Shower tray former: tiles and waste height

[DazJWood]

Hi,

I have installed a shower former; the type that is a foam core sandwiched by a meshed cement layer either side:

The mosiacs that I wanted to install will be lower than the drain surround (even with the adhesive).

I have included some pictures below of the mosiac layed next to the drain:

The board to board joins and board to former will be tanked shortly.

I was intending to fix them with a 6mm notched trowel but now I have offered them up to the drain it's clear that they won't be level with the top of the drain surround.

Can I still use these mosiacs? Should I use a thicker bed of adhesive?
Would I be better to use full tiles and cut them to the fall of the tray (envelope cut)?

I would be grateful for any advice anyone can offer.

Many thanks in advance,

Daz

 

[Tony_C]

Hi Dan, have you checked the minimum tile size for that brand of tray? Most can only take down to 50x50mm for point loading issues. There are brands than go go lower but its something I'd be checking also which may help sway you towards larger tiles

 

[DazJWood]

Thanks for the response Tony.

The documentation that came with the tray does not describe any restrictions on tile size or point load information. In fact it says nothing about tiling onto it at all. I've checked the manufacturer's website (nassboards.co.uk) and there is no information that I can find on there either. The tray I've got is also not on there.

I can ring them up on Monday and ask for their advice.

Any further advice, in the mean time, based on any experience of a similar issue, would be gratefully received.

Thanks,

Daz

 

[Dumbo]

Thanks for the response Tony.

The documentation that came with the tray does not describe any restrictions on tile size or point load information. In fact it says nothing about tiling onto it at all. I've checked the manufacturer's website (nassboards.co.uk) and there is no information that I can find on there either. The tray I've got is also not on there.

I can ring them up on Monday and ask for their advice.

Any further advice, in the mean time, based on any experience of a similar issue, would be gratefully received.

Thanks,

Daz

When you phone them up and ask for their advice regarding tile size get them to email their limitations so if it goes wrong you have something in writing.
Don't use a bigger notch trowel the adhesive will just come through the joints .
You could may be consider overboarding the tray with a 4 or 6 backer board if they are ok with point loading issues

 

[DazJWood]

When you phone them up and ask for their advice regarding tile size get them to email their limitations so if it goes wrong you have something in writing.
Don't use a bigger notch trowel the adhesive will just come through the joints .
You could may be consider overboarding the tray with a 4 or 6 backer board if they are ok with point loading issues

Thanks, will ask them.

Over boarding with backer board? How would I maintain the fall to the drain if I did that? Envelope cut them?

 

[Dumbo]

Thanks, will ask them.

Over boarding with backer board? How would I maintain the fall to the drain if I did that? Envelope cut them?

Yes and tape the joints

 

[DazJWood]

Yes and tape the joints

Surely I couldn't just envelope cut a whole backer board. Wouldn't I need to cut the board up to a smaller size as well? A whole board just envelope cut wouldn't follow the fall of the former surely.

 

[Dumbo]

Surely I couldn't just envelope cut a whole backer board. Wouldn't I need to cut the board up to a smaller size as well? A whole board just envelope cut wouldn't follow the fall of the former surely.

Of you were fixing xxl tiles you would just envelope cut one tile , so why not

 

[DazJWood]

Of you were fixing xxl tiles you would just envelope cut one tile , so why not

Would the mosiacs then fix over the enveloped cut backer boards ok (where the diagonals are) ?

 

[J K Tiling Cornwall]

Just an idea but could not not stick mosaic mesh sheets to the former and trowel over with adhesive? Will make the base pretty solid and will follow the fall/fleet.. Then fit the mosaics as normal fixed to mosaic mesh. Not sure if 2 layers would be enough? Should get over any point loading issues and will achieve a 100% bed.

 

[DazJWood]

Just an idea but could not not stick mosaic mesh sheets to the former and trowel over with adhesive? Will make the base pretty solid and will follow the fall/fleet.. Then fit the mosaics as normal fixed to mosaic mesh. Not sure if 2 layers would be enough? Should get over any point loading issues and will achieve a 100% bed.

Think I understand what you mean.

Do you mean the rigid plastic mesh sheets that are about 30 by 30?

Do you mean stick these to the tile former and then level them with adhesive? Can you elaborate?

Thanks,

Daz

 

[jobdone]

How does the tray sit with the rest of the floor. Raising all the tray will effect the floor height.

 

[J K Tiling Cornwall]

Yep those are the ones a plastic mesh 30x30cm. They are self adhesive, really sticky with wax paper you peel off. I'd make sure the former is really clean, free from dust. If you adhere them to the surface then fill the voids flush with adhesive using a plastering trowel or rigid grout float. Let it go off then tile as normal but use mosaic mesh also on the back of the mosaics. Hopefully with 2 layers you should be close to the height but if not you could double up the layer on the former. In response to Jobdone I'm guessing you only have mosaics in the wet area? What tiles do you have on the rest of the floor? Thanks

 

[DazJWood]

How does the tray sit with the rest of the floor. Raising all the tray will effect the floor height.

No the tray is installed on a raised framework so no problem with matching height of former and tiles to floor.

 

[DazJWood]

Yep those are the ones a plastic mesh 30x30cm. They are self adhesive, really sticky with wax paper you peel off. I'd make sure the former is really clean, free from dust. If you adhere them to the surface then fill the voids flush with adhesive using a plastering trowel or rigid grout float. Let it go off then tile as normal but use mosaic mesh also on the back of the mosaics. Hopefully with 2 layers you should be close to the height but if not you could double up the layer on the former. In response to Jobdone I'm guessing you only have mosaics in the wet area? What tiles do you have on the rest of the floor? Thanks

Great thanks for replying. Yes that sounds like a reasonable way of raising the height and keeping the fall. Thanks for the suggestion.

Still seems strange that the drain height is so high considering mosiacs are used a lot in shower floor installations.

I'll ring the manufactured Monday for their recommendations but the mesh idea sounds good as a solution.

 

[Tony_C]

That same manufacturer does a tray with a drain that drops to 5mm for tile height, its unfortunately just the tray and drain you have ended up purchasing.

I don't think you will find any thin backer boards to over board that tray with (xps style) that will take the mosaics. Usually the shower trays themselves are stronger than building boards you can buy

 

[DazJWood]

That same manufacturer does a tray with a drain that drops to 5mm for tile height, its unfortunately just the tray and drain you have ended up purchasing.

I don't think you will find any thin backer boards to over board that tray with (xps style) that will take the mosaics. Usually the shower trays themselves are stronger than building boards you can buy

Ah OK. Yes must admit the tray to top of drain height was not something I looked at when purchasing the tray. Just didn't even consider it to be honest.

Surely though I could use 6mm Hardie backer board if I decided to go down the route of over boarding the tray. Why would it need to be XPS backer board?

 

[Tony_C]

It wouldn't have to be xps. I was just letting you know that the thinner 4mm boards probably wouldn't be an option. If you do opt for hardie just make sure you fully tank those boards also 👍.

I just perhaps see each extra layer added as another step for potential failure of not done 100%. Skip the headache and get bigger tiles

 

[DazJWood]

It wouldn't have to be xps. I was just letting you know that the thinner 4mm boards probably wouldn't be an option. If you do opt for hardie just make sure you fully tank those boards also 👍.

I just perhaps see each extra layer added as another step for potential failure of not done 100%. Skip the headache and get bigger tiles

Why would I need to tank the Hardie backer, if I chose to use it? The shower former has an XPS waterproof core. Raising the height of the former wouldn't then require the need to tank the top layer again, unless I'm missing something. What's the logic behind tanking it again?

 

[Tony_C]

Hardie isn't waterproof, just has a resistance to water. Yes your xps tray is waterproof but you don't want to be letting hardie sitting submerged in water it's the layer between the tiles and tray so it would be. You would want to help the water pass off it and not through it.

If your unsure read the hardie instructions or call them, Its stated in their manual to tank it also in a wetroom situation.

 

[J Sid]

Just buy some new tiles

 

[DazJWood]

Hardie isn't waterproof, just has a resistance to water. Yes your xps tray is waterproof but you don't want to be letting hardie sitting submerged in water it's the layer between the tiles and tray so it would be. You would want to help the water pass off it and not through it.

If your unsure read the hardie instructions or call them, Its stated in their manual to tank it also in a wetroom situation.

Yes I know that Hardie is water resistant only and not waterproof. It wouldn't be submerged in water; displacement would mean the water would sit above the top layer. Yes if left then the adhesive and hardie board would absorb some of the water; if the drain was blocked then yes it could soak through and down to the foam core below it.

It's the same as saying the tile adhesive under the tiles is submerged in water all the time.

Unless I'm missing something I can't see the need to tank again if I used Hardie to increase the height. Anyone else any thoughts on this?

Thanks,

Daz

 

[hmtiling]

There's not many foam core formers that'll accept mosaic that small. Also, over boarding with xps you'll have the same issue.
I'd change the tiles but if I had to go the hardie route I'd tank it as otherwise you'll have a 7/8mm layer of absorbant material under the drain height as that former has no sub tile drainage. There's a possibility of efflorescence issues then as the water has nowhere else to go

 

[Tony_C]

You need the tanking to displace the water that reaches the hardie, not bare hardie which would soak it up rather than displace it. Water will pass through the grout and reach it unless you go down the epoxy route.

It's the same as saying the tile adhesive under the tiles is submerged in water all the time.

It's not. Whatever water would reach through to the tray/adhsesive would then run down the falls to the drain as the top layer of the tray is waterproof along with the core, the hardie isn't.

In these types of job you are trying to limit failure, for the sake of what it would cost to tank less than a square meter i don't know why you are dead set against the advice?

Anyhoo i've already advised all i can on it. I'm sure others will come along with similar advice

 

[DazJWood]

You need the tanking to displace the water that reaches the hardie, not bare hardie which would soak it up rather than displace it. Water will pass through the grout and reach it unless you go down the epoxy route.

In these types of job you are trying to limit failure, for the sake of what it would cost to tank less than a square meter i don't know why you are dead set against the advice?

Anyhoo i've already advised all i can on it. I'm sure others will come along with similar advice

Thanks for the advice. Lol I'm not dead set against tanking the area; I was merely questioning the need to do it.

 

[J Sid]

Slc is the route I'd take if I had to fix those tiles

 

[DazJWood]

Slc is the route I'd take if I had to fix those tiles

How would you maintain the fall to the drain with SLC? Thanks

 

[J Sid]

You need to work it as it sets. Not easy if not done before.
If you must do something you will find it easier to use tile adhesive.
With a notched trowel trowel floor with trowel size you need, 6mm, 8mm. When ribs are set enough infill teeth gaps to make a solid smooth finish.
Job done 😁

 

[DazJWood]

Been out looking at tiles again today to replace the original mosiacs.

Have found a square porcelain tile that's 160mm by 160mm. See below:

Would I need to envelope cut this rule to follow the fall of the tray or as it is 160mm would it be small enough to still follow the fall?

If I need to envelope cut them then could I rotate them and fit them as a diamond pattern where then it would follow the fall to two corners and be close to the other two corners of the shower (tray is 1200 by 900). I've probably not explained that very well but see below :

If you imagine I have cut the tile where the drain would be then maybe this would be an option to avoid envelope cuts.

Thanks in advance,

Daz

 

[DazJWood]

Can any one offer any guidance/ advice?