greatly change the over all look/intent of the design, plus it will kick up your level of difficulty greatly).................if I HAD to, I'd frost the cakes in butter cream but then do all my decorations out of fondant. The decor is so much easier out of fondant (you'd save sooo much time) that I wouldn't compromise on that issue with the bride at all.

This is a 3 tier cake with two foam dummy separators. NOT five tiers when you count servings.

Each cake tier sits on a HARD board (separator plate ideal) you can't see it behind the ribbon

Each cake tier has scads of dowels under the styrofoam parts.

AI would think this cake would be a good candidate for a center dowel or 4...

AI have done 2 cakes of a similar design and 1 of them was a total of 9 tiers. Both of the cakes were buttercream, so it is possible. Here are my suggestions: 1. The "riser" tiers should be made out of styrofoam. 2. The "riser" tiers are best if they are only 1" smaller than the tier sitting on it. For example if the cake tiers are 10" and 8" the "riser" tier should be 7". 3. The shorter the "riser" the better. The first time I made a cake like this the spacers were 2" tall. The next time I made them 1" tall and be cake was definitely more secure.

Thank you all for for help!  I am definitely making this cake out of buttercream.  I have stacked a tiered cake before but just had some concerns about which layers to do as dummy cakes and also if I could stack a heavier cake board on top of a smaller cake (even though I am using dowels) without it smashing or being unsecure. 

Even though you are using dowels (in your real cake), make sure each dummy is on its own plate or corrugated cardboard to prevent the dowels below from piercing into the dummies.