I am making my daughter a half sheet (11x15 in.) cake this weekend for her birthday & am thinking about covering it in fondant. Is this size hard to cover in fondant since it's a large coverage area? I'll be using a regular rolling pin (not a fondant rolling pin). Will this work?

You can also use a piece of ABS pipe, 20" long it will just make it so you don't get as many lines on your fondant. I have never covered a slab with fondant before, so I cannot comment on that. Good Luck

soapy_hopie's suggestion to use PVC pipe, or ABS pipe if that's the same thing is a good one rather than a regular rolling pin. I think it's easier if you smooth the corners first then the sides.

When doing rectangular cakes, I find it easiest to roll the fondant around the pin, just because the size of the piece affects it's tendency to tear. I roll the fondant a few inches longer than the total length I will need - this is because the first time it goes around the pin the edge of the fondant will mark another area, but after that it will roll round smoothly. Dust the fondant with cornstarch or PS before rolling to avoid sticking. Once you have unrolled the fondant over the cake, you can cut the extra marked fondant off.

I agree that doing the corners first helps. And use a piece of pipe if your rolling pin is not wide enough to avoid marking lines in it.