Silicone before grout or grout before silicone?

[Handyman in Sussex]

Hi All,
Just interested to know what anyone's opinion is on this one.... I would normally grout a shower/bath/kitchen or whatever tiling and then seal the bath/shower tray/worktop to tile joint or internal corner joints afterwards.
But if I have time to do it, I prefer to seal the important joints with silicone before grouting, then grout the tiles the next day.... It's the best seal you can get because the sealant goes right into the joint and stays there, not just superficially over the grout..... But it only works if you have other things to do on the job to fill the day, because the drying time of the sealer means you can't grout or do anything else in the area straight away.... I know a lot of tilers who would grout the tray to tile joint and then silicone over it, but I just wondered if anyone does it the other way round if they have time (and other things to do on site) whilst it dries?

[royaloakcarpentry]

I would never silicone first and grout next day. Never worked with, around or had any one work for me that would, either.

Be very interested for a link to the data which states doing the work back to front is the 'best seal you can get'.

[philprime]

I agree with ROC I always grout first an silicone once dry

[Handyman in Sussex]

I would never silicone first and grout next day. Never worked with, around or had any one work for me that would, either.

Be very interested for a link to the data which states doing the work back to front is the 'best seal you can get'.

I only ask because I regularly get asked to deal with leaking shower trays which 99% of the time is caused by failure of the tile to tray joint.
I would then rake out the joint completely (normally mostly thin air and brown scum, or tiny amounts of silicone stuck to nothing!), before drying it thoroughly and applying Dow Corning well into the crack, and outside and then smooth off...... Not had a problem yet in performing repairs in this way............ Or would it be better to grout a repair like this?
On my own bath I tried doing it the other way round with the theory that the silicone is trapped and stuck in the tile/bath joint by the fact that it is also inside the joint and once set cannot physically come out. The silicone applied after grouting has nothing to stick to or in and is filling no hole therefore is acting purely as a superficial covering which inevitably peels off and looks pants....
I did my one back to front about 6 years ago as an experiment and it still looks like I did it yesterday and is well and truly stuck in place and firmly not leaking which is a damn site better than most of the work I repair after only a few years............
I know it's back to front and that wasn't the question, the question I meant was has anyone else tried doing it this way and if so do you think it's better or worse? I was just interested having tried both and seen which looks better after time, and having repaired tons of leaky bodges!

[royaloakcarpentry]

Well the example of the repair was on a job that was not done correctly to begin with.

If you silicone first and then grout later, what happens with expansion and contraction when you get a crack between the grout and silicone?

Silicone will stick to grout (after tiles have been properly cleaned of residue) better than grout can ever stick to silicone.

If some one doesn't know where to and where not to apply grout followed by the knowledge and skill of proper application of silicone joints then you get bet your bottom dollar they are clueless about how a shower tray should be installed correctly. These are probably the same bodgers that seal all shower screens/enclosures internally, also.

[Colour Republic]

Hi All,
I know a lot of tilers who would grout the tray to tile joint and then silicone over it,

They do not know what they are doing then!

Grouting should always be done first and anywhere which is to be siliconed should be left free of grout.

After the grout has dried then you can startto silcone, it should go right in to the gap and then any excess that spills out of the joint should be smoothed down to form a neat bead.

Silcone sticks to grout, grout does not stick to silcone.

[Handyman in Sussex]

Well the example of the repair was on a job that was not done correctly to begin with.
That's very true, as with most repairs.

If you silicone first and then grout later, what happens with expansion and contraction when you get a crack between the grout and silicone?
I've got no cracks at all between the silicone and grout after 6 years... In my experience the first crack to appear (and the point at which there actually potentially could be expansion and contraction, unless you're saying that hardened grout expands and contracts) is normally the grout/tray or grout/bath joint, which is why I'm wondering if that joint consisted of a properly flexible and waterproof material would it survive longer?

Silicone will stick to grout (after tiles have been properly cleaned of residue) better than grout can ever stick to silicone.
That is true too, but if the grout has done the waterproofing, and no movement is supposed to occur, what is the silicone doing?
If movement does occur, which it inevitably does at this point, the first failure is always the silicone (normally peeling up from the tray), followed by the hairline crack in the grout, and then the leak. Once all that is raked out and sealant applied right into the joint, it stays there, and it will flex.

If some one doesn't know where to and where not to apply grout followed by the knowledge and skill of proper application of silicone joints then you get bet your bottom dollar they are clueless about how a shower tray should be installed correctly. These are probably the same bodgers that seal all shower screens/enclosures internally, also.
That's very true!!

I know to grout first is normal way round, it's just that I have tried it the other way around and the results were incredibly good... The theory was to have a flexible joint where the most likely movement is, and so to allow that movement to happen; and it still looks like it was done yesterday, whereas most well used showers after 6 years with silicone over grout need resealing..... I just wondered if anyone else had tried this, but I'm obviously the only one to try it!!
On my own house of course!

[Handyman in Sussex]

Hi All,
I know a lot of tilers who would grout the tray to tile joint and then silicone over it,

They do not know what they are doing then! Clearly!!

Grouting should always be done first and anywhere which is to be siliconed should be left free of grout.

After the grout has dried then you can startto silcone, it should go right in to the gap and then any excess that spills out of the joint should be smoothed down to form a neat bead. That's what I'm saying!! It is vital that it goes right in the gap in order to form a seal... I just thought it may be easier to do this first and then grout, rather than try to keep the grout out of the gap so I tried it out that way on mine...and it was very clean and easy... I hear what you're saying about the grout not sticking though, so will stick to the conventional way round! Cheers

Silcone sticks to grout, grout does not stick to silcone.

[Wes]

I've wondered about this loads of times. Never felt right siliconing over the grout. Cracking little thread

Good tip there from CR and nice post HiS

[royaloakcarpentry]

I have to be blunt with you. With your answers and questions to my reply to you.

maybe for someone charging for working in wet zones, it would be useful to do some research on the net. British standards etc



There is no grout to tray or grout to bath joint......never has been and never will be. My flipping apprentices know that during week 2.

there are no internally grouted joints....also week 2.

Cement based grout is not water proof. week 1.

Building materials can expand and contract. Most city and guilds courses include that info as standard.

[Handyman in Sussex]

Hi All,
I know a lot of tilers who would grout the tray to tile joint and then silicone over it,

They do not know what they are doing then!

Grouting should always be done first and anywhere which is to be siliconed should be left free of grout.

After the grout has dried then you can startto silcone, it should go right in to the gap and then any excess that spills out of the joint should be smoothed down to form a neat bead.

Silcone sticks to grout, grout does not stick to silcone.

Just out of interest how would you keep the grout out of the bottom and internal corner joints if you were grouting 3 walls of a shower in 1cm mosaics? Or do you grout it and then rake these out before it's fully cured? And if so how without catching the grout in the vertical joints?

[Wes]

The number of tilers I've seen slapping grout in joints is ridiculous!! Next time I'm going to take them to school, I'm going to teach them such a lesson, ooooo you just wait

[Colour Republic]

Hi All,
I know a lot of tilers who would grout the tray to tile joint and then silicone over it,

They do not know what they are doing then!

Grouting should always be done first and anywhere which is to be siliconed should be left free of grout.

After the grout has dried then you can startto silcone, it should go right in to the gap and then any excess that spills out of the joint should be smoothed down to form a neat bead.

Silcone sticks to grout, grout does not stick to silcone.

Just out of interest how would you keep the grout out of the bottom and internal corner joints if you were grouting 3 walls of a shower in 1cm mosaics? Or do you grout it and then rake these out before it's fully cured? And if so how without catching the grout in the vertical joints?

Use your grout spreader carefully in the corners and don't force it in to the internal corners, if some does get in then wait until it starts to set then clean out with something thin. I normally use a tile wedge as plenty are knocking around... or a screwdriver wrapped in tape... or a lollypop stick... or or or... If you have waited long enough normally only 30 mins or so then it gives a clean break from any other joints and does not pull them out.

[royaloakcarpentry]

The number of tilers I've seen slapping grout in joints is ridiculous!! Next time I'm going to take them to school, I'm going to teach them such a lesson, ooooo you just wait

Wes, not all tilers are trained. Some tilers absolutely hate grouting and so slap it on as quick as possible. Some tilers love doing grouting.
There are probably more unqualified house bashers than qualified apprentice served tilers.

[Handyman in Sussex]

The number of tilers I've seen slapping grout in joints is ridiculous!! Next time I'm going to take them to school, I'm going to teach them such a lesson, ooooo you just wait

Same here, the amount of times you see it happen is amazing, that's why I was asking, because I'd rather see silicone in the tray to tile joint, even if someone else thinks I don't!