You are always taking a big chance when tiling over "contaminated concrete", and Las Vegas odds makers will bet against your success. Scrape all you want and it will not be enough. Sanding, or grinding is also required or "shot blasting' by a professional. Other option is to use a "slip sheet" membrane to neutralize the glue effect. I have mentioned this resolution many times in older posts, which should make good reading when there isn't anything good on the "Boob Tube" to watch, and that is quite often these days. Besides, you get a free education on tiling. Let us assume you choose one of the membranes to neutralize your glue problem.

The dip in the floor stays, unless you are comfortable with blocking it, leveling it and then tiling as if it was never there. However, if it was planned as a way to get rid of water from sources unbeknownst to you, you had better check it out. Many hot water systems have pressure relief valves that expel water at intervals and unless you have a bucket placed at the “outlet pipes”, and monitor them, you can anticipate water damage to furnishings and flooring. You asked a question without giving me all the facts, so I can only assume this obvious scenario for a drain in a basement floor. You can soften the pitch a bit by raising the drain a bit with adaptors. Or:

Cut a pattern into your tiles near the drain or several tiles approaching the drain, as you may have seen in many commercial bathroom and restaurant kitchen installations. Laying the floor tiles in a diagonal pattern helps soften a pitched layout. If there is only one drain, and it is in the center of the room, you can plan your layout starting with a full tile quartered and centered on the drain or have the corners of four tiles meet exactly over the drain, so all the cuts are uniform is size. You can be creative with a “starburst pattern” for a conversation piece. Much depends on the use you have planned for this room. A ‘Man Cave”, for instance, could have a pool table centered over the drain to conceal it. If the tiles are installed properly, a great bond, and no air under the tiles, you should never have a problem. 18” tiles must be “respected” and their backsides “buttered up” before installation, as we recommend. Need more help, just ask. Armen Tavy

I am not aware what the building practices were in NC 60 + years ago. The popular way in most cities was wire-lath, and cement which we respectfully call a “Mud Job”. If this is the case in your home, I can see the reluctance of your contractor to tear it out. It can be several inches thick and a “bear” to remove. Can you tile over it if it is sound? It does work and it does save you money. Marble transitions at doorways can make up the difference in height and is esthetically correct. Floor dips can be filled with a self leveling cement that is prepped with its own liquid primer. A new natural stone floor can be installed over an old ceramic floor. There are a variety of ways and I don’t know what your contractors preferences are? Get a bid, ask him how he intends to prep the floor and get back to me.

The main problem with older homes with dips, is, if the dips are caused by the home’s foundation settling, other floors can dip can dip as well in the future. An building engineer can tell you if your floors need to be jacked. Interior load bearing walls, seem to be the weakest in older 100 year old homes, and these walls usually sag inwardly. Will it harm your floors? Not as a rule, because the walls tend to sag at the load bearing partition and you will can compensate for the pitch by tipping your body a little whilst walking. ‘Just a little humor, on a rainy afternoon, here in Florida”.

 I don’t believe you have anything serious to worry about. If you and your contractor decide to tear out the floors, the first layer of wood is most likely 1 x 4 boards on a diagonal and sometimes these boards are tongue and groove. In the first case a second layer of 3/4” plywood secured with sub flooring adhesive and roofing nails in an 8” grid pattern in the field, and 6” along seams and perimeters. In the second example with T & G, the adhesive becomes an option, the plywood can be reduces to 1/2”, and the fastening remains the same. We, in the Tile Industry, do not favor installations directly over wood, so the addition of a monolithic membrane, aka “slip sheet” or 1/4” cement backerboards (CBU) is the way to go (installed correctly). Because you are mentioning “natural stone”, I have to make you aware that price is usually a factor in the quality, so beware of “good deals”, and buy only from reputable dealers. You will enjoy your floor for years. Armen Tavy

You have several options: A great deal also depends on the size of the floor and if it is over wood, backerboard or concrete.

Use a long handle tile removing bar that has a stiff blade at the end. Reasonably priced and available at any "Big Box Store", Lowe's, Home Depot, Menards, etc.. You use it while standing.

On your knees with a hammer and a 2", 3," or 4" wide cold chisel.

Rent a tile removing tool from a rental yard. They have an electric motor, are on the heavy side, have a 6" blade that gets under the tiles and does the chiseling for you. (They work quite well)

Purchase a $366 + - Electric Demo Tool made by MAKITA model # HK1810, an amazing tool, with many other uses around the home for a "Handyman" or "Handywoman".

OR: If you have elevation room, tile over tile with a variety of "Thin" Tile Underlayments or High End Mortars. (Ask Me again on this one).

If you are tiling over a "slab" and have hairline or larger cracks, a heavy duty tile crack supressant underlayment will be neessary if your Travertine Tiles are "Low Grade". Easiest way to determine this is usually by the retail cost. You get what you pay for. + - $3 a square foot, the slab must be perfect. The less dense the tile, the easier it cracks over sub-floor defects. Need more help? Write again. Armen Tavy

I have no idea where you came up with that information. There are no rules except that there should be a joint large enough for grout to enter and lock in. There are recommendations for esthetics. Besides, how would anyone know how thick a tiles was before it was installed just by looking at the finished installation. Sanded grouts are limited to a 1/8" minimum and no maximum and non-sanded from hairline to a maximum of 1/8". Otherwise, "Beauty is in the eyes of the beholder". Thanks for the vote of confidence. Armen Tavy

No matter what, they still charged you for “AIR”. I am, and always will be, a "Neat Freak" when it comes to these tiles and I have installed mega thousands of feet. After an installation I would trim the floor tiles to even out irregularities that I did not like using a 4" angle grinder. I never installed with a 1 inch grout joint, preferring a finger width. I always got compliments on my  installations from everyone. However, this is not authentic. Irregularity is "old world" and some people prefer it. One customer told me that he had heard I was a “Neat Freak” and pleaded with me to install the tiles with a “crude touch”. It was the most difficult thing anyone has ever asked me to do.

However, in your case there is a 1,000 square feet down and putting a curve/angle in the floor at this time would be very noticeable. These tiles cut very fast on a saw and you only have to cut two sides to get 11 inches not four sides. A slight irregularity to the saw cuts is advisable, so the even saw lines are camouflaged. This is done by running the dry saw blade of a 4” angle grinder lightly along the cut tiles sides, with a variety of pressures. A slight erratic dig into the sides on occasion does wonders. A very, very, slight rounding/softening of the three outside corners of each cut tile, to match the one original corner, is advisable. A good helper could do this in one 8 hour  day, and at $12.50 an hour, it would only cost 100 bucks, or .06 cents per tile, an affordable price to get what you want.  Armen Tavy

As in #12279, I hope you fastened the "Wonderboard" properly with an adhesive and corrosion resistant fasteners, spaced the boards 1/8" apart, filled the spaces with modified mortar, taped the seams with Alkali Reistant Tape and skim coated the tape with more thin-set mortar. If you set the "Wonderboard" DRY, you should remove them as well and re-install the boards upside down to rid yourself of the "contamination". Use a sub-flooring adhesive (there is a specific glue pattern, ask me) or thin-set mortar under the boards and then use the fasteners. You should be an expert by the time you are done and will be able to advise others. Armen Tavy

If you have some free time you should scan past questions as I have covered this subject often. Here are the "rules": Never try to set Porcelain Tiles on floors or walls with pre-mixed mastic. Mastics are organic and they dry/set up by "evaporation". Since Porcelain Tiles are very dense, they do not allow the mastic to evaporate quickly, properly or sometimes NEVER. Air must get at the mastic from the sides inward to the center to allow evaporation which is necessary to cure the mastic. Installing Porcelain Tiles with mastic is like "putting the lid back on the bucket", so to speak. You did a good thing putting down “Wonderboard”, (as long as you fastened it properly, and I have covered this many times as well) but you backtracked when you switched to an organic product to install Porcelain Tiles over a cementitious product. Like materials like one-another. I do not want to upset you but, you have already messed up any chances of getting a “perfect” mechanical bond to the Wonderboard. Pre-mixed mastics are better used on kitchen backsplashes and non-wet areas of sheetrock walls, and tiles should not to exceed 6". But, all is not lost.

If you are ready to admit you made a mistake and “chalk it off to experience” and would rather save your tiles and the “Wonderboard” floor, here is what you must do. Remove each tile and wash off all the mastic. The mastic will emulsify if you get it wet. Soaking the tiles in tubs of water may be required. Clean each tile completely and dry them with towels setting them aside "vertically" and not in flat stacks to air dry overnight. Clean the "Wonderboard" ” with a 6” putty knife as you remove each tile so the mastic does not dry making it more difficult to remove. Wash the mastic off the floor with wet rags. You may have to scrub with a stiff brush as well, then sponge it as clean as you can. You should then purchase a 2-part "Liquid Latex Modified Mortar" to skim coat (very thin) the entire "Wonderboard" area that had mastic on it, and let it cure overnight to return the “Wonderboard” to a “tileable” surface.

You probably should consider using the same mortar to set your tiles. Multi-Purpose Modified Thin-Set Mortars (a little less expensive) mixed with water will work but the “Liquid Latex Modified Mortar” would assure you the best possible mechanical bond to the “contaminated” “Wonderboard” and to the backs of the Porcelain Tiles. Please “hide” that 1/4" trowel somewhere and purchase a premium handle (also much more efficient and comfortable) 1/4" x 3/8" x 1/4" trowel to reset your tiles. Skim Coat the mortar onto the floor with the straight edge side of the trowel. This coating only has to be paper thin, then comb more mortar “the consistency of mayonnaise” in neat "corn rows" left to right (like straight rows of corn in a field) holding your trowel at, no less than, a 60 degree angle to the floor. Press as hard as you can while spreading so you only leave the correct amount of mortar the trowel was designed for. Skim Coat (very thin again) the back of each tile just before you lay them in place, push the tile down, push it forward about 3/8 of an inch, then pull it back into position, and if you use my TAVY “Tile Spacers” you will find that it will be easier to align your tiles. If you are concerned about your ability to lay the tiles flat without “lippage”, try using my TAVY “Tile Puck”, you won’t be sorry. I hope this helps you regain your sanity. Need more help, just write again. Armen Tavy

Sorry, I was out of town on the 26th and missed your question. You are talking about "Cut-Back" adhesive residue. You have cleaned it some, but not enough. Lacquer Thinner is the most dangerous product to use in a residence. Turning on a light switch or a heater/air conditioner cycling, etc., can cause a fatal explosion. Besides, it still would not get the concrete slab "clean enough" to tile over. Grinding, shot blasting, sanding are the only mechanical ways or the use of tile underlayment membranes is your only alternative now. If you had done your homework sooner and reviewed other options, instead of removing the vinyl, you could have used a variety of membranes first and just tiled over the vinyl.

Too late now, so your only option is to use one of those products to solve your dilemma. Any of these products will also give you crack suppression protection for those old fractures. Schluter Kerdi or Ditra Mat, Noble T/S, Tavy "Thin-Skin" and “Protecto-Wrap”, are just "five", and there are that many more. Check your "pocket book" and choose one you can afford or feel the most comfortable with. Do not use any solvent-based products that will congeal with the "Cut-Back" Residue. The first three would require an overnight "skim coating" followed by a "Test Removal", to be certain you achieved a sufficient mechanical bond "skim coating" with mortar products that require a "Liquid Latex Additive", i.e., “Laticrete Megabond” with “Liquid Megabond Additive”, Mapei “Kerabond Keralastic” with “Liquid Keralastic Additive”, Custom's "Mega Blend" with "Custom Flex Additive",  etc., to get an initial "mechanical" bond to the minimal residue you have left on your floor.  Armen Tavy

A #3-wear rating is not sufficient for this kind of (miss)use. A minimum #4, Light Residential, and of course #5, Heavy Residential and Commercial, would have been better. The mortar transference to the backs of the tiles should be 100% around their perimeters (to prevent or reduce chipping from chairs and instrument’s legs) and not less than the minimum requirement of 80% on the rest of the tile's backside.

This question is more important than you realize, and it is sad that many installers are in a hurry, spread mortar in swirls instead of left to right horizontal rows and do not take the time to pop a tile on occasion while installing, to check for full coverage around perimeters and a minimum of 80% in the field. If, upon inspection, they find that there is not sufficient mortar coverage, spreading techniques must be reviewed. Correct "Notched Trowels" are a must. Never less than 1/4" x 3/8" x 1/4" for any floor tiles and larger notches for tile formats over 13". Some 12" & 13" tiles and Most Porcelain Tiles should be back buttered (a flat and level skim coat) just before installation. Many experienced installers always put a "tad" of mortar on each corner of a tile before they set them, because this is the weakest part of any tile and the first to break. "TIRTGIM" 

(Tile It Right To Give It Might") is my motto and I always use a 1/4" x 1/2" x 1/4” U-Notched Trowel and back butter Porcelain & larger format tiles, all the time. I have on on-going problem with TV Home Improvement programs that make tiling "look so easy" and do not bother to use or explain (probably because they don't know how) these very important issues that are the major causes of job failures all over the world. I plan to make and market some self help videos and publications in great detail, that will address all the issues. You will be able to view important excerpts free on www.tavytools.com .........soon. My picture will be on the cover/s, pointing my finger at you,

Joyce, You can sign on and post this same question on our other forum, that accepts pictures in the correct format. www.thetiledoctor/forum.com I can review it/them, and comment further. 

      "You Must Have a Passion for a Trade or You Don't Belong In It". Armen Tavy

You did not loose your post Rose. I was writting my answer to #12275

You have heard the "ditty" "Never Put Bananas in the Refrigerator" (which is not true, by the way). Well we say, "Never use Ceramic Tile Mastic/Adhesive to install Granite or any natural stone tiles. In order for mastics/adhesives to cure, the moisture in their make-up must “evaporate”. The discoloration may only seem yellow because of the stones natural coloration. It may or may not be a permanent stain. What the mastic/adhesive is trying to do is evaporate thru the stone, and if it can, it can take as long as a year before the "darkness" disappears. Stone that gets wet "naturally darkens" because the mastic/adhesive is "wetting" the stone as it leaches into it. This gives you only two options, if you hate the look and cannot wait a year to see if the discoloration disappears, you will have to tear it out and start all over again or, read on.

Re-read the label on the mastic/adhesive bucket to see if there was a warning about not using their product to install natural stone. Do not impede the evaporation process with carpets and the like, over the tiles concerned. The damage is already done and “Patience is a Virtue”, which may save you a lot of money. Pick a tile and measure the stain/discoloration. If the darkness or discoloration is only on parts of the tile, check it once a month to see if the discoloration is growing smaller. As time goes by, the area around the perimeter of the stones should lighten first. Air movement or a small fan blowing softly enough not to disturb you, can expedite the evaporation process. Do not SEAL the stone at this point because you want it to "breath". If after + - a year you are still not happy, a Liquid Stone Enhancing Sealer may darken the entire stone/s to one uniform color to make the discoloration less obvious. I would not go this route yet, be patient. Armen Tavy

Sure you could, but would you "Bet the Farm" on the gypsum board not being compromised by a "water leak" someday, even from a small leak in a water diveter valve? If the gypsum "disintegrated", it would take the waterproofing and tile with it. Whether you are talking about a shower stall or tub surround, removing the gypsum board is not a difficult task and you don't necessarily have to remove it all the way up to the ceiling. Replace it with five or six feet (off the floor) of cement board (CBU) blended into the gypsum at a height that won't come back to haunt you, makes better sense. To spend all the money and labor and then chance a failure for a "frugal reason" is not the best way to save money and labor. The best advice I can give you is to "Bite the Bullet" and rid yourself of future concerns up front. Armen Tavy

With one hand tied behing your back all day, with two hands about 30 minutes. All cement based grouts should be allowed to dry for at least 24 hours. Sealing times are at the discretion of each sealer manufacturer. Instructions on the containers must be followed. Generally speaking, the minimum for aresol sprays is 2 hours and other wipe on types can have as long as  a 48 hour wait. Armen Tavy

I always say that "Air is the enemy unless you are breating it or it is in your life jacket, it does not belong under tile. Air under a tile is a weak spot that will not support a tile properly in case something is dropped on it, or it is walked on often, as in a high traffic area of a room. The Industry has determined that spreading the tile mortar in, neat as possible, "corn rows" left to right, will help eliminate air as the tiles are pressed into place. When placing the tiles they should be pressed in and moved forward to collapse the high ridges of mortar, into the low cavities, then adjusted back to a correct position for alignment. Tiles should be placed against each other and then pulled way to the approximate grout size by eye and then ideally be spaced with tile spacers. Tile spacer are more accurate, should stay on the joints overnight to prevent "drifting" and also as a warning to possible trespassers to stay off the newly tiled floor. The moving and sliding of the tiles, while setting, also removes air as well, and assuring that mortar spreads uniformly, or as we say "transfers" to the backs of the tiles to a minimum of 80% coverage indoors and as much as 95% outdooors, which is aldo the minimum for marble and granite tiles.

Mortar should not be used to level a floor because it is uneven, those issues are bettter addressed before tiling commences. f

For the best results, all sub floors should be checked for level within 1/8" in a 10 foot span  and leveled as neccessary at that time with levelers or patching materials. Leveling as you go can, and does get all that try it, into "trouble". Using extra mortar under a tile, other than what the trowel (1/4" x 3/8" x 1/4" for floor tiles over 6 inches) was designed to leave, can cause tiles to sag under their own weight after they are set, and this usually happens after you walk away and tomorrow is to late to fix it. Tiles should also be tapped or "beat in" to assure a perfect bond. Checking set tiles for "lippage" is best done at this time and corrected as required. My TAVY "Tile Puck" should win an award for that job. Many home improvement TV programs show tilers placing tile ever so gently into place, as if they were delicate pieces of china; these tile are destined to FAIL. All large format tiles larger than 12 or 13 inches, should be skim coated before installation. Armen Tavy

The pattern can be broken at the steps. I see no benefit in trying to tile the steps and risers in a diagonal. It could even look awkward. The area in front of the patio doors can be in a rectangle, diagonal rectangle or 1/2 an oblong circle. The tiles generally should extend + - 24 inches into the room. No other rules other than what you and your family finds pleasing to the eye. Please research all the "rules" for tiling, especially since you are covering so large an area. Try never to have to do a job twice. You can learn much just by reviewing many of the previous posts. Armen Tavy

These soap dishes usually have a raised lip overlapping the wall tiles, in which case you would set it just like a piece of tile, however, it is always prudent to secure a shelf with duct tape until the mortar has set. Overnight always works for me and grout the perimeter of the shelf with tile grout or fleixible caulk/adhesive. If it does not have a rased lip you will have to cut the tiles to fit around it, and as close as possible, so it looks professional. All exposed cut tile edges should be softened with a tile rubbing stone. Armen Tavy

Never cross a bridge unless you know it can support your weight or, tile is as strong as the floor it is attached too. If your floor is strong enough to support an elephant so is the tile on it. More important is the way the tile is installed. If it is installed like they do on HGTV and DIY Television Shows, I don't give it much hope.

Need help on the techniques to achieve perfection, just ask here or review many of the older posts, because they are loaded with guidelines and installation tips. If you intend to install the tiles yourself, PLEASE do your "homework". If you submit questions here, they must include all the information you can give about the condition and size of the location and which products you intend to use. It is also of interest to me and our readers what inspired you to take on a project like this, with little or no experience. Armen Tavy

If the V-Cap and the field tiles are from the same manufacturer and it is designed with those tiles in mind the height will be automatic. If you are using a tile from another source all you have to do is make a "Wet Run" of a single V-cap and a single "field" tile to see if you might have to shim the V-Cap up a bit. This would have to be done up front because the V-Cap should be installed first and the "field" tiles second. If you would rather tile the "field" first and then adjust the height of the V-caps with a stiffer mortar mix, you could gauge the location of the V-Caps and nail a straight board in their place, tile the "field" first, then install the V-Cap last. Of course you would have to allow for grout width as well.

The latter scenario can get you into trouble if your measurements are not correct and you do not control the possible sag of the V-Cap from its own weight on top of extra mortar. You could use Duct Tape to hold them in place until the mortar is set. Try the experiment both ways, and then decide which way is easier for you. You can watch my video for tiling over counter tops by going to: www.tavytools.com and clicking on Ron Hazelton in the upper left margin of my home page for a counter top demonstration using V-Cap. Good Luck, and do your homework!!! Armen Tavy

I am running a test, as we speak, on a brand new fiberglass base to test it with my TAVY "Thin-Skin" System. It may take a week or two before the test is complete with running water. I will let you know, so keep tuned in. Please send me an e-mail if you can to: spacerman@tavytools.com  I can give you a heads up after I complete the test so you can read my reply here on the forum. Are you the visitor whose post # 12254 I accidentally deleted? ArmenTavy

13" natural stone tiles is a new one on me. If you copied techniques you saw on a TV Home Improvement Channel that was probably your first mistake. Stone tiles installed with a butt joint or tight can be difficult to get out without damaging them or adjacent tiles. Go to your local tile store that sells tile tools and purchase a small suction cup with a finger pull especially designed for tile lifting. It is obvious to me that you did not install the tiles with enough mortar on the floor, as well as skim coating their backs before installation. If I am correct in that assumption, then you may be "lucky", if you can call it that, and with a little tapping and pulling with the suction cup, you may be able to break what little bond you have left. The worst that can happen is that you break one tile to get under adjacent ones. However, lift full pieces or smaller chunks slowly, so adjacent tiles are not chipped. All grout must be removed from the exposed sides of the tiles you will not be removing as well as any tiles you salvage

Once the bad tiles are removed, you will have to get all the mortar off the floor, and what is left on the back of the/any tiles you can salvage. You may have to invest in a new tool that is ideal for removing both. It is hand held and has an extended flat vibrating blade for removing mortar and grout. It oscillates at incredible speed to grind off the mortar without damaging the tile or the sub-floor. They are referred to as "MultiMaster" and there are three brands on the market that I know of, the original "Fein", "Dremel", and one other, can't remember the name right now, that is being "hawked” on TV infomercials. Rental yards may have them and you should check.

Re-installation of the tiles will require you to pay closer attention to the techniques required to get a sufficient bond to the floor and tile. Apply mortar to the floor with a 1/4" x 3/8" x 1/4" or 1/2 x 1/2" x 1/2" trowel and skim coat the back of the tile just before placing them back in place. The mortar should be no thinner than mayonnaise and no thicker than peanut butter. If the re-set tile is higher than adjacent tiles, because you installed it properly, you have no choice but to remove a little mortar at a time, off the tile and or floor, until tiles are the same height. The same suction cup will help you lift tiles out to do this. If you are able to scratch grout out from around the tiles, lifting them out for repairs will be easier, however you don’t want the knife to “skip” and scratch the tiles, so be careful and work slowly. These few loose tiles may be a prelude of others that can come loose after they are walked on in days to come. conduct a tap test on ever single tile and use a piece of making tape to mark ones that sound hollow (any where on their surface). The handle end of a (dull) kitchen knife works well. Tap the tiles gently, and listen. Armen Tavy

You are a wise mom to ask, and your wisdom is going to save you a lot of grief. Call your local plumber as fast as you can because the tile floor cannot cause your floors to sweat. Grout does get darker when it gets wet. You must have a leak in the wall and your allergies are probably being aggravated by mold growth. There are many copper pipes and fittings leaking these days, and I can personally attest to that with three such occurrences in homes that I own. One leak caused $12,000 in damages. Armen Tavy

I don't understand what you mean by, "cutting a piece of tile that is 1/2" to place on top of the backer board". I would not recommend "Liquid Nails" or caulk to install tiles. I would not recommend removing drywall and substituting backerboard in its place when there are other simpler solutions. You can use the same grout for both as long as the grout joints are in the same size range. Non-Sanded for grout joints from "tight" up to 1/8" and Sanded for 1/8" or larger. For 1/8" joints, non-sanded grout has to be a bit stiffer to prevent "crazing" (shrinkage cracks).

"Hardy Board" is a workable product for countertops but you don't have to add any extra height to your counter if you review your other choices. You can save yourself a lot of worry, energy and money buy using Paint on, Peal and Stick on, and a variety of "mat" materials/products or TAVY "Thin-Skin" on your countertop, and the backsplash. "TAVY" is .009 inches "THIN" and can be easily installed over any solid surface without any preparation what-so-ever. No weight, no height, no fight. Look in the right margin of this forum for the display ad. I know this sounds like a commercial, but I have 48 years experience in this trade, and I am the inventor of this and other tile related installation products, which are the solutions for many of the questions asked on this forum.

It is a "Catch 22" situation for me as a moderator on this forum, and I try to refrain from mentioning my own product, but there is no other product like it and, it does work. You have choices, you have to decide what is best for you.  You appear to be a first time tiling novice and you should do more research on tile installation procedures before you jump head on into this project. It would be a shame to  do all the work, only to have it fail, or look less than professional, because you didn't take the time to ask any questions. Browse and Read many of the past questions, 12,263, to be exact, to learn what you can, and it is FREE. If you are still confused and would like specifics and details on other products and tiling techniques for your project, please write again.  Armen Tavy

Yes. I have 20" Rectified tiles over 8" ceramic tile in a condo bathroom that I own, and it is "spectacular". I also recommend tiling the front of the bath tub. How do you do that? You install TAVY "Thin-Skin"over the tiles on the floor walls and the front of the bathtub going over the edge, terminating at a shower door. Kitchen counter V-Cap tiles are used to make the turn at the top of the tub. If you have curtains instead of a shower door, the V-Cap will help keep shower water from running down onto the floor at the tub ends. By the way, the floor area was less than 35 square feet. Tiled over the wall tiles in the tub area and the 3 painted wainscot walls as well. The "Thin-Skin" over the tub's glossy enamal, transforms it into a perfect surface to tile over. If the front of the tub has a raised design, extra mortar on the tiles will fill the depressions so you can install the tiles  "plumb".

Regards,

Armen Tavy

Before I can recommend I need to know more. Where : patio, driveway, portch, etc., Place: City/State; how large an area, and what kind of tiles. Waiting, Armen Tavy

Glass tiles can be used on bathroom floors with limited "shoe" traffic however, it would be best to ask the manufacturer this question about the "specific product" you have purchased.

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PSI stands for Pressure or weight that is applied in Pounds of Pressure per Square Inch of surface at point of contact, i.e. a hundred pound woman standing in "stiletto heels" would exert appox. 1200 lbs of pressure at the heels point of contact. None of this is important in your scenarios, however, a mud room would be best tiled with a commercial grade tile with a # 5 rating, which is the highest from 1 to 5. A bathroom used by family or guests on lower levels of a home should be tiled with a minumum #4 rating. Bathrooms on sleeping levels that are walked on in bare feet, stocks or slippers, would need a #3. Decorative "dots" with ratings as low as #1  can be used here and there, but there is always a chance of surface scratches and visable surface wear. Generally speaking #1 and #2 are for walls and #3 can be used on both, depending on locaton. All retailers should have information as to the wear rating of the tiles they sell. Armen Tavy

Use the right ratio of water to cement powder and use the correct size trowel to spread the mortar holding the trowel at a minimum 60 degree angle to the floor. Larger format tiles, 16" and larger, always need a "thin" back coating of mortar just before installation. The abolute minimum trowel size is 1/4" x 3/8" x 1/4" and 1/2" x 1/2" x 1/2" is an option as long as you compress the tiles into the mortar and just don't "lay them on it".

Have your husband remove a solid sounding tile next to a hollow one to inspect the back to see if it has a minimum of 80% mortar transference, if not, your entire installation should be checked before grouting. My gut feeling tells me that you may have to try and salvage as many good tiles as you can and re-do the installation following strict guidelines set forth in setting tiles, especially 18". I can help you if you need it, just ask. Armen Tavy

Manufacturers of individual crack suppressants have their own sets of rules as to what products will bond to them. It is hard for me to say not knowing the brand name of the membrane (that has a layer of rubber in its makeup) and the type of installation mortar. Include the type of tile and tile's size.  I will however generalize for you.

The correct adhesive, if any, to install the membrane must have been used.

The correct bonding suggestions to the top side of the membrane must have been used.

The correct trowel size for the tile and your technique of mortar application.

Hollow sounds mean "Air" trapped underneath and this can be the result of not enough mortar or too small a trowel size to spread the setting bed.

You are experienced but when some jobs fail when tiling over unfamiliar surfaces, and beating tiles "in" can be an important step not to skip.

Flooding of an installation can weaken already questionable "bonds" and cause them to fail sooner. Your best bet is to remove a "hollow" tile and inspect the mortar transference from floor to the back of the tile. If it is less than 80%, as required, this could be the reason. If the membrane "did not stick" to the substrate and is only "floating", a hollow sound would/could be the result. If the hollow tiles are in the flooded area, water could have compromised the bond of the underlayment to the substrate, which could result in hollow sounds. I am sure you already know all this, but are mystified why it has happened to you on this one project, and unfortunately a fairly large one. You have to give me more to go on, so please respond with more information so I can try to help you further.

We have a recent episode of an installer with 35 years experience loosing a 2,000 square foot installation and it is still in the "forensic" stages of investigation. If you are a member of, and you should be, of the "National Tile Contractors Association", they will or would have, jumped in to help you if the failure was because of things or issues beyond your control. The "National Tile Contractors Association" is in Jackson Mississippi, 601-939-2071 or www.tile-assn.com  Armen Tavy, spacerman@tavytools.com  Any questions directed to my e-mail should be duplicated for the forum's readers.