Tuesday, April 8, 2014

DIY Mosaic Back-Splash


- Enough tile mosaic for the area you are hoping to cover (I used 2 ft of white marble mosiac)
- Thin set mortar (I used white) 
- Square notched mortar trowel
- Putty knife
- Un-sanded grout (I used white)
- Grout float (or rubber spatula in my case)
- Measuring tape and pencil
- Straight edge / level
- Drill with mixing attachment
- Carpenter's square
- Wet tile-saw
- Utility knife


STEP 1: Measure & Mark the Area You Want to Cover

Start by measuring the length and height of the area you want to cover with your mosaic (in my case it was a small strip at the back of my bathroom vanity):

I used a square to draw a line on the wall marking the desired height of my mosaic on either side of my bathroom vanity, and then used a long straight-edge to draw a line connecting the two lines:

STEP 2: Mark & Cut Mosaic

Most mosiac material will come looking something like this (a bunch of small pieces of tile attached at the back by a webbing):

Typically they are patterned and designed to fit together, so you need to take them out of the package and fit them together like a puzzle:

Flip the mosaic over web-side up, and use a utility knife to cut out a strip of your desired width:

Flip your mosaic back over right-side up and find where the end of your strip fits along the edge of your excess piece:

Flip the mosiac over web-side up and cut along the line where your strip fits:

Trim off excess:

Flip the mosiac right-side up and measure to see if you have enough to fit your space (measure from farthest inset piece to nearest inset piece).  If you have enough, proceed to the next step - if you don't have enough, repeat the previous step until you do have enough.

Starting at the furthest inset piece, use a square to mark the finished edge of your mosiac:

Use a wet tile saw to cut the mosaic along your line:

Repeat on the other end.

Piece your cut mosiac together along the area you are hoping to cover to ensure that it is the right size (make any necessary adjustments if it is not):

STEP 3: Prepare Mortar

Using a bucket, drill and mixing attachment, mix thinset mortar according to product instructions:

Use a putty knife to evenly spread mortar on the area you want to cover with mosaic.  You don't want to get the mortar too thick or it will squish out between the cracks of your mosaic and get really messy, but you don't want to get it too thin either, or your mosaic won't adhere sufficiently.  I found about 1/8" - 3/16" good.

Drag a square-notched trowel across your mortared area, creating grooves in the mortar:

STEP 4: Install Mosaic

Starting at your marked edge with your first piece, place the mosaic against the mortar on the wall right-side out and press firmly in place. Check to make sure it is straight and even:

Once the first piece is secured, proceed with the 2nd piece and so on until you have reached your end mark:

I chose to cap off my mosaic with some marble edging, so once my mosiac was installed I proceeded to install the marble edging on top of my mosiac:

 Run a putty knife along the edges of your mosaic to remove any excess mortar from the wall and surrounding area:

Use a damp rag to clean off any mortar on the surface of your mosaic, wall, and surrounding area (remember that any mortar left will turn to cement when dry and become extremely difficult to remove, so make sure you don't have any mortar left in places where you don't want it).

Make any final, fine-tuned adjustments that may be necessary and leave to set according to product instructions (usually 24 hours).

STEP 5: Grout

Mix grout according to product instructions (typically you will mix it, let it rest for a couple minutes and then mix it again before you use it).

I like to mask off the rough ends of my mosaic with painter's tape to help me get a clean, straight line along the edge:

Apply grout to the surface of your mosaic, filling in all of the cracks.  Typically you would do this with a grout float, but because I choose a mosaic that included rough, uneven, tumbled marble pieces my surface was not entirely flat which made a typical grout float pretty useless.  Instead I found an old rubber spatula to spread the grout and it worked great!

 Scrape off as much excess grout as you can from off the surface of the mosaic and leave it to rest according to product instructions:

When the grout is set just enough (not too hard, but just soft enough that you can still wipe it off with a little effort without pulling it out of the cracks), wipe the surface of the mosaic clean.  If you have a smooth surfaced mosaic use a flat, small-pored sponge and a bucket of clean water for each wipe (usually 3 wipe-downs is enough).  In my case because of the rough, tumbled marble pieces a rag was better - however, I had to be very careful because the rag was notorious for pulling grout out of the cracks.  After my first wipe-down, I let it rest a little longer and then gently went over each of the tumbled marble pieces with a tooth-brush to clean the grout off, and then one last final wipe.

When you are satisfied that the grout has been sufficiently cleaned off of the mosaic leave it to set according to product instructions. 7-10 days after the grout has set, go back and seal it with grout sealer.

Enjoy your new back-splash!


  1. You are so talented. Thank you for posting these step-by-step instructions! I'm needing to do this in both of my bathrooms (*dreading it*).

  2. WOW - such a dramatic change! Worth all that hard work, though; it's gorgeous!

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