I recently made a couple of 2 tier cakes, ad somehow the buttercream on the bottom tier seemed to be sliding downwards. 

In the picture, the cake on the left is before delivery, and the cake on the right is at the location. I've circled where the problem is and this happened to my other cake too. 

I'm using Swiss meringue buttercream, 4 bubble tea straws as support in the bottom tier, and a wooden dowel through the bottom and top. The cake would have been kept in an aircon room at the location. 

Would anyone know why this is happening and how I can fix it? 

Thanks! 

First of all your cake is beautiful and very well crafted! Second of all- I wish I could tell you why this happens as it's happened to me before maybe a time or two as well. Hopefully someone can give us an answer.

I know that when I was watching Cake Boss I heard Buddy remark while dirty icing a cake: Make sure you press the frosting into the cake very firmly as you turn the cake.

Hopefully someone has more solid advice for us.

Your icing may have been too thick- either consistency thick or too thick in amount on the cake.

At what temperature is this happening?

Is it possible that your cake board underneath the whole cake isn't firm/ stable enough? By lifting the cake it might have bend a little bit and pushed the smbc up. Cause your bc doesn't look melted to me.

Hi Cheatize - strange thing is that it is only happening on my 2 tier cakes and i'm using the same SMBC recipe and method of icing, So the thickness should be consistent with my single tier ones. i'm estimating about 0.5cm? I'm wondering if it could be the weight of the cakes and the way that i'm stacking them. 

Hi Pastrybaglady - the temperature would be about 24-26degC. 

Thanks for the replies :)

Hi julia1812 - that might be one reason actually. I'm using the same wooden cakeboard as what I would for a single tier cake but the weight of 2 tiers may be too much for it.  I'll have to try a thicker & stronger cake board next time to test that theory out. thanks!

Try 2 boards next time and see if it happens again.  Hope not! Good luck with it...

You're so smart @julia1812  I never would have thought of the board as the culprit!  @karybakes  try foam core.

Lol, I was talking out of experience @Pastrybaglady  

We only have those thin cake boards and I hate them because this is what they can do^^^

Thanks @julia1812  !! I have seen the thicker boards in the shops here in Singapore but didn't purchase them cos they had a floral type embossing which I wasn't too keen on. Never thought the thinner boards could make such a difference. 

@Pastrybaglady  do you mean styrofoam boards? those I've seen are pretty light and don't seem as sturdy. have you used them as cake boards before? I presume you would cover them as well but what would you use that is food safe and looks nice? 

No, foam core is different from styrofoam. For a single tier 1/2" is plenty, for 2 tiers go to an inch.  It's very sturdy and yes you can cover with foil wrap or fondant.  I'm not sure where you are but in the states it is readily available in craft stores.

Hello. Just had to reply (first time) because I have been experiencing the same thing! I have noticed this happens when the cake has not set for several hours, the frosting consistency is a little thinner than normal, and two much frosting on the side of cake. I think maybe all three factors are playing a part, but the setting time is a big one!

This has only been happening lately as I have gotten very busy and the cakes are not setting as long before delivery. This may or may not be the reason, still trying to pinpoint it, but wanted to share what I am experiencing. Have to get this one figured out!  ;-)

@Pastrybaglady  I'm actually in Singapore, and perhaps those boards go by a different name here. I'll try to find them and see if they work. 

@Getyourcakeon  Do you know how long your cakes used to set (I presume in the fridge?) vs now? My frosted cake was in the fridge overnight, and I had taken it out to do some touch ups in an aircon environment for an hour before delivery. So i'm not sure it would be attributable to the setting time. 

I would normally frost the day before event,let set overnight, then finish next day. Everything set firm, no problems!

I use a shelf stable all shortening frosting. So they are not in the fridge.

In my state home bakers are not allowed  to use anything that requires refrigeration.

I'm sure different types of frosting might be a factor also and consistency. 

The one I delivered yesterday slid a little on one side. Did not set overnight. The one I am doing today will set. So we will see what happens tomorrow! :-)