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Bath & Faucets

Tile over Tile Bathroom - Walls and Floors

Hello everyone ,

First time posting here , been reading and enjoying the great Home Depot Community for while now :)

This time is my turn to ask a question and help is appreciated please 

I have 12 x 12 inches tiles on my bathroom walls and floor 
These tiles are not Glossy but Mat and the surface on the tile is not too very smooth.
My wife and I wish to remodel the bath with going to the big mess of breaking the tiles ( Dust , breaking the Drywall ...)

I wish to install Home Depot Onyx Crystal 18 x 18 Glazed Porcelain tiles  over the old tiles without removing the old ones.

Could you please advise how to complete this project please ?
  • How to prepare the surface ( Walls & Floor )
  • Type of Cement / Glue 
  • Ceramic / Porcelain cutting ( Tile saw or Tile Cutter )
  • Type of Lash Tile Leveling Clips if required on the floor
  • Type of Grout suggestions for this project
  • Grout Sealer for Porcelain floor & Porcelain Walls
  • Your advises how to prevent floor tires from breaking once installed ( cement laying )

I'm running late for this project since we have family coming Next Friday 
I appreciate your inputs and advise 

Kindest Regards

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Posted 2017-02-04T16:21:20+0000  by VIP VIP
Good afternoon Karim,

Thank you for taking the time to ask us these questions, and thanks for being a fan of the community!

I will attempt to answer your questions in the order in which you asked, so here we go:

  • How to prepare the surface ( Walls & Floor )

  For starters, it is possible to install the larger newer tile over the existing surface of tile. Just make sure the already installed 12" x 12" tile is clean, level, and firmly secured to the wall before continuing. Cleaning is the biggest step to ensure the new tiles can and will be installed over it without issues.

  • Type of Cement / Glue

Since you have a large format (18" x 18") porcelain tile, you'll need to use a thin-set mortar or tile mastic that is rated for holding that much vertical weight. 

The best mortar I can recommend in your situation is a high-quality and tough version we sell at your local Home Depot.

It's shown below and linked here. Click on the link to read more about this great mortar. As the image shows below this one, it's best to install it via a notched trowel. 


  • Ceramic / Porcelain cutting ( Tile saw or Tile Cutter )

Whenever you can, always opt for using a wet tile saw for cutting the sizes needed for your tile. Even if you are just cutting tiles for one room, a wet tile saw always cuts faster, better, and cleaner than any manual cutter.Large Tile Saw

Your best option would be to rent a large wet tile cutter from your local Home Depot that has a Tool Rental Center. Renting at a fraction of the cost of buying one is the best way to cut and get the correct shapes for your tiles. 

  • Type of Lash Tile Leveling Clips if required on the floor

You said it yourself...IF they are needed for the floor. You can see if you need to use them via putting a level on the floor. If the floor is level, then using just basic tile spacers can work. 

  • Type of Grout suggestions for this project

It's actually up to you what grout and color to use. Just remember that any grout joint that is 1/8" or wider, you'll need to use sanded grout. This is a great option for floors, since sanded grout is less prone to cracking and damage. You can use non-sanded grout on the walls for joints less than 1/8" wide.

At the end of the day, it's really up to these points I just mentioned, as well as personal preference.

  • Grout Sealer for Porcelain floor & Porcelain Walls

Sort of the same rule as the grout...personal choice. But, I would suggest to refrain from high gloss sealers as they can create slip hazards in the bathroom. 

Most sealers simply penetrate the tile and grout without changing color or giving it a sheen. These sealers are sold at your local Home Depot. Opt for using a tile sealer in a ready to use spray bottle. 
TileLab 24 oz. Grout and Tile Sealer

The biggest thing you'll need to do with sealing your tiles is to reseal them when it is needed. This is usually done yearly or 18 months. To test areas to see if you need tile sealer, simply place a few beads of water on the surface of the tile/grout. 

If the water is still in place within a minute or so, then no resealing is needed. However, if the water soaks into the tile, it's time to reseal. Always reseal higher traffic areas first, like the shower floor and entrance areas on the floor.

  • Your advises how to prevent floor tiles from breaking once installed ( cement laying )

As I stated earlier, just make sure the tiles are installed on a clean and level surface, with the existing tiles firmly attached to the wall or floor.

If you do this, you'll greatly reduce the chances of any damage to the tiles. One of the biggest reasons of tile failure after installation is the neglect of cleaning and resealing the tiles and grout over time.

Water can and will seep into the grout joints, and can loosen and damage the grout, and then the bond to the tile. To eliminate that factor, simply reseal the tile and grout via a grout sponge as mentioned earlier.

The last thing I want you to know that whenever you place tile over an existing surface of tile, is that you will be raising the level of the floor as well as thickening the depth of your walls and vertical surfaces.

This means adjusting any base moulding, toilets, and faucets in the shower. Plan this accordingly so you can reduce the amount of cuts and alterations to those areas. Even your door may not close or will be tight to open. You may need to adjust the height. 

Let me know if you have any further questions, and we will be more than happy to assist you.

Posted 2017-02-04T20:23:04+0000  by Joseph_HD_ATL
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