Ditra Matting On Part Of A Floor

[J Sid]

Why put a piece of plastic between a sound floor and a tile when a good quality flexible addhesive will do

As @Aston reply 😉

 

[Two-Trowels]

I'm with Jonesy7 on this, no doubt there are certain cases where it's needed but what was used before it came along?

Millions of metres of floor have been laid without it and any that failed could probably have been avoided with better prep or better tiling, ie, no dot and dab etc.

 

[J Sid]

Surely you shouldn't be tiling on floor that's going to be moving lol ... How did we manage before plastic when adhesive were know we're near as good as they are today

@jonesy7 and @Two-Trowels how do you guys deal with the problems of a substrate that moves?
All materials move due to change in temperature, change in moisture levels, or just badly mixed or laid floor screed or a poor quality / stored outside wet plywood for wall or floor. Tiles also move due to these same outside agencies, heat and moisture, at a different rate, stone, glass, resin, porcelain or ceramic.
We find ways to work with the substance, using a uncoupling membrane or replace it with a more stable product. Ply is replaced with a cement board or cement covered insulation board.
Do you ever test the moisture content of the screed or ply before fixing? Do you test the strength of the cured screed before fixing? No, not many do, me included. I assume the ply is either wet or not fitted correctly, backs and sides not sealed, and refused to fix to it. I also assume, most of the time, the screed is not good and take steps to get over the potential problem, uncouple it.
Don't mean to have a pop, but I have, as many off have, seen failures on these materials when there is ways to negate this.
If you customer doesn't want to use an uncoupling membrane, cement board, expansion or movement joints, is up to us to educate them. 😉

 

[Spare Tool]

On this particular floor long as the screed is dry and stable with no evidence of cracking I would fit without uncoupling.
However
2 years ago I tiled 6 out of 7 kitchen floors in a cluster of newly referbed barn conversions all with piped under floor heating and S&C screed, good quality porcelain tiles, uncoupled all mine before tiling. The tiler that did the first one didn't bother, i was up at the houses only yesterday to discuss a new ensuite and my customer informed me that her neighbour had seven cracked tiles in her kitchen that need replacing if i have time while i'm up there...yep the only one without the ditra 🙂

 

[bcd-87]

What's wrong with tiling straight on to the screed floor why does everyone want to use ditra all the time it just over complicates things you never herd of 5 years ago never used it never will and if every floor I tiled in the last 30 years was only 6 mm out I would be well chuffed

Iv been tiling 11 years 12 yrs this dec 1st.. My mentor always used Ditra, he's been a tiler 35 plus yrs..

It's been around a while

 

[Old Mod]

Iv been tiling 11 years 12 yrs this dec 1st.. My mentor always used Ditra, he's been a tiler 35 plus yrs..

It's been around a while

Ditra 25 has been around for a little over 25yrs Ben.
It was rebranded on its 25th birthday 🙄

This is schluters explanation of 'tiling shift' which is what led to the development of Ditra Matting.


Bringing History Up To Date - Understanding The Tiling Shift
Tiles debond from the substrate because bonding the tiles directly to the building structure means there is no "give" between the two separate parts of the assembly, and movement and stress cracks in the substrate are transferred to the surface, damaging the tiles.

While the methods of installing ceramic tiles and stone have changed over the years, the physical dynamics of the assembly have not. The old traditional methods, used for centuries, addressed these dynamics by uncoupling the tile from the structural base through the use of a forgiving shear interface, in the form of a layer of sand.

Following the development of the thin-bed method of bonding the tile directly to the substrate with a very strong adhesive, problems occur because the rigid tiled surface moves at a different rate from the substrate.

An installed tile surface can be compared to a large sheet of glass. In addition to being a hard, brittle material, the tile also expands and contracts in reaction to environmental changes, but at a different rate from the substrate.

So, when the tile is strongly bonded directly to the substrate, it results in what is known as a "force transfer assembly," where this differential in the movement manifests itself as cracks in the tiled surface. One of the major causes of tiling installations failing is where stresses from the substrate are transferred in this way, into the finished covering of stone or ceramic tiles.

The solution is to install an uncoupling system - which utilises modern technology to bring the "sandwich" technique bang up to date. (This sandwich, used by ancient builders, comprised a structural base and a layer of sand, then a mortar bed - a mixture of sand, cement or other binder, and water - was laid, with the tile adhered on top).

Neutralising stresses by uncoupling the building structure from the tile is particularly important with the use of today's thinner, larger-format tiles and lightweight building materials.

The up-to-date method of uncoupling uses the Schlüter®-DITRA 25 polyethylene membrane, which safeguards installations over any even and load-bearing substrate.

Tiles will move independently from the screed because of different thermal expansion and contraction. Schlüter®-DITRA 25 neutralises this differential movement, preventing stresses being transferred to the tile covering. The system supports applied loads by transferring them directly to the load bearing substrate.

Schlüter®-DITRA 25 is a polyethylene matting with a fleece laminated to a grid-type structure of square cavities on the top. The fleece is adhered to the substrate with standard adhesive, and the adhesive used to stick the tiles actually anchors into the dovetailed configuration, mechanically locking the tiles onto the top. The cavities allow any stresses that occur between the substrate and the tiles to be neutralised evenly in all directions.

The matting itself has four main functions -- uncoupling, waterproofing, vapour diffusion over green screeds, and it bridges cracks such as timber board joints and cracks in screeds.

It protects the surface covering over a wide variety of substrates, including green concrete; green cement-based screeds, gypsum-based screeds, poured bituminous screeds, plywood and pressed wood, existing tile coverings, solid vinyl coverings or coatings, mixed substrates, gypsum plaster and plaster block, mixed masonry, and metal.

Today's tile installers have an array of materials and installation systems at their disposal to meet the UK's growing demand for this ideal surface covering. Setting materials are available in ever-increasing numbers to address the variety of substrates and tiles commonly used. Underlayments continue to be developed to protect tiles and guarantee a successful installation. Other developments include drainage, waterproofing and uncoupling membranes for use in both interior and exterior applications.

It's crucial that today's installers understand the physical dynamics of the entire tile assembly in order to achieve consistently successful results. Accepted wisdom regarding tile installation is now shifting away from the direct-bond philosophy, back to an understanding of the need for a forgiving shear interface to absorb stress.

This shift, with its resulting successful installations, represents a great deal of potential for the professional tiler.

 

[Time's Ran Out]

2nd to last paragraph of the above says it all!

 

[bcd-87]

Ditra 25 has been around for a little over 25yrs Ben.
It was rebranded on its 25th birthday 🙄

This is schluters explanation of 'tiling shift' which is what led to the development of Ditra Matting.


Bringing History Up To Date - Understanding The Tiling Shift
Tiles debond from the substrate because bonding the tiles directly to the building structure means there is no "give" between the two separate parts of the assembly, and movement and stress cracks in the substrate are transferred to the surface, damaging the tiles.

While the methods of installing ceramic tiles and stone have changed over the years, the physical dynamics of the assembly have not. The old traditional methods, used for centuries, addressed these dynamics by uncoupling the tile from the structural base through the use of a forgiving shear interface, in the form of a layer of sand.

Following the development of the thin-bed method of bonding the tile directly to the substrate with a very strong adhesive, problems occur because the rigid tiled surface moves at a different rate from the substrate.

An installed tile surface can be compared to a large sheet of glass. In addition to being a hard, brittle material, the tile also expands and contracts in reaction to environmental changes, but at a different rate from the substrate.

So, when the tile is strongly bonded directly to the substrate, it results in what is known as a "force transfer assembly," where this differential in the movement manifests itself as cracks in the tiled surface. One of the major causes of tiling installations failing is where stresses from the substrate are transferred in this way, into the finished covering of stone or ceramic tiles.

The solution is to install an uncoupling system - which utilises modern technology to bring the "sandwich" technique bang up to date. (This sandwich, used by ancient builders, comprised a structural base and a layer of sand, then a mortar bed - a mixture of sand, cement or other binder, and water - was laid, with the tile adhered on top).

Neutralising stresses by uncoupling the building structure from the tile is particularly important with the use of today's thinner, larger-format tiles and lightweight building materials.

The up-to-date method of uncoupling uses the Schlüter®-DITRA 25 polyethylene membrane, which safeguards installations over any even and load-bearing substrate.

Tiles will move independently from the screed because of different thermal expansion and contraction. Schlüter®-DITRA 25 neutralises this differential movement, preventing stresses being transferred to the tile covering. The system supports applied loads by transferring them directly to the load bearing substrate.

Schlüter®-DITRA 25 is a polyethylene matting with a fleece laminated to a grid-type structure of square cavities on the top. The fleece is adhered to the substrate with standard adhesive, and the adhesive used to stick the tiles actually anchors into the dovetailed configuration, mechanically locking the tiles onto the top. The cavities allow any stresses that occur between the substrate and the tiles to be neutralised evenly in all directions.

The matting itself has four main functions -- uncoupling, waterproofing, vapour diffusion over green screeds, and it bridges cracks such as timber board joints and cracks in screeds.

It protects the surface covering over a wide variety of substrates, including green concrete; green cement-based screeds, gypsum-based screeds, poured bituminous screeds, plywood and pressed wood, existing tile coverings, solid vinyl coverings or coatings, mixed substrates, gypsum plaster and plaster block, mixed masonry, and metal.

Today's tile installers have an array of materials and installation systems at their disposal to meet the UK's growing demand for this ideal surface covering. Setting materials are available in ever-increasing numbers to address the variety of substrates and tiles commonly used. Underlayments continue to be developed to protect tiles and guarantee a successful installation. Other developments include drainage, waterproofing and uncoupling membranes for use in both interior and exterior applications.

It's crucial that today's installers understand the physical dynamics of the entire tile assembly in order to achieve consistently successful results. Accepted wisdom regarding tile installation is now shifting away from the direct-bond philosophy, back to an understanding of the need for a forgiving shear interface to absorb stress.

This shift, with its resulting successful installations, represents a great deal of potential for the professional tiler.

That great info.. that was my point exactly it's been around years..

 

[Stu Lilley]

Hi,

We have a 55 square metre kitchen that we want to tile with 80cm x 50cm limestone tiles. We have NO UFH.

80% of the room is a newly screeded floor (extension) which is perfectly level (to within the tolerance of an 8 foot level placed in various places). The screed is dry having been down for 3 months.

Our challenge is the existing screeded area (20% of the floor and in one “strip”) is not level and runs out to approximately 6mm higher at one end of the room and 2mm lower at the other end when compared to the new screed.

We want to avoid having to pour self levelling compound over the whole area so one solution we have is to lay ditra matting on the new screeded area on a 6mm adhesive bed to raise the level by approximately 6mm. We can then use self levelling compound on the old screeded area to bring it up to the level of the ditra – and end up with a level surface.

What are the opinions out there on this solution? Is self levelling the whole area the only way to go? I looked at the ditra and it seems to have very little vertical flex.

Thanks for taking the time to read this.

James

Chop up and level the old section... Ditra the whole area using a 4mm notch trowel and a expansion joint should be used at the junction of the two screeds

 

[Stu Lilley]

What's wrong with tiling straight on to the screed floor why does everyone want to use ditra all the time it just over complicates things you never herd of 5 years ago never used it never will and if every floor I tiled in the last 30 years was only 6 mm out I would be well chuffed

 

[Stu Lilley]

All floors expand and contract new or old and using Ditra is def not complicating things.. Since the development of thin set adhesives decoupling Is a must ... i have been using ditra for approx 20 yrs now... Surly it makes sence to protect your work from cracking... You would not lay a decent carpet and say no to the underlay as it complicates things

 

[SJPurdy]

All floors expand and contract new or old and using Ditra is def not complicating things.. Since the development of thin set adhesives decoupling Is a must ... i have been using ditra for approx 20 yrs now... Surly it makes sence to protect your work from cracking... You would not lay a decent carpet and say no to the underlay as it complicates things

I think this is overstating things a little, it sounds like a salesman's spiel. There are many circumstances where using Ditra or similar uncoupling layer should be used but to say it is a must for all floor is overstating it I think. All floors expand/contract with heat as do the tiles but the relative difference can be taken up in the floor structure without cracking the tiles. Even my own badly done (before insulation boards readily available) electric heated kitchen floor direct onto a concrete slab which must have a large temperature difference between the top (tiling layer) and the bottom of the concrete hasn't shown any signs of cracking.
I don't really see how thin set adhesives is much different to the previously used cement bonding layer on top of a screed - admittedly usually the screed itself was debonded from the concrete base (building papers/polythene (in my experience) or as stated earlier a layer of sand in older structures); so tiling a screeded floor with thin set is presumably alright (if it wasn't just about every tiled floor would be cracking!).
The carpet analogy is not really relevant because the customer can feel the difference in the softness of the floor as they walk on it; whereas they take a lot of convincing that the bit under the tiles that they can't see or feel is worth £x even when you are explaining that there is some risk of cracking with their floor structure that can be reduced by using. (Note I say "reduced" to customers as well - It's really good stuff but to say it will prevent all cracks!(implied in other posts/threads/elsewhere).