Cake was 8â & 24â high (replica of a building tower), it had 2 dummies on bottom and 4 â 3â high tiered cakes on top. It was supported well with plenty of wooden rods between tiers and a long thick rod on middle attached to bottom board. Had BC all around and was covered with thick fondant.

I let it cool and set on fridge overnight. It looked perfect.

It was transported on my minivan with A/C at max, I drove slowly so it took me over 1 hr to get to the venue, a place on the country side. It collapsed on the drive, fondant cracked all over and began to slowly drag down the sides.

Please⦠expert professionals out there⦠help me understand⦠what went wrong?

I am confused about the "let it cool" overnight, this was BEFORE you decorated correct?

Sparkle, thanks for asking.
I cooled it overnight with the 2 layers of BC spread all over it and then again overnight after covering with fondant. I am emphasizing the fact that the cake had, in my opinion, enough time to "set".
I forgot to mention that I brushed it with piping gel to act as "glue" before covering with fondant. Now I wonder if the piping gel was not a good choice, although I've used it before and it worked.
What do you think went wrong?

Perhahs the fondant was too heavy? Was is scratch cake or boxed cake? The box cake usually can't hold up to a lot of weight on it.

Yeah I once had a tall cake like that with too much fondant on it. It too cracked and slid.

Sorry this happened to you. Hopefully some of this will help you in the future.

This cake points out exactly what I've thought for years - tiered cakes are like buildings. And you need building methods to construct them.

Tall buildings have an internal skeleton made of steel. All pieces are attached at each end. Wooden dowels do not do this. They provide a modicum of support and stability, but not nearly enough for a cake like you described. They will help with downward pressure on a cake, but have little or no lateral stability.

A system that would have worked would be a plate and separator system. There are a few on the market. When the pillars lock into the plates, you get vertical and lateral stability, regardless of the type of cake.

Good luck in the future.

I think the problem was the fondant.

Too long a strip will come off this way because some fondants have very little tensile strength. Too thick fondant will come off faster than a very thin layer.

The pros use chocolate clay for this reason, on their largest structures that are RKT on top of wood or plastic frames.

Search on separator plates - SPS and Wilton both make different styles. There are other styles out there as well. They provide a lot of stability.

Cakes need supprt every 4 vertical inches. I absolutely recommend SPS. So every 4 verticsl inches there would be a plate and leg assembly.

From what i read in your posts, the *cake* did not collaspe but the fondant came off/cracked etc. Big difference.

It sounds to me like you rolled the fondant too thickly. There was too much weight.

Thank you Kakeladi... You are right, cake resisted well, it was the Fondant that collapsed, so BakingIrene you might be right that it could have been the weight of the fondant that caused it as I rolled very thick.
BTW.... What is chocolate clay?
Thank you all for replying... I am loving this site!

I would suggest 3 things for the future for this sort of cake:
1. Use ganache under fondant, instead of BC.
2. Mist water on ganache as your adhesive for the fondant instead of gel.
3. Apply your fondant in bands around the cake, instead of vertical 'drapes'. Make each band 4-8" wide, or even wider if you're comfortable handling sheets this big, roll off board onto your pin, then vertically apply around your cake. Joins can be hidden with building 'floor' levels, or other decoration.

It's not your dowels that were the problem, the cake itself did not fail. It was your application of fondant. While not as stable as SPS, using dowels and separator boards every 4" will also give you vertical AND lateral support as the boards interact with the dowels. Centre doweling provides a bit more lateral stability, especially when affixed to the thick base board.

HTH

Thank you very much Evoir!
I am saving yr suggestions for the future. Really appreciate it