Best way to remove thinset from plywood underlayment

R

RonMiller

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Oct 17, 2009
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I know some of you do this regularly, so...

What's the best way to take up 12" tiles that are thinsetted (?) down to a double layer of plywood? The homeowners decided to redo the kitchen tile floor AFTER having their custom cabinets refinished so I need to take up the tile and remove the thinset without alot of grit and dust flying around. There is a kitchen, small bathroom, and a large laundry/entry room to do, about 300 sf. I'm planning on using Ditra as an underlayment for the 18" tiles they've chosen but don't want to remove the plywood top layer unless absolutely necessary.
 
I use my Bosch rotary hammer drill in the hammer mode with a spade bit to remove as much the tile and thinset as possible.  Placing a sheet or towel on top of the tile while working keeps down the flying shards and dust.  Clean up the tile and dispose.  Vacuum up the dust with a CT.  Then use the RAS to grind off the residual.

Good Luck!

Peter
 
Peter, I have the typical grits of 60 - 80 - 120 for my RAS. Is that what you use or  something else?
 
I am redoing my master bath and had not thought of using the RAS to level/grind off the old thinset.  What paper is best for this -- Saphir?

Scot
 
I just checked.  I use 24 and 36 grit Saphir the most.  I would lay up a test piece to show, but I guess I threw away the last partial bag.  I do have some for marble and granite mortar that I could mix up, but I think that is a softer mix.  Let me know if you want a demo in a couple of days.

By the way, I am pretty sure that one of the Chris's did a thread showing this and of course one of our members is a tile setter in Northern VA.  Unfortunately his member name escapes me right now - someone will remember - he was one who tested the new CT-s and had one bounce to the bottom of the stairs.(  ROB Z is the tilesetter.  His thread:  Using the CT-26

Peter

Some threads: 

http://festoolownersgroup.com/festool-tools-accessories/sandinggrinding-down-unmodified-thin-set-mortar/

http://festoolownersgroup.com/member-projects/kitchen-bath-remodel/

http://festoolownersgroup.com/festool-tools-accessories/sanding-floor-tile/

 
Thanks Chris. When I clicked on the Klingspor link it took me to the aluminum oxide discs. But your note recommended the super zirconium. Are the zircs better or ?
 
RonMiller said:
I need to take up the tile and remove the thinset without alot of grit and dust flying around.
Click to expand...

With a double layer of plywood, I would use a hammer to break the tiles and remove them.  Then cut the top layer of plywood (circ saw and multimaster) and replace it.

This will produce the least dust and grit and leave you with the smoothest substrate as well as being the least time consuming.  Trying to remove thinset off of plywood is difficult to do without damaging the plywood.  It really isn't worth the $200-$300 for new plywood.  IME.

If you are dead set on leaving the plywood, roll up the sleeves, put the knee pads on, get a dust mask, put up some zipwall, cover the cabinets/appliances with plastic and tape.  Break out a rotary hammer with a tile removal tip and get to work.  You will tear up the plywood a bit as the plywood is much softer than the thinset.  It will be near impossible to removal all the thinset.  You can turn to abrasives to flatten the remaining bits of thinset.
 
This is a case where taking up the plywood isn't an option. Thanks again for the suggestions. I'm going with the Peter and Chris method on Tuesday and we'll see what happens!
 
Easy squeezy lemon peasey...  I have now done several jobs of this type.  I like the Hilti rotary hammer with a hooked chisel to pop the tile.  Set the drill to hammer mode and get under a corner.  Most of the time the entire tile will lift in one piece.  The biggest problem used to be getting the thinset mortar off the subfloor so I could set new tile but I could a tool even better at dust extraction than the ras. (please forgive me).  Bosch has a 5" grinder with a diamond cup, very effective on masonry, but the entire cup is shrouded, has brissles, and a dust port.  Omg, this tool is fast and clean.  I recently did two small powder rooms with no outside air supply, a job I would consider suicide by dust inhalation.  I took the door handle off to sent the ct hose through and wore my dust mask just in case.  No problems.

I bought this tool because I do a lot of kitchen and Bath remodels.  Tile demo has always the messiest portion of this job, even with dust wall.  Now I have little concern for this tedious job.
 
Well I followed Peter and Chris' advice and used the RAS (which I already owned) with the 24 grit Klingspohr zirconium (?) oxide fiber backed sanding discs. WOW, did that work fast, smooth, and clean. Very little dust or residue and a new 24 grit disc tore through the thinset. So for about a $45 investment I can do many of these floors with what I bought.

Thanks for the great advice.
 
Hi Ron,

Thanks for the update.  Did you happen to take any pics before/after? I am knee deep in my bathroom demolition and need to tackle the floor and was going to use the same set-up. 

Thanks,

Scot
 
Sorry, no pics. I'm really bad at remembering to do that - it never even crossed my mind. Perhaps I can do some mid and final shots.
 
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