Waterproofing under screed?

[Ozzy]

Ok, I'm a bit confused. I've been talking to my customer about her bathrooms as she is having mostly wet rooms. She has said the waterproofing is being done under the screed. Is this normal practice abroad?

 

[Dumbo]

When you say screed are you talking screed or a levelling product .

 

[Italy]

Ok, I'm a bit confused. I've been talking to my customer about her bathrooms as she is having mostly wet rooms. She has said the waterproofing is being done under the screed. Is this normal practice abroad?

in Italy, is as in uk

 

[Italy]

sometimes, it is waterproofed before the screed, but it's just an extra precaution. then proceed as usual. waterproofed before the tiles.

 

[Ajax123]

from a purely technical point of view a screed should always be divorced from the substrate by means of an operational DPM. This is usually a simple 1200 gague polythene membrane and sometimes a more complex drainage membrane or liquid DPM. if there is insulation also under the screed i.e. floating construction then a second "slip" membrane, typically a thinner 500gague membrane should be placed over the insulation before any underfloor heating pipes or screed. so waterproofing under the screed is perfectly normal. However this will NOT protect from the effects of water from above so in the case of wetrooms and showers and of course if possible bathrooms then a separate tanking system is ideally used prior to tiling.

 

[Ozzy]

That's great, I now have all the info I need to insist on tanking the wet rooms myself, I'm rubbish at explaining things so thanks. I always tank shower areas and wouldn't have been happy leaving this out. Probably off to Qatar on the 10th March, I can't wait to get started, she has some amazing Tiles! Looking forward to some sunshine too 😀

 

[Ozzy]

When you say screed are you talking screed or a levelling product .

She said screed. It's so hard to get things clear talking to her through email. I just want everything right before I go over.

 

[Dan]

Call her.

 

[Ozzy]

Spoke to her last night, I'm supervising the screeding when I get there and she's agreed for me to do the tanking.

 

[Dumbo]

Spoke to her last night, I'm supervising the screeding when I get there and she's agreed for me to do the tanking.

What about screed drying times . Isn't that going to hold you up .

 

[White Room]

To be honest I feel your getting a lot put on you, do you have any experience with screeds.

 

[Drainage by Design]

Probably off to Qatar on the 10th March

The pactice there is normally to use bitumen-based LAW (sometimes torch on, like rooing felt) and the screed is then laid to cover it up neatly before tiling. Sometime insulation is used under the screed. UFH not normal
Under-tile waterprofing is not always accepted as necessary.

 

[Kevbos]

In Sweden they use plaster board on the wet room floors then tank room all into one drain. All pipework is surface mounted mostly .so only weak point in wet room is the 1 drain. Yes plaster board. It breaks and flexes with there floors. It was a shock but it worked

 

[Drainage by Design]

Plasterboard - it breaks and flexes with their floors.

But is the substrate concrete slab or timber ?

 

[Kevbos]

There usual building is made mostly out of wood etc .

 

[Kevbos]

Most houses out of cities are timber built and on top of rock that constantly moves .so they have to flex and move with ground movement and extremes of weather

 

[Ozzy]

Probably off to Qatar on the 10th March

The pactice there is normally to use bitumen-based LAW (sometimes torch on, like rooing felt) and the screed is then laid to cover it up neatly before tiling. Sometime insulation is used under the screed. UFH not normal
Under-tile waterprofing is not always accepted as necessary.

Yes they're doing exactly that now.

 

[Ozzy]

Sorry for the late reply everyone. I've been here 3 weeks on Sunday. Damn slow going as some work hasn't been finished, didn't have all the tools I needed either but it's full steam ahead now.
Regarding the screeding, I'm letting them get on with doing it the way they normally do, I don't want to be responsible for any problems.
I'm working in a half built house with no electric or plumbing and all the other workers are from India or pakistan. We communicate with sign language lol. There is no health and safety, I really should have taken a video of them trying to wire up my drill to the generator, hilarious!
It's bloody awesome though!

 

[Kevbos]

Life experiences can't beat them

 

[Ozzy]

Fixing some beauty's at the moment, 1.2m x 0.6m and 12mm thick porcelain. Wouldn't be too much of a problem but she wants them on her 3m high walls (platform on way)! I'm so happy that the solid walls are perfectly flat . I swear they weigh more than me . I'm using Keraflex Maxi S1. I haven't fixed these before but it seems to be going ok.

Can anyone tell me their fixing method for these so that I don't do it wrong and kill someone?

 

[NZ_Tiler]

12mm porcelain is probably 30kg m2 so one full tile ca.22kgm2.

No doubt you're back buttering... when trowelling your walls keep the notches parallel and running across the narrowest part of the tile, that way the air can escape easy and notches collapse.

Also use levelling clips. 1. They stop the tiles touching and chipping when you first lay them. Spacers are fiddly and fall out...

2. You get flush edges. Don't be tight, put a couple in, its a nuisance if one breaks and potentially have to pull a tile off to replace it.

 

[Ozzy]

12mm porcelain is probably 30kg m2 so one full tile ca.22kgm2.

No doubt you're back buttering... when trowelling your walls keep the notches parallel and running across the narrowest part of the tile, that way the air can escape easy and notches collapse.

Also use levelling clips. 1. They stop the tiles touching and chipping when you first lay them. Spacers are fiddly and fall out...

2. You get flush edges. Don't be tight, put a couple in, its a nuisance if one breaks and potentially have to pull a tile off to replace it.

Thanks, yeah I'm back buttering. The problem is finding things out here, going to look for one thing seems to take up half a day, it's driving me nuts. I would have no idea where to find levelling clips.

The plumbers decided to lay all the pipework in the bathroom I'm working in yesterday so I can't use the platform for the higher tiles. I'm being held up so much. They also have strange ways of doing things here, the window fitter said he wants me to tile before he fits the window (in one bathroom, the rest are fitted inside so the sill is on the outside), I rejected this though.

I'm off to Dubai tomorrow for a few days so they can get on and finish before I get back.