# SLC over Hardibacker?



## ridgeline_dev (Apr 10, 2006)

Finishing up a job, and it turns out the floor in the bathroom isn't quite level. It looks like one of the floor joists is crowning, and one of the adjacent joists is slightly lower. 

Anyways, the hardibacker is down, and bonded to the floor with Versibond, but now there is a small area that needs to be leveled. Is it ok to use self leveling cement, directly on the hardibacker? There will be a 3/8 travertine going down once the floor is level.

Anyone have experience with this?


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## ridgeline_dev (Apr 10, 2006)

I should mention, the area to be leveled is very small. Maybe 2 x 2.


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## kevjob (Aug 14, 2006)

What is the structure of the floor? 2x8 2x10? what is the span of the joists? and how many layers of plywood do you have? for stone you need at least 3/4 and 1/2 inch ply for defelection, if all is good then I would use medium bed thinset if it is over a 1/4 inch and float it one day the set the next.


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## ridgeline_dev (Apr 10, 2006)

I don't think deflection is a problem. 2x10s @ 16 OC, with a span of about 8 feet. 1/2" hardibacker set in thinset on top of 3/4" plywood. Feels like a rock when walking on it.

So you are saying just use some thinset to level it out, let it dry, and set tile on top of that. It could probably come up about 1/4-3/8" at the lowest point. Definitely not more than 1/2".

Thanks for the help.


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## JazMan (Feb 16, 2007)

You may not think deflection is a problem, but every tile pro will tell you that your single 3/4" spanning 16" o.c. has too much deflection for natural stone tiles. You're correct though that the joists' deflection meets requirements. But......I guess it's too late now? 

The out-of-plane dimensions seem to be growing, how much is it? You may need to go back to an SLC? The floor needs to be very flat, level is not required. It should be within 1/4" in 10 ft. AND 1/16" in 12" of the required plane. With large or stone tiles, I recommend within 1/8" in 10' and 1/16" in 12". 

Is this your own house, or you doing it as a job?

Jaz


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## ridgeline_dev (Apr 10, 2006)

JazMan said:


> You may not think deflection is a problem, but every tile pro will tell you that your single 3/4" spanning 16" o.c. has too much deflection for natural stone tiles. You're correct though that the joists' deflection meets requirements. But......I guess it's too late now?
> 
> The out-of-plane dimensions seem to be growing, how much is it? You may need to go back to an SLC? The floor needs to be very flat, level is not required. It should be within 1/4" in 10 ft. AND 1/16" in 12" of the required plane. With large or stone tiles, I recommend within 1/8" in 10' and 1/16" in 12".
> 
> ...


This happens to be in my own house.

After looking at it again the lowest point is only 1/4", so not as bad as i thought. The floor is flat and level with the exception of this one area.

So back to the original question...SLC or thinset. I am leaning towards thinset at this point.


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## JazMan (Feb 16, 2007)

You should be able to correct the dip if it's about 1/4"? You measure this with a long straight edge? Latex modified of course. What thinset are you planning to use to set the travertine? I assume the tiles are 12x12?

Jaz


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## ridgeline_dev (Apr 10, 2006)

JazMan said:


> You should be able to correct the dip if it's about 1/4"? You measure this with a long straight edge? Latex modified of course. What thinset are you planning to use to set the travertine? I assume the tiles are 12x12?
> 
> Jaz


Yep, 3' level, and a 1/4' drop is all that is there at the lowest point.

Yes, these are 12 x 12 tiles. It's not a large area, about 5 x 8 or so. Was planning to use normal versabond as that is what our tile guys have used in the past for travertine, but I may go with versabond flex. I believe both are latex modified.

Any thoughts on one or the other.


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## Mike Finley (Apr 28, 2004)

In the future if there is a future time you might want to invest in a power planer, for such a small issue as you are having, we would have wacked that high spot with the planer (nails are a ***** on the blade, but that's about all we use it for), then when you put down your thinset for your underlayment we would have again made up for it a bit. Going just a hair thinner on the high spot and a hair thicker in the low spot with the thinset and put in the underlayment. Anything left over still high and low would have now been taken care of with the tile setter. 

What I'm explaining is doing small 1/16 or 1/8 corrections between all the layers which would have ended up in a flat floor in the end. You can't use this technique for the extreme problems but when you are just making up for a few problem areas it works quite well.

We also only use Flexbond for both layers.


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## JazMan (Feb 16, 2007)

James,

A 3 ft. level is not long enough to measure the dip. Get something longer. 

Versabond is a good value, but it's a very cheap entry level modified thinset, nothing to brag about. It'll probably work though, certainly meets minimum specifications. VersaBond Flex, FlexBond or actually Marble & Granite would be much better. 

Jaz


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## ridgeline_dev (Apr 10, 2006)

JazMan said:


> James,
> 
> A 3 ft. level is not long enough to measure the dip. Get something longer.
> 
> ...


Sorry I meant a 4ft level. The bathroom is only 5 feet wide, so can't go much longer.

Planning to switch to a Flexbond when setting tile.

Thanks.


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## kevjob (Aug 14, 2006)

try customs marble and granite thinset which is a medium bed which will support the stones better while setting up, sometimes the heavy stones will sag regular thinset and usually happens after you left it looking perfect. :furious: use white, whatever thinset you choose.


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## Bud Cline (Feb 12, 2006)

James if you use thinset you will absolutely want to get the Hardie wet before you apply the thinset. Put a bunch of water on the Hardie and let it soak in before you screed it. Thinset will also shrink somewhat so be prepared to address that issue if it happens drastically.

Thinset will be your best bet in this case. You can work it as you install it and feather the edges. Should work fine.


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## ridgeline_dev (Apr 10, 2006)

Marble and Granite thinset it is.

Thanks all for the help. I'll throw some pics up once it's done.

Cheers.


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