Mortar for laying DITRA on subfloor

Reply

  #1  
Old 09-05-16, 04:33 PM
M
Member
Thread Starter
Join Date: Aug 2016
Location: us
Posts: 44
Received 0 Votes on 0 Posts
Mortar for laying DITRA on subfloor

Hello:

Is it OK to use Custom Flexbond modified "crack prevention mortar" to lay DITRA on top of the subflooring? If it is not, what would be best for this application?

Thanks in advance for any help!
 
Sponsored Links
  #2  
Old 09-05-16, 09:37 PM
J
Member
Join Date: May 2007
Location: USA
Posts: 1,604
Received 0 Votes on 0 Posts
Hi Moogy,

Custom's Flexbond is plenty good enough to install Ditra if your (unknown) subfloor is the proper grade of plywood or OSB. You could use something cheaper, but, it's only money.

What do you plan to use to install the tiles over Ditra?

Jaz
 
  #3  
Old 09-06-16, 06:37 AM
M
Member
Thread Starter
Join Date: Aug 2016
Location: us
Posts: 44
Received 0 Votes on 0 Posts
Hi Jazman:

Thanks for quick reply!

(1) I am going to try and place mesh resin-backed 2" x 2" travertine tiles (mesh holds it in 12" x 12" pieces) using LATICRETE LATAPOXY 300 ADHESIVE. All of the thinset bags or mortar said don't use regular mortar on resin backed tiles.
(2) I was debating whether to do anything else with the subfloor. It seems solid with no squeaks, etc. but I had peeled off a layer of pretty old vinyl linoleum and it left a very thin layer of what looks like paper. It's less than a millimeter thick. It doesn't want to come off. If I dampened it first (so it would not suck the water out of the thinset too quick) do you think it's OK?
Any additional advice will be much appreciated!

Thanks,
Moogy
 
  #4  
Old 09-06-16, 03:25 PM
czizzi's Avatar
Member
Join Date: Jul 2007
Location: USA
Posts: 7,388
Received 14 Votes on 12 Posts
Good chance that the paper from the linoleum is over 1/4" underlayment grade plywood. That needs to come out before you begin your installation. Can you see a cross section of the subfloor in a HVAC vent?
 
  #5  
Old 09-06-16, 08:27 PM
M
Member
Thread Starter
Join Date: Aug 2016
Location: us
Posts: 44
Received 0 Votes on 0 Posts
Dear czizzi:

Thanks for the reply.

I drilled out a 1.25" core from the floor. This house was built in 1975 and all three floors/cielings are made from 2" x 8" tongue and groove Doug fir. The core was 2" thick with the first 1/2" a sawdust//glue composite on top of the 2" x 8" Doug fir.

Please advise on what I need to do to lay the Ditra. I'm disinclined to tear out the composite unless it means the end of the world as we know it.

Thanks!
-Moogy
 
  #6  
Old 09-07-16, 05:55 AM
czizzi's Avatar
Member
Join Date: Jul 2007
Location: USA
Posts: 7,388
Received 14 Votes on 12 Posts
1/2" a sawdust//glue composite
This is particle board and the absolute worst substrate for tile and needs to be removed. You can not tile directly to dimensional lumber (your 2x8 T&G) so you need to go back with a layer of plywood screwed down. Minimum 5/8" plywood or 3/4" OSB.
 
  #7  
Old 09-07-16, 08:08 AM
M
Member
Thread Starter
Join Date: Aug 2016
Location: us
Posts: 44
Received 0 Votes on 0 Posts
Thanks for the reply. As you can tell I am very much a tile novice so I had a couple more questions:
(1) if one were to lay tile onto the particle board/T&G subflooring, how does it fail?
(2) Is there anything that I can put over the top of the particle board (cement board) and keep going?
(3) The vanity and shower stall is over the top of the particle board. If I want to remove the particle board, how is the best way to do that and cut it along the shower, vanity, etc? Would a compact circular saw work? Tearing out the vanity and shower stall isn't an option.

Thanks!
 
  #8  
Old 09-07-16, 03:33 PM
czizzi's Avatar
Member
Join Date: Jul 2007
Location: USA
Posts: 7,388
Received 14 Votes on 12 Posts
how does it fail?
Add any moisture or water spill and watch it swell and disintegrate.

I'm not going to offer any advice on how to make this work, it needs to come out. Rent a toe kick saw and be careful using it. It will cut flush to the item you are trying to take out. I doubt that the partcle board goes under the tub or the vanity Remove the 1/4" underlayment talked about earlier and see.
 
  #9  
Old 09-08-16, 07:45 AM
M
Member
Thread Starter
Join Date: Aug 2016
Location: us
Posts: 44
Received 0 Votes on 0 Posts
Thanks for the info.

(1) What is the 1/4" underlayment? The attached photo shows a 1.25" diameter plug drilled out of the floor as described earlier in the thread. The photo shows the 1/2" particle board on top of the 2" x 8" T&G subfloor. The bathroom is on one side of this plug and the crawl space under the house on the other. Is the 1/4" underlayment you're referring to somewhere else?
(2) I guess I thought the Kerdi and Ditra would provide some protection against water as the manufacturer claimed.
(3) I guess I'm lucky that the unprotected particle board didn't fail over the last 42 years since installation.
(4) The particle board does go under the vanity but not the shower stall. In fact, it appears as though the entire floor of the house is this 1/2" particle board on top of the T&G Doug fir boards.

Thanks!
 
Attached Images  
  #10  
Old 09-08-16, 03:39 PM
czizzi's Avatar
Member
Join Date: Jul 2007
Location: USA
Posts: 7,388
Received 14 Votes on 12 Posts
OK, traditionally, there is a 1/4" underlayment beneath the linoleum - in your case there is not. But regardless, remove the particleboard, add back some plywood and then you may ditra or cement board. Must be the ply buffer between dimensional lumber and the ditra/cement board.
 
Reply
Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: