I have been looking at some of the topics about using a "dam" so as to avoid bulges...

my question is what is a dam? obviously it is some sort of barrier, but what do you use, and how? do you pipe something around the outer edge???

I want to fill with ganache, but do I have to do a dam first? frosting in fondant

A dam is an inner ring made around the inside of a cake before you put the other layer ontop.You usually make it about 1/2 inch in from the edge of the cake.You pipe it with medium to stiff buttercream so it will hold the filling in...I like to pipe with a open ended piping bag and let the icing come out like a skinny sausage.Sometime I make it 2 rolls high.Once you fill it with the filling and put the top layer on I like to gently press down so it will squeeze together.I also like to refridgerate cakes that are being filled so they firm up and settle.I usually do this over night.The next day I will crumbcoat the cake and scrape off any excess buttercream/bulges etc..Then do final coat of icing.The trick is too not fill the inside too full as that causes the bulging...just enough to have a bit of filling ...not 1/2 an inch or it will ooze out.HTH

Kiddiekakes,
When you refridgerate your cakes overnight, do you cover them or put them in something? or do you just set them in the fridge uncovered? I have wondered about that, like do they dry out if left uncovered? My fridge is not very big, so I would have a hard time covering a filled cake and fitting it in there. Thanks!

Could I use anything else apart from buttecream?? Maybe if I whip some ganache...then pipe that around the edges and fill with normal ganache?

I actually have a large flat table in my garage and I leave it there uncovered because I use WBH icing and if I covered it all the icing would stick.The shortening in the icing protects the cake from getting dried out!Crusting BC you can cover with a bag etc..