Help! Tiled wetroom floor looks perfect but grout doesn't dry out!

[Paula]

We had a wet room installed about 8 months ago. The floor is tiled with large 60x60cm porcelain tiles laid on Impey Waterguard membrane and the shower tray is Impey Aquadec Easyfit with the membrane laid over the top. It is a new-build first floor bathroom (new extension on older house) with a suspended timber floor. The tiles appear to be laid well and there has been no obvious movement or cracking of grout (Bal Micromax). However, almost immediately we noticed that in the shower area some areas of grout (which is light grey) did not dry out, and over time about 50% of the grout lines were permanently dark, even when the shower was not used for a few days. I searched tiling forums and became concerned that the tiles had been laid on an incomplete layer of adhesive, and that water was pooling underneath them, leading to permanently wet grout, but could not see any evidence of the tiles coming up or moving about, which usually seems to happen with problems like this.

Our builder called back the tiler who swore that he had used the correct amount and type of adhesive, and said that if he had not done so then the grout would have cracked on the floor. Bal, the grout and adhesive manufacturers, were called, but their "expert" tried to claim that the dark patches were not, in fact, wet, but possibly mould or even dirt! He agreed that it looked like the tiles had been correctly laid and suggested leaving the floor to dry and then replacing the grout and then using a sealer to stop water soaking through the grout. When I mentioned the possibility of adhesive not covering the back of the tiles, he agreed with the builder that it was very difficult to achieve a completely flat bed of adhesive, suggesting that it was almost inevitable that some pooling of water under the tiles would occur, leading to patches of wet grout.

We agreed to wait for the floor to dry out. We are now on week 5 (in a warm room with underfloor heating in the rest of the floor away from the shower tray!) and there is still a small wet patch, but most is back to the normal light grey colour. It took about 3 weeks for most of the moisture to go and the dark patches to disappear, so we have now discounted the mould/dirt theories, but are concerned that there must have been quite a lot of water sitting under the tiles for them to remain wet so long! The builder now just wants to seal the dried grout, and not re-grout at all. He is refusing to do anything else.

I have talked to most of the manufacturers of grout sealers, and they all say that their products will not completely waterproof grout, so I cannot see that this will be a long-term solution (also, don't fancy waiting for the floor to dry out each time it needs re-applying!). Epoxy grout seems like a good idea, but the builder seems to think that it would eventually crack if used on a timber floor (although when I spoke to Mapei about Kerapoxy they said that it should be fine as long as the floor is not bouncing around a lot, which it is not).

What I'd really like advice on is:

- is it normal to have permanently wet patches in grout on wet room floors even if the floor appears to be well laid?

- if we leave the floor as it is, will we be storing up trouble for the future? Am I being too fussy??!

- Is it possible to lay tiles in a pre-formed shower tray on a completely flat bed of adhesive, or will there always be gaps for water to collect in?

- Should we consider a grout sealer or epoxy grout to solve the problem or do the tiles need taking up and re-laying? (massive Job I imagine as
there is a huge glass shower screen resting on one grout joint and the membrane may be damaged in the process?)

It does feel like I am being fobbed off by the builder and the tiler, but admittedly the wet grout patches are the only problems so far. It would be great to hear from anyone who has had similar problems. I can't quite see the point of having tiled shower trays if they always look different to the rest of the tiled floor!

Thanks!

 

[Paula]

Shame I'm not a plumber, Walton's not far from me.
In the words of Manuel "I know nothink!"
If after ALL of your options are exhausted, and you still get no joy from the plumber who did the work......
I do know people who do know somthink!
If you need someone.

Thanks very much. That's nice to know. You'd be very welcome to swing by and have a look if you think it would help?

 

[Old Mod]

If I was any kind of plumber I would Paula, unfortunately I'd be clueless.
Sorry.

 

[The D]

Tell the plumber that if it is not sorted within the next month you will be getting quotations together from competent wet room installation companies, to identify a rectify the problem and then you will be starting legal proceedings against him to recover the cost of fixing the leak he has left you with

also any additional costs you have already laid out as in epoxy grout and tilers time and compensation for your new and very expensive wet room being out of action for months on end. you have to make it so it is more hassle for him to leave it than just getting it sorted.

 

[Paula]

Tell the plumber that if it is not sorted within the next month you will be getting quotations together from competent wet room installation companies, to identify a rectify the problem and then you will be starting legal proceedings against him to recover the cost of fixing the leak he has left you with

also any additional costs you have already laid out as in epoxy grout and tilers time and compensation for your new and very expensive wet room being out of action for months on end. you have to make it so it is more hassle for him to leave it than just getting it sorted.

I have to deal with the builder rather than the plumber direct, but yes I think unless we get some action this week we'll have to get heavy-handed. Just out of interest do you know of any 'competent wet room installation companies' we could get in to have a look?

 

[Dan]

I have to deal with the builder rather than the plumber direct, but yes I think unless we get some action this week we'll have to get heavy-handed. Just out of interest do you know of any 'competent wet room installation companies' we could get in to have a look?

Whoever you choose you want them to be reputable in their field. You need them to be highly qualified plumbers. It won't ever get to court or even small claims I'm sure, but if it did, you wouldn't want to have a guy who's winging it.

Take a look on our plumbing forum. Perhaps reply to the thread I created with an update and mention you may need an independent assessor that can carry out an inspection and provide a written quote with what's required to repair the job. You might need to pay for the report, but if you end up taking legal action, I'm pretty sure you'd get that cash back.

Obviously perhaps start to communicate (or at least confirm after speaking on the phone) via email or something so you have some records of the builder saying he'll be there on such a day to do such a thing.

Pretty sure as Deano said, if it's more hassle for him to leave it, he'll be around sharpish to make his headache stop.

 

[Paula]

What's with the blank messages?

Sorry about that: the whole system seemed to freeze and I couldn't write anything! Can you delete them?

Anyway, was just going to update you as the plumber came today (at last!). It was the first time he had been back since installing the bathroom and was quite surprised at the extent of the damp patches on the grout. He pressure tested the two outlets (see the picture attached) at 2 bars and there was no drop in pressure over half an hour or so. He seemed to mend the drip in the elbow of the hand-held shower by putting some more tape on, but thought this had been unlikely to be the cause of the problem as we hardly ever use the hand-held shower. When he dismantled the valve there was no sign of leaking behind it.

So....not sure where that leaves us now! He wondered if there was still a pool of water under the shower tray tiles dating back to pre-epoxy, and that since applying epoxy grout, this dampness can only escape by travelling to the areas outside the shower tray which still have normal grout. I suppose that it is possible that this drying out is not an even process, and that maybe some days there is more evaporation than others, which we mistook to be leaks from the pipework, but could be unconnected?

He thought the only way to test this was to turn up the underfloor heating (which is all over the floor apart from in the shower tray) and try and completely dry the damp patches. Then to start using the shower again and see if it comes back. If it does, we know it's not coming from the pipework, but getting through the shower tray somehow. I wonder if it is getting in around the drain, as the tiles have been cut very tight to the drain here, so there is not much grout in the gap?

In any case, if it is getting through the grout it should not be pooling under the tiles, should it? The tiler thought he had fixed this problem by pouring more adhesive down the gaps when he removed the old grout, but perhaps this didn't work?

So that's how we left it. I'd be interested if anyone disagrees with this logic, or has any other suggestions on how to proceed? It seems we have ruled out plumbing problems!

Meanwhile, we have a very warm bathroom floor!

 

[Dan]

Sorry about that: the whole system seemed to freeze and I couldn't write anything! Can you delete them?

Anyway, was just going to update you as the plumber came today (at last!). It was the first time he had been back since installing the bathroom and was quite surprised at the extent of the damp patches on the grout. He pressure tested the two outlets (see the picture attached) at 2 bars and there was no drop in pressure over half an hour or so. He seemed to mend the drip in the elbow of the hand-held shower by putting some more tape on, but thought this had been unlikely to be the cause of the problem as we hardly ever use the hand-held shower. When he dismantled the valve there was no sign of leaking behind it.

So....not sure where that leaves us now! He wondered if there was still a pool of water under the shower tray tiles dating back to pre-epoxy, and that since applying epoxy grout, this dampness can only escape by travelling to the areas outside the shower tray which still have normal grout. I suppose that it is possible that this drying out is not an even process, and that maybe some days there is more evaporation than others, which we mistook to be leaks from the pipework, but could be unconnected?

He thought the only way to test this was to turn up the underfloor heating (which is all over the floor apart from in the shower tray) and try and completely dry the damp patches. Then to start using the shower again and see if it comes back. If it does, we know it's not coming from the pipework, but getting through the shower tray somehow. I wonder if it is getting in around the drain, as the tiles have been cut very tight to the drain here, so there is not much grout in the gap?

In any case, if it is getting through the grout it should not be pooling under the tiles, should it? The tiler thought he had fixed this problem by pouring more adhesive down the gaps when he removed the old grout, but perhaps this didn't work?

So that's how we left it. I'd be interested if anyone disagrees with this logic, or has any other suggestions on how to proceed? It seems we have ruled out plumbing problems!

Meanwhile, we have a very warm bathroom floor!

I still want updates but I'm starting to think we're out of options on here. It's not the tiling that's to blame per se.

Sounds like if he's pressure tested it, then that's ruled that out? I don't know if that's the way to check that. But it sounds like he's done the right thing to me?! - I don't know.

Nice to know he's at least tried. And hopefully if it carries on he'll come back.

Did the wetroom not get tanked into the drain then? So any "pool of water" wouldn't exist? It'd just go down the trap?

 

[Paula]

I still want updates but I'm starting to think we're out of options on here. It's not the tiling that's to blame per se.

Sounds like if he's pressure tested it, then that's ruled that out? I don't know if that's the way to check that. But it sounds like he's done the right thing to me?! - I don't know.

Nice to know he's at least tried. And hopefully if it carries on he'll come back.

Did the wetroom not get tanked into the drain then? So any "pool of water" wouldn't exist? It'd just go down the trap?

Yes, there is tanking all over the floor, which goes straight into the drain. I am just thinking that if somehow water is getting under the tiles around the drain (but on top of the tanking) then it could somehow get wicked away into the rest of the floor (although it would have to go up a slope!). Obviously any leak from the drain would be below the tanking and would appear on the ceiling below.

So surely it must be a tiling problem?

 

[Dan]

Yes, there is tanking all over the floor, which goes straight into the drain. I am just thinking that if somehow water is getting under the tiles around the drain (but on top of the tanking) then it could somehow get wicked away into the rest of the floor (although it would have to go up a slope!). Obviously any leak from the drain would be below the tanking and would appear on the ceiling below.

So surely it must be a tiling problem?

I can't really see how it is as the water must be coming from something to do with the water inlet or water outlet. As we've ruled out condensation and whatnot.

The tanking is doing the job, and as you say the drain isn't leaking below the tanking. Water won't climb uphill even in a warm room. So I can't see how it's evaporating up to the grout in the rest of the floor personally.

I'm still on the leak side of the fence so am assuming it's plumbing.

The tiles and grout aren't the cause of the water though that's for sure. I just don't see how that can be the case.

I'd perhaps ask these lads what they would do maybe: Problematic thread on TilersForums might be a leak in shower - can you help us? - Plumbing Forum

 

[Kris Farquhar]

Yes, there is tanking all over the floor, which goes straight into the drain. I am just thinking that if somehow water is getting under the tiles around the drain (but on top of the tanking) then it could somehow get wicked away into the rest of the floor (although it would have to go up a slope!). Obviously any leak from the drain would be below the tanking and would appear on the ceiling below.

So surely it must be a tiling problem?

Sorry about that: the whole system seemed to freeze and I couldn't write anything! Can you delete them?

Anyway, was just going to update you as the plumber came today (at last!). It was the first time he had been back since installing the bathroom and was quite surprised at the extent of the damp patches on the grout. He pressure tested the two outlets (see the picture attached) at 2 bars and there was no drop in pressure over half an hour or so. He seemed to mend the drip in the elbow of the hand-held shower by putting some more tape on, but thought this had been unlikely to be the cause of the problem as we hardly ever use the hand-held shower. When he dismantled the valve there was no sign of leaking behind it.

So....not sure where that leaves us now! He wondered if there was still a pool of water under the shower tray tiles dating back to pre-epoxy, and that since applying epoxy grout, this dampness can only escape by travelling to the areas outside the shower tray which still have normal grout. I suppose that it is possible that this drying out is not an even process, and that maybe some days there is more evaporation than others, which we mistook to be leaks from the pipework, but could be unconnected?

He thought the only way to test this was to turn up the underfloor heating (which is all over the floor apart from in the shower tray) and try and completely dry the damp patches. Then to start using the shower again and see if it comes back. If it does, we know it's not coming from the pipework, but getting through the shower tray somehow. I wonder if it is getting in around the drain, as the tiles have been cut very tight to the drain here, so there is not much grout in the gap?

In any case, if it is getting through the grout it should not be pooling under the tiles, should it? The tiler thought he had fixed this problem by pouring more adhesive down the gaps when he removed the old grout, but perhaps this didn't work?

So that's how we left it. I'd be interested if anyone disagrees with this logic, or has any other suggestions on how to proceed? It seems we have ruled out plumbing problems!

Meanwhile, we have a very warm bathroom floor!

I was looking at his pressure test , the way your plumber has had that rigged up its only testing the two outlets unless hes done the test from the main stopcock and not the actual shower valve , by using the main your actually testing the whole house but its the only way to test the actual shower valve unless youve access to the pipework,

 

[Paula]

I was looking at his pressure test , the way your plumber has had that rigged up its only testing the two outlets unless hes done the test from the main stopcock and not the actual shower valve , by using the main your actually testing the whole house but its the only way to test the actual shower valve unless youve access to the pipework,

Hi Kris

yes, you are right, but he took the faceplate off the main shower valve and inspected inside (it is buried in quite a large void in the wall) and there was no sign of any leakage from any of the pipes leading into it (I had a look myself). I can double check this with him, though if you think it's relevant.

Meanwhile, we'll carry on toasting the floor and see if it dries out!

 

[The D]

so how did he explain the patches outside the shower getting wetter even when there was no water touching the tiles or the grout or the drane ??

 

[Paula]

I was looking at his pressure test , the way your plumber has had that rigged up its only testing the two outlets unless hes done the test from the main stopcock and not the actual shower valve , by using the main your actually testing the whole house but its the only way to test the actual shower valve unless youve access to the pipework,

Just thinking about this, when you look at where the inlet pipes are in relation to the tiles, they are well behind the plasterboard and tiles. So surely if there was a leak here, then the water would be much more likely to run down the inside of the plasterboard and eventually through to the ceiling below, which definitely hasn't happened. As I said, there was absolutely no sign of leaking anywhere near the valve when we looked in the cavity.

 

[Dan]

And the waste wouldn't cause water to go above the tanking, and as you said, you'd see it in the ceiling below, eventually (at least by now anyway - some staining or something if not a full blown disaster type leak situation).

I'm absolutely baffled I must be honest.

But tiles don't cause water issues like that. It HAS to be something to do with the plumbing, somehow. I just can't think of anything.

The fact it was happening before the epoxy was installed, only means it has been pushed further into the bathroom, the epoxy hasn't fixed the issue per se. So it will still be a problem somewhere around the drain or shower heads. But if theres no sign of leaks there, then I can't see what it can be.

 

[The D]

you need to start removing tiles to see what is going on underneath

 

[Paula]

so how did he explain the patches outside the shower getting wetter even when there was no water touching the tiles or the grout or the drane ??

He was as perplexed as the rest of us! The only thing he could think was that there was still water trapped under the tray tiles from before the epoxy (our original grout still had damp patches after weeks and weeks of no use) and that this was now gradually working its way out beyond the shower tray (as it can't evaporate through epoxy, but can through the grout in the rest of the floor). Maybe it's not a steady process, and perhaps some days there is more evaporation than others (due to differences in humidity/full moon etc!!). But as Dan said, water is unlikely to travel uphill up the slope of the shower tray, isn't it?

That's why he said turn on the underfloor heating and see if we can get to a position of no wet patches, then try again.

 

[Paula]

you need to start removing tiles to see what is going on underneath

Which ones?

 

[The D]

for there to still be water that is just trapped under the tiles you must have had buckets full under there to start with and where did that come from if there was no obvious cracks or missing grout.

 

[The D]

Which ones?

start on the floor in the shower and work back

 

[Paula]

for there to still be water that is just trapped under the tiles you must have had buckets full under there to start with and where did that come from if there was no obvious cracks or missing grout.

Well if you remember there was quite a lot of missing grout around the drain, plus I think one of you spotted small cracks in some of the grout lines in the tray, so it could be that loads of water got in there during the six months or so we were using the shower every day?

 

[The D]

also if it was trapped water why is it moving there must be more fresh water coming along to make it travel up hill and out of the shower area

 

[Dan]

He was as perplexed as the rest of us! The only thing he could think was that there was still water trapped under the tray tiles from before the epoxy (our original grout still had damp patches after weeks and weeks of no use) and that this was now gradually working its way out beyond the shower tray (as it can't evaporate through epoxy, but can through the grout in the rest of the floor). Maybe it's not a steady process, and perhaps some days there is more evaporation than others (due to differences in humidity/full moon etc!!). But as Dan said, water is unlikely to travel uphill up the slope of the shower tray, isn't it?

That's why he said turn on the underfloor heating and see if we can get to a position of no wet patches, then try again.

Water wouldn't disperse from behind the tiles like that. It would equally spread across the whole floor at the lowest point. The moon makes waves move because of mass. It doesn't make individual molecules move anywhere. It's not a magnetic attraction.

Gravity is stronger on earth (because of the greater mass) therefore the molecules collect and form a drop and it falls down.

Different when water is in air they're rising with heat not the moon though lol clouds don't follow the moon.

The particles in the grout aren't close enough together to cause 'suction' which is what can happen in a thin straw and the shape of the convexed surface area causes the water to climb because the weight of the water doesn't have enough mass to fall down and work against the shape of the surface area.

Evaporation only really starts when it's at the surface already. So it's not evaporating behind the tiles.

It's dispersing, spreading around, and it will try to disperse equally. But that would mean it would be a much slower process and the whole floor would have the same damp feel. And I dare say nowhere near enough to cause a droplet. Let alone enough to wet tissue.

Look at all dispersion related threads on here search for "my grout is patchy" or something and you'll see what dispersion issues are like.

The patchy grout doesn't come and go. It's constant until it dries out. Unless there's a plumbing fault!

This is a plumbing issue and the fix is going to be the same. Time to start popping tiles. And I thought this ages ago but we need to go through whatever process your plumber wants to go through to satisfy him.

Or else he's going to tell you to **** off.

 

[Dan]

for there to still be water that is just trapped under the tiles you must have had buckets full under there to start with and where did that come from if there was no obvious cracks or missing grout.

The original grout dried so I assume it's only got wet again when the shower is being used.

Might take a while to disperse out but the fact it comes back again only means fresh water is being adding again. As you say.

 

[Paula]

Water wouldn't disperse from behind the tiles like that. It would equally spread across the whole floor at the lowest point. The moon makes waves move because of mass. It doesn't make individual molecules move anywhere. It's not a magnetic attraction.

Gravity is stronger on earth (because of the greater mass) therefore the molecules collect and form a drop and it falls down.

Different when water is in air they're rising with heat not the moon though lol clouds don't follow the moon.

The particles in the grout aren't close enough together to cause 'suction' which is what can happen in a thin straw and the shape of the convexed surface area causes the water to climb because the weight of the water doesn't have enough mass to fall down and work against the shape of the surface area.

Evaporation only really starts when it's at the surface already. So it's not evaporating behind the tiles.

It's dispersing, spreading around, and it will try to disperse equally. But that would mean it would be a much slower process and the whole floor would have the same damp feel. And I dare say nowhere near enough to cause a droplet. Let alone enough to wet tissue.

Look at all dispersion related threads on here search for "my grout is patchy" or something and you'll see what dispersion issues are like.

The patchy grout doesn't come and go. It's constant until it dries out. Unless there's a plumbing fault!

This is a plumbing issue and the fix is going to be the same. Time to start popping tiles. And I thought this ages ago but we need to go through whatever process your plumber wants to go through to satisfy him.

Or else he's going to tell you to **** off.

Thanks for that, Dan: very impressive! Are you a physicist as well as a tiler??!

I can see your logic, but (and forgive me if I am being daft), are you saying that it is not possible at all that water could have seeped under the tiles (but on top of the membrane) through small gaps in the grout where the metal edge of the drain meets the edges of the tiles? Due to the slope of the tray there is a lot of water pooling in this area when the shower is being used (although it runs away efficiently) so it would be easy to go down the gaps. If there was then a lot of space under the tray tiles (as we originally suspected), then a subterranean pool will have developed. As more and more water gets in when the shower is used, would it not then travel up the small slope (to be honest the Impey trays are not very sloped) to the flat of the floor beyond the shower screen? Or would we see water trying to come to the surface around the drain? (which we don't).

If, as I think you are suggesting, water is coming from the shower valve or outlets (there are no pipes in the floor as all the water comes from up in the loft), then it would still have to travel across the tray and uphill to beyond the screen the other side to make those damp patches. Is this possible?

 

[Dan]

Thanks for that, Dan: very impressive! Are you a physicist as well as a tiler??!

I can see your logic, but (and forgive me if I am being daft), are you saying that it is not possible at all that water could have seeped under the tiles (but on top of the membrane) through small gaps in the grout where the metal edge of the drain meets the edges of the tiles? Due to the slope of the tray there is a lot of water pooling in this area when the shower is being used (although it runs away efficiently) so it would be easy to go down the gaps. If there was then a lot of space under the tray tiles (as we originally suspected), then a subterranean pool will have developed. As more and more water gets in when the shower is used, would it not then travel up the small slope (to be honest the Impey trays are not very sloped) to the flat of the floor beyond the shower screen? Or would we see water trying to come to the surface around the drain? (which we don't).

If, as I think you are suggesting, water is coming from the shower valve or outlets (there are no pipes in the floor as all the water comes from up in the loft), then it would still have to travel across the tray and uphill to beyond the screen the other side to make those damp patches. Is this possible?

Would you believe I'm not even a tiler! I just make the tea for the lads on the forum.

I guess in a nutshell (I had a lot of codeine last night it must be said! My back is bloody killing me!) I'm saying it wouldn't be damp behind the tiles, which then might reach the surface of the grout, because it would be much more constant and equally spread.

When somebody has used dispersion (tubbed) adhesive behind huge tiles, and are having issues related to water not drying out, making the grout patchy, that's all it really does, make the grout look a bit wet, but sometimes it's not even wet to the touch. It just looks darker.

For yours to be so intermittent, and so strong when the problem is occurring, it HAS to be plumbing I'd say. Fresh water is being added behind the tiles when it's happening. And it's drying out fine after a period of time. So I wouldn't say it's a problem with a feed pipe (hot or cold further back than the mixer or whatever). My guess it it's either the drain, or the piping AFTER the mixer. So only when it's being used it's causing the issue.

The tiles just wont cause any problem like that.

When the guy re-grouted, if there was a bit of a puddle behind the tiles, the epoxy wouldn't have took so well as it has to have a dry surface to bond to. So he'd have raked the grout out, and if at that point he say moisture of any great amount, he'd have had to dry it out.

 

[Paula]

Would you believe I'm not even a tiler! I just make the tea for the lads on the forum.

I guess in a nutshell (I had a lot of codeine last night it must be said! My back is bloody killing me!) I'm saying it wouldn't be damp behind the tiles, which then might reach the surface of the grout, because it would be much more constant and equally spread.

When somebody has used dispersion (tubbed) adhesive behind huge tiles, and are having issues related to water not drying out, making the grout patchy, that's all it really does, make the grout look a bit wet, but sometimes it's not even wet to the touch. It just looks darker.

For yours to be so intermittent, and so strong when the problem is occurring, it HAS to be plumbing I'd say. Fresh water is being added behind the tiles when it's happening. And it's drying out fine after a period of time. So I wouldn't say it's a problem with a feed pipe (hot or cold further back than the mixer or whatever). My guess it it's either the drain, or the piping AFTER the mixer. So only when it's being used it's causing the issue.

The tiles just wont cause any problem like that.

When the guy re-grouted, if there was a bit of a puddle behind the tiles, the epoxy wouldn't have took so well as it has to have a dry surface to bond to. So he'd have raked the grout out, and if at that point he say moisture of any great amount, he'd have had to dry it out.

Well that's a surprise: how do you know so much about tiling then? (mind you, I think I may end up in that situation soon!).

Anyway, I think I see what you are saying. But our wetting and drying out is a bit unpredictable... I just wish we could say that it definitely relates to one particular event. A plumber on the other site thinks we should have pressure tested at a higher pressure for longer (that's going to go down well with the builder!), so perhaps that might show up a problem?

I'm pretty sure, by the way, that the tiler didn't use tubbed adhesive, but I'll check. It's only in one place that we actually can see beads of moisture sometimes: the other patches are as you described: just darker (and eventually lighter, but with a lot of brown crust left behind when the water evaporates). The heating's been on for 24 hours now and we still have dark patches, although they have diminished slightly.

As I said to one of the plumbers, I struggle to see that it could be a problem with the drain as the waste pipe runs UNDER the membrane. How would this produce wet in the grout above the membrane?

 

[Dan]

Well that's a surprise: how do you know so much about tiling then? (mind you, I think I may end up in that situation soon!).

Anyway, I think I see what you are saying. But our wetting and drying out is a bit unpredictable... I just wish we could say that it definitely relates to one particular event. A plumber on the other site thinks we should have pressure tested at a higher pressure for longer (that's going to go down well with the builder!), so perhaps that might show up a problem?

I'm pretty sure, by the way, that the tiler didn't use tubbed adhesive, but I'll check. It's only in one place that we actually can see beads of moisture sometimes: the other patches are as you described: just darker (and eventually lighter, but with a lot of brown crust left behind when the water evaporates). The heating's been on for 24 hours now and we still have dark patches, although they have diminished slightly.

As I said to one of the plumbers, I struggle to see that it could be a problem with the drain as the waste pipe runs UNDER the membrane. How would this produce wet in the grout above the membrane?

I used to be a tiler a while ago, only for a while though, before that I sold tiles for a few years in a tile retailer, and after tiling for a bit, I setup one of the first independent training centres teaching tiling. After that setup the forum to chat tiling.

I wasn't saying he's used dispersion adhesive, I was just saying if you look for dispersion-related threads, the grout wetness or damp is different to your problem. So it wouldn't be dispersion, or evaporation as the plumber called it (which it is once it his the surface but not while it's behind the tiles).

He's used cement-based for sure, because if it was tubbed adhesive and you had that much water behind there, the tiles wouldn't still be fixed today! They'd have come off a good few weeks ago.

 

[Paula]

I used to be a tiler a while ago, only for a while though, before that I sold tiles for a few years in a tile retailer, and after tiling for a bit, I setup one of the first independent training centres teaching tiling. After that setup the forum to chat tiling.

I wasn't saying he's used dispersion adhesive, I was just saying if you look for dispersion-related threads, the grout wetness or damp is different to your problem. So it wouldn't be dispersion, or evaporation as the plumber called it (which it is once it his the surface but not while it's behind the tiles).

He's used cement-based for sure, because if it was tubbed adhesive and you had that much water behind there, the tiles wouldn't still be fixed today! They'd have come off a good few weeks ago.

That's very interesting. I think you do a great job by the way!

Yes, I think I remember seeing him lug bags of powdered adhesive about and mixing them up. He is an ex-plasterer by the way, so I have always worried that he was a bit of a "dotter and dabber", hence my obsession with water collecting under the tiles!

I can see what you're saying, but you never really answered my question about whether it was possible that water is getting under the tiles around the metal drain during showering?

 

[Dan]

That's very interesting. I think you do a great job by the way!

Yes, I think I remember seeing him lug bags of powdered adhesive about and mixing them up. He is an ex-plasterer by the way, so I have always worried that he was a bit of a "dotter and dabber", hence my obsession with water collecting under the tiles!

I can see what you're saying, but you never really answered my question about whether it was possible that water is getting under the tiles around the metal drain during showering?

Well, the tanking is meant to fall into the trap/drain. So the tiles then just become aesthetics to make it all look nice and easy to clean. They're not there stopping water getting anywhere sort of thing.

So it's usually okay for tiles to have cement-based grout, it get wet, water get behind the tiles and soak a bit into the cement-based adhesive, because the water that collects will fall into the drain, and the remaining water behind the tiles would disperse and dry out via the grout generally across the whole floor.

You'd get wet / darker grout using the shower, and a hour or so after, it'd dry out. Wouldn't stay patchy, but might be a bit patchy during drying out etc.

The epoxy has perhaps if anything stopped a bit of that and is pushing the moisture further into the bathroom maybe.

But the fact you're getting droplets of water and it's in quite a few grout lines, but then not others right next to it, would suggest as Deano's said, it's fresh water that's quickly gathering, and taking ages to dry out.

So I'm not sure what's going on around the drain. But it's okay for water to get there usually, as the drain would get rid of it (gravity) and the rest would disperse into the floor generally and evaporate once it's (evenly) reached the surface of the grout. But I've never seen droplets like the earlier images.

I don't think I've still answered you lol sorry. I just don't know what to say about it.

I'm with deano though, I'd have pulled a tile or two up around the drain by now.

 

[Dan]

This was doing my head in. Couldn't for the life of me remember what it's called when water climbs something due the the skin shape on the surface of it.

"Capillary Action" it's called. Capillary Action of Water: Definition & Examples | Study.com

So the water keeps trying to level out, but the edge of the water where it touches whatever it's climbing ends up higher than the centre of it. So it starts to climb. Weird effect of H20.

I didn't realise this, but it appears not every chemical does that. Every day's a school day.