# New Flextherm grid system for in floor heating/underlay



## jarvis design (May 6, 2008)

I just saw this product yesterday and wanted to see if anyone else had seen it. Its pretty new. 

These plastic 5/16" thick 12x12 grids are snapped together and screwed to the subfloor. They have "special" tool that you can then use to run your heating cable through. 

You can then fill and tile (at the same time) using a medium bed mortar.

My one concern is they claim you can go over a single layer of 5/8" ply. This assembly has passed the Robinson floor test with a Heavy Duty rating, but I still have concerns of going over a single layer.

In theory it looks like a good system. I would like to get more input on it before I try it out though!! (got a job in January with a heated floor)

Heres the link:
http://www.flextherm.com/en/products/flexsnap


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## ChrWright (Jul 17, 2007)

Interesting. It would be nice if they had a video of the installation.

I'm a little skeptical on the rating over single ply as well. Cost psf?


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## PrecisionFloors (Jan 24, 2006)

ChrWright said:


> Interesting. It would be nice if they had a video of the installation.
> 
> I'm a little skeptical on the rating over single ply as well. Cost psf?


Ditto.


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## jarvis design (May 6, 2008)

Cost is going to be around $2.00 sq ft

I had one other concern - if your floor is not level or flat - do you level first then screw this down or do you screw this down then level - 
I contacted them this morning and while I got an answer, I do not have that warm fuzzy feeling that the answer is correct!! I will wait till I talk to the technical rep.

The other question I am waiting to hear back on is filling the grids, allowing that to cure, then tiling. They are reccomending installing the grid, glazing (or filling), and tiling at the same time. I asked about layout, etc, and the local store sales guy said - "you can do it before you put the grid down" - I don't think I like that idea. Reminds me of the one time I installed a heating system and tiled right over it - it worked, but what a PITA!!

I would rather fill it, let it cure, then tile. The say to use a polymer modified mortar for filling/setting but have a list of "approved" mortars.
Again, I should have a better answer in a couple of days.

Still don't agree going on single layer of ply though - would have to install a 2nd layer


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## angus242 (Oct 20, 2007)

Yeah, the 5/8" thing.....:sad:

What about screwing down, laying PEX then using a SLC? Now you're filled _and_ level.


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## jarvis design (May 6, 2008)

angus242 said:


> Yeah, the 5/8" thing.....:sad:
> 
> What about screwing down, laying PEX then using a SLC? Now you're filled _and_ level.


 
Angus,

I am trying to clarify with Flextherm, but it seems the approved fill/mortar is a modified medium bed mortar - I am specifically trying to find out if Laticrete 255 will work (multi-purpose thin/med bed).

From what I heard today SLC is not recommended - 

oh, and this system is an electric system - not water


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## bconley (Mar 8, 2009)

It seems like Shulter could do Ditra like this


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## angus242 (Oct 20, 2007)

jarvis design said:


> Angus,
> 
> I am trying to clarify with Flextherm, but it seems the approved fill/mortar is a modified medium bed mortar - I am specifically trying to find out if Laticrete 255 will work (multi-purpose thin/med bed).
> 
> ...


I'm very curious to why an SLC wouldn't be approved but a medium bed would. I'm thinking that's A LOT more labor, no?


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## jarvis design (May 6, 2008)

bconley said:


> It seems like Shulter could do Ditra like this


 
Totally different principle between ditra and a system like this. 
This would be considered a direct bond underlayment while ditra is a uncoupling membrane.


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## jarvis design (May 6, 2008)

angus242 said:


> I'm very curious to why an SLC wouldn't be approved but a medium bed would. I'm thinking that's A LOT more labor, no?


 
I think you would have issues with the SLC not spreading out evenly because of the grid pattern. If you have a 14" flat trowel it would almost be like filling the dove tails in ditra


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## PrecisionFloors (Jan 24, 2006)

angus242 said:


> I'm very curious to why an SLC wouldn't be approved but a medium bed would. I'm thinking that's A LOT more labor, no?


I don't see why it wouldn't either, doesn't make any sense. What does a medium bed mortar offer that an SLC does not???


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## bconley (Mar 8, 2009)

jarvis design said:


> Totally different principle between ditra and a system like this.
> This would be considered a direct bond underlayment while ditra is a uncoupling membrane.


I was thinking of the heat cable aspect of the product.


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## jarvis design (May 6, 2008)

bconley said:


> I was thinking of the heat cable aspect of the product.


 
my bad!! good idea actually!!


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## jarvis design (May 6, 2008)

PrecisionFloors said:


> I don't see why it wouldn't either, doesn't make any sense. What does a medium bed mortar offer that an SLC does not???


 
I wish I could give you an answer for that, but alas, I will have to wait and ask the tech guy.


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## angus242 (Oct 20, 2007)

jarvis design said:


> I am trying to clarify with Flextherm, but it seems the approved fill/mortar is a modified medium bed mortar - I am specifically trying to find out if Laticrete 255 will work (multi-purpose thin/med bed).


Actually, I just read their installation instructions and in them it said to use a dry-set mortar. Isn't 255 modified?

I like the concept but to me, SLC over the grid, let dry, Ditra and tile would be how I'd _want _to install it. 

I'll stay tuned for the answer...


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## jarvis design (May 6, 2008)

angus242 said:


> Actually, I just read their installation instructions and in them it said to use a dry-set mortar. Isn't 255 modified?
> 
> I like the concept but to me, SLC over the grid, let dry, Ditra and tile would be how I'd _want _to install it.
> 
> I'll stay tuned for the answer...


 
Yeah, I saw the same thing. I asked and was told that in that other Country, known as Quebec, they sometimes get things *****ed up in translation. The line I saw in their literature read "polyimer modified dry pack", uh, houston, I think we have a problem!!

And yes 255 is modified.

Hopefully have some answers by the end of the week. -


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## jarvis design (May 6, 2008)

*Update*

Spoke to a technical rep today. As of now there are 2 approved thinset mortars for this grid system:

Mapei Ultra Contact & Ultra Contact RS

This is the only mortar they used when they did their Robinson Floor test and therefore are the only "approved" mortars at this point.

They are apparantly testing other mortars, however, I could not find out which ones.

As for SLC, didn't really get an answer - it has yet to be tested and the rep I talked didn't know if it was slated for testing.

One other question that was answered was filling the grid, allowing it to cure, then tiling. Although it seems they think it should all be done at once - which I think is because they are marketing this as a one day install from start to finish.

I think they have brought this to market a little too quickly and should have had more testing done before now.

Funny thing is the dealer I buy Flextherm from and who showed this to me doesn't sell Mapei anymore!! He was recommending Lat 255. 

Damn, now I don't know if I should try it or not!!


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## jarvis design (May 6, 2008)

Oh, and one other thing.... I informed them that the installation guide specifies polymer modified mortar (no type specified...which is odd) and then talks about dry set mortar and the fact that these are not one in the same and it is going to create a lot of confusion.


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## angus242 (Oct 20, 2007)

BUMP!

Mike, any more word on this product?


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## orson (Nov 23, 2007)

angus242 said:


> Actually, I just read their installation instructions and in them it said to use a dry-set mortar. Isn't 255 modified?
> 
> I like the concept but to me, SLC over the grid, let dry, Ditra and tile would be how I'd _want _to install it.
> 
> I'll stay tuned for the answer...


I agree with this sentiment, however, why not use a different electric heating system, either a cable embeded in a mat or an electroplastic mat and then do SLC then Ditra? 

You just saved 2 bucks a foot and installation time to boot.


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## jarvis design (May 6, 2008)

Unfortunately, nothing new to report. My local supplier (who sells laticrete) has been trying to get answers, but, as far as I know, has had no luck.

The job I am now on I will be using the Flextherm system - just no grids

If I hear anything new, I will be sure to pass it along


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