Ceramic Tile Advice Forums - John Bridge Ceramic Tile

Welcome to John Bridge / Tile Your World, the friendliest DIY Forum on the Internet


Advertiser Directory
JohnBridge.com Home
Buy John Bridge's Books

Go Back   Ceramic Tile Advice Forums - John Bridge Ceramic Tile > Tile & Stone Forums > Tile Forum/Advice Board

Sponsors


Reply
Thread Tools Search this Thread
Unread 01-31-2020, 08:42 AM   #1
JamesA_84
Registered User
 
Join Date: Jan 2020
Location: Virginia
Posts: 31
Newbie Here! Kitchen/Laundry Tiling Questions

Hi everyone!

I have visited the forums numerous times before and have gained valuable insight. This is my first post, as I am starting a new tiling project in my house.

Here are the project details, with a few subfloor questions following my rambling that I am hopeful to gain some guidance/advice on.

Project:
- Tiling 470 sq foot of kitchen, eat in kitchen, two halls and a laundry room
- Installing 12x24" 8mm thick cermaic tile from Home Depot (sku-1004094919)
- 1/4 CBU (either Hardie, Permabase) OR 1/2 CBU if you guys recommend

Current Flooring and Subfloor setup:
- Sheet vinyl that is glued all throughout and tons of staples connected to 1/8 Lauan (in the process of removing)
- 3/4 plywood (seems to be in good shape, I have screwed down into joists where the nails had popped loose)
- Joists are 2x10 16"OC 12' length (deflection calculator L/558)
- 4 Sets of doors with 1.3" of open room to floor (after lauan and vinyl removed)
- 3 joining different floors (living room carpet, two halls have 1" thick wood flooring)

After all of that rambling, my main question(s) are around the subfloor.
- Should I feel comfortable with the 3/4 plywood currently in standing as is?
- Should I add additional 1/4 plywood? (12224 Lowes)
- Should I add additonal 11/32 plywood? (12231 Lowes)
- My main concern of adding additional subfloor height is hitting up against the 1/3" of space I have for door openings -- I am okay if the tile sits higher than the hardwood and the carpet connections. Also, a little concerned with the weight added by the additional layer of plywood (maybe shouldn't be)

Anyways, hopeful someone can give me some pointers/guidance on the subfloor. Thanks in advance.
__________________
James

Last edited by JamesA_84; 01-31-2020 at 09:13 AM.
JamesA_84 is offline   Reply With Quote
Sponsored Links
Unread 01-31-2020, 08:56 AM   #2
speed51133
Registered User
 
Join Date: May 2017
Location: Milwaukee WI area
Posts: 1,061
I would recommend ripping out the vinyl and the luan (however you spell it).

If you are considering 1/4in plywood just to raise the height, I would not do that. I would use 1/4in cement board that is embedded in a full bed of mortar properly notched into place, and screwed down. Using 1/4in or 1/2in is no difference. Just use one or the other depending on what you want your final height to be.

If adding more plywood is simply for structural concerns, 1/4in will do NOTHING.
__________________
Mike
speed51133 is offline   Reply With Quote
Unread 01-31-2020, 09:33 AM   #3
rmckee84
Moderator
 
rmckee84's Avatar
 
Join Date: Feb 2012
Location: Southern Illinois
Posts: 3,006
Strip it to the 3/4". Is the 3/4" tounge and groove? If not you'll need to block all the seams from underneath. Once that is done you can use cbu or an uncoupling membrane. If you decide to add another layer of plywood it should be a minimum of 3/8", exterior glue, b/c or better grade.
__________________
Jack of most trades, master of none...
Ryan McKee
McKee Construction & Custom Tile
rmckee84 is offline   Reply With Quote
Unread 01-31-2020, 09:56 AM   #4
JamesA_84
Registered User
 
Join Date: Jan 2020
Location: Virginia
Posts: 31
Thanks Mike and Ryan for the prompt replies.

I do not believe the 3/4 plywood is T&G as it is gapped to 1/8. I am trying to load pictures.

If I add the 3/8 plywood to the 3/4 would I still need to block seams underneath? If I go with 3/8 would this item be sufficient (12227 Lowes item number). - rated bcx
__________________
James
JamesA_84 is offline   Reply With Quote
Unread 01-31-2020, 10:10 AM   #5
JamesA_84
Registered User
 
Join Date: Jan 2020
Location: Virginia
Posts: 31
here are pics of my subfloor (3/4 plywood)
Attached Images
   
__________________
James
JamesA_84 is offline   Reply With Quote
Unread 01-31-2020, 10:29 AM   #6
ss3964spd
Moderator
 
ss3964spd's Avatar
 
Join Date: Jul 2005
Location: Fairfax, Va
Posts: 2,966
Send a message via Yahoo to ss3964spd
Welcome, James,

Poke something skinny into the gaps between the ply. If the skinny poker goes in 3/4" of an inch the ply is not T&G. If it goes in maybe only 1/4" an inch it is T&G. Test it at multiple joints to be certain.

If it is T&G - and it should be, no need for blocking under the seams.
__________________
Dan
---------------------------------------------------------------------------------
If I recall correctly my memory is excellent, but my ability to access it is intermittent.
ss3964spd is offline   Reply With Quote
Unread 01-31-2020, 10:55 AM   #7
JamesA_84
Registered User
 
Join Date: Jan 2020
Location: Virginia
Posts: 31
Dan - great advice, would have never thought to do that! Yes, you were right, it is T&G. Measured several different areas and most readings came out to be right around 1/4, nowhere more than 1/2. So doesn't look like I need to do the blocking thankfully.

So now that I discovered it is the 3/4 T&G, should I add to that subfloor (at least 3/8 as folks have mentioned) or just go ahead with the thinset/1/2cbu/thinset/tile/grout the 3/4.
__________________
James

Last edited by JamesA_84; 01-31-2020 at 11:07 AM.
JamesA_84 is offline   Reply With Quote
Unread 01-31-2020, 04:47 PM   #8
ss3964spd
Moderator
 
ss3964spd's Avatar
 
Join Date: Jul 2005
Location: Fairfax, Va
Posts: 2,966
Send a message via Yahoo to ss3964spd
Given your joist structure, James, the 3/4" T&G ply (long as you're sure it's 3/4" ply), with 1/4" CBU embedded in mortar will be fine. Don't forget that you'll need to fasten the CBU per the manufactures screw schedule, using the appropriate screws and joint spacing. Pick you up some CBU mesh tape for doing the CBU seams whilst you are buying supplies. You might consider only taping the seams while you're tiling - thus avoiding a hump at the seams.

Take the time, iffn you've not done so already, to screw down that 3/4" ply to the joists with some 2" construction screws, about an inch over from each nail.
__________________
Dan
---------------------------------------------------------------------------------
If I recall correctly my memory is excellent, but my ability to access it is intermittent.
ss3964spd is offline   Reply With Quote
Unread 02-01-2020, 09:29 AM   #9
JamesA_84
Registered User
 
Join Date: Jan 2020
Location: Virginia
Posts: 31
Thanks again Dan.

The only concern I have with the subfloor at this point after the great pointers is that I am not sure if the 3/4 plywood (100% on size) is exterior glue/rated or not. That said, I am hesitant to put down thinset under the backer board as I have been planning on doing. I just don’t want the wetness to harm the drywall if in fact it isn’t exterior. Is there an easy way to tell as I see no markings on the wood after ripping up the vinyl and luana.
__________________
James
JamesA_84 is offline   Reply With Quote
Unread 02-01-2020, 11:54 AM   #10
ss3964spd
Moderator
 
ss3964spd's Avatar
 
Join Date: Jul 2005
Location: Fairfax, Va
Posts: 2,966
Send a message via Yahoo to ss3964spd
Not an invalid concern, James, the issue is delamination of the ply if the moisture of the mortar seeps through the first layer and dissolves the glue underneath.

I don't think it's a serious problem though, as I don't believe there will be enough moisture drawn out of the mortar to cause delamination. If the ply were subjected to more prolonged, or frequent moisture I'd be a bunch more worried.
__________________
Dan
---------------------------------------------------------------------------------
If I recall correctly my memory is excellent, but my ability to access it is intermittent.
ss3964spd is offline   Reply With Quote
Unread 02-01-2020, 03:45 PM   #11
JamesA_84
Registered User
 
Join Date: Jan 2020
Location: Virginia
Posts: 31
Good deal!

The last couple of questions -- sorry so many. The plywood that I do have does have a few areas where there is minor cracking (not sure if proper term but "checking"). Would you recommend apply wood putty to those areas prior to putting down the thinset that will be directly on the plywood? Also, should I add any to the gaps where the boards are connected?

Any recommendations on specific thinset types to use? I have been planning on using the following, but open to different options is better products:
- thinset under CBU - Mapei Keraflor non-modified thinset
- mortar under tile - Mapei Ultraflex LHT modified

Thanks again for all of the help Dan, promise I will be done hammering you with questions soon.
__________________
James
JamesA_84 is offline   Reply With Quote
Unread 02-01-2020, 04:08 PM   #12
D & D Reno
Registered User
 
Join Date: Jan 2020
Location: Northern Michigan
Posts: 51
Just as an FYI, most T&G have that 1/8” gap you see built into the tongue. It’s so contractors can only slide them together so far and already have the gap required. No need to add more to the gap, it’s meeting the manufacture’s recommendation.

I see your using unmodified under the CBU. Check the instructions for the CBU your using. I know Custom’s Wonderboard states modified thinset.
__________________
Antonio
D & D Reno is offline   Reply With Quote
Unread 02-02-2020, 08:57 AM   #13
JamesA_84
Registered User
 
Join Date: Jan 2020
Location: Virginia
Posts: 31
Thanks for the feedback Antonio!

Mainly what I am concerned with is the thinset under the CBU impacting my plywood and causing for the install to fail at some point. I figure if the plywood has that 1/8 gap and some cracking areas (I included pictures) that the thinset would leak into those and potentially cause big problems. So my thought is that I could use wood putty to seal those areas prior to the thinset. Maybe I am overthinking it, and I putting the thinset down without fixing/sealing those areas will be fine.

The reason I was planning to use non-modified thinset is that it is much cheaper and based on my research is only there to reduce any voids, etc. so I wasn't worked about the adhesion. Correct me if I am wrong here and need to rethink that as warranty isn't a concern for me.
Attached Images
    
__________________
James
JamesA_84 is offline   Reply With Quote
Unread 02-02-2020, 09:23 AM   #14
cx
Moderator emeritus
 
cx's Avatar
 
Join Date: Jul 2001
Location: Boerne, Texas
Posts: 89,796
Look at it this way, James. If that's an exterior glue plywood (I suspect it is), it'll be fine under your CBU. If it's not an exterior glue plywood, you'll need to remove and replace it anyway, so why not mortar and screw down a section of one of your Wonderboard panels and see how it goes? Give it a few days and pull it up and see if it's damaged your subfloor (which looks a bit damaged anyway).

While I can't argue with Antonio's reading of the installation instructions for Wonderboard, knowing the way Custom has always treated their installation instructions for their products, I'd agree with your use of an un-modified mortar for bedding the panels. They even use the word laminating in their instructions as though the Wonderboard panels were a structural component after they have specifically instructed not to use it as such. And if they truly wanted it bonded or laminated to the plywood, they would surely have specified a modified mortar meeting ANSI A118.11, which they do not do. They've always tended to wander about a bit on such instructions to my thinking.

They also manufacturer Custom Blend thinset mortar which has no useful purpose except perhaps for bedding their CBU panels. I will say that the use of a modified thinset mortar would give you more time to bed and fasten the CBU panels than will the Custom Blend.

My opinion; worth price charged.
__________________
CX

Y'ALL NEW VISITORS READ THIS HERE!

Last edited by cx; 02-02-2020 at 10:02 AM. Reason: typo
cx is offline   Reply With Quote
Unread 02-02-2020, 09:41 AM   #15
JamesA_84
Registered User
 
Join Date: Jan 2020
Location: Virginia
Posts: 31
Great feedback CX, thank you.

I do like the suggestion of testing a particular area with one cbu panel. Is it worth the effort to go under the house (crawlspace) and pull some more of the insulation to see if the plywood is marked? The plywood is directly above our crawlspace so it does make sense they would have used exterior, just can't figure out how to know (outside of the recommendation you have which is great).
__________________
James
JamesA_84 is offline   Reply With Quote
Reply

Stonetooling.com   Tile-Assn.com   National Gypsum Permabase


Thread Tools Search this Thread
Search this Thread:

Advanced Search

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
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Newbie considering tiling laundry and mud rooms mgordo98 Tile Forum/Advice Board 3 01-04-2018 08:46 AM
Floor prep questions for kitchen/laundry travertine cblome Tile Forum/Advice Board 4 07-03-2012 04:03 PM
Tiling newbie with some questions - tiling over tile, etc rickcr Tile Forum/Advice Board 4 12-05-2010 04:00 PM
Newbie questions about kitchen floor johnrgrace Tile Forum/Advice Board 5 03-29-2004 01:35 AM
laying tiles in kitchen. newbie questions pnj Tile Forum/Advice Board 10 12-22-2003 11:27 AM


All times are GMT -6. The time now is 04:26 AM.


Sponsors

Powered by vBulletin® Version 3.7.4
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.
Copyright 2018 John Bridge & Associates, LLC