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question mixing it 
Oct-08-2014 09:28
Prep for ceramic or porcelain tile Post 4
Prep for ceramic or porcelain tile Post 4 I appreciate you responding to my post and offering an alternative. But I would have to disagree with your statement: Although it was quite short, I did answer your questions on 9/29/14.   I could not find a response to the following. !- Multi Purpose Sand and Portland 5:1 and water. Would this provide an ideal bed for ceramic or porcelain tile? 2- What could be done to prep the slab? 3- What would be used to bond the slab and Sand / Portland Mix? Slab has Radiant Heat embedded, so no mechanical fasteners.   In post 2 you stated: I can help you with that as long as you can follow my instructions. Not complicated; however, you would have to pay close attention to my detailed directions. ? In post 2 I stated I want to create additional mass for the embedded radiant heat. Didn’t state I was adding additional radiant. Fortunately all the problems you are trying to help me avoid don’t apply. My concerns are in the ideal mix and the bonding. My post was looking for a simple response.         Thanks
Prep for ceramic or porcelain tile Post 4

I never meant to imply that you were trying to add more radiant heat. I was just saying that I could not see why you needed additional heat at all.

A slightly damp 5 to 1 ratio is ideal for a “dry-pack”; however, we both know that the dry pack would not bond to the/any concrete slab on its own without help. There are two choices to get it to bond. The first is to skim coat the floor with a modified thin-set mortar and then comb fresh modified mortar over the skim coat with a ¼” x ¼” notched steel trowel; as if you were going to set tile. The difference here is that instead of tile, you are imbedding your Hydronic tubing into the fresh “wet” mortar using the clips to hold the tubing down as (perfectly) flat as possible without any bouncing. While the mortar is “wet”, the “dry-pack” is installed over the tubing and the “wet” mortar.

In addition a paint brush should be used to coat the topside of the exposed tubing and exposed (combed) modified mortar so the “dry-pack” bonds mechanically to the tubing and the clips as well. There is always a chance that this required initial skim coating of the slab may not bond properly to an “old slab” that may be “contaminated” for any number of reasons. The best “insurance” to guaranty a perfect bond to the slab, is to use my TAVY “Thin-Skin” tile underlayment first. This assures you a 100% bond to any kind of slab, contaminated or not, for this most important initial skim coat. When modified mortar is applied to my “Thin-Skin”, you have my assurance and personal guaranty that a catsup viscosity of modified thin-set mortar applied to “Thin-Skin”, will bond the mortar to my “Thin-Skin” FOREVER. The instructions on the thickness of the “dry-pack” and the method with which it is applied must be as I have stated previously.

1- Install “Thin-Skin” over the entire slab following the simple instructions.

2- Skim-coat (newspaper thin) TAVY “Thin-Skin” with modified thin-set mortar and let it dry hard.

3- Install your Hydronic tubing using the clips to keep the tubing perfectly flat. A hot glue gun will be required to hold the clips and tubing intact. A heat-gun may be necessary to bend the tubing easily without causing “natural” upward pressures caused by the short radius turns of the vinyl tubes. Weights placed on 4’ x 4’ plywood panels may be required to hold the clips and tubing flat until the mortar dries hard enough so the tubing and clips do not move.

4- Using a large painter’s brush (4” to 6”), “paint” catsup consistency modified mortar over the tubing and all exposed mortar. Everything must be “wet” with fresh mortar just before you install any “dry-pack”, or the “dry-pack” will not bond (to the combed mortar, tubing, and clips).

5- Do not try to complete the entire floor at one time unless you have enough help to do each step methodically. Any pausing of the installation for any reason/s would create “cold joints” in the dry pack; so special attention will be needed to “wet” any surface areas that look like they are drying (skinning over) prematurely. “Dry-Pack” only fills spaces, it is not designed to stick or bond to anything unless it is desired (as we wish it to do in your project). If you cannot finish the “dry-pack” in one day of continuous work with No Stops, special care must be taken before stopping or quitting work until later or the next day. The installation of the/any “dry-pack” already completed must be perfectly flat. Again, no “dry-pack” is loaded, tamped (packed) hard, and then screeded flat, followed by smoothing with a large rubberized bottom (appox) 5” x 12” Darby” unless it is preceded with a paint-on coating of fresh modified mortar just before the/any “dry-pack” is loaded.

6- Once the entire floor is completed, an over-night curing of the “dry-pack” is prudent. The entire “dry-pack” should be skim-coated with a “thin as newspaper” (catsup consistency) of modified mortar. The floor should now look much like it was poured. Steel trowels must never be held at less than a 60-degree angle to the substrate. You must always hear the loud scrapping noise created when dragging mortar over the dry “dry-pack” using heavy downward pressure. Any visible swirls, lumps or trails of mortar left by the spreading trowel left on the face of the “dry-pack” can easily be sanded using a tile-sanding stone the following day. (vacuum after) A lot of necessary words for a rather simple installation. I hope this clears things up for you. Still not sure, ask again. Armen Tavy

question Lou 
Oct-07-2014 10:48
I thought I had a crack in my ceramic tile in the floor by the door frame.  I have been told it is a  splice.  Could you describe this or give me a photo?
Dear LOU:

Lazy installers will make a cut(or splice) instead of making an "L" cut or the like. Instead of crafting the piece, they cut it and butt it up. Totally un-professional. Armen Tavy

question Marcelo 
Oct-06-2014 17:46
8x8 white, Monocibec
Need 48-72 white, 8x8 Monocibec floor tiles. Installed originally circa 1991. For replament purposes. Any idea where to get?
8x8 white, Monocibec

Your request is now out there for all to see, but the odds are not in your favor. Why not be more specific about your needs and maybe I can help you be "creative" with complimentary tiles.

Armen Tavy

question mixing it 
Oct-03-2014 08:08
Prep for ceramic or porcelain tile Post 3
The system is Hydronic Heating. Yes I am handy with a screed, so fire away with those instructions. The room is a rectangle no columns. My climate zone is 4. And if you would also please address my question from my post on Sept 29   #12950                  Thanks
Prep for ceramic or porcelain tile Post 3


Although it was quite short, I did answer your question on 9/29/14.

My new questions to you are: Why do you need a heated floor if the floor already has a built in radiant heating system. Do you feel that it is not enough? Radiant heat systems in slabs or mats do not make the floors a “hot plate”. They do warm, slowly, and methodically. If not, the floors would be difficult to “live on”. The same goes with the Hydronic heating systems you desire. Of course, you would save energy on the second (Hydronic) system however; you must follow certain “NTCA” rules, and your wish to raise the floor an additional 3/4” is not quite the space a Hydronic System requires.


It would raise your floor, above the original slab the thickness, the diameter of the tubing and the new “dry packed” cement floor that would encapsulate the tubing. And the “dry pack” must be higher by a minimum of ¾” above the tubing. There must also be some mortar, about ¼” under the tubing in order to encapsulate it 100%. 1/4” "dry pack"below, plus the tubing is which is usually 1/2” inside diameter, plus the thickness of the walls, usually 1/8” x 2.


Now let’s do the math:

1/4 “+ 1/8” + 1/2” + 1/8” plus 3/4” of Dry pack. Total = 1 ¾”. Of course, this does not include the thickness of the new tile which could add another ½”. In addition, the tubing must remain flat with no curls that might lift up by natural resistance when you are bending the tubing at each wall, to loop again and again until the entire floor is covered. Typically, heat tubing, as well as electric wires should be no closer and no further apart than 3” apart. You might consider less tubing coverage for more important living areas.


Since you do not wish to injure the radiant slab, you would have to be creative with galvanized half circle tubing clamps by gluing the clamps/clips with a hot glue gun to keep the tubes from lifting in the bends or anywhere. In addition you would have to do serious math in calculating the unbroken total length of the tubing required for this huge slab so you refrain from splice-joints which can be trouble waiting to happen down the (wet) road. If you can’t or do not wish to raise the floor this total height.


If there are stairs going down into a basement. The height of the first step would be lower than the others violating the minimum code variations allowed; usually 7 1/8” to 7 ½”.

The distance between the tops of all the steps combined (usually 11). If the installation is getting inspected there are no exceptions to this steadfast ruling. If it is not being inspected and you sell the home, you would have to reveal this lower first step variation in your disclosure statement to a buyer. It could “kill” a sale or cost a ton of dollars to revamp.


Lastly, is your 4 season climate. You must never turn off the Hydronic heating system in cold weather, or if you go on vacation, or some other mishap happens. A tile installation must have room to expand and contract around the perimeter, or you could have a bunch of tile “teepees”. To play it safe, in this 4 season climate, I would recommend two expansion joints, + - 13’ apart, perpendicular to the 37 ft longer length.


If you still wish to proceed after all I have said, please let me know.

Your friendly, knowledgeable, guide.   Armen Tavy



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