# does the floor really need to be level before laying tiles?



## dougrus (Sep 16, 2006)

Ok...first of all, I think I gathered that you are tiling your washroom which is in a basement. I assume that the floor is concrete, no?
If so, you will not be using backerboard on top of the concrete...If you wanted to do a decoupling type membrane you could use Ditra (made by Shulter Systems) that would be ideal for a concrete basement floor...it is a membrane that you thinset to the floor and then thinset on the membrane and then tile.
If you are not using Ditra you would set the tile on the concrete.

As fo the floor being out of level, how far off is it?


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## KUIPORNG (Jan 11, 2006)

Actually, my basement washroom floor is in fact cover with plywood... strange... just think of it as Dricore....although it is not really, but somthing very similar...

anyhow... the level is not too far off, but I would think if you put a marble on the floor, it probably will roll over some somewhere.... for human standing on it, don't feel any unlevel...


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## dougrus (Sep 16, 2006)

That is strange...How is it secured to the floor? This is important because if it is clicked and locked into place only, it is "floating" and that may affect movement of the floor and therefore cause tile and grout cracking.I dont know what the protocol is for this kind of floor and installing tile other then what is stated below...you would need to permently attach the subfloor to the concrete to prevent movement.
Here is the information from the Dricore site regarding ceramic tile installation if it is indeed like this product:

*"Ceramic Tile:* DRIcore is designed to act as a floating subfloor. It is not recommended that Ceramic tile be directly attached to DRIcore as the movement of the floating subfloor will cause tile and grout lines to crack. There have been successful installations that are *not covered under a warranty* using ¼” underlayment or ½” cement board suitable for ceramic tile installations. 
In the case of a ceramic installation, prepare concrete floor by applying liquid concrete leveling compound to the concrete floor surface to level to eliminate concrete floor height variances. It is acceptable to fasten each panel with four, flat head and countersunk, concrete fasteners per panel to the permanent concrete floor to prevent movement or shifting of the finished ceramic tile floor. If you are concerned about moisture penetration through fastening points, a dab of silicone in the fastener openings will help seal these holes. 
DRIcore panels must lay perfectly flat without bounce or deflection. Follow the underlayment manufacturer’s installation guidelines for fastening to a subfloor, using fasteners that will not penetrate the moisture barrier underneath DRIcore panels. 

_Please note that we also do not recommend gluing underlayments or other wood flooring materials to DRIcore. As a general practice, it is best to minimize the amount of fastening through DRIcore panels to maintain the integrity of the moisture barrier."_


OR are there sleepers or some other kind of floor joist there that the wood is secured to then, depending on its thickness and strength, would be ok for cementboard and tile.
As for the slope, if you are installing large format tiles, you may get excessive lippage on the tile...

Hope this helps.


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## KUIPORNG (Jan 11, 2006)

I tapcon the plywood onto the concrete, it is concrete, a thick plastic sheet with studs... then plywood... I put enough tapcon so that the plywood is quite strong, no bounce...

I used 1 ft by 1 ft marble tile, would it get "excessive lippage " what is "excessive lippage " means actually... I did look at the dictionary before asking, but couldn't figure out...

I did read the Dricore article above before... doesn't say much to me... I am not buying their product and their warantee to me is meaningless... but I know you means that means they are not recommending doing so...

I kind of knowing this too late, after doing it and now I kind of don't want to pull them out either...as may be it give some insulation effect with the plastic and plywood...etc...


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## Hammatime (Oct 2, 2006)

Are you saying that the floor is not level or has dips in it? If the floor is flat but not perfectly level and you don't mind you can put the tile down with out a problem. If the floor has dips or sags in it, that is where you will get the excessive lippage. Which means one tile is higher or lower than the next and there will be a lip sticking up.


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## dougrus (Sep 16, 2006)

Kuip,

I wasnt showing you the Dricore info to let you know about the warentee information, I was trying to show you that if the subfloor was like dricore in that it is "click and locked" into place and not secured to something, that they would need to be screwed into concrete...the bold type was in the text origianlly.......*but* from what I gather you are saying that there are joists there and that the plywood is secured to the joists....this is not like dricore...dricore is "floating" in that it is not actually attached to the concrete below...
Bounce is not the issue...the issue is movement in the subfloor compromising the tile installation.
SO from what you describe, it should be OK to thinset and screw backerboard into the plywood and then install tile.
In any case, the subfloor needs to be secured to the concrete in some way to prevent movement...
Excessive lippage just means that if the floor is unlevel in an area or has dips as stated above, the edge of the tiles may "stick up" when layed next to eachother...


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## KUIPORNG (Jan 11, 2006)

Thanks a lot Dougrus and Hammatime. I would do what Dougrus recommended, put in backer board..etc. No there is no dips... thanks a lot...


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## dougrus (Sep 16, 2006)

Glad to help...be sure to thinset and screw the backerboard to the plywood.


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## KUIPORNG (Jan 11, 2006)

Thanks again Dougrus, but now you remind me to ask the other question, can I use long tapcon to secure the backerboard onto the plywood then onto the concrete... Making it tripple secure...?


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## dougrus (Sep 16, 2006)

Dont secure the backerboard with long screws into the concrete. 
Comb a layer of thinset onto the plywood, embed the backerboard in the thinset and screw it in with "Rock-On" screws...that is a particular brand but they make others...just to be sure to use one that is approved for backerboard they work best...dont use drywall screws.
I like the 1/4" Hardibacker because it is light and has a screw grid so you can verify that you have put enough screws in it...You dont need to use 1/2"....the backerboard purpose is not to add strength to the floor it is simply to provide a good bond for the thinset.


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## dougrus (Sep 16, 2006)

Also, I was thinking....

Do you have something to mix the thinset with?

Do you have a 1/2" drill? If so, you could then buy a "paddle bit" to mix the thinset...otherwise to mix it by hand is very very difficult.


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## 747 (Feb 11, 2005)

dougrus said:


> Dont secure the backerboard with long screws into the concrete.
> Comb a layer of thinset onto the plywood, embed the backerboard in the thinset and screw it in with "Rock-On" screws...that is a particular brand but they make others...just to be sure to use one that is approved for backerboard they work best...dont use drywall screws.
> I like the 1/4" Hardibacker because it is light and has a screw grid so you can verify that you have put enough screws in it...You dont need to use 1/2"....the backerboard purpose is not to add strength to the floor it is simply to provide a good bond for the thinset.



That is exactly the best way to do it. Thinset then hardi.


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## KUIPORNG (Jan 11, 2006)

Thanks a lot Dougrus, for the detail clarification, I do have the mix paddle, but I don't have the 0.5" drill, I only have 3/8" drill... well, may start shop around for that ...

Could you tell me the length of the "Rock-On" screws? would it be too long that it penatrate the thinset then the plywood then the concrete, which causing problems...


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## J187 (May 19, 2006)

Kuiporng, You can buy paddle bits in varias sizes to accomodate different drills. I too only have a 3/8" drill, when I did my tiling, I bought a nice 3/8 paddle bit.


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## KUIPORNG (Jan 11, 2006)

now I have no reason to acquire another toy.... I suppose you are talking about an adaptor type of bit.... thanks...

to reread your post, I think you meant to buy another paddle bit, well I think that heavy metal thing is quite expensive, reason I have one is I got a complete tapping set tools from someone which including this guy... for $50 bucks... now... I better visit home depot see if they have adaptor to convert 3/8 to 1/2 for the 1/2 bit...


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## dougrus (Sep 16, 2006)

The only reason I said to use a 1/2" drill is because, usually, a 3/8" drill has a harder time turning heavy cement/motar type products. I burnt out my craftsman 3/8" mixing thinset.....I bought a dewalt 1/2" spade handle drill because I do alot of tiling....plows through thinset like nothing...
If you have a powerful 3/8" drill you may be fine.


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## KUIPORNG (Jan 11, 2006)

now I have a reason to accquire the toy...

what about the questions regarding the lengh of the "on-rock" screws, is it suppose to screw onto the plywood through the thinset only? the thickness of my plywood may be only .25 inches,,,I am not quite sure, may be .5 inches... but it is the regular one selling at HD...


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## dougrus (Sep 16, 2006)

Well, if I understand your situation correctly, there are joists and then the subfloor so there wouldnt be danger of going into the concrete with screws and therefore, whatever is the standard size screw at HD should be fine. You are securing the backerboard TO the plywood with the the screws and thinset...yes the screws will be going through the thinset and through the plywood.
By the way, it is important that you know the thickness of the plywood because it needs to rated for subfloor use...if you used 1/4 and that is the only layer that is a BIG problem. It is probably 1/2" which is a little undersized as well. You should be using 3/4 T&G ply.


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## KUIPORNG (Jan 11, 2006)

there is no joists, only concrete, plastic sheet, plywood...

that is why I thought of tapcon in my earlier message...


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## dougrus (Sep 16, 2006)

dougrus said:


> *but* from what I gather you are saying that there are joists there and that the plywood is secured to the joists....r...


In my previous post I verified that ther were joists so I assumed that is the way it was constructed...

I have never secured a floor this way, attaching hardibacker to plywood that is SCREWED into concrete, so Im not sure how to tell you to proceed...I guess you could measure and try to get the exact thickness and then get an appropriate screw. ANyone else have a suggestion here?

If it were me, I would rip out the plywood, thinset Ditra to the concrete and then thinset then tile...Just becuase having plywood on a basement floor you are asking for trouble...especailly THIN plywood...Moisture finds its way up through the slab probably through the barrier and into the wood...The thiner it is the more it will swell in temperature and varying mositure levels...The swelling will cause the floor to move up and down, the grout may crack and the tile as well...Maybe not tomorrow maybe not next week but eventually you may have a problem...Just trying to save you work in the long run.
Not trying to be a pain I just dont want to see you go through all this and then have to redo eventually.


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## dougrus (Sep 16, 2006)

Wait if you are going to keep the plywood down, this is what you should do....
Go get Ditra.
Thinset the Ditra to the plywood.
Thinset the tile onto the Dirta.
The Ditra will act as an isolation membrane.
It is a little more costly then cement backerboard but I would do it in this situation.


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## KUIPORNG (Jan 11, 2006)

Thanks a lot Dougrus, I have thought about doing what you said also... but I am quite confident my basement floor is very dry.... and you are right, I don't want to going through the pain to rip off the pine wood, not only it takes considerable amount of work, it also means I spent money for nothing... after weighting both sides , I think I will just leave the way it is... 

what is wrong with tapconing the backer board onto the concrete then, I will drill hole on the backer borad before screwing for sure...


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## KUIPORNG (Jan 11, 2006)

Oh yes, I saw those thing in HD before... Thanks.... I will read more about it...


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## dougrus (Sep 16, 2006)

See the recent post above...I think that is best route if you are keeping the plywood. The Ditra...
But if you definetly are going to do the backerboard I guess you could screw all the way into the concrete...
I dont have any specific reason for not doing this, it just doesnt sit well with me...I guess it will be ok.


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## dougrus (Sep 16, 2006)

KUIPORNG said:


> Oh yes, I saw those thing in HD before... Thanks.... I will read more about it...


 
This is NOT a fad type material...Pros are using this alot now....


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## Tommy Plumb (Oct 7, 2006)

Why not just put a mud floor ontop of the plywood?
Probably about the same price as backerboard and you can level the room.


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## KUIPORNG (Jan 11, 2006)

leveling mud is actually much more expensive then backer board if I remember correctly... anyone know how much it cost for 70 sq. ft x 0.25 inch approx ... I think it would be a few hundred dollars...


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## dougrus (Sep 16, 2006)

Kuip,

Here is the Ditra link...

http://www.schluter.com/english/products/2002/sectionf/ditra/601-index.html


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## Tommy Plumb (Oct 7, 2006)

KUIPORNG said:


> leveling mud is actually much more expensive then backer board if I remember correctly... anyone know how much it cost for 70 sq. ft x 0.25 inch approx ... I think it would be a few hundred dollars...


Don't use the self leveling stuff. Get yourself float and a decent level.

Tar paper - $15 (if you can't dig it up free somewhere)
Mesh $14
Bag of cement $12
Sand $6

That will get you about a half inch mud floor. With the mud floor you can pitch it to the middle and install a drain if you like as well. That way should you have any sort of flood in that room your basement stays dry.


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