Is water damage on an internal wall or something else?

Thank you for your question and welcome to the Bunnings Workshop community, it is fantastic to have you with us.

This is very strange and not something I can say I've seen before.

It's certainly possible that it could be due to moisture behind the paint, but I would expect there to be moisture present and more of a bubbling effect than these oddly straight lines. You might like to grab a moisture meter to check if there is any moisture present.

Is this an external wall and is your house made of brick? The somewhat straight lines made me think a similar thought to you about water seeping through grout lines.

It could be a form of mould, or it may be related to some kind of insect. I am honestly not sure and am very intrigued.

Allow me to tag some of our helpful members to see if they have any ideas, @Dave-1, @Noyade, @robchin, @DIYGnome.

Let me know if you have any other questions.

Jacob

Dave-1

Afternoon @UrVeggieMate

Is that wall below ground level? It really looks like water is wanting to creep through and the lines are scratches...

Some ideas maybe

If its a plaster wall maybe it was a sheet that was damaged (slashed by freddy Kruger) and they patched it up and painted but the slashing had a mould compound?

If its concrete and depending on if that is below the ground level then its def water creeping through.

How long has the paint been like that? And last question is there a puddle of water nearby or under the house at this point?

Dave

Hi Jacob, thanks for your comment and yes very strange that there seems to be no wetness present. Although I can say that it is an internal wall. It's my bedroom wall which is shared with the ensuite bathroom, specifically with the shower. Yes my house is made of brick. Hoping that this provides more clues to go off of?

I have someone coming out to do leak detection just to confirm once and for all whether it's a water related problem (i.e. pipe burst in the wall, or any residual water leftover in the wall). Hoping that it gives me a bit more info at the very least.

Hi Dave, thanks for your comment. My house has only one storey, so the wall is ground level. There is no water puddle nearby that I can see, although I can tell you that it's the shower in the ensuite bathroom is behind it. So there is a source of moisture. I don't know if there's water under the house, but I do have someone coming out to do leak detection soon.

In terms of how long the paint has been like that, I'm not 100% sure. I noticed the heart shaped bubbling (the final picture) on 27/07/24, which I'm fairly positive was new at the time I noticed it. Otherwise, I wouldn't be able to tell with absolute certainty how long the cracks have been around for, but I noticed them on 22/07 and had never noticed them prior to that. What's weird is that as soon as I noticed the cracks, I stopped using that particular shower and used the second shower instead. Yet that final heart shaped bubbling showed up after 5 days of not using that particular shower.

If it is a masonry wall, my suspicion is that this is efflorescence. Efflorescence is essentially salts that occur naturally in stone. These salts are gathered by water and then deposited after the water dries.

It's possible that this is occurring due to the moisture from the bathroom seeping through the brick wall.

You should still get the leak detection done for peace of mind, but if they don't find anything I'd suggest the moisture from the bathroom is the culprit.

Is it possible to get some photos of the other side of the wall? This might help to come up with a plan to stop it reoccurring.

In your case, as the efflorescence is on a painted surface, you should be able to simply scrape it off with something like a Craftright 5-in-1 Scraper. If it is slightly more troublesome, you can use Efflorescence Remover to get rid of it.

Let me know what you think and if you have any further questions.

Jacob

Hi Jacob,

Please see the photos of the wall on the opposite side. The red circles correspond to where the majority of the cracks are on the other side.

Here's also a close-up of what the grout looks like closer to the corner between the hob and the wall. Not in the greatest condition, which was what led me to suspect water getting through the grout initially.

This is what the corner looks like from inside the shower.

Hoping this provides a bit more info.

Thank you for those additional photos.

Its certainly possible that there is water getting through this gap in the grout and has entered the back side of the wall, but the height of the efflorescence makes me suspect the source is elsewhere.

If there is water coming from this side of the wall, I suspect it would likely be coming from higher up and then tracking down the wall.

Assuming there is an entry point for water, this would mean the waterproof membrane behind the tiles is failing and allowing water through.

Unfortunately, if this is the case, the tiles would need to be removed and the waterproofing membrane reinstated.

I'd suggest going ahead with the leak test so you have some better information to make an informed decision on.

Let me know how you go.

Jacob

Hi Jacob,

Letting you know that I had someone come out to assess the damage a few days back. He did use a moisture meter and reading was above 100% (he told me that 100% would be a normal reading so above 100% means there is definitely moisture in the wall).

They are sending a plumber to run a pressure test just to be doubly sure it's nothing plumbing related, but they do suspect for now that the main culprit is probably faulty grouting. Will post an update once the plumber does the pressure test.

Thanks again for your help so far.

Thanks for the update.

I'm glad to hear that you've gotten some more definitive answers and we're well on the way to a solution.

Once the plumber has conducted the pressure test to rule out further issues, feel free to get back in touch with their findings, I'd be happy to assist further if required.

Jacob

Hi Jacob,

The plumber came and did the pressure test today. The good news is that there's no leaks. He said that by the height of the damage, he didn't suspect it would be pipe related. This would take us back to grout failure and/or faulty waterproofing being the culprits, but more likely the grouting.

Would you be able to recommend a good waterproofing sealant to paint over the top of the tiles once I've redone the grout?

Thanks again for all your help.

MitchellMc