mastic or thinset

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  #1  
Old 11-15-10, 03:38 PM
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mastic or thinset

i just spent most of yesterday afternoon cutting and setting 12" square tile (1/4" thick) in a small powder room floor with Mastic (big bright pink tub). of course, after the fact, I'm reading online that thinset is the better, cheaper, more appropriate adhesive for tiles of this size. i did just check the pliability of the adhesive and it seems a little bit soft on a place where it squeezed out between backerboard and tile at the doorway but it's been less than 24 hours.

in very small print on the tub, it says 'not for floors with larger than 6" by 6" tiles. i guess i didn't notice that in Lowes.

question, am i screwed here? is this stuff going to slide around, breaking my grout (which i have yet to do that part)? it was no easy job but i'd have to have to pull all the tile up and start over again...

thanks, Pat
 
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Old 11-15-10, 04:46 PM
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i would rip it up and start over. tile wasnt expensive was it? that mastic will never cure properly and your grout will crack after time..
 
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Old 11-15-10, 06:05 PM
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2.48 per tile, used 20 of them. how about the backer board? is that wasted too?
 
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Old 11-15-10, 06:05 PM
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I would get it up as quickly as possible. If a Lowes associate said you could use that for your project, I would raise this negligent advice to management and they will usually give you some new tile if you broke any.

Get a powered thinset like Mapai, Laticrete from Lowes, or Flexbond/Versabond from HD. It will be cheaper then that mastic and be much better.

You typically can scrape most of the mastic off the backboard if it hasn't fully cured, which it prolly has not happened.

This begs a new question, I take it you did not apply thinset under the backerboard which the instructions tell you to do?
 
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Old 11-15-10, 06:09 PM
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Oh boy, this again.

It's gonna keep happening if you people keep going to those no nothing big box stores for tile projects. Unless you know what you need and how to do the job, chances are you're going to mess up some how.

What did you put between the backer board and the subfloor?

Jaz
 
  #6  
Old 11-15-10, 06:13 PM
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backerboard is over old linoleum which was over old particle board over plastic sheeting over bottom level plywood. backerboard is tacked down every 8 inches with green backer screws.
 
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Old 11-15-10, 06:22 PM
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UGH! Particle board is the worst enemy to a tile installation. I'm not liking the outcome of this. Not to scold you, but you should have known to check here first before this project. Also, don't watch those DIY shows. 99% of the time the installers are doing it wrong giving millions of people awful advice.
 
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Old 11-15-10, 06:38 PM
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but the particle board is over 2 layers beneath the tile.

tile
mastic
backerboard
linoleum
particle board
plastic sheeting
base plywood

[below that is the basement joists]
 
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Old 11-15-10, 06:40 PM
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You forgot to apply thin set mortar under the backer too.

Particle board - No thin set under the backer - mastic for any floor tile - 3 strikes!

Start over.

Jaz
 
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Old 11-15-10, 06:51 PM
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what does thinset do under the backerboard? it's screwed down plenty tight.
 
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Old 11-15-10, 07:01 PM
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also, now that it's looking like i have to pull it all up, what's the best way of getting 12" tile up without breaking (as many or all of) them? can i salvage the backerboard? i'm about $200 into this and can't afford just throw all that into the dumpster.
 
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Old 11-15-10, 07:08 PM
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It's supposed to be screwed down pretty good. The thin set supports the backer so there's no movement. You are guaranteed to develop hair line cracks in the grout, at minimum, within 5-7 years. Your floor will move up and down a bit where there are no screws. In time even the screw heads will break down the board. Backer board has no grain like wood and so adds very little stiffness.

The screws hold the board down, the thin set supports the board up so it doesn't move.

Jaz
 
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Old 11-15-10, 07:37 PM
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so getting the tiles without breaking them? ideas?
 
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Old 11-15-10, 07:42 PM
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That mastic is still soft you should be able to pry them up using a stiff putty knife. Another way is to use wire, since it's still not grouted.

What are your thoughts?

Jaz
 
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Old 11-15-10, 07:58 PM
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i like the wire idea. could even use a pvc cutter since it's got the plastic handles on it. how long to i have before the mastic is going to be unworkable? there are some spots around the walls where it has squeezed out that's as soft as day old, left out, cake icing.
 
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Old 11-15-10, 08:15 PM
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so i gotta ask now also. wtf is mastic used for? i'm only reading bad things about it. i'm guessing 'not tile' is a common answer...
 
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Old 11-15-10, 09:03 PM
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mastic can be used for wall tile if its not in a wet location. I prefer to use the premixed portland based thinset for wall tile though. Ive used the mastic before but the smell of the stuff is enough to drive me crazy.

Hey we live and we learn right.. Hopefully you can get those tiles up without breaking any, and take the cement board up to and reinstall it the right way.
 
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Old 11-15-10, 09:17 PM
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That's about all it's really good for, back splashes as an example.

Joe, can you direct us to a "pre-mixed Portland" thin set mortar? Never seen it, never thought it was possible to store mixed Portland.

Jaz
 
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Old 11-15-10, 09:57 PM
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yeah, ill get back to you tomorrow. got a tub of it at a job im doing. i could be wrong, but i know its not the same as mastic. it does have an additive in it so it dosent harden in the tub. got almost the same but not as strong of a smell as the mastic does.
 
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Old 11-16-10, 05:30 AM
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What Jaz was illuding to is portland is a powder mixed with water. Joe, you are talking about a adhesive in a bucket that is labeled "ThinSet."
 
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Old 11-16-10, 05:55 AM
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yeah i was probably mistaken by saying portland what i meant to say is its more like a regular bagged thinset then the mastic stuff. I dont use it for laying cement board or tubs or showers, but i love it for walls. dosent smell as bad as mastic and sets up pretty fast.
 
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Old 11-16-10, 02:35 PM
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Joe,

It's mastic irrespective of what they call it. They might add a little sand to it, but it's mastic. It's OK to use on walls if it's a dry area. It's also good for those who like to spend 3-5 times more than necessary to get an inferior product. It does come in a nice reusable bucket though.

Jaz
 
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Old 11-16-10, 03:22 PM
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Hey, buckets are $4 at big orange, WITH their advertising on it. I just ask my rock guy where his job is today, and get 20 or so at a time, fairly clean.
 
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Old 11-17-10, 09:50 AM
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I have just one question. If mastic sucks so bad that Pat's job is doomed to fail what does he gain by tearing it up now? Why not wait to tear it up when it meets all of your expert predictions?

These are the same predictions that I got from the experts here when I used mastic in a master bath renovation several years ago. Tear it up was the advice. I didn't and the tile is still perfect.
Even if it is dumb luck and it all falls apart tomorrow I've gained nearly 5 years of use with no indication that the tile will fail soon.
 
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Old 11-17-10, 11:54 AM
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It was suggested he remove and re do the job because he had just done it AND it wasn't grouted yet. He should be able to remove the tiles and re set them with little or no breakage.

Then we learned he didn't install the backer correctly either. So, might as well done it right cuz it'll be a much harder job latter.

Many jobs are done wrong, it happens all the time. That does not guarantee a complete failure. There are many installations out there that in my opinion have failed, but the owners still don't realize it.

We just have to give advice that complies to industry norms and follow the directions of the manufacturers. The manufacturers know best how their products should be installed.

Jaz
 
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Old 11-17-10, 04:16 PM
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thanks for all the help everyone. definitely some lessons learned here.
 
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