Wetroom grout failing

Pete43 · Jan 3, 2021

Hi all,

Looking for a bit of advice. I had my bathroom refitted about 18 months ago and the grout appears to be failing in the shower area (impey shower tray underneath). I’ve let it dry out over the last four days but there are still damp patches - in particular closest to the drain. My assumption is that the grout has failed due to cleaning products used, but i guess it’s possible that it’s something else - eg movement in subfloor. That being said, the issue only seems to be in the shower area. I think the sealant also looks like it is insufficiently adhered to the wall in the corners in some small areas.

I was planning on raking out the grout and regrouting with the same grout (a porcelanosa sand cement mix), and also replacing the sealant. I wondered if there is anything I haven’t spotted that means this won’t fix it, and also whether I should be using an additive with the grout?

I’ve attached a couple of photos. You will see it’s drying out patchy and there is evidence of efflorescence. Some dark patches also exist on the dry side of the shower screen right next to the glass (which don’t seem to be going).

Any thoughts and advice gratefully received.

Pete

Jon_Hall · Jan 6, 2021

Pete43 said:
Hi all,

Looking for a bit of advice. I had my bathroom refitted about 18 months ago and the grout appears to be failing in the shower area (impey shower tray underneath). I’ve let it dry out over the last four days but there are still damp patches - in particular closest to the drain. My assumption is that the grout has failed due to cleaning products used, but i guess it’s possible that it’s something else - eg movement in subfloor. That being said, the issue only seems to be in the shower area. I think the sealant also looks like it is insufficiently adhered to the wall in the corners in some small areas.

I was planning on raking out the grout and regrouting with the same grout (a porcelanosa sand cement mix), and also replacing the sealant. I wondered if there is anything I haven’t spotted that means this won’t fix it, and also whether I should be using an additive with the grout?

I’ve attached a couple of photos. You will see it’s drying out patchy and there is evidence of efflorescence. Some dark patches also exist on the dry side of the shower screen right next to the glass (which don’t seem to be going).

Any thoughts and advice gratefully received.

Pete

Hi, If there is a small void beneath the grout, then it can take a while for the grout to dry out as it is probably full of water. I cant tell from your photos if the grout has cracked, if it has then it will need replacing. If the grout is patchy, then sometimes using a cement residue remover will bring it all back to a uniform colour. If the surface of the grout is darker than you think it should be, then it sounds like it is contaminated. This could be an oil or acrylic based substance and will be tough to get out. If you are happy to rake out and re grout the area I would consider using an epoxy grout as it is imperious and will not go patchy.

Pete43 · Jan 6, 2021

Thanks Jon, unfortunately it has cracked - in some places it is crumbling a little and in other places there are hairline cracks between the grout and the tile. Part of my concern is why the grout has failed so quickly.

I’m probably going to keep away from epoxy, whilst I’m a regular diyer I’m a first time grouter, so if I screw it up I think sand based grout will be easier to fix. Plus I believe is is more forgiving if there is any floor movement.

Frankly I’d rather get a pro to do it but it’s such a small job I’m struggling to find someone, so I’m going to give it a bash. Wife may kill me!!!

Dave · Jan 6, 2021

Pete43 said:
Thanks Jon, unfortunately it has cracked - in some places it is crumbling a little and in other places there are hairline cracks between the grout and the tile. Part of my concern is why the grout has failed so quickly.

I’m probably going to keep away from epoxy, whilst I’m a regular diyer I’m a first time grouter, so if I screw it up I think sand based grout will be easier to fix. Plus I believe is is more forgiving if there is any floor movement.

Frankly I’d rather get a pro to do it but it’s such a small job I’m struggling to find someone, so I’m going to give it a bash. Wife may kill me!!!

Is there any movement in the tiles/ floor ?

Pete43 · Jan 6, 2021

Dave said:
Is there any movement in the tiles/ floor ?

Doesn’t appear to be from what I can tell - would I be able to notice just by standing on it?

Dave · Jan 7, 2021

Pete43 said:
Doesn’t appear to be from what I can tell - would I be able to notice just by standing on it?

Press down with your foot (body weight) on a tile next to the grout line that’s failing, do you see any slight movement in the tile.

Jon_Hall · Jan 7, 2021

Another way you can check for movement is do the meniscus test with a glass of water, if the water spills from the glass then there is too much movement.

Pete43 · Jan 7, 2021

Thanks for the tips both, movement seems to be negligible so I think I can continue. I gently raked an area where grout is crumbling and still appears dark - underneath the grout looks dry so I think it must just be staining.

I’ve attached a couple of close ups of where there is cracking. Would you say these are bad enough to warrant me regrouting? And can I just regrout the effected area and join up to the old grout or will that cause a weak point?

thanks again for your help, much appreciated.

Dave · Jan 7, 2021

Needs to be around 2 to 3 mm depth for grout to hold.

Pete43 · Jan 7, 2021

Dave said:
Needs to be around 2 to 3 mm depth for grout to hold.

Where the new and old grout meet in a line is this ok?

Jon_Hall · Jan 8, 2021

If I'm doing a re grouting job I rake the grout out to at least the depth of the tile. Obviously hoover out the joints once this is done before re grouting. As Dave said you can get away with 3mm, but if the grout you're removing is very week and you only rake out 3mm it could fail again.

Jon_Hall · Jan 8, 2021

Sorry forgot to say, if possible don't use the shower for a week after re grouting. When cleaning the shower avoid harsh cleaners especially ones containing bleach. your local tile shop should be able to advise you on what you should use.

Pete43 · Jan 8, 2021

Jon_Hall said:
If I'm doing a re grouting job I rake the grout out to at least the depth of the tile. Obviously hoover out the joints once this is done before re grouting. As Dave said you can get away with 3mm, but if the grout you're removing is very week and you only rake out 3mm it could fail again.

Thanks Jon, will give it a try this weekend 👍

Phil Kearns · Aug 15, 2022

Thanks for the advice. My problem is exactly the same as that of Pete43

Lou · Apr 13, 2024

Don't mind me while I bump up some older but good threads. If you can contribute to the thread, go ahead. But if it's nothing for you then don't reply and it'll soon drop off the What's New page etc.
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