1) What is the difference between ceramic and porcelain tile? Which is best for indoor flooring and why? How do I know when I am buying a good quality, durable tile–are there ratings I need to be aware of?
Answer: In all actuality, porcelain IS ceramic tile, just made with a much denser clay, and fired at much higher temps. As for which is best, all around porcelain is the answer. It’s harder, will take much more abuse, and won’t chip scratch, or stain as easily as most others. In addition, it’ll stand up to much higher and lower extremes temperature wise. However, especially for residential applications, most glazed floor tiles will stand up to whatever you have in mind. There are two indicators to the quality of the tile you’re interested in, when it comes to glazed tile– first, the PEI (Porcelain Enamel Institute) rating, which rates the hardness of the glaze on a scale of 1-5 as follows: CLASS 0 – Tiles technically unsuitable for floors
CLASS 1 – Residential and Commercial wall and bare foot traffic
CLASS 2 – Wall and Residential bath floor, soft soled traffic
CLASS 3 – All residential floors and Light Commercial
CLASS 4 – Medium Commercial, Light Industrial and Institutional, moderate soiling
CLASS 5 – Extra heavy traffic, abrasive dirt, chemically more resistant.
Secondly, although some may disagree, and there ARE exceptions, price is a good indicator. For the most part, you get what you pay for, and although two tiles may look exactly alike, there may be a big difference in the hardness of the glaze, as well as the density of the bisque, or body of the tile.
2) My tile’s/ grout’s cracking! What’s happening? Can I just replace it?
Answer: Any time tile or grout cracks, it’s a SYMPTOM, not a problem, and just repairing the tile or the grout will not take care of it. Until the REAL problem is found and rectified, the same tile or area of grout will continue to crack, no matter how many times you replace it. 99% of the time, it can be attributed to seasonal movement in the structure, either under, or surrounding the tile in question, and the tile needs to be isolated from that movement. Sometimes it can be as simple a fix as adding soft (caulk) joints. Other times, it may be necessary to either add joisting, or beef up the existing joisting to minimize the deflection of the floor. What the fix is depends on the individual problem, but in all cases, again, the problem has to be identified and resolved before the cracking will stop.
3) How good is premixed thinset?
Answer: Premixed thinset is nothing more than organic adhesive (mastic) with a fine sand mixed in to give it some bulk. For wall applications where mastic is appropriate, it’s fine, although I don’t see any advantage over traditional mastic. But for the use it was intended, that being replacing portland cement based latex modified thinset, it’s an extremely BAD idea, for several reasons. First, ALL mastics are formulated to be used in very thin applications. The thicker it’s used, the longer it takes to dry, and for some of the heavier notches that are used in flooring installations, it never completely dries. I personally know of one case where premixed thinset was used on a floor in April, and the following November, it was STILL soft. ANY kind of pliability will cause flex in the tile, which will cause the tile floor to fail, allowing either tile, grout, or both to crack. Secondly, even if it’s used in a thickness that WILL allow it to dry, all it takes is a little moisture to cause problems. All mastics are water based, and any moisture will allow the mastic (or premixed thinset) to re-emulsify which, again, causes a failure in the floor.
4) Do I really need thinset under my backerboard?
Answer: The short answer is ABSOLUTELY. The manufacturer requires it, and if, for some reason, there’s a problem with the floor afterward, you’ve immediately lost any kind of warranty protection. Now, there’s a big controversy in the industry right now concerning the TYPE of thinset to use. The manufacturers, for the most part, recommend latex modified thinset, whereas the Tile Council of America (TCA) recommends UNmodifed, or dryset thinset. The reason is that the thinset isn’t there to bond the backerboard to the subfloor. If it were, then the modified thinset would make a difference. In reality, it’s actually there to fill the paper thin voids between subfloor and backerboard, thereby eliminating another source of flex, or movement, and extending the life of your floor.
5) What size trowel do I need?
Answer: This all depends on the size and thickness of the tile, as well as how smooth or rough the substrate is, and how deep the embossed pattern on the back of the tile is. For the most part, 3/16″ v-notch for ceramic mosaics (1×1 and 2×2) or mastic walls, and either 1/4×1/4 square notch or 1/4×3/8 for just about everything else. There ARE some exceptions though. If there is a question as to which you should use in your particular case, your best bet would be to go to and ask one of the pros there. You’ll be sure to get a good concise answer.
6) Do I spread thinset on the tile, the floor, or both?
Answer: Either or both. Usually floors are gridded out, and then the thinset is spread on the floor. It’s a lot easier and quicker. However, for those who would rather backbutter the tile, that’s fine, too, as long as you flat trowel thinset onto the floor to “burn” it into the floor. In other words, you want to make sure you get a good bond by pushing the thinset into the “grain” of the floor, be it concrete, backerboard, or plywood.
7) Can I tile right over my brick fireplace?
Answer: Yes, you can. You might want to make sure the brick is clean and free of any contaminants, such as dust or soot (TSP– trisodium phosphate works well for this). If the brick is painted, it needs to either be sanded or, if this is a renovation, sandblasted. Do NOT use any kind of chemicals to remove the paint, as they tend to leave behind residues that will inhibit the thinset bond later. Once the brick is clean, your best bet would be to flatcoat the brick with a latex modified thinset. This will do two things for you. First, it’ll give you a flat surface to tile over, and secondly, it’ll show up any errant bricks that might be sticking out too much, and they can be addressed before the tile is going up. Once the flat coat dries, you can take a rubbing stone to take care of any ridges in the thinset from the trowel.
8) Can I tile over sheetrock?
Answer: So long as it’s not a wet area (i.e. tub enclosure, shower area, tub deck, etc.) yes, you can. Even stone tile will adhere well.
9) Can I tile right over plywood?
Answer: Yes, you can, and it’s done on a daily basis. However, you really need to KNOW what you’re doing. There are additional steps you need to take care of, as well as pitfalls to watch out for that either don’t exist, or aren’t as important when using backerboard (CBU– cementitious backer units) as your underlayment. The thinset you use, how you lay your plywood down, how you SCREW it down, even the species and rating of the plywood used, all make a difference.
10)Can you tile over ceramic tile?
Answer: Yes, you can, as long as the original tile is sound (i.e.– no cracks, tile is still well adhered, etc.). You need to make certain there are no contaminants on the face of the tile, such as cleaner residue, solvents, skin or cooking oils, etc., and then especially if the tile is bright glazed, hit it with an orbital sander to rough up the finish and allow a better bond from the thinset, and use an UNMODIFIED thinset that’s mixed with a liquid latex additive, as opposed to a thinset that’s already modified and mixed with water. The reason being that with the liquid latex additive, there’s more of a latex content, and therefore, a stronger bond to the original tile.
11) Should I seal my tile?
Answer: Most tiles should NOT be sealed. Most glazed tiles, as well as porcelains, will not allow the sealer to absorb into the surface, and as a result, it dries on the surface as a white haze, which is a BEAR to remove. The only tiles which should be sealed are most natural stone tiles, quarry tile, or terra cotta.
12) Do I really need to seal my grout?
Answer: There are a lot of contractors who will tell you yes, and still others who will tell you no. The reason for sealer is to make cleaning and maintenance easier. There has been a trend in recent years to use light colored grouts in the main floors of the home in order to match lighter colored tiles, and a sealer is used to prevent “wear paths”– darkening of the grout joints in areas of main traffic in the home. Unfortunately, sealers will not prevent this. You’re much better off to use either a medium or darker colored grout. As for using sealer in the bathroom, sealer WILL help, but again, over time, grout will discolor somewhat, or “age”, and cleaners will be, for the most part, just as effective, with or without sealer. (Obviously, I’m one of those who doesn’t believe in them)
13) Can I use mastic in my shower, or over my tub?
Answer: Although on just about every pail of mastic it says “approved for wet areas”, no, you can’t. Mastic is used extensively in commercial projects for these kinds of areas– places such as hotels, apartment buildings, college dorms, all use mastic in wet areas, because it’s so much faster to install the tile, thereby reducing budget costs. However, they also have maintenance staffs, not to mention that these buildings get renovated every 5- 10 years, and from the contractor’s standpoint, the work only has to be warrantied for one year. After that, it’s not their problem any more. A home is a different story, though. You want your tile to last for years and years. Once it’s up, you want it to STAY up, and last. The problem with mastic is that it’s water emulsive, and even after being up for a while, it can still re-emulsify, become soft, and even wash out, causing your tile to fail. It’s one of the leading causes of tile failure in wet areas.
14) Is tile or grout waterproof?
Answer: No. Even with a grout sealer, most sealers used these days are “breatheable,” meaning the moisture can transmit through it, both in and out, so even sealer won’t make it waterproof.
15) How long do I wait before sealing?
Answer: This depends on the sealer being used. Because of the different formulations, different sealers require different waiting times, anywhere from 3- 28 days, and the best advice I could give you is to check your particular brand of sealer for its recommendation. Generally speaking, there are two types of sealer base — water and solvent, and the solvent based sealers generally require the shorter waiting period, but they’re also much more expensive.