Before tile backerboard became available, setting tile for a shower floor required laying down a substrate of troweled cement mortar, known as a mud job. Veteran tilesetter and frequent Fine Homebuilding contributor Tom Meehan continues to use this method for curbless showers. In this Master Carpenter article, he demonstrates how. He begins by lowering the subfloor in the area of the shower so that he doesn't have to use so much mortar. There are three ways to do this, and Meehan describes each one. When the subfloor is ready, he puts down a layer of builder's felt, followed by galvanized diamond-mesh wire lath. After mixing the mortar, Meehan dumps it around the perimeter of the room up to the shower area, tamps it down, and checks to make sure that it's level. When the perimeter is done, Meehan fills in the interior, screeding the mortar with a level or other straightedge. He then moves to the shower area, where he creates a 3/4-in. pitch down to the drain, marks the location, and sets the drain. To seal the mortar, which is porous, he installs a waterproof membrane, beginning with 5-in. strips split between the floor and the wall. When the perimeter is complete, he moves on to the rest of the floor, making sure to have at least 2 in. of overlap on all seams. At this point, the floor is ready for tile and then grout.