- Q.When installing a mortar-bed
shower floor, should the gap between the drain and the
adjacent tiles be finished with grout or with
A.Tilesetter Tom Meehan,
owner of Cape Cod Tile Works in Harwich, Mass.,
responds: Use grout. Since the shower floor,
if installed properly, has a mud base (Portland
cement and sand) at least 2 inches thick, there
should be almost no potential for deflection. Caulk
is used mostly at the joint between vertical and
horizontal surfaces, where movement is more likely.
One reason to limit the use of caulk is that many
caulks will mildew and discolor in wet areas.