Expert: Stephen Hayes - 6/8/2007

Question
QUESTION: I have removed some tiles from my downstair family room and they had that black adhesive but all gone.I want to install travertine but I notice that water beads up on the concrete floor. How should I prepare it for stone tile? Seal? and if so with what? Or strip with what?
Thanks in advance

ANSWER: Since you indicate that the old adhesive was black, in color, it was probably old cut back adhesive.  Concrete is porous and absorbs that old adhesive.  When you apply a new adhesive, and sometimes a sealer, a chemical reaction occurs that causes new adhesive and certain types of sealer to become gooey, as well as the old cut back adhesive in the concrete, so any installation is doomed to fail.  By the way, usually old tile that was installed with black cut-back adhesive, may have contained asbestos, so we certain hope that your old tiles were asbestos free.  If they did contain asbestos, for your and your family's health, we strongly suggest checking your ventilation system, the concrete, other absorbent surfaces, clothing, upholstery, other fabrics, etc., for any signs of microscopic asbestos fibers, and get them removed before ANY more work is done, unless you confirmed the old tiles did not contain asbestos, and/or removed those old tiles in accordance with government health regulations by having the area isolated with plastic coverings and anyone who took up the tiles wearing full hazmat type suits and masks.  If you have no indication if those tiles did contain asbestos, we do suggest that you and other occupants immediately visit your doctor to be evaluated for possible asbestos contamination, especially in lungs.  We certain hate to scare you, but asbestos in old tiles on concrete, is extremely dangerous and MUST be removed and/or sealed properly.  Back to you installation questions.  First a moisture test should be taken of the concrete.  If you have a moisture problem (concrete always moves and absorbs), it must be rectified.  Perhaps a water table may have changed, you have a leak of which you were not aware, the cover that the builder of the home put over the ground during construction of the foundation may have failed, etc.  So if your moisture tests result in readings above what the adhesive or sealer manufacturer indicates in his installation instructions, the moisture problem must be properly addressed.  If the moisture tests indicate that the moisture content of the concrete is acceptable, that concrete should be sealed and then adhesive you are going to use for your new flooring applied properly to the top of the sealer.  You MUST check with the adhesive manufacturer as to what type of sealer you should use that will, not only properly seal the concrete, but also be compatable with the adhesive that you will be using to install your new flooring.  Follow the adhesive and flooring manufacturer's installation specifications, including the specifications of the adhesive.  What size trowel should be used, how much open time should be allowed for the adhesive to properly set up before installing the flooring, the acceptable temperatures and humidity factors that should be present when using the adhesive, how long the adhesive and flooring should be in the actual installation environment to acclimate before being used, what type of roller should be used, how many times should the flooring be rolled, how soon after the installation of the adhesive and flooring is foot traffic allowed on the flooring, maintenance specifications of the new flooring, etc.  Sorry to be so technical, but there is a lot that goes into a successful flooring installation, and we certainly don't want yours to fail.  Note that you may have to properly seal the concrete and then install a proper underlayment over the concrete, such as plywood, etc., but check with the suppliers of your flooring and adhesive.  Their websites usually have telephone numbers or links to receive written installation specifications.  If you diligently follow those written specifications your installation will most likely be successful.

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QUESTION: Thanks for your answers. Luckily, no asbestos. The flooring is above ground concrete and I want to install travertine but your answers seem to refer to hardwoods or linoleum? Can I just put thin-set right over the concrete? Thanks in advance

Answer
Sergio;  Our answers pertained to any type of flooring, vinyl, linoleum, hardwoods, laminate, ceramic, travertine, etc.  You indicate that there is evidence of moisture on the concrete.  That needs to be addressed before thin-set or any other approved sealer.  Again, just properly address the moisture, make sure thin-set is approved by the manufacturer of any flooring or adhesive you plan to use, and review their pre-installation and installation specifications beore you do anything.  Usually thin-set will do the job, however check to see if the subfloor concrete, jipcrete, a synthetic concrete, etc., and read the instructions on any thin-set you use for proper preparation and acceptable conditions for its use.  We are a nationwide floor covering inspection service.  We inspect all types of floor coverings and have 860 inspectors servicing every city and town in all 50 States and Canada.  We are called upon when problems arise, so our answers to you relate to all types of problems that we find arise, before, during, or after an installation.  Just be thorough and check everything out so you won't be disappointed later.