Ceramic tile has grown more and more popular throughout the United States, due in large part to the development of thinset systems. These alternatives to tiling over a thick mortar bed have cut down on installation costs. But they've introduced new problems, as well. The new thinner, more flexible substrates, including cementitious tile backerboards, are unable to protect the tile from seasonal movement in the structure, particularly in climates with wide temperature swings like New England. Even tile jobs set on thick mortar beds can have problems in modern construction because of excessive building movement. Also, the new substrates do not protect the underlying structure from damage when water leaks through the tiles. To guard against problems with
