everything you ever wanted to know about tile but were too afraid to ask

We planned to go to Home Depot last night and buy all of our supplies for this weekends tub-tiling project. As it turned out, though, Don’s idea of preparedness for such a shopping expedition was—well, unprepared. Fortunately for everybody, I hold a degree from a research university. And it ain’t for nothing! Let’s talk tile.

Lowe’s has an article on the tile tools we’ll need to buy, including nippers and the ubiquitous notched trowel. And here’s the reason for a notched trowel, incidentally: You spread the adhesive over the wall, then run the notches through it to create a little Zen garden type of look. What happens is that the tile gets put onto the adhesive, and the weight of it smooshes the Zen garden down. The little runnels of adhesive then partially collapse from the pressure, and they in turn squeeze all of the air out by way of those convenient little valleys you made with your notched trowel, forming a solid bed of adhesive. This makes sure that no air bubbles are lurking under your tiles, waiting with evil oxygenated glee to break the adhesive seal holding your tile to the wall, or to cause cracking or other problems related to temperature changing. So that’s why you need the notches, if you were wondering.

When you’re tiling a plain old wall, you can feel free to tile over drywall or plaster. When you’re in a bathroom, though, you have to use cement-fiber board as the surface to which you’re going to attach your tiles (Lowe’s very snootily calls it an ‘underlayment’). This stuff is cement and fiberglass mesh, all smooshed together into a very heavy sheet that is either half an inch or a quarter of an inch thick.

The ever-helpful Lowe’s (I feel so disloyal!) has a really thorough article here about exactly how one goes about installing tile on a wall. There’s another good one here from one of the grout and adhesive manufacturers.

For this project, we’re using simple ceramic tile. When we do our own bathroom, we’ll explore the options a little further (I’m partial to travertine), but Mr. and Mrs. V just want to sell their townhouse. So let’s talk a little bit about choosing tile. Color and style are, of course, totally up to you. If you’re trying to sell a house, though, your byword should be “neutral.” But when it comes to actually choosing the substance of the tile, you need to get the right kind for the right part of your house. All tile feels hard, but some types of tile are actually harder than others. Tile is rated by the Porcelain Enamel Institute in a series of standardized tests. The tests evaluate a tile's relative hardness according to the Mohs scale, which was actually developed to test the hardness of minerals by seeing how hard it is for something harder to scratch something softer (genius, I know). Diamond, incidentally, is rated a 1500 on the Mohs scale, while fingernail is rated a 2. If you’re curious. Anyway, the PEI tests also rate the tile’s ability to stand up to wear and the percentage of water absorbed.

The Porcelain Enamel Institute hardness ratings are:
-Group I - Light Traffic: residential bathroom floors where bare or stocking feet are the norm.
-Group II - Medium Traffic: home interiors where little abrasion occurs. Don't use in kitchens or entries.
-Group III - Medium-Heavy Traffic: any home interior.
-Group IV - Heavy Traffic: homes or light to medium commercial areas.
-Group V- Extra Heavy Traffic: use it anywhere.

Finally, about adhesives and grouts: If you’re tiling an interior room (provided it’s not, like, a sauna or something), thin-set mortar is fine (for saunas and exterior applications, use a latex modified thin-set mortar). You can also use a Type I Mastic, which has a longer drying time than a portland cement-based thin-set (it’ll stay goopier longer, which is why professionals like to use it for big jobs; it won’t dry out in their buckets). Pictures of both are here. If your grout lines are an eighth of an inch or smaller, you can use unsanded grout. If they’re larger, use sanded grout. Your grout lines, of course, are going to be determined by what size of spacers you choose to separate your tiles with when you're laying them. When you’re grouting, use a rubber float to push the grout into the lines between the tile. It’ll ensure an even grout layer without messing up the tile you’ve just sweated into place.

Hopefully my superior research skills have given you—and us—an edge in the wonderful world of tile. If you have any questions about tile that I didn't cover, please leave a comment. I'll post everyone's questions and my answers to them in the next couple of days.