Wet Room Floor Advice Please

[EdinTiler]

I have a friend that's building a wet room at the moment. He doesn't want to use a formed tray but just wants to make the floor in its entirety. This will comprise of a run from one end of the room to the drain end. It's a linear drain that he plans to have roughly 30cm from the shower wall. The room is 2.2m in length. It'll be framed appropriately and topped with 18mm ply.
Can someone tell me the run/gradient that'll be needed from entering the room to the drain please. The walls will be Wedi board that's taped and tanked. I'd also like some suggestions about what I should do with the floor before tiling it.
EdinTiler
Thanks in advance

 

[EdinTiler]

Change of plan. The drain is goin against the wall at the bottom of the run. All I can find from Schluter is a 2% gradient, which over 2.2m would be 44mm. I don't think this seems enough. Anyone got any suggestions. I hate workin for friends that won't listen. I want then to put an entire Schluter system in but they're havin none of it.
EdinTiler

 

[EdinTiler]

No takers?

 

[Old Mod]

2% fall is sufficient, try these,

http://www.pcsboard.com/pcs/wp-content/uploads/2013/04/Wedge-Boards.pdf

 

[EdinTiler]

@3_fall Good man. Muchos appreciatos signor!

 

[One Day]

2% as above. Don't make a former from wood or hardi. Guaranteed fail in my experience.

 

[Chalker]

Whatever you do mske sure you tank it! Ardex is the best for what you propose.

 

[EdinTiler]

Guys I don't have much say in how he goes about making the floor. One thing I'm sure of is that it'll be solid and fit for purpose. He's a joiner which is what makes this harder than ever to explain to him. Thinks he knows everything. I'm only tiling it as I've suggested the proper way to go about it and he wants to do it his way. It's out of my hands unfortunately. I'll be taking no responsibility other than the tiling. He knows this. Fed up of trying to make him see sense.
@impish Tell me why this is a guaranteed fail please?
EdinTiler

 

[One Day]

Guys I don't have much say in how he goes about making the floor. One thing I'm sure of is that it'll be solid and fit for purpose. He's a joiner which is what makes this harder than ever to explain to him. Thinks he knows everything. I'm only tiling it as I've suggested the proper way to go about it and he wants to do it his way. It's out of my hands unfortunately. I'll be taking no responsibility other than the tiling. He knows this. Fed up of trying to make him see sense.
@impish Tell me why this is a guaranteed fail please?
EdinTiler

I've attended loads of failed wet trays and showers which have had timber or hb 'custom' made floors. Aside from the smallest of failures in waterproofing causing failure, the link between the drain assembly and the floor is the real weak spot. Far safer to use a tray with the drain assembly built in and all watertight. Plus the tray itself is inherently waterproof.

 

[EdinTiler]

This is a brand new floor being built in a room that was a boiler room Impish mate. As I said the one thing I know is that it'll be solid. Mike Holmes solid, overkill.
As stated previously, I have made him aware of all of the above and he still wants to do it his way. Nothing I can do about it. He's gone and bought a wet room linear drain and trap etc. and his plumber says it's no problem to fit so my hands are tied.
It's just another case of 'what does the tiler know' unfortunately.
EdinTiler

 

[Chalker]

Just explain that grout is not water proof . Plywood expands. And it will fail.
Before tray formers were widely available, I worked on a job for a footballer. He wanted a large two person shower room. Again a joiner constructed the floor (very well) and a quality drain ( (Harmer) was fitted. It looked great.

Fast forward a couple of years later when the grout cracked here and there, then they could not get rid of the musty smell. Went in and removed the tiles and the whole thing had turned black with bacterial growth in the ply.
Mate or no mate, he needs educating.

 

[One Day]

This is a brand new floor being built in a room that was a boiler room Impish mate. As I said the one thing I know is that it'll be solid. Mike Holmes solid, overkill.
As stated previously, I have made him aware of all of the above and he still wants to do it his way. Nothing I can do about it. He's gone and bought a wet room linear drain and trap etc. and his plumber says it's no problem to fit so my hands are tied.
It's just another case of 'what does the tiler know' unfortunately.
EdinTiler

For the sake of our profession then - tell him he's wrong!
But it's no good telling someone they're wrong without telling them why - and then what they can do about it.
If he is insisting on HIS way then I'd personally suggest that you tank everything flat with BAL tank-it (but not from Topps - way too dear). BAL tank-it outperforms Ardex WP. Then using the same gear - fix kerdi-keba or Wedi tape etc to all joints around the drain assembly and the same on all internal corners.
photograph everything closely before you tile so that if a leak occurs - you have proved that you have done your bit.
Remember - just one slight break in the waterproofing and water WILL find it's way into the substrate. If it's timber or cement board, it will soak it up like a sponge.

 

[One Day]

Just explain that grout us not water proof .

They never believe it. As EdinTiler said - we're just tilers! 😡

 

[EdinTiler]

For the sake of our profession, I HAVE told him and explained exactly why there could be possible future problems. It's in my best interest to isn't it.
Absolutely everything will be taped and tanked regardless with the appropriate products. Just a stress that I don't need at the moment. Apologies if I'm biting a bit.
EdinTiler

 

[EdinTiler]

@impish What would you suggest goes over the top of the plywood? I've only ever fitted the Schluter systems on raised plinths and platforms with the formed trays and membrane before. With no problems I might add. He'll be using ply regardless of what I say so anything that'll make my work as fool-proof as possible will be a consideration.
Thanks in advance
EdinTiler

 

[EdinTiler]

I learn all the time in this great trade of ours and this is something I've never had to deal with before so I do totally appreciate all advice suggestions from all of you in whatever shape or form. I'm not scared of a bit of constructive criticism either. It's just that, as I'm sure you'll all understand, if it did go **** up then it's a 20yr friendship out the window and that's not something I particularly want.
EdinTiler

 

[J Sid]

My advice......DON'T do work for a friend who thinks he knows more about YOUR trade then you do.
It will end in tears 🙁

 

[Old Mod]

Make him read this thread!

 

[One Day]

@impish What would you suggest goes over the top of the plywood? I've only ever fitted the Schluter systems on raised plinths and platforms with the formed trays and membrane before. With no problems I might add. He'll be using ply regardless of what I say so anything that'll make my work as fool-proof as possible will be a consideration.
Thanks in advance
EdinTiler

Over ply? I'd use BAL Tank-it. BAL Technical say no, but I've done tests of my own - (for a terrace build up) and it stayed bonded and waterproof even after the wbp ply failed and delaminated.
No matter what you cover the ply with, be it a sheet membrane or liquid, it's just prone to absorbing any water it can get - even damp and condensation from underneath.
If the shower is used more than once a day, I'd guess it won't last more than 5 years - and that's if you make everything watertight from above.

 

[EdinTiler]

Thank you. So what would you use for the sub-floor if not ply?
Just spoke to my mate, expressed my dissatisfaction at nor wanting to listen to me and now he is prepared to listen. Thank god.
EdinTiler

 

[One Day]

At 2.2m length I would let him have his ply and even create the fall with it.
If it's all well supported and deflection free then get the best quality ply he can. BAL SBR to backs and sides to prevent moisture ingress, then for me - 12.5 mm Kerdi or Wedi board bonded and screwed down.
Ideally - Kerdi to a kerdi drain but if not, just tape and waterproof all fixings, joints and corners.

 

[EdinTiler]

Again, thank you very much for your patience with me and my stress levels. That's a big help. I will let you all know how I get on.
I'm off to watch This is England '90.
See you all tomorrow
EdinTiler

 

[One Day]

Don't sweat it. Just don't ever apologise to the other trades for wanting to do your job right! 😉

 

[p4ulo]

I would lay on top of the ply with a wedi or schluter board or similar "waterproof" board, all joints glued, taped and stuck down with Kerdi Coll adhesive, then a layer of Schluter Kerdi over the whole lot....Best to build it to last. The pre-formed Kerdi corners are excellent for total piece of mind.