Expansion or not?

[kaharrison9]

Hi There

The floor below is a wet heated screed and the long corridor is 17m long there are 2 doors on this corridor and i intended to fit 1 or 2 expansion joints under the doors to break up the corridor span.

Where the off the corridor doors are the rooms are about 5m deep so including the corridor around a 6m span.

With Ditra, a one zone heating system running through the floor and a flowing screed i dont think there needs to be expansion on these side doors.

Any thoughts anyone

Cheers

 

[Ajax123]

The screed should have had joints. These should reflect through the tiles. I think if you don't put movement joints in you are asking for trouble later on...

 

[beanz]

Alan, if there were joints in the screed, would/should they not be visible!?!

 

[Ajax123]

Alan, if there were joints in the screed, would/should they not be visible!?!

Joints in the screed will usually be visible so if you can't see them they are probably not there. There are occasions where joint strips are cut to 5mm below the screed surface and screeded over but the screed doesn't crack. But that is quite a rare occurrence although possible.

 

[kaharrison9]

Thanks Alan/Carl.

If I could just run through the floor with a few more details (difficult explaining without seeing).

Basically it is a 17m x 6m gyvlon LL slab around 75mm thick.

There are no expansion joints in the screed.

All the rooms are stud and on top of the screed.

There is a 17m x 1m run and then 4 rooms and doorways coming off the corridor.(see previous photos)

On the 17m run are 2 doors where I intend to put expansion joints under to break the run into 3.

Do I need to put expansion joints in the side run doorways.

My thoughts are not to due to the floor been one temp zone so the floor in the corridor or bedroom will be the same.

No break in the doorway substrate as the screed flows through.

The walls and doorframes are sat on top of the screed(knock out the walls and I wouldn't put an expansion joint there)

Ditra been installed.

All the false walls, perimeter expansion and the 17m run with 2 expansion joints leaves the tiling zone well broke up.

Finally Carl do you know in the uk any stockists of the stand up Ditra or Karl Dahm rollers. Have 15rolls to put down in the next couple of months so trying to make things easier.

Cheers guys.

Kevin

 

[Ajax123]

Aah I think I see. If all walls are on top of the screed and there is only one temperature zone then there would be no need to put joints in it. you need joints where the actual screed takes an abrupt change to its aspect ratio.

On that basis I would say ditra is not necessary with porcelain. Make damn sure its dry though as the LL can hold up the drying in some instances. My recomendation for testing would be to use the carbide bomn test rather than a surface hygrometer.


Also avoid cement adhesive like the plague.

 

[kaharrison9]

Morning Alan.

It is stone and I will be putting down the Ditra with gypfix.

I have 2 digital hygrometers more due to reading previous posts suggesting they would fine.

Why would a carbide bomb test be better?

Kind Regards.

Kevin

 

[kaharrison9]

Hi Carl

Typing into google I have come across a couple of sites that sell a embedding roller for ditra by Schluter.

The sites happen to be American why I mentioned if there was any UK stockists of this product.

It appears to have a ledge over the roller possibly to hold tiles so one can alternate the weight required.

Final question looking at some of the stand up rollers which do you think would be to heavy for ditra as I have briefly seen a 75kg ,50kg and a 28kg?

Regards.

Kevin

 

[Ajax123]

Morning Alan.

It is stone and I will be putting down the Ditra with gypfix.

I have 2 digital hygrometers more due to reading previous posts suggesting they would fine.

Why would a carbide bomb test be better?

Kind Regards.

Kevin

Hi Kevin. Give me a call in the morning and I will talk you through it by all means. The hygrometers are perfectly ok for measuring normal screeds but I have some concerns where it comes to the LL screeds unless the top has been sanded off to open the surface. Fir some reason I thought it was porcs... Must have my threads mixed up... Yes ditra is appropriate.

 

[kaharrison9]

Thanks Alan
Will ring tomorrow.
The floor has been sanded.
Kevin