Preventing stacked tiers from messing up frosting'elow?

I have never done this myself, but I saw on a wedding special on television where the bakery cut circles of parchment the same size as the cake boards and laid them on each tier.

Well, first of all, in addition to the boards, you are planning on dowelling the lower cakes right? You must dowel them. Then you know that you must let the icing set on the lower cake before putting some icing sugar or cornstarch in the area where the next tier will sit. Let the icing set or crust for about a half hour or more.
Yes, it is quite possible to not damage the lower cake's icing when stacking a cake as long as the cakes are dowelled and boarded correctly, the icing is set before placing the next tier on top and sprinkle some icing sugar or cornstarch on top of the lower cakes.
Hugs Squirrelly Cakes

Hi. I always make sure I use plenty of dowel rods for support. After frosting my tiers...I place them in the icebox to let the icing get firm. After about 15 minutes...I take them out for stacking. The firmness of the icing helps me get the tiers centered without messing up the icing on the tier below. I then finish my decorating. I have never had a problem with the icing being messed up when serving the cake. Hope that all made sense!
traci

I've only done one stacked-tier cake but I made the dowels a tiny bit taller than the cake so that the cake on top didn't sit directly on the bottom cake. It left enough room to slide a cake server under and lift the top cake off and the icing looked perfect on the bottom cake when they were separated. The border that you put around the bottom of the top cake hides the small gap.

jjandascog is absolutely right - don't cut your dowels absolutely flush! I think that about 1/4" is about right. Another thing that I find works well is to cover the surface of the bottom layer's icing with dessicated, untoasted coconut rather than sugar - the sugar might suck up moisture from the icing below and go gooey. The coconut seems to avoid that and adds a bit of flavor if you're using a white or complimentary cake.

Illy

Well, I know a lot of people have taken to leaving the dowels a bit higher, but actually they should be flush or a bit lower. This is because it makes it easier for there to be a slip and slide issue when a cake is just sitting on the tiny edges of dowels. Your dowels must always be exactly the same height. Your cakes should be perfectly level. If you think about it this boarded cake is sitting with only the little dowels supporting it whereas when they are flush or just slightly lower, the board is fully supported.
Regardless, if the icing is set and the dowels are adequate, the cake is supported by the cake, the dowels and the board.
I have yet to have a cake stick to another cake, it just has never happened. Not being a fan of coconut, I don't use it in between but of course it works. So will cookies crumbs, cake crumbs, shaved chocolate anything like that. I tend to use icing sugar as this blends into the icing easily and still provides a barrier.
If you are stacking a cake that has a non crusting form of icing or topping, like a whipped cream topped cake, you will need to have a substantial barrier like coconut as the nature of whipped cream is to be not firm. Personally I don't stack cakes with these toppings.
I think that it is always good to do a dry run or experimental cake, when you are trying something new. Even a small version will give you a better idea as to how things will work out. It is beyond my understanding why so many folks take on orders for something like this and do their experimenting on a customer. Heeehee, one of my pet peeves, those posts or emails that start with: "Help, I am doing my first wedding cake for a paying customer, she wanted a stacked cake, I made it and it isn't working, it is due tomorrow, what do I do, help?" What is that line about, "Proper planning prevents poor performance", haha!
If you have never stacked a cake, make up a 4 inch and a 6 inch cake and experiment. Even only two tiers will give you the experience.
Hugs Squirrelly Cakes

I use the Wilton plastic dowels... I puts one into the bottom tier in the center to mark how long it's to be cut... I use it as my template to cut the others... I leave them sticking up about an inch... I get above the bottom tier to make sure that I'm even from the edges all the way around, then I lower it to the plastic dowels and let the weight of the cake push it the rest of the way down ... by doing this, you can get your fingers out of the way before the cake lowers... I make sure there is very little gap between the cakes, but enough where the icing won't stick to the tier below.. I continue up to the final tier doing this... I won't use anything but the plastic dowels as they do not shift.. I had a lady that I know from another town that exclusively does wedding cakes show me how she did hers.. she's the one that got me started on the plastic dowels instead of the wooden dowels.. to me, in my opinion, they're just better to use for tiered cakes of 3 or more tiers

The plastic dowels have a much larger circumference than the wooden dowels which are about 1/4 inch around. Also because they are hollow they have all of that cake in the middle acting as cement. I can see going that route if you are leaving a space, but with the wooden ones, they should be cut to the height of the icing or slightly lower. This is more of a safety precaution than anything, if you think about it, if someone hits the table it wouldn't take much to slide cakes off of 1/4 inch dowels. Haha, I guess I have seen too many emails and posts where this has actually happened. The plastic dowels are being used in a sense, as pillars when you leave a space. This is one of the reason why they were developed. In the instructions they say not to leave a lot of space between them and the cake they will be supporting and there is good reason for this.
Hugs Squirrelly Cakes

Haha, I have a policy of usually charging friends cost. But if I try something new and it doesn't turn out as perfect as I would like, I make it free. I did a wedding cake for cost more than once, just to be able to experiment. So sometimes it is a really good thing. However, haha, as hubby tells me, it is better to experiment small scale than work for nothing, haha!
I have learned a lot of things by trying out practice cakes, I think it is a great way to learn. Think about it like doing your cakes for the courses.
I have one wonderful customer who lets me experiment and often gives me free reign over design and type of cake. Then she tells me to charge her what I feel is fair. Of course with a customer like that, I always undercharge her. I get to experiment and get feedback from her, so it works out great for me.
Yes, what young girl wouldn't love a tiered cake, or anyone for that matter! They just look so darn special.
Good luck with it, I am sure it will be wonderful! Don't stress yourself out over it either!
Hugs Squirrelly