Go to your nearest lumber yard or big box store and purchase enough 1/8" paneling to run thru a table saw the width of your wall studs and fasten them with staples or small brads. Do not use nails because they will just cause you grief when you "hit them" while fastening the backer boards. Just a tack here and there because the Cement board installation will ultimately hold them in place. You could also use liquid nails to hold up the stips of wood. Do not skip any studs or horizontal plates at the ceiling. If your backer boards are 7/16" purchase 3/16" paneling. "Lauan" is the least expensive and works well for this purpose. It also cuts easily with a sharp utility knife with no need for a table saw. 5/8" dry wall is standard proceedure between "common-walls" in multiple dwellings. Armen Tavy

Ditra is a popular underlayment, but as in post # 12458, there are exceptions to the "perfect installation" rule, if you take the time to read and understand the fine print. They, others, and even myself, must protect ourselves from installers who do not read the instructions to the "T".  The non-modified mortars are recommended to install their underlayment so the underlayment does not "stick" to the substrate. "Schluter" has made the word "uncoupling" synonymous with a "perfect tile installation, because there are so many problems with all un-tileable substrates.

We are better off "biting the bullet" by installing a monolithic membrane up front, so we can avoid the inevitable probabilities that just cost everyone heartache and money. However, as you point out, you must read the fine print and "obey" all the installation guidelines.

As far as using the same un-modified mortar to install Porcelain Tile over their membrane, I do not have a clue, why they recommend such a procedure, because we all know quite well that we need a high-end modified mortar to "reach in" and grab into and onto the bisque of a Porcelain Tile.  Armen Tavy

Yes, Yes and Yes. It could be a combination of "expansion joint" and or "control joints" and elongated "shrinkage cracks". These issues require tile removal, substrate correction with a "suitable" membrane, and re-tiling. In reality, there is not a single substrate  today done by others that is suitable industry approved sub-surface that can be tiled over, as is, with a written warranty by the installer. Every manufacturer of installation products, including the "best known mortars" as well as monolithic membranes have some sort of "tricky disclaimer", because they are aware of these facts. I say it again, there is no suitable substrate prepared by others that can be tiled over without doing some sort of prep work first by a qualified tile installation "expert".  I uaws the word "suitable" because I have a product that is not officaly on the market as yet that resolves all the issues that you are presently confronted with. I call it: "008" Easy To Eliminate". It is my TAVY "Thin-Skin" System installed with a new compound I call "008". It is a compound that never dries, always stays moist and flexible; is non-toxic, no VOCs, Bio-Degradable, and does not promote the growth of mold or mildew. It truly creates an un-coupled tile floor, that is actually held down with a "flexible" suction, and that suction is "completely" forgiving, if the movements are on a horizontal flat plain. The flexibility of the system is not a detriment to the grout in the joints, which always stay intact, if mixed and applied correctly, that is.

There are claims and law suits, and days in court, with just about every known installation product sold today. One of the exceptions to that statement is my TAVY "Thin-Skin" Underlayment System, which states in writing, that it can be used to install tile over any "solid" and "sound by industry standards" surfaces, with the only three logical, understandable exceptions being; carpeting, upholstery, (and/or any other "soft" objects" and floor wax or floor wax residue.  

Since its first introduction, over 7 years ago, there have been no claims brought against my products or my company. There have been a few issues with "007" adhesive waste and overuse, but no claims or job failures as a result.

I, Armen Tavy, personally stand behind my product/s and claims without any "gimmicks".

I wish I could help you on this one. Only a call to the manufacturer can answer this question.

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Armen Tavy

If I am reading you correctly, you are asking me if the tile surround should begin at the edge of the tub, exactly where it makes a turn down towards the floor or towards the back wall or is installed a few inches forward from the vertical face of the tub. The answer is what you prefer; however, a professional would wrap the outside corner and stay a minimum of two inches away or in front of the tub's vertical surface. If you were using 2" x 6" surface bullnose tile or "mud" bullnose tile,  this would be the general distance so the tiles remain whole. Depending on your layout, the tile at the turn of the tub can be cut in an L shape so it wraps around the tub or it can be a full tile extending past the tub's edge, which would require the tile under it, the one that is only 2" wide for example, to be cut a tad narrower so the upper portion of it can wrap a bit into the turn. This would make the transition smooth and pleasant to look at. 

In cases where the tub is not perfectly level, the first row of tiles around the tub are usually cut less than a full tile so the tiles can be tappered as necessary to fit, and all the tiles above the first row install perfectly "bubble" level. This also keeps the width of the grout joint at the tub constant on all three walls. Tiles must never fit tight against a tub. A slight lift with wedges or scraps of cardboard is necessary to leave a space for grout and or caulking. This also prevents water from "wicking" or "bouncing" up behind the tiles. In cases where there is a slight upward roll where tub meets the walls it would require a beveling of the lower back edge of the tiles in those areas to keep the face of the tile perfectly pumb. GREENBOARD is NEVER EVER used in "wet areas" of any bathroom tile installation. Armen Tavy

Good question Ron because the entire installation depends on it, so yes to all .

 The first rule of thumb is that all ceramic floor tiles 6" x 6" and larger should always be installed with no less than a 1/4" x 3/8" x 1/4" rectangular notched trowel. The angle of the trowel to the substrate should be held at no less than 60 degrees. However, “IF” the tiles are thinner than 5/16", the angle of the trowel could be reduced accordingly to no less than 45 degrees. Thin-Set Mortar is just that, a thin layer of mortar with high ridges that when compressed seat the tiles in a flattened bed of mortar that should be no thicker than about 1/8 inches when compressed. A flattened bed of mortar is best achieved by spreading the mortar to get it on the substrate and then combing it in neat "corn rows" left to right.

With the trowel held at a 60+-degree angle while spreading, it should leave the ridges nearly 3/8" tall and the spaces in between the ridges should be paper-thin. The tiles should be placed on the thin-set mortar's high ridges and then pressed into place flattening/collapsing the high ridges. The tile should be pushed forward while applying downward pressure to completely collapse the ridges of mortar spreading them into the empty "valleys" between the ridges. This will remove most, if not all the air that would otherwise be trapped under the tile. I always say, "Air is the enemy unless you are breathing it or it is in your life vest, it does not belong under the tile/s. To complete the placement of the tile, the “flattened” tile should be pulled back into its intended position with a slight downward pressure this time. This simple maneuver should coat the backs of the tiles to a near 95 percent and possibly 100 percent transference of mortar from the substrate. Once the technique is perfected, the grout joints should ideally be vacated of most of the mortar. It has been a long time practice to see ridges of mortar between the tiles. This practice is no longer tolerated. As far as I am concerned, the walls should be treated the same as floors except when installing 5/16" thin and thinner tiles in which case the 3/16" saw tooth V-Notch should be the minimum with 1/4" V-Notch the largest before switching to 1/4 x 1/4 x 1/4" square notch trowel. The latter should be avoided for floor tiles larger than 2" x 2".

 Each additional tile to be set is held at a 60 to 45-degree angle while pressing its lowest point against the last tile that was installed. The edge of the tile is then used to drag the excess mortar in the grout joint away from that previously set tile a distance of about 1/2 inches before the body of the tile is pressed down horizontally, flattening the ridges of mortar. The tile has been used much like a putty knife to pull the ridges of mortar in the joint away leaving a very thin flattened layer of mortar in the grout space between the tiles. To clarify; this procedure removes the high ridges of mortar that would otherwise remain in the grout joint between the tiles and that “always” compromises the ideally uniform grout thickness during the grouting process the following day. Grout in the joints should be full of grout not intermittent ridges of thin-set mortar.

 There are many causes of grout shading issues and most of them can be attributed to “OE”, "Operator Error". Ridges of “green” mortar in the grout joints have been known to stain the grout, especially if grouting is not delayed at least 24 hours after the tiles have been set. Mortar “ghosting” from “high ridges”, especially if it is “grey” mortar, is another direct cause of grout shade complaints.

 Mixing less than the full contents of the grout “package” that has not been thoroughly “boxed” (mixed dry) before it is used is probably the worst mistake most installers make. To clarify: A new package of grout must be opened and the contents should be blended together with a margin trowel, paint mixing paddle, or emptied into another container for electric blending before water is added to any portion of it. NEVER open a grout container and pour out only a portion of grout. Unless the entire contents of grout in the “package” is used at one time, “a portion” could lack some of the important ingredients that are necessary to get uniform coloring as well as “strength”. During transit from the manufacturer important ingredients can separate from the mass from bouncing across the country in a truck. Heavier ingredients can settle to the bottom and lighter to the top of the packaging. TOO much water in the mix and TOO much water when washing the grout can also pull color out of the blend and weaken/dilute the Portland cement compromising its strength. The colored water in the wash water has to come from somewhere.

 The surface texture of the backside of the tile does have a bearing on the trowel size or tooth configuration that will be used to install the tile. Tile mortar spreading techniques are also improtant. Smooth or near smooth with shallow depressions require the trowel mentioned above; deeper depressions in the bisque that are similar to a "Belgian Waffle" require a thin back-buttering of thin-set mortar. Large and larger format tiles in the 16, 18, 20 inch and larger may require additional buttering in their centers. There are two larger tooth design size trowels, 1/2" x 1/2" x 1/2" and "Half Moon" 3/4" wide by 1/2" deep marble trowels. These trowels must be used with discretion so as not to overload the mortar under the tile. The ramifications of "Overloading" are tiles that will "sink" or "drift" after they have been set and "lippage". A tile should be removed on occasion to inspect for sufficient transference of mortar from the substrate to the back of the tile. The mortar should always be modified and you do get what you pay for when purchasing modified thin-set mortar, so always go for the best if you care.

 Lastly, a flat "lippage" free floor is always the "goal", and the best way to achieve that is to use a TAVY “Tile Puck” during the install, and always remember to use common sense when performing any task and ask questions when in doubt.

Armen Tavy

Non-Modified mortars sold today should have a lable that says: Part 2, must be used with Part 1, a "Liquid Latex Additive". Most tiles today are not capable of being installed properly with a non-modified mortar. Non-Modified Mortars are less expensive but what a stupid place to try and save a few of bucks. Green board should never be used in a "wet area" and is reserved for areas outside the immediate wet area, although I would avoid it like the plague.

With any brand of modified mortars, you do get what you pay for. The more polymers the more costly and better is the bond to the tile and the substrate, plus the mortar is more flexible. Mortars with their own Liquid Latex additives are always the best as well as the costliest. The denser the tile, i.e. Porcelain, Glass, the better the modified mortar should be. All paint-on and other membranes should be skim coated with a or the best modified mortars, and that skim coat should be allowed to dry to the touch before the normal installation begins. Believe it or not, natural stone could be installed with a non-modified mortar, but the non-modified mortar probably wouldn't stick well to the substrate, so Duhhhh...... Armen Tavy

There are different issues depending on your choices. One option is to tile directly over old tile and save yourself a "ton" of money. Floors are easier than walls with a simple addition of a marble threshold to accomodate a thicker tile floor. Toilets can receive a thicker wax ring and a tile underlayment can be added to the floor so it can be tiled over with a warranty. The walls are another matter and your tiling experience can save you money if you are mechanically as well as creatively inclined.                            

Removing a "Mud Installation" "installed properly" can be done in two ways. Remove the tiles leaving the wall's cement substrate intact with minor repairs, or removing all the mud and lath down to the studs and starting from scratch. The latter is the messiest and most costly in time and money and the saving of the substrate not so bad and tiling over the old tiles the least expensive and easiest.

Removing the mud floor may not dramatically effect your tub height if the tub was installed before the mud base was installed. Let me know otherwise and I can advise you appropriately. Matching up to adjacent flooring can be adjusted with new plywood underlayment at appropriate thicknessess, or "sleepers" and plywood, as well as a thicker or thinner marble threshold at the doorway. Now that you have more insight, give me more pertinent information and I will gladly help you further. Armen Tavy

Muriatic acid can pull the color right out of the cement grout leaving blotches. Re-grouting would require removal of grout to a depth of at least 1/8". It would be simplar to use a specialy designed grout paint to obtain a inform color. It should be available at most tile stores or on line. Aqua Mix is one brand. The added benefit with this chore is the protective coating that is as good as any sealer. Armen Tavy

The backerboard manufacturers are asking you to do so. there reasoning is to help level the imperfections in most if not every floor to be tiled on.The galvanized or alkali resistant fasteners must be used as directed. We recommend an 8" in all direction fastening pattern, plus 4 to 6" spread on both sides of every seam and perimeters. Boards should also have a 1/8" space between them to be filled with mortar and taped with alkali resistant tape. Spead mortar with a 1.4" trowel and do not leave clumps or globs. Armen Tavy 

I am not quite sure if I read you right. You have only 4 tiles plus some smaller ones? How big is this table and what is the finish you will be tiling over? Armen Tavy

This failure has been going on for the 48 plus years I have been in the trade. Cleaning ladies are notorious for ruining polished stone surfaces using vinegar as well as many other caustic cleaning products. This is the first time I have heard of one using the most dangerous of chemicals to clean marble or grout. There is no salvation other than "grinding and then polishing the marble floor. The Listellos are a total loss and the cement grout has been literally "scorched" and must be replaced. The most economical way is to use a tool called a "Multimaster" by "Fein Tools" or a less expensive copy by "Dremel" etc.; or one called the "Grout Grabber” by "Midwest Trade Tools". These tools oscillate aggressively and make short work of the chore. You do have an option of applying a grout paint avoiding the laborious chore of the other tools; however, all acid residues must be totally neutralized. Armen Tavy

Sorry about the time lag for your answer, it is because of a 2500 mile move from Florida to California. It will be another week before I am fully settled in the new surroundings. I am answering questions on a Notebook PC and it is not as easy.

 If you have read anything I have written you would know that there are no quick yes or no answers to your question. There are a LOT of "If’s". The first thing to always remember is the dollar and labor cost of any project and how much you value the money and labor involved if the installation fails. First rule is L/360. The Deflection must not exceed one inch in a 30 foot span for tile and 1/2" for "stone” and the industry unanimously agrees that there should be two separate layers of plywood or other approved wood substrates totaling 1 1/8" minimum thickness with staggered seams and proper fasteners in the approved nailing pattern. Mercrete 500, Red Guard and all the other "paint on", stuck on or glued on membrane surfaces can be prone to failure if these guidelines are compromised.

By the book, it would be two layers of wood underlayment for a sound floor and then any of the approved substrates to avoid tiling directly to the wood itself. Cementitious backerboards are an approved substrate providing they are installed correctly and since they do not add significant structural strength on their own the two layers of wood are always recommended by industry experts. Manufacturers of many underlayments, including my own product, can deviate from the industry guidelines, but in doing so they must carry the burden of warranty, in which case it is prudent to follow their installation guidelines to the “T”. Job failures are many and “homework” must be done to prevent catastrophic losses when the companies shrug their shoulders and refuse to pay claims because of installation mistakes. Tiling over a single layer of wood underlayment 5/8” to 3/4” thick is always chancy, even if it is tongue and grove. Tiling over a plasticized paint-on underlayment is frowned on by most professionals who must guaranty their work. When water is introduced to Portland Cement, like a “plant” that grows a root system, it grows “tentacles” instead, similar in a sense to the plant’s roots. These tentacles work best if they can entwine themselves to each other and into somewhat porous underlayment surfaces. Going the right way is usually more costly, and shortcuts can save money and time, you just have to choose which path to take.

 I as a professional, know that most surfaces today are not “tile-able” and shortcuts are here to stay as a result; that is why I developed my own system. My underlayment is attached to any questionable substrate changing it to a tile-able one, and yes, I guaranty it as required. On the plus side, my product has been tested by “TCA” and passed their stringent testing. It has also passed the test of time, over 7 years with “zero” claims. You must choose, so choose well. Armen Tavy                                                     

I am a mix your own type of grout guy so pre-mixes turn me off. There could be more than one reason for your problem but I would skip to the chase and scrape/dig out what you can and mix some dry grout powder with water and see what happens. If it solves your problem just keep tabs on it for any changes. If it does not solve your problem come back and tell me what is going on and I will try to help you further. Armen Tavy