Silicone internal corners...

[Rich]

I did a repair on a Huge house a few months ago because the tiler had not sealed properly around the shower tray, water had got behind the tiles and ruined the plasterboard. I got a call from the lady the other day asking if I could go round and take a look at the other shower room, the silicone had gone black and could I replace it. As I was only working round the corner I popped round yesterday. I wish I had taken my camera...
The tiles were hanging off the wall, huge cracks along the grouting, the internal corners had been grouted then siliconed, the silicone was totaly black, the shower screen hadnt been siliconed and there were several holes in the grout. The worst part was that she told me that he is a 'really good tiler'
I told her that I could only do a patch up job there and then but she was going to have problems down the line. Let this be a lesson to all, grout in internal corners will crack and come loose taking any silicone ontop of it with it.

[Dave]

I see quite a few bathrooms that have no expansion in the corners..

[faithhealer]

I missed out on a bathroom last year because I was too busy, and , same as you Richard got asked to go and look at another guys work. Huge cracks in the grout in the corners. Just backheeled it and told her to get the tiler back

[united]

I have always put in expansion joints, it's common sense IMO

[Dave]

I have always put in expansion joints, it's common sense IMO

Not to some i tell thee..

[merlecollins]

I 'LOVE' siliconing

[Scott]

I 'LOVE' siliconing

Me too cos when you have the silicone out its almost time to go home!!!

[StanleyES]

From the post's i have read it seems the general consensus is to leave an expansion gap in internals, then silicone internals and allow to dry, then grout.
This made sense to me (although i'm only a DIY'er). I was about to start siliconing the internal corners of my shower yesterday and started wondering about the butt joint that will be formed between the grout and the silicone. Won't this be a weak joint and a likely source of water penetration?

[paulyoung666]

From the post's i have read it seems the general consensus is to leave an expansion gap in internals, then silicone internals and allow to dry, then grout.
This made sense to me (although i'm only a DIY'er). I was about to start siliconing the internal corners of my shower yesterday and started wondering about the butt joint that will be formed between the grout and the silicone. Won't this be a weak joint and a likely source of water penetration?

not sure i have read you right here , but , the silicone takes the place of the grout

[Scott]

If you apply a bead of silicone to the vertical joint before you grout the grout should be pushed in behind the silicone bead (after silicone is dry obviously)

I tend to grout first but leave the vertical join and silicone after its all dry

[united]

not sure i have read you right here , but , the silicone takes the place of the grout

I agree

[brinkley]

always grout first imo

[StanleyES]

I thought that you pretty much filled the expansion gaps with silicone, (When you smooth it off with your finger). Once this had been done you then grout. This would mean the grout would simply butt up against your dry silicone joints. I just couldn't imagine the grout would seal against the dry silicone very well, i may well be wrong! Does grout shrink at all as it dries, if so this would definitely make the joint weak.

Whereas, doing it the other way round (As Scottley says) i can see the silicone will make a good seal when you smooth it off.
(My only thought with his method is that you need to have more accuracy applying the grout, making sure you get right up to the vertical joint without getting any in it)

What do think, am i worrying needlessly?

[paulyoung666]

What do think, am i worrying needlessly?

yes you are , buy colour match silicone and you will not notice it is there

[mikethetile]

I thought that you pretty much filled the expansion gaps with silicone, (When you smooth it off with your finger). Once this had been done you then grout. This would mean the grout would simply butt up against your dry silicone joints. I just couldn't imagine the grout would seal against the dry silicone very well, i may well be wrong! Does grout shrink at all as it dries, if so this would definitely make the joint weak.

Whereas, doing it the other way round (As Scottley says) i can see the silicone will make a good seal when you smooth it off.
(My only thought with his method is that you need to have more accuracy applying the grout, making sure you get right up to the vertical joint without getting any in it)

What do think, am i worrying needlessly?

I understand your point

yes grout does shrink back a small amount as it dries but ive never known this to be a problem

I grout first leaving corner corner clear and then silicone when grouts dry

its just common sense to me as the other siliconing is done after grouting and I do it all in one

[Rich]

As above. I grout first, then when the grout is just setting off, I run a paint scrapper (gently) along all the joints that are going to be siliconed to remove the grout. Then I come back to silicone when the grout is dry and the room clean.

[carole m]

I want the internal corner in my shower just grouted with bathroom grout, i hate the sight of silicone, in many hotels in showers you never see silicone and in many new builds i do not see silicone, i have had silicone in bathrooms before and it has gone mouldy and looks bad, i understand i would have to re-grout every so often. if it is the case that it is because it is an internal corner. can ti be siliconed and then grout on top so as to make all the tiling look the some.

[DJS]

Hi Carole, the internal corners should not be filled with grout. The gap is filled with flexible silicone, so that it does not crack due to heat expansion. If it is filled with grout it will crack, it is not the way it should be done.

I'm not saying all contractors working on commercial projects such as hotels and new builds are bad, I have seen both excellent and some shocking examples myself.

If you are having problems with mould growth, then you need to ensure your background is prepared properly, use suitable grout protector, and a decent mould resistant silicone (preferably matching your grout colour, so it look like a grout line). Plus using a proper cleaning product, to remove soapy residues from grout and tile surface once every few months, should all add up to keeping it looking like new.

Also, if your tiler uses a silicone shaping tool, and cornertape/masking tape, then the silicone joint will be nice and tidy. Not sploged in and smoothed over with a finger, which I guess is what alot of people are used to seeing. So, just because your used to seeing something done a particular way, doesn't mean it is the right way to do it!!

Good Luck

[diamondtiling]

HI Carole and welcome to Tilersforums. All good advice from DJS, you do need silicone rather than grout in the internal corners. Just get a quality brand and someone who can apply it properly. Silicone turns black and unsightly because of soaps and bodyfats during showers etc
and showers are always worse than baths for these types of problems.

[Rich]

I agree with both the guys above and I doubt you will find anybody on here that will say we are wrong. I really couldnt count how many rooms I have put right after thousands of pounds worth of damage has been done to the house just because the "tiler ()" didnt know or couldnt be bothereds to use silicone.

It is not that we like to use silicone, it would be a lot easier and quicker just to grout the joints in but it WILL fail and water will destroy the wall and floor behind the tiling.

As has been said above, a neat silicone joint that has been done by a pro will blend in with the rest of the room, a bad messy joint done by a monkey will look awful.

[jubba]

Hi Carole, the internal corners should not be filled with grout. The gap is filled with flexible silicone, so that it does not crack due to heat expansion. If it is filled with grout it will crack, it is not the way it should be done.

All makes sense about using silicone in the corners.

So when you fix the tiles should a deliberate gap be left (use spacers) in the corner rather then butting the tiles together?

[Rich]

All makes sense about using silicone in the corners.

So when you fix the tiles should a deliberate gap be left (use spacers) in the corner rather then butting the tiles together?

Yes, I use wedges and leave about 2mm

[FreeD]

I alway use a flexible grout, and grout everything, then silicone when grout is dry.

[jubba]

Would the same expansion gap be left when tiling down to bath, to leave a void to fill with silicone?

Or should the tiles actually rest on the edges of the bath then silicone across the joint?

[hillhead]

Jubba and FreeD, leave a gap down the internal corner 2mm minimum.
Do not use flexible grout then silicon over.
Grout all walls leaving the vertical corners clear of grout.
When grout dry and any cleaning off done silicon the corners with a colour to match the grout.

[hillhead]

Would the same expansion gap be left when tiling down to bath, to leave a void to fill with silicone?

Or should the tiles actually rest on the edges of the bath then silicone across the joint?

Yes jubba, leave again about 2mm along bath and fill gap when grout is dry.

[Rich]

As above, if you grout then silicone over the top, the grout will tend to crack and come loose and take the silicone away with it over time.

[RichieHall]

I'm just about to do a similar job, so let me just recap the above advice to make sure I understand,

For an internal corner I would need to leave a gap between the wall and tile of the tile depth (+ Adhesive) plus about 3mm on both walls, leaving a 3mm diagonal gap between the two tiled walls, then fill the gap with silicone?

[JMW]

I'm just about to do a similar job, so let me just recap the above advice to make sure I understand,

For an internal corner I would need to leave a gap between the wall and tile of the tile depth (+ Adhesive) plus about 3mm on both walls, leaving a 3mm diagonal gap between the two tiled walls, then fill the gap with silicone?

Spot On.

[Mike]

I'm just about to do a similar job, so let me just recap the above advice to make sure I understand,

For an internal corner I would need to leave a gap between the wall and tile of the tile depth (+ Adhesive) plus about 3mm on both walls, leaving a 3mm diagonal gap between the two tiled walls, then fill the gap with silicone?

i'm trying to understand your post, when tiling the first wall into the corner, leave a gap of 2/3 mm for expansion. when tiling the second wall into the same corner leave a gap of 2mm between the 2 tiles again for expansion. rake out any grout from the expansion joint prior to siliconing