Ditra matt vertical movement. - Tile Advice

[ncfc_andy]

Hi there

Just looking for some advice as I'm caught in the middle of 2 tradesmen. I'm a decorator so have don't really have any knowledge on tiling.

Currentry having my bathroom re vamped bought some nice floor tiles but yesterday the bathroom fitter said he was concerned about laying tiles as there was vertical movement in the joists.

I then spoke to my tiler who said use ditra matt and said he would have no hesitation in tiling using that underneath says it was sound compared to floors he'd done before.

So my question is will ditra matt be ok ok with vertical movement or not????
He seems to think yes but the fitter says he will do it but won't guarantee it.

Stressed

 

[Andy Allen]

Sub floor needs to be sorted before tiling to get rid of the deflection .
Dittra mat is more for lateral move that you get with ufh.
It may help a bit.....but the big question is how much is your floor bouncing .
Either way if you're tiler tiles it them he's liable for it....end of !!

 

[ncfc_andy]

Sub floor needs to be sorted before tiling to get rid of the deflection .
Dittra mat is more for lateral move that you get with ufh.
It may help a bit.....but the big question is how much is your floor bouncing .
Either way if you're tiler tiles it them he's liable for it....end of !!

 

[Old Mod]

As Andy above, Ditra does not prevent vertical movement, deflection or bounce, which ever your preferred term.
It combats only lateral movement, expansion and contraction of a substrate.
Two simple tests can help determine the effectiveness of your floor.
1. Cross haired laser places on the floor with a horizontal bea switched on.
Walk around it and watch for vibration in the beam, don't tip toe around it, walk like you mean it.
If there's excessive movement it will show up immediately.
2. If you don't have a laser to hand, use a brim full glass of water, if it spills, you have your answer.

Simplest fixes are either lift your floor and reinforce the joists, or overboard first with a cement board.
The boards don't officially strengthen a floor, but experience says that it does.
Lay boards perpendicular to existing floor making sure joints beneath don't line up with the new ones.
Use tile adhesive to stick them down, then screw them to the floor when dry. 300 centres max.
You can dispense with the Ditra then.
As long as you are not using a natural stone, the boards will have some decoupling properties.
If you are, an antifracture matt would also be useful,
They're about 1mm thick on average, so not too much extra build up.