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August 2012

Tile Floor Failures

By How To, Knowledge No Comments

There may be many causes for a tile floor to fail.  I will show you the most common causes, and how to prevent them from occurring.

1.  Improper thinset(mortar) used to adhere the tile to the substrate.

2.  Contamination of the substrate- Concrete, plywood, or underlayment could be affected by paint, dust, coatings, or sealers adhering to those surfaces.

3.  Failure to install the substrate properly.

4.  Improper perimeter expansion space.

5.  Little or no soft joint expansions in the floor(especially on a space that is exposed to temperature swings).

6.  Too much flex in the wood subfloor, usually as a result of inadequate floor joists or a subfloor that is too thin.

7.  Hydrostatic pressure from underneath the slab(usually due to a copper waterline leak).

8.  Not wetting the hardeebacker prior to applying the thinset and tile.

9.  Allowing the thinset(mortar) to skim over(airdry) before placing the tile down.

10.  Not applying thinset to the wood subfloor prior to installing the backerboard.

11.  Thinset failure itself.  This may happen on occasion, but it is rare; failures due to a thinset manufacturer problem are few.

In most cases of floor tile failure, there is usually more than one cause; Seeing cracks in the grout, tiles that are loose, and big “humps” in the middle of the floor are strong indicators of a problem.

Here are some suggestions to keep your floor beautiful and lasting for years to come:

*  start with a clean floor.

*  allow proper expansion around the perimeter and proper expansion(soft joint) at recommended intervals in the floor.

*  use the best quality thinset(mortar) that is acceptable to the substrate.  Don’t skimp on the thinset.  If after reading the bag you find that your thinset is acceptable, go a grade higher.  For a few more dollars a bag, you can save a lot of money and headaches.

*  install your substrates(both plywood and underlayment) on a “brick joint”.  The joints should be “T”‘s, not “pluses”.  This is very important.  There is strength in the staggered joint of anything(brick walls, honey combs and floor substrates).

*  make sure that you have adequate space for expansion of your floor.  Tile is not hardwood, but should be treated as so.  Temperature changes can expand and contract a tile floor tremendously.  If the temperature of the home is 78 degrees, and the temperature outside is 10 degrees, an open door can create a large thermoshock to the floor.

*  be sure that the floor has big and frequent floor joists(check your codes).  Too much flex(spring) in the floor is not good.

*  if you have tile installed on your slab and get an underslab waterleak, get it fixed as soon as possible.  Bear in mind, an underslab leak doesn’t mean that your tile is going to fail, but it can cause enough pressure to brake the bond if the slab was contaminated.

*  hardeebacker underlayment must be wet with potable water prior to applying thinset and the substrate tile.  Failure to do so may result in the tile not adhering to the backerboard.  I think what may happen is that the backerboard “sucks” out the moisture from the thinset before any good bond can be made with the tile.

*  allowing the thinset to “skim” over is a problem in hot, dry, windy air.  The sun skims thinset quickly.  I liken it to painting a wall.  When you paint a wall, the paint is wet and sticky to the touch, but after a few minutes it is dry to the touch but still wet underneath.  It is the same way with thinset.  The tile will not make a good bond if it is placed over the thinset after it has skimmed.

*  when installing backerboard to a wood subfloor, a good thinset must be applied prior to nailing the backerboard to the wood.  The thinset fills in the voids and bellys the wood.

*  thinset failures do occur from time to time.  It has been my experience that the wrong thinset was used on the sublfoor and it is usually not the fault of the manufacturer.  If the thinset itself fails, it is usually due to the thinset being used past its shelf life.  Never use old thinset.  The money you try to save will cost you more later.

This covers most of the reasons for tile floor failures.  The best way to avoid these problems is to use a reputable tile installer for you job.  Hire someone who knows the best products and how to use them.