Here in Israel, floors are laid on 2 inches of sand, with concrete as the bonder. the tiles are usually limestone. This floor is ceramic, 12 in. tiles. they keep coming up. the original tiler left no room for grout. i mix new cement 3 parts sand, 1 part portland. i have two choices, using beach sand or “machine” sand, which is limestone crushed. any thoughts on how to do this better? thanks. i keep doing this differently each time.
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Replies
Wow.
So a cross-section of the installation would be dirt floor, 2" of sand, a tad of 3-1 portland sand and then the tile? Wow.
You say the tiles come loose. I'm not surprised. Does the portland sand mix actually bond to the tile? If so, it is probably not bonding to the sand. Since the sand is not solid I can see why.
I make exterior brick patios that way, but leave out the portland, but bricks are much thicker and harder to work loose, like impossible.
Do me a favor and ask your question over at JB Forums. I'd love to have those yahoos respond to this.
http://johnbridge.com/vbulletin/forumdisplay.php?s=090f2dccbfc46429ecc058667012434b&forumid=1
Boris
"Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934
Yeah, the floor is a concrete slab.the cement normally bonds to tile. the tiles didn't do it this time. i wonder if it was because of the beach sand, as "Waynel5" said afterward.the dried cement under what i just did was almost white , and i wonder if that was a sign of the drynesss or dampness of the mix. i usually mix cement to where i can slice it with the trowel and the lines disappear within 3 seconds. BTW, a famous incident occured with Winston Churchil and Lady Acton in British Parliament. She accused of him of being a drunk. He returned that she was ugly but that on the morrow, he would be sober.
I wouldnt use beach sand.....no way!
I also would make my mud job at least 5:1.
It makes for a much stronger mix....another thing is to use a liquid latex mortar additive instead of water. That will really help you!
Shalom
Avi
In his first interview since the stroke, Ram Dass, 66, spoke with great difficulty about how his brush with death has changed his ideas about aging, and how the recent loss of two old friends, Timothy Leary and Allen Ginsberg, has convinced him that now, more than ever, is the time to ``Be Here Now.''
http://CLIFFORDRENOVATIONS.COM
Aha.
Others have covered it as well as I could. Mason's sand and porland cement, about a 5-1 ratio, mixed very very dry. In the 60's, we applied the tiles to the wet mortar bed, a technique called wet setting, by sprinkling some fresh portland cement onto the sand mix bed, about a sixteenth of an inch, waiting about 5 minutes, and then pressing the tiles into the bed.
Haven't done this for a couple decades now, since they mercifly invented thinset.
Good Luck!Regards,
Boris
"Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934
Hey Andy, not to start a debate, but I don't use latex additives for med beds. They make the bed too hard and too strong, and you don't need it, certainly not in this application.
I like mud beds to be sandy, and "workable", so if there are any slight highs or lows, the bed can be worked. If one adds latex or acrylic milk, it brings the whole bed up to about 24-3600 psi. Great for a driveway, but not very good for a home floor that one might be tiling with 1" hexes. And this application is over a concrete slab, I don't even see the necessity of a mud bed. If Israel had thinset (which apparently they don't) you could just tile over that. I am having a hard time believing that one can not order nor obtain bonding mortar there. But hey, I take these questions at face value.
I wonder if one could make a "home brew" thinset with portland and other ingredients?
Regards,
Boris
"Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934
Boris, what is it exactly you are saying about acrylic additives? Unnecessary for tiling in doors? I just thought it was an insurance for good bonding? What could be bad about that? It is costly, however, so if it is not necessary so be it.
Here is the deal. A mud bed is formed by dragging a straight edge over some screeds. If the mud is dry enough, it will be fairly flat. If it isn't flat, your wooden trowel can get it pretty close, usually within a sixteenth or so. If its late, and I'm tired or drunk, then heck it might even be an eight off.
Now once it dries and you are tiling, the mud bed will probably have these minor dips and humps. I am not perfect and sorry guys, but they are there.
On humps, if you are tiling with a large format tile, like 12-16 inch, and you put the tile there, it will rock. Yes you can smoosh some extra thinset in there but what about the tile next to it? More thinset there to avoid lips on the tile? You're just raising the mud bed. This is not good.
On a small format tile, it is even worse. Those stupid little 1 inch mosiacs echo every wrinkle in the mud bed, smooshing down extra thinset just makes it ooze between the tiles and makes a bloody mess.
So what ya'all need to do is knock down that hump.
If you've added acrylic admix and the mud bed is now 3600 psi and used a flat steel trowel to finish the bed for a nice smooth finish, the bed is smooth as a babies bottom and rock hard. You'll need a friggin jack hammer to knock down that hump. I have to go to the truck and get a 4" grinder and grind that sucker down. Messy, smelly, and time consuming. Might average 5-10 minutes per hump. The typical 100 sq ft bath might have 3-4 of those stupid little humps, more if I was really drunk.
The acrlic milk you've added to the bed has nothing to do with increased bonding to the thinset, it just increases the strength of the bed. I have used the milk in concrete work as a bonding agent (used straight) on pre-existing slabs to increase bonding to it when pouring a "cold joint", but what you were talking about is mixing it in to the mortar. Nope, it just increases strength.
If you don't add admix, and you use a wooden trowel to smooth it out like I do, the finish is rough and sandy. Indeed, that rough surface may actually increase mechanical bonding rather than the smooth rock hard bed that you floated with admix. The bed is about 1800 psi at tops, and the edge of a knotched trowel can easily knock off that hump. It takes about 5 seconds. I don't even have to get off my knees to install the tile on the setting bed, just keep moving on.
Now if you are floating a tile floor for a commercial mall or car repair facility, then yes, I'd want the mix to be a bit richer (more cement) and I would probably add some acrylic admix to get it up to 23-3600 psi. Heck I have had some beds come out to 4500 psi. And we'd have to be real careful in floating it.
But for the average home shower, or 100 sq ft bathroom, you just don't need that kind strength and honestly don't want that kind strength. It becomes a disadvantage and more labor intensive to install the tile.
Its not like the bathroom floor will have a 1000 per hour foot count on it.
This is why I don't use nor recommend admix in mortar floors. I know others do. Maybe they are better at mud beds than I am, maybe they have a better grinder, or like to grind out mortar; maybe they don't give ####s h i t about what the setting bed looks like. I dunno. This is just my experience.
Regards,
Boris
"Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934
Hi Boris -
In (one of) my past lives I was a tile setter. None the less, there have been many, many advances in materials science since then and I wouldn't profess to be current with most of them. In any event, 'back then' we never looked for a bond between a mud bed and a concrete substrate. In fact, we often took pains to prevent the bed from bonding to the concrete. The slab is/was sure to move. The drypack setting bed with a much lower water/cement ratio tends to shrink a lot less. Thus,.... don't want the two bonded.
Humps & valleys in the setting bed happen. Even when we're sober (grin). That's why I much, much prefer to fresh set floors. And walls for that matter. They may not be any smoother of flater than yours, but all it takes is a big enough rubber mallet with a delicate 'touch' and you've got the tile well bedded in the setting bed.
Ceilings are another thing. My arms just aren't what they used to be for floating ceilings anymore so for the shower I'm building in our new place, it will probably be WonderBoard. Sorry to whouse out like that but.....
There's a new product I saw at the Dal Tile distributors a week ago. On the surface it looks like WonderBoard, the fiberglas reinforced concrete sheet stuff. But the core is, if you can imagine, styrofoam.
It appears to be pretty amazing stuff. For use on walls only, of course. And I suspect it should be backed up with drywall, at least. They even give it thumbs up for countertops but I don't think I'd do anything but a 'traditional' mud set drainboard if it were my place.
Have you seen of this stuff? Used it?
Just curious.....
...........
Dennis in Bellevue WA
[email protected]
I agree that if one actually puts a mud bed onto a concrete substrate (I can't imagine why one would do this by the way, unless the slab was not level, cracked, or the wrong elevation), you actually don't want it to bond. Indeed, when I tile on a slab, I pretty much insist upon a fracture membrane on top of the slab. But I'm out here in shakey city.
I haven't seen the DalTile product, but I suspect it is a knock off of a German product called WEDI, which has been on the market for about 5 years now. Lightweight and completely waterproof.
Regards,
Boris
"Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934
Been using Ditra lately on floors. Expensive but sure beats carrying up bds of Wonderboard up two flights of stairs and is sure easy to use.
Hope it holds up is all.....gulp.
Be well
andy
In his first interview since the stroke, Ram Dass, 66, spoke with great difficulty about how his brush with death has changed his ideas about aging, and how the recent loss of two old friends, Timothy Leary and Allen Ginsberg, has convinced him that now, more than ever, is the time to ``Be Here Now.''
http://CLIFFORDRENOVATIONS.COM
I rarely use wonderboard on any floor. On the old homes that I usually work on its mud. Still use CBU's for walls though.
If I ever find a sturdy plywood floor (still looking) I'll use Ditra. For slabs, peel and stick fracture membranes work better for me. Ditra is sometimes hard to set, it keeps curling up, and I have to stack bricks on it to get it to lay flat.
Regards,
Boris
"Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934
sent my listing to John Bridge. Love it. dov
I can't answer your whole question, but do not use beach sand. It has salt and other contaminants in it which would weaken any concrete made with it. Also, the grains are rounded, which makes for weaker concrete than concrete made with sharp-edged sand. I recommend using whatever professional masons in your area use. Here we call it "mason sand". It's washed, and the correct size and shape for high strength.
Sand does not sound like a solid base for tile.
Teesquare -
I'm going to have to assume that the 2" setting bed is *not* over just plain dirt. Please say it isn't. That's in no way adequate in my opinion.
Now - assuming the tile and setting bed is over something like a concrete slab ....
Do *NOT* use beach sand as has already been advised. Dirty, salty, etc., etc. Get sand from a mason's supply place. They will know what you need for a tile setting bed.
Mix the sand 1:4 for a "dry pack" setting bed. Add the *DRY* ingredients together in a suitable mixing vessel. A good contractor's wheel borrow will do in a pinch. Don't mix too much at one time, you'll have a mess. Using a hoe (all this is if you don't have a mixer) thoroughly mix the dry ingredients together until there are no streaks of cement or sand ... nice homogenous blend.
Add water slowly until you get a mix that's just damp enough to hold together when you squeeze it into a ball. You really don't need or want anything that's in any way fluid. Just enough water to hold the mix together in a ball. It makes placing it a lot easier.
By the way ... I assume you've pulled all the tile and the old setting bed up by this time. If not .... there's not much sense in continuing. If, on the other hand you have ....
Place the drypack bed and carefully level it off with a nice straight edged board of one kind or the other. You're looking for a level, flat, smooth surface that's the thickness of your tile below all adjacent abutting floor surfaces.
To get the tile to stick to this setting bed, - "dust" the surface of the setting bed with pure, dry portland cement. This is all donee while the setting bed is still fresh, by the way. Make sure you 'dust' on at least an 1/8" or so of pure cement. Needn't be exactly even, just aim for fairly even dusting with an average of about 1/16 - 1/8" thick.
When you've got the cement applied as above, take a large sponge and *lightly* sprinkle the area where you've spread the pure cement. Here you're aming to get the cement wet but still not add so much water that the setting bed becomes fluid.
When the pure is adequately moistened, set your tile directly on the pure. Use a rubber mallet/hammer to lightly tap the tiles into place and to level them.
Again, all this has to be done in a continuous process. If the setting bed is left too long, you won't get a decent bond and it will be too hard to level the tiles.
You can also "float" - that is place the setting bed - the floor out, let it cure at least a day or three, then use a "thin-set" setting mortar but you'll have to be dang sure the bed is level and smooth. There's not much correction available using thin setting bed methods.
Then, on the other hand, if the guy that installed this floor is still in business, I'd go after *HIS* hide to fix the problem. Doesn't sound like he bonded the tile to the setting bed very well.
Dennis in Bellevue WA
[email protected]
Nice system, i like this. it was only 2 tiles that i had to do, and the base under th sand is concrete.and the guy who did the floor is not building. i keep getting calls on the houses he did, making corrections on outta-kilter boo-boos. thanks
I doubt if the original mechanic actually used just sand but maybe so. Sometimes with the larger tiles it helps to mix up some pure cement to about the consistency of pancake batter then brush it on the back side of the tiles before setting them. This is in addition to sprinkling the pure on the setting bed. Be sure to get the dry pure sprinkled on the setting bed good and damp before setting the tiles but again, no so damp as to make the drypack 'soupy'.
Cement, the powder, doesn't take nearly as much water for hydration (getting hard) as we usually put in it. Concrete or mortar has to be workable which means we have to add really more water than is required for this hydration thing. Thus we can afford to make the drypack setting bed just damp so it hangs together but the tiles don't float around when we tamp them into it.
...........
Dennis in Bellevue WA
[email protected]
this is a great forum for a new take on tile-setting. I've never heard of this way, and i've never seen anybody do it. gotta try it on another patch job(the way this is going, I may redo what i just did) before I try a larger job. I've got one coming up, 6 sq. meters. thanks loads. If you ever come here, bring an order form from Home depot so i can get what i need. yuk. Dov
Hey everybody, Dov tells me that they do have thinset in Israel.
My recommendation is to bond the tiles directly to the slab with thinset. Unless the slab is severly cracked, this will work fine. With a cracked slab, I'd use the mortar base and the wet set method, with sprinkling the portland and backbuttering the tile with a fairly dry mix of portland to set the tile. Remember, mix everything dry. Water is not our friend in tiling. It shrinks and therefore causes cracky. Think dry.
Regards,
Boris
"Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934