A River of Mosaic Tile

I will describe how I work with tiles and stones of varying thickness and sizes. Tile thicknesses vary from 3/8” to 1/8”. Face dimensions range from large, 1’x2’ to tip-of-the-finger! Most of the tiles will be laid on flat surfaces. Some will be installed on curved walls and the dual pitched shower floor. A good tile job depends on an even substrate. I need plumb and level surfaces in order to create a functional and appealing work of art. Therefore, my work is guided by a laser level.

Before This is what the bathroom looked like before work began! It was dingy, crowded. Walls were out of plumb and the floor needed to be re framed.

V2 tile 1

A “Greek Theme” guides the remodeling process of this bathroom and the adjoining bedroom. Walls and ceilings are covered with DensShield, pseudo plastered and painted. Nooks will provide places to showcase works of art.

Nomenclature Let me briefly explain the terms associated with tile work. Tile backer is the substrate material unto which tile is laid. It is usually cement-based (Hardy backer) but also comes in a drywall form (DensShield). It is available as a fabricated mat. Tile backer and tile are laid into a bed of mortar, called Thinset. Grout is the stuff that fills the spaces between tiles.

Tile types The floor I am laying consists of 12”x24”x3/8” thick porcelain tile. Porcelain tile is hard and durable. Large slabs of granite cover two shower walls, the shower bench and the cabinet top. This work is handled by a specialist. Split face marble – it varies in thickness and comes on pre fabricated 12” square mats- will cover curved walls and spaces between the medicine cabinets. Mosaic ¾” squares of stained glass tile will grace one wall and a center section of the floor.

Floor tile preps I vacuum and dampen the water-resistant OSB subfloor and lay a bed of thin-set mortar. Dampened OSB assures that not much of the mortar’s moisture wicks into the subfloor. I lay ½” thick sheets of fiber cement board (by Hardy) into the mortar (photo left), and screw them to the wood subfloor. Screws are spaced 6” apart, ensuring a rock-firm tile base. This is absolutely crucial for the thin bed of decorative mosaic tile to follow. The tile base is 1.25” thick.

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Now I install a large, custom fitted electric heat mat into a bed of thinset. It covers the entire bathroom and shower. The feed wires are carefully routed along the walls and to an electric box. I document this process with cell phone photos. There are wires and a sensor embedded in this large mat. They will make tile laying a challenge, so I lay another thin bed of thinset on top of the mat, smooth it over, and let it dry. Now it’s time to carefully lay out the tile patterns.

Square-up and layout Since this is an existing structure, I can’t assume that the re framed room is square. Therefore I square up and lay reference lines down the middle of the floor. That yellow metal strip seen in the photo below represents the edge of the first run of floor tile. I screw this guide to the floor. Two shorter metal strips secure perpendicular lines.

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A river of mosaic tile The cabinet maker hands me a cardboard template for the long run of curved base cabinets. I lay this template on top of the tile backer. With a large compass I trace a line approximately 24” off the template. This represents the central area of the floor that will be covered with a “river” of mosaic tile. I flip the cardboard template over, and mark the opposite side of a free-flowing pattern on the floor. The curvatures on each side do not match, creating an appealing, undulating effect. Having reviewed the layout with the owner, I use a permanent marker to make crisp, dark lines on the tile substrate (photos above and below). Now I transfer this pattern onto a roll of thin, pliable water-proofing material. I can see my floor marks through this material.

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Now I dry-lay large, thick floor tiles up to and into the pattern marked on the floor. I use ¼” blue tile spacers to keep tiles from moving. I can see my pattern lines through gaps between the tiles. I unroll my tile pattern, carefully align it with my reference marks, and tape it to the tile on the floor. I trace the edges of the pattern onto the floor tile, using a magic marker. I make templates for difficult tile cuts (photo right). I number my tiles and write down corresponding numbers on the floor. I take cell phone photos to be sure I have all my details covered! Then I remove the tiles, stack them, and sit down for a cup of coffee. Whew!

The floor tile is cut! The cutting tool of choice is the Gemini XT 10” ring saw! It is the latest, somewhat expensive baby in my growing family of tools. A 10” ring blade is driven by a belt. I slowly feed porcelain tile into the water-cooled blade. Occasionally I make rough cuts with a grinder. Crisp, clean edges are lightly rounded over with a carbide file. I lay a bed of thinset on the floor and thinly back-butter each tile. Back-buttering ensures full contact. I carefully lay and align one tile to the next.

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Earlier, I had suggested tiled baseboard, but my client remains uncertain. He wants to see the completed job before deciding. Therefore each floor tile that butts against a wall is rough-cut and dry-laid in place. Using the wall as my guide and with a thick pen in hand, I mark cut lines. Tiles are re cut and installed. I end up with an eye-appealing, even grout joint all around the room!

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Preparing the mortar bed for decorative mosaic tile
Now comes the tricky part. The floor tile is 3/8” thick, but the decorative mosaic glass tile is only 1/8” thick. Both tiles must lie in essentially the same plane! Mosaic tile should lie a tad lower so that its sharp edges are embedded in grout.

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First I build up the mosaic tile bed with a mixture of stiff white, thinset and silica sand. I embed a roll of 4.5 oz. sticky mesh (normally used for synthetic stucco). This mesh guides the leveling work and secures a tough bond. With two controlled applications I achieve a tile base a bit more than 1/8” below the surface of the large floor tiles. White mortar optimizes the appearance of blue mosaic tile.

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Starting near the middle of the floor and working both ways, I lay sheets of 12”x12” mosaic tile into a shallow bed of V-grooved mortar. It is very important to not allow thinset to creep into the spaces between the tiles. Another reason the keep the mortar bed relatively thin is that a mat of mosaic tile is difficult to lay in a perfectly flat plane. It distorts easily. Now I lay a small piece of plywood on the tile and lightly tap the tile into place. With lots of patience and an aching back to boot I mark, cut and lay mosaic tile along the edges of the pattern. You may wonder why I do not make a ¼” thick wood template, tape the mosaic tile to it and, using the edges of the template as guide, cut the mosaic tile on the ring saw. The simple answer is that I can’t achieve the kind of perfect fit I am looking for. Plus, the tape can’t withstand the vibrations of the ring blade. So, I prefer to work tile-by-tiny-tile! I use a stiff brush to gently clean any residual mortar off the tile.

Grout When the mosaic tile has set I use a small, battery-powered detail saw/grinder to cut an even grout joint along the edges of the “river bank”. Now I clean the mosaic tile with a scouring pad and a small grout file. I want to make sure no thinset clings to the spaces between tiles. I vacuum thoroughly. I prepare a batch of non sanded grout, since the joints are less than 1/8”. I apply, and let the grout set for a short while, and then I carefully clean grout lines, using a damp sponge. I avoid getting water directly on the grout, because each cleaning lightens the color.

Cleaning up Mosaic glass tile is easy to clean with a soft scouring pad. I dry-wipe with a towel to remove any residual grout haze. I check my grout work and fill the pin holes that may have arisen earlier. Let me point out that the large floor tile has a non-smooth, slip-free surface, making it difficult to clean off residual grout. It is absolutely imperative to clean the grout off the tile before it hardens. I might advise sealing each tile prior to laying it. The sealant is cleaned off later.


V2 tile 12

V2 tile 11


1 Comment

  1. Erika Blair November 25, 2014 at 4:30 PM #

    Ecquisic workmanship!! A bathroom to dream for. I love the extra shelving and shower seat.


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