How To Build a Marble Mosaic Tile Backsplash

When my wife and I bought our current house about a year ago, we knew exactly what kind of kitchen backsplash we wanted. Although the builder didn’t have the option, we did succeed in convincing them to not charge us to leave the tile off. (That’s right. They were going to charge us to not tile our backsplash.) Months later I finally got around to doing the project myself – using marble mosaic tile. If you like it, read on; this … is its story.¹

The starting point

Your starting surface will require various levels of preparation depending on your kitchen. As I mentioned above, we saved ourselves the trouble of removing old tile by having the builder leave it off. If you have tile to remove, I suggest following the instructions given in How To Build a Glass-Mosaic Tile Fireplace.² Here is how things looked before I started:

I should probably explain the small PVC pipe sticking out the wall. It’s a water line we requested when our house was built so I could install a pot filler later. (I’ll explain what that is and how to install it in a separate article.)

Prepare materials

Tiling with marble mosaic tile requires the usual tools/materials:

• Tile – Marble mosaic tile typically comes in mesh-mounted sheets. One square foot sheet can cost anywhere from $5 to $30. Ours was purchased at Lowe’s and ran around $10/sqft.
• Mortar – Use tile mortar with polymer.
• Grout – Use unsanded grout with polymer.
• Grout float
• Notched trowel – A 3/16″ × 5/32" V-notched trowel is good for mosaic tile.
• Spacers – 1/16" spacers will usually work well, but get whatever will match the spacing on the sheets.
• Utility knife – This is needed to cut the tile sheets.
• Sponge – I recommend a high-quality, large sponge. It can save a lot of work. (Something from the hardware store is fine. Just don’t try and use an old t-shirt or something.)
• Sealant – You’ll apply this liberally, but a little goes a long way.
• Bucket
• Fiberglass tape – (optional)
• Spackling – (optional)

Preparing the surface

To prepare the surface for tiling, I:

1. removed outlets and outlet/switch covers
2. removed the wood trim behind the sink
3. uninstalled the range hood
4. removed the wood trim above the stove
5. masked around tile area (optional … and not recommended unless completely necessary)

The last is rather self-explanatory, but the rest deserve some explanation.

Remove outlets and outlet/switch covers

Use the following steps at your own peril:

1. TURN OFF THE POWER.
2. Remove all outlet/switch/phone/etc cover plates with a flathead screwdriver.
3. Unscrew plugs and switches from their mounting boxes and pull them out from the wall slightly. (This will allow the top/bottom tabs to “land” on top of the tile, aligning the plug face with the new backsplash surface.)

I recommend not turning on the power until the outlets/switches/etc are installed again. If you must have power, the key thing to avoid is touching the screws on the sides.

Remove trim behind sink

The backsplash behind my sink, skinny as it is, had a strip of quarter-round trim at the top under the counter edge. Tiling up to this rounded surface would be ugly and difficult – so I removed it. It was easy enough using a flathead screwdriver to pry it away from the sheetrock. Once it was off, I found out why it was there in the first place. Between the top of the sheetrock and the bottom of the countertop was a half-inch gap. Nasty.

Uninstall range hood

I wasn’t planning on removing the range hood, but cabinet trim extended up between the sides of the hood and the cabinets, making it very difficult to remove with the hood in place. To remove the hood:

1. Unplug the hood. It’s most likely plugged into an outlet in the above cabinet.
2. Remove the light bulb. This is optional, but I recommend doing it just to keep from breaking the bulb.
3. Unscrew the mounting screws. There are usually four of these going through the top of the hood and into the cabinet wood. If you’re “lucky” like me, the two of the screws won’t actually be installed into anything, so you can just pull them out with your hands.
4. The hood should stay in place after the screws are removed, as it is taped to the vent conduit. Loosen the tape to free the hood.

Remove trim above stove

After the range hood was uninstalled, I removed the wooden trim adjoining the cabinets behind the stove in the same manner as the trim behind the sink.

Cover unwanted outlets

Many of you may like to have four outlets within arm’s reach of your kitchen sink, but we’re just fine with half that many.

Tiling the backsplash was the perfect time to cover a couple of them up. This involved the following:

1. TURN OFF THE POWER TO THE PLUGS. – This could involve tripping the breaker or GFCI circuit, flipping a switch, etc.
2. Remove the plugs. – Unscrew the plug unit. Cut or remove the wires. Keep them as long as possible.
3. Remove sheathing from last half-inch of wire. This may not be necessary if you separated the wires from the plug without cutting them.
4. Make up the matching wires. – Use wire nuts to connect the white, black and copper wires separately. Push the groups back into the outlet box.
5. Cover the box with fiberglass netting. – This is your typical sheetrock/plaster netting tape.
6. Plaster over the netting. It doesn’t need to be pretty; you’re going to tile over it anyway.

Mix and apply mortar

Now that the surface and materials are prepared, you’re ready to start tiling. Mix a batch of mortar in a bucket according to the directions on the package. How much you mix depends on how much time you have. I mixed small batches at a time, as I needed to work in shifts over a number of days. (If you end up mixing too much for your tiling session, scrape the extra out onto a piece of cardboard or plastic. It can be easily discarded when dry, and you don’t want it to dry inside your bucket.) A small batch will also allow you to mix without purchasing a mixing paddle. If you do use a paddle, however, do so at low speeds (less than 300rpm).³

“Key” the mortar onto the wall using the flat edge of the trowel and then “comb” it using the notched end. To comb the mortar, drag either notched edge of the trowel over the surface keeping the trowel at a 45º angle to the plane. Good spreading technique will ensure consistent and correct mortar thickness to produce flat and secure tiling.

Cover only a small section of the wall at a time, staying about one full sheet ahead of the tile. (In other words, cover two square feet on the initial application, set one sheet, cover another square foot, set another sheet, etc.) This will keep the mortar from drying before you have a chance to set the tile, but will also keep you from having to key the mortar up to the edge of a set sheet (which is quite annoying).

Set tile sheets

Once you prepare a small area with combed mortar, set the net side of the tile sheet into it. Use the grout float (or a block of wood) to press the tile sheets evenly into place and ensure mortar coverage on the set-side of the tile.

Orient the sheets after setting them to maintain proper spacing. Place spacers either in-plane with the tile sheets, which will align four tile pairs, or normal to the sheets, which will only align one tile pair. The latter is much easier to remove after the mortar is set, but the former can sometimes be pushed deep enough between the tiles to cover it with grout.

After laying a few sheets, it’s generally a good idea to scan them (both up close and from a step back) to find off spacing. Make any necessary adjustments and clean up excess mortar before the mortar hardens.

Going around obstacles

When necessary, measure and cut the tile sheets to fit smaller space or to go around obstacles. If you have enough spacers, feel free to piece the leftovers together to fill larger spaces.

If you masked the tiling surface, it’s a good idea to remove the tape before the mortar dries, but after the tiles are semi-set. If you remove it too early, the tape may dislodge some tile. If you do it too late, it can be very difficult to get from under the dried mortar.

Sealing

After the surface has been tiled and the mortar has dried (per the manufacturer’s instructions), apply two very liberal coats of sealant with a rag or sponge. Marble is pourous and sealing it now will help with grout cleanup later.

Apply grout

After the sealant has dried (per the manufacturer’s instructions), you’re ready fill the inter-tile spaces with grout:

1. Mix grout per the manufacturer’s instructions.
2. Scoop up a dollop of grout with the rubber float.
3. Position the float at a 45º angle to the surface and the tile orientation and push/pull the grout into the inter-tile spaces.
4. 20 minutes later, wipe off the excess grout with a dry, lint-free cloth and then a sponge and warm water until reasonably clean.
5. Let it dry for 15 minutes.
6. Wipe away revealed grout “haze” using a moist sponge or cloth. Repeat as necessary. (This step can actually take quite a bit of Karate Kid-like wiping.)

Seal again

After the grout has fully dried (about 24 hours), apply two more liberal coats of tile sealant.

Putting stuff back

The tile work is done after the sealant dries, but a few other tasks remain.

Replace the outlets/switches/etc

1. TURN OFF THE POWER.
2. Screw the outlets/switches/etc back into their original mounting boxes. Make sure the tabs on the top/bottom of the plugs/switches “land” on the tile surface. (Longer screws may be necessary, depending on the mounting of the box.)
3. Screw on cover plates.

Re-install the wood trim behind the stove

Nail the trim into position over the new tile surface. New nails may need to be used, being careful not to split the trim. Keep in mind the trim beside the range hood will not be visible.

Re-install the range hood
To re-install the hood:

1. Feed the plug into the upper cabinet.
2. Push hood up into general position.
3. Afix the hood vent to the conduit using the existing tape (as best as possible).
4. Mount the hood using the same screws/holes.
5. Plug it in.

Install new trim under counter behind sink

Hopefully you’ll be able to re-install the trim you removed – or better yet, to go without. In my case, the previously used trim was too big to fit under the counter and in front of the new tile surface. I bought a couple pieces of very inexpensive trim to cover the gap between the top of the tile and the bottom of the countertop.

Of course, because the trim covered a gap, there was nothing to which to nail it. After a few days of thinking, I decided to super-glue it in place. It was tedious and not nearly as sturdy as I would like, but it worked.⁴

Finished product

After the extras were installed, there was nothing left to do but admire the finished product.

Notes

¹ I reserve the right to change the details of the story to make me look like a better handyman. So, if I did X before Y and realized it would be much better to do it the other way around, I’ll probably just say, “be sure and do Y before X,” like I knew it all along.

² Hansen, Brandon. “How to Build a Glass-Mosaic Tile Fireplace.” OmniNerd_, 3 February 2006. Accessed February 2009 from [http://www.omninerd.com/articles/How_To_Build_a_Glass_Mosaic_Tile_FireplaceFireplace].

³ I gave myself express written permission to copy stuff from my previous articles.

⁴ Funny story: I got the clamps I used to hold the trim in place while the superglue dried as a white elephant gift at a Christmas party. Oddly enough, the thing I should have used to hold the trim in place I also got as a white elephant gift – at the same Christmas party and from the same person – a year later.