Mosaic and accent tile

Sheet layout and hiding the seams between sheets

Mosaic tile comes on mesh sheets. The sheets are twelve by twelve or twelve by twenty four most of the time. My job is to set them so you cannot tell where one sheet stops and the next begins. That means I stagger the joints between sheets the same way you stagger the joints between the tiles themselves. On penny rounds and hexagons the mesh backing can shift if the sheet gets handled wrong, so I check each sheet flat on the floor before I mix thin set. If a sheet is folded or bunched I throw it aside and pull a fresh one. The trick is to press the whole sheet level at once and then tap the edges with a beating block so the small tiles on two different sheets sit at the same height. I comb the thin set in one direction so the sheets collapse evenly. A sheet that is not fully embedded will crack in a few months when somebody steps on it.

For sheet seams in a straight run I start at the center of the wall and work outward. That way the cut sheets land at the edges and the trimmed edges are hidden behind baseboard or under a cabinet. On a floor that runs from a doorway to a wall I lay the first row along the door threshold so the pattern meets your eye full and unbroken. Every seam on a mosaic floor gets pressed again after the thin set firms up for fifteen minutes. I run a margin trowel flat along the seam to levitate any high point. On large floors I pin the sheets with a few staples into the backer board before the thin set sets. Staples come out after the thin set grabs. The final seam is a straight line you cannot feel with your fingers.

Penny round and hex on a sloped pan

A shower pan has to drain. The code says a quarter inch of fall per foot of run from the farthest point to the drain. On a forty inch by forty inch pan you get about three quarters of an inch of drop from the wall to the drain flange. Penny rounds are a problem because they are round and the grout joint is already small. On a sloped pan the sheets want to cup. The outer edge of the sheet sits high and the center sags. I fix that by buttering the back of each sheet with extra thin set at the high side and less at the low side. You can also cut the sheets into strips two or three rows wide and set them one strip at a time. A narrower strip bends more easily over the slope. For hexagon tile the geometry helps because the flat sides bridge the slope better than circles. I still notch the thin set and push the sheets down with a grout float wrapped in a cloth so the float does not dent the tile faces.

The real trouble is the area around the drain. Penny rounds have to be cut in a circle to fit the flange. Laying a full sheet over the drain and cutting afterward leaves a ragged edge. I dry lay the sheets and trace the drain opening on the back of the mesh with a pencil. Then I cut the mesh with a utility knife and cut the individual pennies with a wet saw one at a time. That takes about twice as long but it looks like the drain was always part of the pattern. For hex I can often hide the cut line outside the first row around the drain so the visible area is all full hexagons. On any pan I flood test the slope before I grout. I pour a bucket of water on the tile and watch where the water pools. If it puddles anywhere I pull that section and redo the slope. A puddle on penny rounds will hold soap scum and mildew in a month.

• Penny round sheets curve better if you cut them into strips three rows wide and set each strip separately.
• Hex tile sits flatter on a sloped deck because the flat edges share load better than circles.
• Drain openings are traced on the back of the mesh and cut with a knife, not hacked through with a wet saw.
• A flood test with a bucket of water confirms the pan pitches to the drain before grout goes in.

Glass and metal accents

Glass accent tile is not the same to cut as ceramic. A wet saw with a continuous rim blade works fine but glass chips if the blade is dull or the feed is too fast. I cut glass with the tile face up and the saw blade traveling upward so the chip stays on the bottom where nobody sees it. For metal accents I use a regular wet saw but I tape the face of the metal tile with blue painter tape to keep the saw from scratching the finish. Metal tile expands more than ceramic when the thin set heats up from the hydration reaction, so I leave an extra small gap at the ends of a metal strip. One eighth of an inch at each end is usually enough. A metal accent that butts tight against a field tile will buckle when the thin set cures.

Metal accents also react with certain grouts. A dark cementitious grout can stain a silver or brass accent because the cement particle is abrasive and leaves a haze. I seal the face of the metal with a thin coat of wax or a clear sealer before I grout. Then I grout the whole assembly and wipe the metal clean with a damp sponge before the grout dries. If the grout dries on metal it leaves a film you have to scrub off with a nylon pad. Glass accents are easier that way because glass is nonporous and the grout wipes off clean most of the time. The one rule with glass is to back butter each piece if the thin set is open time dry or if the wall is hot. A dry thin set pulls water out of the glass and the bond fails. I always spot check the first tile I set by pulling it off after thirty seconds. If the back is not fully covered I change my thin set consistency or wet the wall first.

A listello or a picture frame band

A listello is a decorative band that runs horizontally across a wall. On an accent wall or a shower surround a listello usually sits at eye height, somewhere between forty eight and sixty inches off the floor. The problem is the listello width never matches the field tile height perfectly. If the field tile is twelve inches tall and the listello is four inches tall you have to cut the field tile above and below the band to make the pattern work. I measure the whole wall before I set anything. I figure out how many rows fit from the floor to the ceiling with the listello in the middle. Then I cut the field tile at the top and bottom so the cuts are even. Splitting the difference looks better than running a thin sliver of tile at the ceiling.

A picture frame band is a listello that wraps around a mirror or a niche. The band has to miter at the corners the same way wood trim miters. I cut the miter on a wet saw with the tile face up and the saw table square. For a picture frame I dry lay the four pieces on a flat surface and check the miter gaps before I set anything. A gap at the miter of more than a sixteenth of an inch means I recut the piece. On a mosaic listello the mesh backing has to be cut at the miter too, and the little tiles on a mesh band can slide around if the glue on the mesh is weak. I pin the miter with a small dab of thin set at the corner and let it set for ten minutes before I fill the rest of the band. That way the miter does not drift when I press the rest of the band into the thin set. A picture frame around a niche gets a bead of caulk at the inside corner between the band and the niche wall so the joint moves with the house and does not crack.

Grout joint size

The grout joint on mosaic tile depends on the tile itself. A twelve inch by twelve inch sheet of penny rounds has a fixed spacing between the pennies because the mesh holds them. You cannot open up the joint on a sheet because the pennies are glued in place. What you can control is the gap between sheets. I leave a three thirty second gap between sheets and fill that with grout. That way the sheet gap matches the tile gap and the whole floor reads as one continuous pattern. On hex tile the sheets usually have a slightly larger gap between the hexagons than between individual hexes on the same sheet. I close that up by butting the sheets tight and tapping them together before the thin set grabs. A consistent joint on hex tile is the difference between a floor that looks handmade and a floor that looks like a parking lot.

For accent tile like glass and metal the grout joint needs to be wide enough to let the thin set bond the tile. A joint that is too tight leaves no room for the thin set to wedge in between the tiles. I use a joint size of one eighth of an inch on glass accents and one sixteenth of an inch on metal strips. The metal expands and contracts so a tight joint will pop the grout in a year. On a listello band I match the joint size of the field tile above and below the band. If the field tile has a one eighth inch joint then the listello gets a one eighth inch joint at the band edges. I spread the thin set and strike the joints all in one pass so the grout flows into the band and the field without a hard line. The customer usually picks the grout color last. I keep a few sample boards on the truck with mosaic tile and different grout colors so you can see what the final look will be before I mix the first bag. A straight quote on mosaic or accent tile is best done after I look at the room. Call me at (512) 297-7493 or email info@merlanstile.com and we can set up a time.