Last night I had a 4 tier topsy turvy Tim Burton style wedding cake (I will post pics later). Well I tried the ganache on the outside for structural support and it didn't work very well.....I know I am doing it wrong so.....a little help from you "ganachers"? Here's what I did....and what happened-
-Pound cake, torted with swiss meringue, and crumb coated the whole thing with swiss meringue. (no s.m.b.c. crumb coat maybe?)
-ganache was the white almond bark with heavy cream, ratio 3:1
-ganache never set up firm and was soft like american buttercream
-fondanted over the ganache after letting the ganache sit over night.

Basically the cake was o.k. at the beginning of the wedding, I could see a little sagging in the back, but I was so worried about it falling! I left and couldn't stop shaking, thinking it was going to fall (I've had previous "fall" experience so I was emotionally frail after the delivery).
I came back 3 hours later to get my wooden stand. I snuck into the kitchen avoiding guests just in case it had fallen. The wait staff were in the middle of cutting it when I walked in. They told me that the bride and groom had cut into the second tier (yikes!) and had basically butchered it...when the wait staff brought it into the kitchen one side of one tier fell off......well luckily that happened where no guests saw it! Anyways long story to say I am so tired of the little heart attacks I have been having over my cakes...Someone please help me with making that ganache a firmer shell!
P.s. I know some of you insist on real chocolate/white chocolate.....is there someone who knows how to make the harder shell with the bark so I can save some money?

I haven't tried a topsy turvy cake yet, but according to Sharon Z's dvd, the ganache is put right on the cake. There was no buttercream layer. I wonder if that prevented it from getting hard.

Ill bet it was the crumb coating before the ganasch.. also the ganach should set up... In sharons dvd.. she adds an additional day to her cakes letting it set up good.. I did one and Loved it.. after ganasch I coated with a simple syurp to get the fondant to stick.. don't give up. It really does make a nice cake..

I'm no ganache expert, but I do believe it has to be real chocolate. It's the content of cocoa butter that make it set up. I think that's is why white chocolate ganache is harder to make, it has less cocoa butter. Please, if I'm wrong, someone out there with more ganache experience correct me. I've been wanting to try it under my fondant for that crisp look.

I have used Ganache (3:1 ratio) on my 2 3d cakes The ganache set up real good You dont need to crumb coat it with SMBC. What I did was crumb coat it with a thin layer of ganache as well put it in the fridge for about 30 mins. (after playing bejeweled in Facebook) Then take the cake out put the final layer of ganache put my MMF and its ready

I've never used bark for ganache. I only use chocolate. Even the cheapest chocolate chips works.

White chocolate is softer because it lacks the coco. Coco butter is very sensitive to heat and moisture. White chocolate is basically coco butter cream, sugar and vanilla.
When using white chocolate you need to use less cream then you would making a dark chocolate ganache.

No crumb coat of icing-the ganache goes right on the naked cake and needs to set till firm to the touch before adding fondant over top.
The more moisture(either in the recipe or your environment) there is the longer it will take to set.

It takes some experimentation before you can tweak a recipe for your kitchen and time of year. Just keep playing with it and when it doubt use a little less cream and it will be firmer.

For a topsy turvy I would only ever torte with ganache - this actually acts like reinforcement. So this is the procedure I would do.

Cut cake into three layers
Torte with ganache. Let set up until firm.
Carve cake
Turn upside down to ganache sides ( I find this easier ) leave to set up
Ganache top.
Thread cake onto centre pole support
Cover with fondant
Insert dowels and cut to size, matching angles with angle of cake

Repeat with layers - eliminating the threading on pole before fondanting for the top tier.

DEFINATELY NO CRUMB COAT under ganache. Ganache IS your crumb coat.

ALSO think that soft type of fillings such as SMBC not advisable for Topsy Turvys.

HTH

I know virtually nothing about ganache (except that it's yummy), but I have done a structurally solid 5-tier topsy turvy cake, and from reading your posts, I wonder if you're doing the topsy turvy differently than the way I learned it. I learned to do it where each tier sits level inside the tier beneath it, so there's no need to angle your dowels or worry about structurally cementing the whole cake with ganache, and there's little threat of any tier falling off. To me, these types of cake can be more secure than a regular tiered cake, because they sit firmly inside each other. I used homemade, relatively flimsy buttercream just to seal the pieces to the cake boards, etc. Crumb coated each tier with buttercream, covered with fondant. It was a big hit. If I misunderstood your post, please forgive me for dropping my 2 cents. Just wanted to try to help if possible.

No - I don't do that style - sorry but I am a Planet Cake devotee (done the classes and LOVE their style of Madhatter)

Bark does not make ganache by the way, only chocolate. I know some people will say otherwise, but no, it doesn't.

LOOOVE your cake Pam...and did I mention I love you too...

Oh yeah, besides ganache, I've used SMBC for topsy. Never had a problem. But you only need one for crumb coat.

That cake is gorgeous. I'm not familiar with Planet Cake or their method. I learned from a lady near L.A. whose cakes I fell in love with. Just thought I'd offer the suggestion since it does virtually eliminate the possibility of cakes toppling over.

Another tip, is to freeze the cake before pooring the ganache over it.
Put the froozen cake on top of a small (smaller than the cake) pan which is standing in a larger pan.
This way it is easy to remove the dripping of the ganache at the bottom of the cake.
Because the cake is so cold, the ganache will set faster too.
And with the cake froozen you don't have to worry about wich filling you use.

Though if you freeze the cake, you have to be careful of condensation. I personally don't freeze the cake and use most fillings. In fact, I can't think of one I won't use...maybe pastry cream.