Thinset or Slurry [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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05-08-2001, 08:55 AM
John, I've read your book and have a question regarding mud on an above-grade slab.

Your book says to use a Portland cement slurry to bond the mud to the concrete. A local flooring guy recommends using thinset mortar. Are you familiar with this method?

Since you write that the slurry is usable for only a short period of time, and I've read that thinset is usable for a longer period of time, I'm considering using the thinset, but would like to know more about that method, particularly from somebody who recommends the other one.

With the short set-up time of the slurry, I'm afraid I'll need a second brain and pair of hands. My wife usually fills in for jobs like that, but she is prone to ask peculair questions at awkward moments, like, "Do you think I'm getting too fat?" and "Did you really like the rutabaga souffle I made last night? I'm thinking about making it for a dinner party after the kitchen gets finished." With the short usable period of the Portland slurry, I'm afraid I would not have time to answer those types of questions.


Sleepless in Des Moines

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05-08-2001, 11:44 AM
Sorry to stick my nose in here John..but I use thin set as a bond slurry all the time to stick concrete to concrete. I find that it works very well, since it has the portland and the latex already in it. Rick, your local flooring guy must have had good luck with it also, to recommend it. And if you think about it, it's not any different to what John recommends...either way the slurry has to be wet to get a good bond.

05-08-2001, 01:15 PM
Thank-you, Brian.

So, is the thinset you use mixed wetter than the standard mix? I ask that because you used the term, "slurry."

I didn't make it all that clear that I'm a DIYer. And I do have some experience with thinset -- bathroom and kitchen stuff that was pretty standard installation over stick construction, some northern patio work where I set well-buttered stone over a concrete base built specially for that purpose. I've even set some Portillo tile over above-grade concrete in another home (my luck I keep finding and buying these built-like-bomb-shelter homes).

Anyway, the advice I'd gotten seemed to recommend using standard-mix, latex-based thinset applied with a notched trowel. Then, lay the mud over it.

Any additional commentary on this subject would be appreciated.


05-08-2001, 02:47 PM
Yes, I do make it a bit wetter than the way I would use it for ceramic tile. I like to make sure that it has lots of contact with the concrete above and below. Your way of using the notched trowel is fine....but the important thing is to make sure there is enough bonding material..and that it doesn't dry out before you get mud on it. John will probably have other thoughts, but it's worked well for me..even outdoors.

John Bridge
05-08-2001, 04:26 PM
Actually, you guys have about covered it. I can't believe I wrote that. I should have specified thin set to begin with. It's just the way we used to do everything (and the book was written 10 years ago).

Nowadays, I usually throw a little water on the deck and sprinkle it with dry thin set until the slurry state is more or less reached. Saves having to clean out an additional bucket, but that's all. Mixing and spreading the thin set is a good way to go. Yes, keep it sloppy, because the slab is usually dry. As Bri indicates, get the mud on it while it's wet, or start over.

John (slippin' and slidin' through that mud) Bridge

05-16-2001, 11:12 AM
Well, the baptism by mud is over and boy, was that a workout.

145 square feet, an inch thick, a ton of mud and it took about 14 hours -- and I still didn't even have enough time to perfect my standing around technique. As for the sitting around part, it degenerated very quickly into falling asleep

Things went fairly smoothly in the beginning when the wife was helping, then fatigue got the best of her about two and a half hours into it and I was on my own.

The location of the job was not really helpful. I had to go through an enclosed porch and up half a fight of stairs to get the mud into the house. So I decided to bring the sand and portland cement into the house with 5-gallon buckets -- one bucket full of sand, the other bucket filled up to a one-gallon mark -- and mix inside. I had a large tub for the job and one round with this method seemed to cover about 6-sq. feet.

Working with the sand was kinda funky. I had the sand delivered the night before the project and it rained that evening. The first few tubs of sand were right at that perfect "sand castle building" consistency and I hardly had to add water. As the day wore on and the sun came out, and I got to the bottom of the pile, the sand was much drier and I found myself making more runs for buckets of water. Late in the game, I'd run into some very moist sand and was too fatigued to realize it and mixed a wetter tub than what was recommended. Not, goopy mind you, but I certainly noticed to moisture coming to the surface much more readily as I troweled the surface.

The room layout presented a bit of a problem. The room is long and narrow with a door separating the kitchen and a breakfast alcove, plus a small alcove for appliances and cabinetry. I worked the first screed and trough from one end of the room until I was across from my exit door and met the wall into the breakfast alcove, then I went back and worked another parallel screed and trough, with a detour into the appliance alcove -- everything was going well then.

At that point, I'd worked as far as I could from one end of the room to the exit door and the passage into the breakfast alcove, that's when I began working the breakfast alcove at the other end. That went well, but by the time I met back up with my early work, it had set up pretty good and that edge was not easy to work with. I tried keeping the edge fresh (I didn't know if I needed to or not, just thought it was a good idea) by adding to it from time to time --all while whittling down my working area around the escape door.

I don't know if it was fatigue, or the hard edge, but that area where everything came together has the most signifigant irregularities. I don't think it's something I can't work with -- nothing more than 1/8" variation, if that -- but it is the difference between "Yeah, it'll work." and something to be particularly proud of. The dining alcove looks the best, though. Maybe because it was only 7'X6' and I only ran one screed through the middle.

I appreciate the advice you've given to get me through this, and all the great writing in your book.

Thought you might a little feedback from one of the mud people you've created.


05-16-2001, 01:40 PM
Sounds like you had a good day! I guess I should have told you to hire a couple of young guys($1.00 hour) to carry stuff up stairs for you...what was I thinking! Next time(yeah right) mix everything downstairs...then just carry the mud up in the the way...any rough spots can be fixed with thin set before you should be pretty good with a trowel now!

05-16-2001, 03:56 PM
On the rough spots ...

Trowel them over and let the thinset set? Or butter up the bottom of the tiles like I've done with stone and portillo tile?


John Bridge
05-16-2001, 04:27 PM
Hey Rick,

You don't know how proud I am of you and your accomplishment. Even though you flunked the John Bridge School of Standing Around, and you apparently abused your "helper," you've still accomplished something others only dream of (will someone please shut me up?).

When I wrote the book, I forgot to address the "hard edge" issue. I handle it by sprinkling the edge with water and portland cement to sort of bond the new to the old. Actually, though, it makes no difference. When you mush thinset down on there, everything will become one again.

I DID cover the issue of hauling the mud in in buckets, though. Even talked about cleaning up the driveway where the mud (in my book) was mixed. Mixing it in the tub must have been a real bitch.

If you can send me some pics, I'll be happy to post them to the Internet for you and place a link to them on the site. Or you can post a pic right here. It must be on the Internet, though, and not just on your computer.

And Bri, Send me down some of those one dollar an hour guys. Wait a minute. Is that a Canadian buck or US?

05-17-2001, 09:54 AM
John, thanks for the compliment. I'll proudly admit that most of the subs I have working around the house seemed in awe of the job. Although my electrician thinks I'm just plain nuts.

I'll have other chances to go back to Standing Around school and perfect the technique. There is after all tile to set, which will offer plenty of opportunities for that. And there's a foyer/ closet (27' X 3') that also requires mud, as well.

And while I realize that you most likely made the comment in jest, no, I did not abuse my helper. I'll point that finger at the real estate agent who refused to write a clause in our sales contract that would have allowed us to rent our former residence while we updated this new home. It was frustrating to learn from our buyers that they would have eagerly accepted those terms at a fair rental rate. Karen has a low tolerance for the chaos of rehab work, and I must be vigilant for any signs of fatigue and frustration from her. So at any time a job -- or life itself -- starts to overwhelm her, she gets a pass. And she's had plenty of opportunities for both to happen lately.

Over the last six weeks she's had to deal with an incompetent real-estate agent, a garage tear-down and re-build, electricians overhauling the wiring, a flooring contractor whose son/apprentice apparently did know how to use a depth-stop on the drill bits he used to attach sub-floor to our above-grade concrete slab main floor, rained concrete particles all over the furniture that was being stored in the basement, then before the job was finished went out and got busted on felony drug charges, delaying the wood flooring job a week. There was a trash hauler who sent the wrong truck (too big), insisted it would not hurt our driveway, and proceed to crack up the driveway. Then, add my own efforts in painting the house interior, gutting the kitchen and repaneling and building cabinets for a sun room and you have a good recipe for spousal frustration.

I know you're absolutely right on the driveway thing, and read about it in your book. In fact, I may have used the driveway to mix but a few factors led me away from that. First was the threat of intermittant rain. It didn't rain that day, but that was a posibility and I was not comfortable with what the rain would do to the mud. This being my first mud job, I was also unsure of how to mix the right proportions on the driveway, and how much to mix at one time. Perhaps a bit more work, but I felt more comfortable mixing indoors.

I'd like to send some photos once I get them developed and burnt to CD, but I'm unsure how to post them here.

Also, Bri mentioned something about using thinset to level out the irregularities in the floor, and if it would not be too much trouble, I'd like to know exactly how to go about that.


John Bridge
05-17-2001, 02:42 PM
Everything I said was in jest but the comliment, which I'll repeat. Good show!

Just email the photos when you get them, and I'll post them to the Internet, where the world will be able to view them.

05-17-2001, 03:06 PM
So what about this using thinset to level out the imperfections? Do I butter the tiles a little extra, or do I trowel over some thinset and let it set up?


John Bridge
05-17-2001, 04:41 PM
If it were my job, I'd just build up a little as I set the tiles. Trowel over the "hump," and then do a little back-buttering on the tiles if that's what it takes. That's the key, in fact. Do whatever it takes. It's gotten me through over thirty years of screwing around with houses.

You might want to balance a piece on the ridge and rock it back and forth a little to gauge the amount of extra material you'll need to apply.

I've been working on a slab floor all week that is up and down. Back-buttering is second nature to me. Put 'em down, take 'em up, put 'em down again . . . then take 'em up . . .

Rob Z
05-17-2001, 07:46 PM
Hi Rick

It's quite ambitious of you to take on such a large project. Keep us posted with all the goings-on. Unfortunately, you're encountering some of the knuckleheads found in the various construction trades.

In our old house, I tore out the master bathroom while my wife was up in New Jersey at her parents. I thought "I'll get most of the rough in work done by the time she gets home and really surprise her." Well, that was the year we got the "storm of the century", and I shoveled so much snow that I hurt my back and couldn't do any work on the bathroom.

There were many things said when Christina came back from her trip, but I swore I'd get that thing done within a month-just as soon as my back got better. I was very convincing at the time.

Well, more jobs followed (the paying kind), and that damn bathroom remained unfinished for FOUR AND ONE HALF YEARS. I finally got my act together and got it finished so we could sell the house. I even ended up PAYING SOMEONE ELSE to set tile in my own house. Unbelievable!!!!

So, when we bought the new house, I agreed to everything my wonderful wife wanted, and let the builder do everything.

Maybe someday my wife can meet your wife, and they can compare notes.

On a serious note, I use ARDEX Feather Finish to take care of little imperfections in concrete slabs amd mortar beds. It's quick and easy to use (soewhat like drywall compound), and dries fast. You can set tile over it within minutes.

Let us know how things are going on your Big Project.


Sonnie Layne
05-17-2001, 09:33 PM
sonds like skim coating drywall, wipe it on, wipe it off.
Or Pickling cabinets, same thing.
Or like an oil finish on a staircase. Difference there is I get $2 per hour insted of $1.50.

I do agree with Admin. Sometimes (especially larger jobs) you pull it up and relay it and ya' just gotta wonder if ya estimated right! Ah well, it's only an estimate. More than half my estimates come in below the quoted figure. Dedicated and happy clientelle.

John Bridge
05-18-2001, 05:54 AM
On one ocassion I paid a helper to help me mud my own bathroom, but I have never paid a setter to screw up my own house. I manage that quite nicely myself, thank you.

05-18-2001, 01:33 PM
Ahhh! I'm laughing so hard over Rob's response. I had a project like that once. Beat-up old house in a very nice neighborhood nobody wanted to rehab. Three years of landscaping, tuckpointing, re-flooring, painting, trim work and cabinetry and it wasn't finished until a week before the house was sold on account of divorce. Don't think the rehab caused the divorce, but it didn't help matters any.

This house, I promised my sweetheart that we'd do all the stuff most folks don't do until a home is sold before we moved in. Only the real estate agent fouled that up. I realize there is a real estate professional in the group, but I'll still say, after selling FSBO and selling through an agent, that the extra money folks spend on an agent is not worth the extra heartache they cause. Hire a good real-estate attorney and a freelance ad writer and you'll save time, money and the frustration of dealing with a profession that operates with a code of ethics that makes Bill Clinton and Monica Lewinsky look like Sunday School teachers. But I rant.

I appreciate everyone's input on this, and I'm thinking of going with John's method. It's what I had in mind when I first noticed the irregularities, and this fix seems similar to what I've done when setting stone patios. Bri seemed to suggest another method and I was simply curious about that.

Right now, we're only a week behind the schedule I'd estimated. And that was because of the wood floor. Big problem of working in a home that you're living in, is that furniture and other personal belongings have to be shuffled about the house and it's hard to have a number of projects going on simultaneously. A funeral this weekend may push us back another week.

Thanks everybody for the advice and encouragement. We'll keep you posted on our progress.


Rob Z
05-18-2001, 06:30 PM
Hi Rick, John, and everyone:

I did do all the mud work in the bathroom-I just had one of my salesman from the tile store do the tile. He did want to help out, and he needed some extra money, so it wasn't too bad. Actually, the house sale prep and sale proceeded quite quickly, driven by the fact that my ex moved in nearly next door. How's that for motivation to get your act together?

All my friends in the trades really pitched in and got things done-electrician, painters, carpenter and landscaper.

Everything looked great. We got four contracts the first weekend the house was listed!