UN-level floor....What to use to level bathroom floor?

tulahMay 5, 2009

What is the recommended method to level backer/hardiebacker board when you're laying it out for a tile floor installation?

If the only method is to float the floor, what do you suggest for a wood subfloor made of individual boards (with gaps) and not plywood?

Any clue?

We have a 1047 house and the floor is not leve, despite the face we installed 2/4s to create subfloor.

BUT there's gaps of abut 1/4- 1/2 inch.

So....what to use to LEVEL the backerboard we need to lay,....so that the tile and floor is ultimately level????

Thank you in advance!? We are novices.....

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I think, if I understand you, we had the same floor- it is tongue and groove pine subfloor? What is "a 1047 house"?

Our specific problem was that we could not take them all up as the walls were built ON TOP of the subfloor--- it would have been such an enormous addition to the project to try to address that. We had to improvise and did not "float" the floor as we felt this would increase the risk of too much deflection.

In theory, you should pull up the planks and level from the top of the floor joists, relay the T&G subfloor or change to a plywood floor (or add the ply layer on top of the TG).

BUT, what we did was get a great solid subfloor with t&G followed by 3/4" ply and some self-leveling cement, which was incredibly easier to work with than I thought! We then used Ditra and were ready to tile. (did I say that sounded easier- actually it really was).

I am sure what we did was a bit of a hack job, but hopefully Bill and some other more seriously knowledgeable folks will chime in!!

    Bookmark   May 5, 2009 at 8:45PM
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I think I misunderstood your subfloor- you used 2x4's? On top of what? Concrete slab? Are they just lined up?

I am confused...

    Bookmark   May 5, 2009 at 8:47PM
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Thanks for the reply!

Sorry I wasn't more clear, and for the typos!

We have a 1947 house. It is pier and beam foundation (2 ft crawl space for the entire house...dirt floor underneath house)

When we ripped out the old tile, the floor had some rot, and plus the tiles were in THICK cement and metal mesh...so the entire floor come out.....

To create a new subfloor (ANY floor,,,since were were looking down a couple of feet to dirt..... we put treated 2x4s side by side and created the "floor". However, they DO ave gaps between them, of about 1/4 inch.

SO..... :-)
My question is...since they are not entirely level from one side of the bathroom to the other, etc....what do I put ON TOP of the 2x4s BEFORE the backerboard, so that ultimately the tiles are level...

Does that make sense?

Here are the issues:
- IF we try to put down some "self leveling cement" or any of that type of thing, most of it will seep through the cracks in the 2x4s and just fall to the dirt under the house....
- IF we put backerboard, plywood or WHATEVER material down and screw it into the 2x4s all the way around the room , etc...it WILL NOT be level.
- We ONLY HAVE about 3/4 inch to work with...for example we have to get backerboard, thinset, and tile...WITHIN 3/4 inch, so that it meets up evenly with the wood floor in the hall. (the ENTIRE house has oak wood floors).

Help!!!! :-)

    Bookmark   May 5, 2009 at 9:57PM
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Depending on how out-of-level your space is, that 3/4" measurement might be out the window anyway. Our bath floor was flat but out of level by 5/8" over 8'. If you want level, you need to find the low point of the floor, and then figure from there.

If your floor is mostly overall level but not flat, that is a little different. I do know you have to have the thinnest parts of self-leveling compound a certain thickness so it doesn't come off...or flake...or something.

Are you saying you intend to not have a threshold? I assume so, from what you wrote, but if this is a full bath, there is an actual functional reason to have one: if someone slops water on the floor or something leaks, the threshold is supposed to hold the water in the room and keep it from spilling into the "dry" areas (in your case, the hallway). Obviously, for a big spurting leak, you're on your own, but for smaller amounts you would at least have a chance.

For us, there is no way we wouldn't have a stone threshold (as opposed to wood, which some people do, and I think is madness from possible exposure to water). Even with just two adults using a bath, that room has water coming into it four different ways, all with pipes and devices that could burst or break or malfunction...all sitting next to the hallway and bedroom that definitely AREN'T built to withstand water. Stuff happens in life, and I would rather not have to rip out our hardwood because of a stupid faucet.

We tried our best to match heights from bath to hallway, but in the end, missed by a bit (3/8"). With the threshold, we beveled it very small on the higher side, bigger bevel on the lower (hallway side). Aside from my disappointment with not getting what I was shooting for, it became "fine" in my head about 17 minutes after the threshold was installed. Doesn't look weird, doesn't look like anything distinctive or different or undesirable. At least to me.

    Bookmark   May 6, 2009 at 10:20AM
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I actually think you may benefit from posting over at the John Bridge site as there are a lot of technical folks over there- I may have concerns about the treated wood and working directly over that, and there may be a very specific way to make a structurally correct floor in your setting. I would strongly consider an isolation membrane like Ditra, what ever you decide to do, as there will be significant exposure with your setup. I think that starting with a 3/4" ply subfloor then Ditra would get you started... if it is just a "flat" issue, that would help- you can shim the low 2x4's to match up. If it is a level issue- how out of level is it at the worst spot??

I wouldn't worry about creating a different height, more to create the correct floor- there are plenty of ways to adjust from one height to another. With our level issue we were left with a fairly large difference in floor height but a good floor, we used a very thick threshold and made a "hollywood" bevel- which is just a very big bevel to bring the floor from one height to another!

    Bookmark   May 6, 2009 at 11:23AM
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Thanks, Tuesday22!

And everyone else!

UGH,,,,this is going to be a pain....

The original tile floor we tore out, met with the wood floor floor in the hall evenly, with no threshold.... but...perhaps that's not a possibility now?
There IS enough room for a threshold without raising the door or anything though, so that's good, since th

There's about an inch 1/2 under the door....

PICTURES of any bathroom thresholds!!???

    Bookmark   May 6, 2009 at 11:27AM
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Why did you use the non standard 2x4s instead of the standard 3/4" plywood for a subfloor? That's a lot of your problem now. Rip out the 2x4s and use 3/4" ply on top of your floor joists for the first layer. You can shim the joists in order to level the ply, if you do it right, with the shims running the whole length of the joists. (Think of small wedge shaped pieces nailed and glued to the tops of the joists.) After you level the joists and apply the 3/4" ply, then use thinset and the right screws on top of that to lay your backer board, then thinset and tile.

    Bookmark   May 6, 2009 at 2:41PM
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We've already installed the new tub..... there's no tearing up the 2x4s.

    Bookmark   May 6, 2009 at 4:04PM
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How did you properly install the tub in it's mortar bed on top of 2x4s?

    Bookmark   May 6, 2009 at 6:40PM
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We screwed down a piece of the outside hard flat siding crap that they construction people down the way gave us.....
Then we put a piece of heavy plastic barier over that, then poured the morter bed (even though the acrillic tub has scqure feet type things on it..it's a Kohler Archer 60 inch acrillic),
THEN another piece of plasic, then the tub....
THEN, we screwed the tub "flange" thing onto the wood strips along the wall studs....

The tub is not going anywhere. It's level....
HOWEVER, I hope the flat hard backerbard type stuff holds. It IS sitting on tip of the 2/4s too...

Keep in mind, this is a pier and beam house. When the floor and walls were ripped out of the bathroom (down to the studs), there was NOTHING underseith except the 2 or 3x6s (?) that run LONG WAY...across the bathoom, with about 2 FEET in between. We needed SOMETHING to build the floor up with....or it would have been about 3 inches below the threshold, etc.

SO...2x4s went in to create a "floor" and there's about 3/4 to 1 inch of space left to fill with any other kindof floor material...i,e, tiel, thinset, plywood,? backerboard, etc...

AND, it's gotta be level of course.... Good thing is we can get under the house. LOL! For any adjustments.


    Bookmark   May 6, 2009 at 11:04PM
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First of all, you still haven't specified whether your floor is "not flat" or "not level." Whatever else you have (or have not) done to get where you are, it would help a lot if you could say whether your problem is level or flat.

Also, just to be sure here, if I am understanding you correctly, you installed the 2x4s ACROSS the 2x6s that make up the underside of the house? (Notice the very very NON-technical terms...so be aware that I'm not a builder or knowledgeable in this stuff like some of these people that post here...just sympathetic to rising note of panic in your posts....) The only reason I'm trying to clarify that is because I am wondering whether you installed the 2x4s "upright" (so the "4" dimension is vertical) or "laying down". I'm not trying to pile on to what you have *already* done, but I don't know what the proper distance for SPANNING that 2x4s have, and I don't know whether they can span two full feet if they are flat.

This makes a difference because you want to install tile. If your subfloor is bouncy or bends ("deflects" I think is it), then all the tile you install will just crack and plague you and your heirs until the end of time...until you rip the whole floor and subfloor out again and re-do it. Or put in linoleum. Whichever comes first.

You say in the top post that the cracks are like 1/4", but in your last post you write that they are up to 1". That's a big difference? Which is it? Does it vary from 1/4"-1"? Have you actually measure or are just eyeballing or going from memory?

IF it were me (and it isn't), I'd probably just put down a very tight layer of Wedi board (thinset and screws/washers), seal the seams so it can hold the next layer, then put down a thin layer of self-leveling compound (though you still haven't said whether your floor is wavy or slanted), and then tile.

Maybe use a layer of plywood (which would be cheaper but harder to cut), maybe tape and thinset the seams (ask someone on this board about this because I'm just brainstorming here), then use the SLC, then the tile. Only plywood will actually help form a floor (which I think you need to do with 1" gaps), not backerboard of any kind.

Instead of Wedi, you could use probably any backer board (ask someone here what to do for the seams). But I only know about Wedi because that is what we went with, and I like it because it is light weight (good if you are a female working alone).

I don't think your solution is in one step. It feels like you are going to have to create a tight subfloor, THEN level or flatten.

I think you have a non-standard thing going on there, and that might not be addressed so easily with just one step before tile.

One more thing, just out of curiousity, WHY do you think your floor must be level?

Oh yeah, and I would start making your peace with a threshold. Given how non-standard your set-up is, AND the fact that this is DIY (or at least the subfloor), I'm not sure it is realistic to think you can get away with no threshold.

    Bookmark   May 7, 2009 at 7:32AM
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3/4" plywood, thinset, backerboard, self leveling compound, thinset & tile. Then do a threshold. You're gonna have to live with a threshold unless you are willing to remove the 2x4s.

    Bookmark   May 7, 2009 at 10:12AM
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live_wire: Just out of curiousity, do you need to do anything to the seams of the backerboard before hitting it with the SLC?

    Bookmark   May 7, 2009 at 11:08AM
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Thank you everyone!!!!

We have not done anything about it yet. Unfortunately.

Let me try to answer your questions...
- The 2x4s are actually 3/4 X 6 inches (DH clarified). He cut them....
- These match the EXISTING subfloor (through the rest of the house, the 1947 one.
- The floor is un-level.
- Each "gap" between boards is approximately 1/4 inch.
- The boards are laid flat (not on end), 6 inch lines up to another 6 inch...to make 12 inches, etc... all across.

Is it possible to put some sort of "TAPE" on top of the gap on each board, THEN pour some self leveling compound? THEN on tip of that thinset, and hardibacker, tile, etc?

Thank you again for you advice! SOON we hope to finish this bathroom...but the last things we'd want is to have constantly cracking tiles or joints...
By the way, on the floor with be 13x13 porcelain tiles (Daltie), RECTIFIED (going to have very very small grout lines... )

Please help if you can. Thank you!

    Bookmark   May 15, 2009 at 9:40AM
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You should rip out the 1x6's and use 3/4" plywood instead. Dimensional lumber of today is not the same as it was even 60 years ago. Fast growing trees are harvested quickly to make into lumber nowadays leading to softer wood. I'm not sure that 1x pine of today can span 2' really. Do yourself a favor and do this job right while you still can.

    Bookmark   May 15, 2009 at 10:05AM
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We did used treated lumber.... does that make a difference?

Also, if we do rip this up.... Will the plywood hold everything and be less likely to cause cracking/movement, etc?

Should we still use some sort of vapor barrier on the floor?
Again, underneath the boards (or if we put plywood) is just the Joists (there's about 1.5 FEET between those)....under that is about 2 ft of space, then DIRT. :-)

    Bookmark   May 15, 2009 at 10:20AM
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I for certain do not know the correct way to address your type of structure, but I am fairly certain that given what I have learned, 1x6 pine boards are NOT the way to go!!

I believe they are likely to warp, split and generally not be the substrate you want to start your floor above the dirt with. What about insulation? What region are you in?? As you can see, many of us seem concerned.

I strongly suggest you consult with someone as to the correct approach. If you like these forums, perhaps the building forum can get you started?

Best of luck!

Here is a link that might be useful: Building a Home Forum

    Bookmark   May 15, 2009 at 9:58PM
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I think this is what we've decided to do... before I lose my hair and have a nervous break down! :-)

- Over the 1 1/2 x 6s.... Wood glue to bottom of 1/2 inch of top grade plywood.
- Screw the plywood down to joists AND boards.
- Thinset
- Ditra
- Thinset
- Tile.

Any last minute warnings, or advice?

Thank you -

    Bookmark   May 18, 2009 at 4:48PM
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2 things: I am not sure about the glue- I hazard that there may not be a role for glue in your setup at all.
Also, with respect to screwing down- typically in a standard setup, you screw the first layer of ply to the joists, and any additional layers of ply to the layer below only NOT all the way to the joists. I can't explain all the reasons, maybe someone else may be able to, but I just know that is the correct way. But I would treat your first layer of wood like ply (which is what it should be) as your setup is not standard and there may not be a "correct" way to approach it.

I think for both of the above comments though, the reason is actually the same (sorry I am not knowledgeable enough to explain this).

And then, just remember that the thinset between the ply and the ditra must be a good modified thinset- you can read this in the Ditra handbook. And between ditra and tile must be un-modified.

Are you going to level?? If so, it should go between the ply and ditra I believe...

Good luck!

    Bookmark   May 18, 2009 at 9:20PM
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