Tile Waterproof Membrane

Here’s the deal:  you install tile in bathrooms, kitchens, showers, bathtubs, and other watery places because tile is great at repelling moisture.

But it’s not 100% waterproof.  You’ve got grout seams to deal with, and any kind of seam can let water in.  Not matter how much grout sealant you put on the grout, there is still the chance of water getting through.

If you really want to take care of the problem, install a tile waterproof membrane.

Yes, tile itself in impervious to water.  It’s just the sub-surface (or substrate, whatever you want to call it) that can be damaged.

Polyethylene Sheeting

A good type of inexpensive tile waterproof membrane.  Staple down the poly plastic to the subsurface, then install the HardiePlank or other backer board, then the tile.  You don’t need a million staples, just enough to hold the plastic in place.  More staples mean more chance of water leakage to the sub-surface.

Roofing or Tar Paper

Tar Paper

This stuff is el cheapo and comes in big rolls at your local hardware store; always great to have around.  Roofing paper has fallen out of favor because there are “better” things like housewrap, but I think that tar paper still is pretty good stuff.

The tile and thin-set mortar do not install directly on the tar paper!

Instead, staple the tar paper on your sub-surface (like drywall, if you’re tiling a wall), then install your cement backerboard over that.

Tile on Particle Board?

I am going to assume that you mean “install directly on particle board.”  In other words, using the particle board as an underlayment for tile.

You can install tile indirectly on particle board, as long as you have a proper intervening underlayment.

But, no, it would be a disaster to install tile on particle board.

Cement board, plywood, and concrete are good bases for tiling.

Particle Board

Particle board soaks up water like crazy.  When you are installing tile, you will use thin-set mortar, which is loaded with water.  The minute the mortar comes into contact with the particle board, the board will begin sucking the water away like a sponge and ballooning up.

By the time your tile installation is finished, the entire floor will be dippy and slope-y and mushy from that wet particle board.

Do not install tile on particle board.

Install Tile on Plywood?

Yes, you can install tile on plywood, but it’s not the very best base for tile installation.

Cement-based surfaces such as concrete and cement board (WonderBoard, HardiePlank, etc.) are more stable and provide a better “stick” than plywood.  But tile on plywood still isn’t bad.

If you feel uncertain at all about your plywood, then screw down cement backerboard over the whole thing.  It’s work, but it guarantees a perfect installation.

  • Choose exterior-grade plywood BC.  “B” is the grade of one side; “C” is the grade of the back side.
  • Use 3/4″ plywood.
  • Make sure that the “B” side–smooth side–is up.  The reason you’ll be installing on exterior grade is because this type of plywood deals with water better, and your thin-set mortar will be loaded up with water.
  • Already have plywood down but don’t know what kind of plywood this is?  You may be able to get in the crawlspace and see grade markings on the bottom.
  • Use only complete sheets, where possible.
  • This plywood must be absolutely stable and bend-free.  Any kind of “give” when you walk will transmit to your new tile, and will eventually crack the tile.
  • Avoiding having the joints of the plywood lining up; stagger the joints instead.
Plywood Subfloor Layout for Tile on Tile Installation - Notice Staggered Joints
Plywood Subfloor Layout for Tile on Tile Installation - Notice Staggered Joints

Install Tile on Tile?

And it can be done, though it’s not the optimal tile-laying base.  Why?

The main issue is glossiness.  Most tile has glazing; that’s why we install tile, after all.  Glazing repels water.  Glazing also repels thin-set mortar, the stuff you’ll be using to lay down your next layer of tile.

Tile Floor

The work-around is to roughen up your existing tile with a belt sander.  Put some heavy-duty grit sandpaper in the 40 to 60 grit range, on your belt sander.  Slip on a pair of safety glasses.  Seal up doorways to prevent tile dust and particles from invading the rest of your house.

End up cracking a few tiles?  Don’t worry; no need to repair.  Your next tile layer will cover everything.

Let the weight of the sander and weight of your hands do the work.  Don’t press hard.  You probably won’t be able to get every single square inch of the tiles, but don’t worry.  Just get most of it.

After sanding, clean the tile surface thoroughly–clean enough for a baby to crawl on.

Then install tile on tile, just as if it were any other type of underlayment.

Tile on Concrete

Yes, in fact concrete is one of the better base surfaces for tiling.  You just need to make sure of a few things first:

Concrete Should Be Dry

Any moisture will affect your tile installation.  No, it’s not as grave a thing as if you laid wood floor on moist concrete, because tiling does involve moisture.  If the concrete has recently been laid, you’ll want to wait several days or even longer to make sure the concrete is properly cured.

How moist is too moist?  Tape clear plastic over the surface and wait a day–beads of water underneath indicate that the concrete is too moist for tiling.

No High Areas

Chop down bumpy, ridge-type crap with your mortar chisel (a nice tool to have on hand, by the way).  Smoother, more undulating hills are actually more of a problem because they can’t be chipped away.  You may need to rent a concrete grinder.

But one of the great things about installing tile on concrete is that tile can conform well to these sloping areas.  It’s just a matter of how much curviness you want to tolerate.

Sealing Tile Grout

Got Holes?

Holes in concrete are easy to repair.  No need to mix up a whole bag of concrete; just get smaller-size concrete patch mix from the hardware store and screed smooth with a piece of waste 2×4.  Don’t make your repair beautiful.  It’s going to get covered with tile.  Flat is all you need.

Stabilize Cracks

If you have a crack now, it will be a larger crack later on.  Cracks always expand.  Get serious about cracks and stabilize them before you put tile on concrete.

Dry and Rough

Get any kind of shiny treatment stuff (i.e., sealers), oils, paint, etc. off of your concrete.  If you rented a concrete grinder, you can roughen up the entire surface with the grinder.  Or you can rough up concrete by hand.  Either way, dry and rough is how the concrete should feel before installing tile.