Ditra Drain4 and Ditra Rake edging

[dedee]

Hi,

I wonder if someone here can offer some independent verification of my what my tiler contractor are telling me. It is too late to change anything but I am keen to understand.


We have a 50sq meter terrace raised 18” above ground level running the width of the house. A new 4” concrete base has been laid to provide the required 2% slope, 2cm per meter over the 5m depth.


10mm Porcelain Tiles are to be laid.


Tiler has spec’d and laid Ditra-Drain 4 drainage mat and Ditra Rake Edging profile for the long 10m front edge. Tiles will also be laid on the 18” vertical surface.


Can anyone confirm the efficacy and even the necessity of these products. Do they work? How does water get under grouted tiles in the first place?


Many thanks

 

[hmtiling]

I specify ditra drain for all my external floors. I'd have thought ditra drain 8 might be better for that area

 

[Dumbo]

I agree with @hmtiling My conversations with schluter regarding ditra drain on a patio of that size they recomend drain 8 and yes it is good practice .

 

[Old Mod]

Excellent product, I always insist on it for external applications, especially terraces and balconies.
If you want longevity from your project, then it’s definitely worth the expense.
And what’s more, it works.

I spilt a full bucket of water on a mat I’d fitted on a terrace, after the initial shock of knocking it over I realised I’d fitted Ditra Drain and managed to get a photo of it draining.
The water is not very easy to see, but it’s there on the left of the image.
And one terrace was saved from partial flooding.

 

[GoneGuy]

I would have used ditra drain 8 on that size patio.
If you have any concerns regarding the ditra rake profile give @Schlüter-Systems Ltd a message or phone their technical department

 

[dedee]

Many thanks for your replies and endorsements. I am still not entirely sure how moisture gets under the tile in the first place. Surely with a sufficient slope the water will just run off the surface.

The concrete base by the way was laid back in june on top of a base that sloped towards the house! We have had plenty of opportunity to see how effective the new slope is.

 

[Blunt Tool]

All cement based adhesives and grouts are water resistant not waterproof so you must prepare sub floor ready for this eventuality.

 

[hmtiling]

All cement based adhesives and grouts are water resistant not waterproof so you must prepare sub floor ready for this eventuality.

Was just typing that

 

[Old Mod]

At some point or other over time it’ll help prevent any moisture below the tiles from freezing and deteriorating the bond between the tile and matting. Any moisture will have migrated into the matting and it’ll be kept away from the adhesive. Which is the biggest cause of failure in an exterior installation.

 

[dedee]

Thanks for taking the time to reply.
OK so it does seem that I am getting a belt and braces job albeit that ditra drain 8 might have been better.
Certainly the previous job was not done well. The old tiles were stuck direct to the concrete and were in a bad state when we moved here 11 years ago. With the new, correctly sloping base, and improved drainage we can hopefully look forward to have a trouble free installation for many years to come.
I will post an image here when the job is done, which weather permitting, should be early next week.

I have spoken to Schulter about the Ditra Rake edge profile (it aint cheap is it?). I asked if there were end caps available as there are none shown on the web site nor in their catalogue. There are no end caps. Which either means running the very expensive profile up the sides of the terrace or finding a neat way of making the corner to the more usual and much cheaper bull nosed profile.

 

[Old Mod]

Thanks for such a positive response and it would Ben great to see final images.

 

[dedee]

Thought you might like to see that the drainage mat certainly works. It rained here on sunday and the ungrouted terrace got soaked. Two days later water is still seeping out of the exposed lower edge.
I hope it can dry out so that edge can be completed before it rains again.

 

[Old Mod]

That’s great Dedee thanks.
I hope we’ve been able to reassure you that it was the right thing to do.

 

[dedee]

As promised photos of the finished terrace

I need to build up the lawn on the right hand corner and along the left edge and I also want to create a drainage ditch/gully, gravel filled, along the front edge. I would welcome guidance on how wide and how deep that ditch should be.
cheers

Andy