My crew and I are on a job for two days of prep and layout work before anyone places a piece of tile or stone, so I've learned to expect the question, "Why haven't you started yet?" My answer? "We're doing our most important work now, and when we finish ahead of schedule, you'll see the payoff." It's all about prep work. Before the job starts, I use the computer to develop a critical path plan for our installation procedures, including takeoffs and color charts. Every installer gets the plan, so they know where they should be and when as the job progresses. This is a team sport and sharing this kind of information is key to increasing team efficiency and output.
With installation plans in hand, my five-member crew and I start to prep the job for layout and installation. We use dry-lines, plumb bobs, and 6-foot levels to determine how straight, flat, and square the walls and floors are. Since they never are, we've developed a number of ways to deal with irregularities.
We use power planers and grinders to knock down proud joints in the subfloor. If a wall has a concave bow, we'll skim it with thinset, floating it straight. For a convex bow, we pull the wallboard and plane down the studs. On wavy concrete floors, I prefer to build up the surface with cement board and use thinset to flatten it. We use self-leveling compound if necessary, but it isn't as durable as mortar. We straighten base cabinets to set countertops properly, and we set proud nail heads.
Next, we set our new substrate. On floors we use USG's Fiberock waterproof gypsum underlayment, which provides some flexibility when the house settles. In areas regularly exposed to water, such as shower walls and steamer units, we use cement board. The substrate must go on flat--humps or dips cause "lippage," which occurs when adjacent tiles do not meet flush and the lip of one tile stands above the edge of its neighbor. It's always easier to prevent lippage during prep than to fix it during installation.
As part of our prep phase, we make sure to shim substrate sheets so they're square in the corners, especially in smaller spaces (showers, saunas, bathrooms). We also build our countertop decking and set it onto the cabinets. We fasten the Fiberock and countertop material with 1-1/4-inch-long 7/16-inch crown staples, and we use 1-1/4-inch screws to fasten cement board to studs.
Perfect layout means a flawless job. We've spent hours laying out one room to maximize the use of full tiles and avoid sliver cuts on the outside. Forethought, patience, and attention to detail not only enhance quality, but also increase productivity. Here's how we approach layout (the same techniques work for floors, walls, and countertops).
First, we establish lines square and parallel to the longest wall. Since rooms are often out of square, "square" is a relative term. We cheat one way or the other to lay out a grid that best fits the room's shape.
Because tile dimensions are nominal, we determine actual dimensions by laying a 6-foot run of tile, including spacers (as necessary) on the floor. We total its length and its intermediate lengths. For example, two 12-inch tiles plus spacers equals 24-1/2 inches; three tiles measures 36-5/8 inches; and so on up to six tiles. From this total dimension we extrapolate how the perimeter cuts will look: wide tiles, thin tiles, or sliver cuts. If the layout shows we'll end up with slivers, we adjust the grid and re-measure. We usually only end up with sliver cuts in the very worst cases.
Lay out tiles from the center of the room so all of the perimeter cuts will be the same. Again, the goal on the perimeter is to install the widest possible tiles. You can start layout with one tile on either side of the center line or you can center a tile on the center line to alter your perimeter cuts.
Next, we re-check square in four directions and snap our final set of red chalk lines. We spray the layout lines with clear coat so they won't be erased by foot traffic.
Any substrate problems should be identified and remedied by this stage, so the installers can concentrate on setting each tile perfectly flat.
Critical Path. Many tile setters literally work themselves into corners and get trapped waiting for mortar to dry. We avoid this by starting with the walls, then counters, then floors. We tile the field first, then the perimeter. No matter what stage the job is at, we have room to move and something to do.
Ceramic, Terra Cotta, and Porcelain. These tiles have eased edges and typically require a grout joint, which provides some room for error. Still, we lay these pieces flat. If I see lippage, the tile comes out.
Stone Tiles. This is our specialty. Due to solid prep work, you can't fit a paycheck between our tiled surfaces and a straight edge.
We set a single tile in thinset, then level it in all four directions. We cut a 1-inch-by-2-inch "puck" of the same material. We build it up to the finished height of the tile we just set.
We then affix that puck to the end of a 6-foot level and run it out in four directions from the first tile. If we've done our prep work well, when we place the puck on the floor, the level lies flat on our first tile. From this we know that all the tiles between the puck and the first tile will be in plane with the first piece.
We use our 3/8-inch-by-3/8-inch notched trowels to comb thinset on the floor.
We check each tile with the level. When we're done, you can slide the puck across the floor and it'll slide like it's on ice because it won't hit any edges or drops.
Grouting and Caulking
Grout. After grouting, we use good sponges and clean water to clean the tile surface.
Caulk. Use grout-colormatched latex caulk to seal between countertop backsplashes and at all horizontal/vertical surface transitions where a tile intersects with another material. Working the caulk firmly into the joint is essential for laying a good bead.
Romarico Nieto owns Apache Stoneworks in Denver. The company specializes in high-end stone and tile work.
Published in TOOLS OF THE TRADE Magazine, January/February 2003