Tile on a concrete floor

Hello, I am about to lay a bunch of those saltillo tiles down on a concrete floor. My tile skills are limited. I have put tile down on wonderboard, and on hardiboard, but never on concrete. Is it the same? Are there any difficulties I am likely to encounter? Any advice will be appreciated. Thanks.
flank
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Flank wrote:

Yeah
You need to divide the room into quarters...just draw lines on the concrete with a felt tip marker so that they are perpendicular to each other and cross in the exact center of the room. Once you have your lines, you need to dry lay two perpendicular courses so that you can tell how to start laying the tile to wind up with the widest possible cut tiles on the room sides. There are two possibilities for each of the two lines...center of tile on the line or center of what will be a joint on the line.
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Handmade Saltillo is irregular in both thickness and length/width. Therefore...
1. Use plenty of thinset and a 1/2" x 1/2" notch comb. If the tile is concave, convex or has a bump on the bottom to the point that the thinset wouldn't contact the entire tile surface, even it up by buttering the tile.
2. Because of the size irregularity, you can't lay Saltillo with nice neat, even joints. About the best you can do is to lay a course with the edges on one side even (an aluminum yardstick is handy to line them up); on the next, parallel course, lay with the same edge lined up. That is, if the right edges of course #1 are aligned, align the right edges of course #2....that means that the left edges of course #2 will be ragged. Can't be helped.
3. Don't try to make small joints...I like 1/2 to 1" joints. If you try to make them too small you may well run out of joint room because of the irregularity in the tiles and/or laying errors. If that happens, correct as much as you can and - after the tile is dry - you can fix it by using a circular saw with a masonry blade set to a shallow cut (3/16 to 5/16 for example) to even up and widen the grout joint as desired. ____________
Some more random thoughts...
1. Saltillo is very porous. I mix thinset so it is pretty thin...thin enough so combed mortar will just barely stand up. It is also dusty...I dip each tile in a bucket of water before laying. That not only removes the dust but it keeps the tile from grabbing the mortar too quickly...it would do so almost immediately if the tile wasn't dampened and once it grabs, you can't adjust it.
2. After the tiles grab, rap them with your knuckles. If you get a hollow sound, you aren't using enough mortar. They would probably be OK but they aren't hard to take up, scrape off the mortar and re-lay.
3. Expect a lot of breakage in the boxes - if you can use the broken ones for the cut tiles, fine; if not, set them aside until you get a box full and take them back for good ones.
4. Even many of the unbroken ones will have minor chips/dings on the edge...the appearance will be improved if you smooth out the sharp edges of the chips/dings with a piece of sand paper (#120 is good).
5. Keep a bucket of clean water and a good sponge handy and wipe up any mortar that gets on the tops of the tiles...wait too long and it will stain.
--

dadiOH
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I nominate dadiOH for the most helpful post of 2006 !
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Do yourself a favor and buy a set of Gel Knee Pads. You won't be sorry.
LJ
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Great advice. I will use it. Thanks dadiOH. dadiOH wrote:

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wrote:

I assume this is a "seasoned" concrete floor? Is it cracked? If there are cracks they will transmit through the tile if it is not on a membrane. If it is solid Daddio has you on the right track.
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