Wonderboard: what is the stuff? Is Wonderboard really wonderful?
Wonderboard is a cement-based backer board used for wet places. The wet places are mostly bathrooms, and the applications tend to be tiling. Exclusively? No. It can also be used for decks, floors, and countertops. But most people think of it as a backer board for tiling in wet places like showers and bathtubs.
Available in half- and quarter-inch thicknesses, Wonderboard is made by Custom Building Products. Dimensions are 36" by 60". This size is most likely due to several reasons: the stuff is heavy, and you likely don't need bigger dimensions for showers and baths
What is backer board? When you lay down tile, you need a "backing" that will accept the thinset mortar
and resist moisture from the shower or bath. Instead of laying down gobs of mortar, backer board basically gives you a mortar-like material--flat, dry, and ready to install.
I do not find Wonderboard to be wonderful. I find it hard to work with due to its crumbly consistency. The only thing that seems to hold it together is the nylon meshing. The moment you cut it, it falls apart. By contrast, HardieBacker, a competing cement backer board made by James Hardie Industries, is smooth and easy to cut. No crumbly stuff. Durock, by USG, is a similar competing backer board that I find easy to cut.