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

Paula · Aug 4, 2015

deanotile said:
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 · Aug 4, 2015

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

Which ones?

The D · Aug 4, 2015

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 · Aug 4, 2015

Paula said:
Which ones?

start on the floor in the shower and work back

Paula · Aug 4, 2015

deanotile said:
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 · Aug 4, 2015

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 · Aug 5, 2015

Paula said:
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 · Aug 5, 2015

deanotile said:
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 · Aug 5, 2015

Dan said:
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 · Aug 5, 2015

Paula said:
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 · Aug 5, 2015

Dan said:
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 · Aug 5, 2015

Paula said:
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 · Aug 5, 2015

Dan said:
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 · Aug 5, 2015

Paula said:
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 · Aug 5, 2015

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.

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