Wetroom Advice (part 2) - Tile Advice

[SimpleSimon]

Hi again

Last week several of you helped me out with advice for a wetroom floor. There were a few different methods, but in the end I decided to go with the following - it's possibly overkill, but I'd rather be safe than sorry (and I'm in the unusual position of not wanting the floor layers to be too thin).

1. 18mm WPB ply
2. 12mm tile backer board
3. Electric underfloor heat mat
4. Latex floor screed
5. Isomat or similar, taped on seams and at walls
6. Tile adhesive
7. 8mm Slate Floor Tiles, washed, dried and sealed
8. Grout
9. Slate Tile sealing solution

I've the ply down, but have few more questions if anyone can help!

Q1. The tile backer board manufacturer says that there should be a layer of tile adhesive between them and the ply. (see here: Multi-Pro MoistSure Fixing Guide - Resistant site - http://www.resistant.co.uk/download/moisture-fixing-information/). Does that make sense with this floor design?

Q2. They suggest priming the boards for tiling with an acrylic based primer on all sides. Do they mean the backs too? And can I miss that step out on the floor as I'm not tiling directly straight on to them?

Q3. They also say to use stainless steel screws, which seems a bit of overkill if I'm putting a layer of isover over the top?

Q4. In terms of the walls, am I OK to just do the following:

a. Studs
b. Tile backer boards (primed on all sides)
c. Tile adhesive
d. Tiles (ordinary 6mm, not the floor slates)
e. Grout and grout sealant

Or do I need a liquid tanking in addition, especially in the shower area?

Thanks again for everyone's help!
Simon

 

[Old Mod]

It’s standard practice to use tile adhesive to lay backer boards on to a timber substrate.
It’s not designed to hold the boards exactly, but to take out in evenness in the substrate leaving the backerboards flat and completely supported. Then you add the mechanical fixings.
If in doubt, prime.
Walls, depends on boards of choice.
Wedi style, tank all joins and transitions and over fixings.
Cement style, tank everything, they are NOT waterproof.

 

[SimpleSimon]

Thanks 3_fall, I'll follow your advice on all those!

The boards are cement, so I'll tank them.

 

[Flintstone]

Couple of things, you would be better using a foam core board on the walls. And floor in my opinion as they are water proof, and much MUCH easier to work with. Secondly, you need an uncoupling layer under the stone. I think isomat waterproof membrane is uncoupling too but double check that with @3_fall as far as I know it’s the only thin tanking uncoupling mat?

 

[Rob douglass]

Hi again

Last week several of you helped me out with advice for a wetroom floor. There were a few different methods, but in the end I decided to go with the following - it's possibly overkill, but I'd rather be safe than sorry (and I'm in the unusual position of not wanting the floor layers to be too thin).

1. 18mm WPB ply
2. 12mm tile backer board
3. Electric underfloor heat mat
4. Latex floor screed
5. Isomat or similar, taped on seams and at walls
6. Tile adhesive
7. 8mm Slate Floor Tiles, washed, dried and sealed
8. Grout
9. Slate Tile sealing solution

I've the ply down, but have few more questions if anyone can help!

Q1. The tile backer board manufacturer says that there should be a layer of tile adhesive between them and the ply. (see here: Multi-Pro MoistSure Fixing Guide - Resistant site - http://www.resistant.co.uk/download/moisture-fixing-information/). Does that make sense with this floor design?

Q2. They suggest priming the boards for tiling with an acrylic based primer on all sides. Do they mean the backs too? And can I miss that step out on the floor as I'm not tiling directly straight on to them?

Q3. They also say to use stainless steel screws, which seems a bit of overkill if I'm putting a layer of isover over the top?

Q4. In terms of the walls, am I OK to just do the following:

a. Studs
b. Tile backer boards (primed on all sides)
c. Tile adhesive
d. Tiles (ordinary 6mm, not the floor slates)
e. Grout and grout sealant

Or do I need a liquid tanking in addition, especially in the shower area?

Thanks again for everyone's help!
Simon

 

[Rob douglass]

Hi yes you prime both sides of board. This minimises any warping of the board caused by the primer according to the rep for no more ply. I would definately use a tanking system.

 

[Flintstone]

Sorry if i have covered old ground there with my post, I can’t remember the whole convo of your previous thread without referring back to it

 

[Dumbo]

Couple of things, you would be better using a foam core board on the walls. And floor in my opinion as they are water proof, and much MUCH easier to work with. Secondly, you need an uncoupling layer under the stone. I think isomat waterproof membrane is uncoupling too but double check that with @3_fall as far as I know it’s the only thin tanking uncoupling mat?

Codex do one

 

[hmtiling]

Couple of things, you would be better using a foam core board on the walls. And floor in my opinion as they are water proof, and much MUCH easier to work with. Secondly, you need an uncoupling layer under the stone. I think isomat waterproof membrane is uncoupling too but double check that with @3_fall as far as I know it’s the only thin tanking uncoupling mat?

Waterguard is too but would only use that with an impey former for a guarantee as it is pricey as hell

 

[Flintstone]

As I said before, the best way here is ditra heat or one of those systems, with sealed joints and transitions to wall.

 

[SimpleSimon]

Thanks again everyone - the tanking membrane I ordered was from AKW (same as the shower tray). I emailed them to check whether it would act as a decoupling for the slate tiles too and they said it would.

I did also get in touch with isomat, who were very helpful, but it turned out they'd have to supply a 15m roll of membrane, which is way more than I need, and it would have been expensive to ship to Ireland.

Localtiler - the main reason I was going to opt for cement rather than foam board on the walls was that it can span 600mm studs, which the walls are (I double checked this with the suppliers of the board by email). The walls are already internally insulated and covered in airtightness membrane so it'd be a pain to pull this off to change the stud spacing, but I could do if using the foam board is critical? I can use the foam board on the floor though.
I didn't mean to disregard your suggestion on ditra heat, but I've already got the standard electric underfloor wires and controller connected up (not actually put them in the layer of latex yet though) so it'd be difficult to change now - thanks again for all your replies.

 

[Flintstone]

600 is wider than the norm, maybe you are best with cement boards with those spacings. A foam board would need to be thick to span that.

 

[Dumbo]

Thanks again everyone - the tanking membrane I ordered was from AKW (same as the shower tray). I emailed them to check whether it would act as a decoupling for the slate tiles too and they said it would.

I did also get in touch with isomat, who were very helpful, but it turned out they'd have to supply a 15m roll of membrane, which is way more than I need, and it would have been expensive to ship to Ireland.

Localtiler - the main reason I was going to opt for cement rather than foam board on the walls was that it can span 600mm studs, which the walls are (I double checked this with the suppliers of the board by email). The walls are already internally insulated and covered in airtightness membrane so it'd be a pain to pull this off to change the stud spacing, but I could do if using the foam board is critical? I can use the foam board on the floor though.
I didn't mean to disregard your suggestion on ditra heat, but I've already got the standard electric underfloor wires and controller connected up (not actually put them in the layer of latex yet though) so it'd be difficult to change now - thanks again for all your replies.

Put some akw down last week it came with all the internal corners broken . So if you got it best check it sooner rather than later.

 

[SimpleSimon]

OK, thanks local tiler and jcr - will bear in mind.

Simon

 

[Mario]

Hi again

Last week several of you helped me out with advice for a wetroom floor. There were a few different methods, but in the end I decided to go with the following - it's possibly overkill, but I'd rather be safe than sorry (and I'm in the unusual position of not wanting the floor layers to be too thin).

1. 18mm WPB ply
2. 12mm tile backer board
3. Electric underfloor heat mat
4. Latex floor screed
5. Isomat or similar, taped on seams and at walls
6. Tile adhesive
7. 8mm Slate Floor Tiles, washed, dried and sealed
8. Grout
9. Slate Tile sealing solution

I've the ply down, but have few more questions if anyone can help!

Q1. The tile backer board manufacturer says that there should be a layer of tile adhesive between them and the ply. (see here: Multi-Pro MoistSure Fixing Guide - Resistant site - http://www.resistant.co.uk/download/moisture-fixing-information/). Does that make sense with this floor design?

Q2. They suggest priming the boards for tiling with an acrylic based primer on all sides. Do they mean the backs too? And can I miss that step out on the floor as I'm not tiling directly straight on to them?

Q3. They also say to use stainless steel screws, which seems a bit of overkill if I'm putting a layer of isover over the top?

Q4. In terms of the walls, am I OK to just do the following:

a. Studs
b. Tile backer boards (primed on all sides)
c. Tile adhesive
d. Tiles (ordinary 6mm, not the floor slates)
e. Grout and grout sealant

Or do I need a liquid tanking in addition, especially in the shower area?

Thanks again for everyone's help!
Simon

You still need to screw the boards down.they dont need priming.and you need to tank all the corners and joints with paste and membrane.