Sealing corners of a tiled shower?

[MAB]

I have grouted the wall tiles in my new walk in ensuite shower at last and now need to seal the two internal corners where the tiles meet. I believe these corner wall joints should not be grouted or they will crack.

The tiles are fixed on Hardi-backer cement board which was sealed in the corners (before tiling) with white Sikaflex EBT and the shower tray was also sealed to the tile backer board (before tiling) with Sikaflex creating an upstand as recommended in other helpful Build Hub posts.

My question is what sealant (or sealants) should i use in the finished tiled shower internal corners, the bottom tiles to shower tray corner, the ceiling to tiles corners and the tiles where edges meet metal tile trims? (the grout i have used is white)

 

Sikaflex EBT (white)?

CT1? (I have read on here white CT1 changes colour over time?)

or Dow Corning 785 Sanitary Silicone sealant? (white)

 

I am no expert at applying sealant....so should I apply it between masking tape, if so how do I prevent a raised edge forming by tape edges and should the tape be removed immediately or after sealant has cured?

Thanks in advance for any help or advice.

 

[PeterW]

@Nickfromwales usually mandates clear CT1 as a backing with white sacrificial sealant on the front of it. 

[ProDave]

You mention wall joints. You are not talking about those plastic strips the tile shops try and sell you to do corners, and worse still, the ones they try and sell you to finish off the bottom?

 

Work of the devil, should be banned from sale as unfit for purpose.

[nod]

1 hour ago, MAB said:

I have grouted the wall tiles in my new walk in ensuite shower at last and now need to seal the two internal corners where the tiles meet. I believe these corner wall joints should not be grouted or they will crack.

The tiles are fixed on Hardi-backer cement board which was sealed in the corners (before tiling) with white Sikaflex EBT and the shower tray was also sealed to the tile backer board (before tiling) with Sikaflex creating an upstand as recommended in other helpful Build Hub posts.

My question is what sealant (or sealants) should i use in the finished tiled shower internal corners, the bottom tiles to shower tray corner, the ceiling to tiles corners and the tiles where edges meet metal tile trims? (the grout i have used is white)

 

Sikaflex EBT (white)?

CT1? (I have read on here white CT1 changes colour over time?)

or Dow Corning 785 Sanitary Silicone sealant? (white)

 

I am no expert at applying sealant....so should I apply it between masking tape, if so how do I prevent a raised edge forming by tape edges and should the tape be removed immediately or after sealant has cured?

Thanks in advance for any help or advice.

 

Your correct no grout on the internal corners 

if you use tape water will get behind 

run an even bead of sealant down the corners Then spray with a 20 -1 mix of washing up liquid and smooth out decal times The sealant won’t stick to the liquid 

Use one of the rubber silicon tools from screwfix or simalar 

Its really that easy 

[Nickfromwales]

First off, let's see some pics. 

If the grout is rammed into the corners and sponged back nicely you may not need any silicone. My current job has none and is looking much the better for it. 

 

No silicone anywhere, just CT1 under the glass. 

[MAB]

12 hours ago, ProDave said:

You mention wall joints. You are not talking about those plastic strips the tile shops try and sell you to do corners, and worse still, the ones they try and sell you to finish off the bottom?

 

Work of the devil, should be banned from sale as unfit for purpose.

 

No not used those plastic strips anywhere.......the joints I mentioned are where the tiles meet at 90 degrees leaving a small gap in the vertical corners for grout or sealant.

[MAB]

10 hours ago, Nickfromwales said:

First off, let's see some pics. 

If the grout is rammed into the corners and sponged back nicely you may not need any silicone. My current job has none and is looking much the better for it. 

No silicone anywhere, just CT1 under the glass. 

 

 

Some pics, the corner gaps where the tiles meet at 90 degrees vary from approx 2-4 mm

The tile trims are around the tiled recess/pocket which used to be a small window.

 

 

 

 

 

I will use clear CT1 under the glass side panel as you have often advised but what about the tiles to shower tray joint, the gap from tray to tiles is very small so I could probably get away with a bead of clear CT1?

 

 

Edited August 12, 2018 by MAB

[ProDave]

Why did they not fill the corner with grout? Are they expecting relative movement between those walls?

[MAB]

3 hours ago, ProDave said:

Why did they not fill the corner with grout? Are they expecting relative movement between those walls?

 

I did not fill them with grout yet as I have read and heard conflicting advice on searches as to whether the corner tile to tile interface should be grout or a flexible sealant (and if sealant you should grout tiles first leave corners ungrouted for the sealant).

eg. Tilers Forum:-

https://www.tilersforums.co.uk/threads/silicone-internal-corners.33500/

 

The back wall of the shower is the external solid brick wall of the original 1930's house, coming off this, one of the shower corners is the new extension external celcon blockwork side wall, the other shower corner is formed by an internal stud wall so I suppose there could be some relative movement over time between the different wall constructions.

 

(As an example a kitchen tiler grouted my worktop splash back tiles some time back but included the worktop to tile interface to save time as he could not get a suitable cream colour sealant on the day........within a year the grout line between tiles and worktop was breaking away and had to be dug out and replaced with the correct colour flexible sealant.)

Edited August 12, 2018 by MAB

[Nickfromwales]

The kitchen is a no brainer for silicone / other flexible sealing. Thats oranges and the bathroom is apples. 

So, for the bathroom, mix a bit of grout up and use the float to push it deep into the grout line / gaps. You should be doing that until you see the force of the float make grout ooze out above and below the float edges. Leave to partially cure before running a square edged float / other up the internals and sponge off the remainder making sure to clean it all off the already grouted bits. 

Id only then recommend getting into the silicone sealing IF the grout lines start to show signs of movement. If they dont, you dont need silicone. If you dont ram the grout in there then dont expect the results