How do you remove water stains from a ceiling?

[#1]

If you have a water stain on your ceiling, the first thing to do is ascertain whether there is an active leak in the structure of your roof. If you are not confident going into your roof space, I recommend you employ the services of a professional. Even if there is an active leak, you might not be able to find it.

The other day I was in the roof as we had noticed a water stain on the ceiling and droplets of water hanging from the plasterboard sheeting. When I got into the ceiling the top side of that ceiling board was bone dry - it was a complete mystery.

The reason for needing to track the source of the damage is that if we repair it, you might unwittingly conceal any further damage that could affect the roof's structure.

Once you've ensured no ongoing issue, you can thoroughly clean the ceiling sheet with Sugar Soap and then flush it off with fresh water. Wait for the area to dry before applying two coats of Dulux 1L PRECISION Stain & Mould Blocker following the application instructions.

Once they have dried, you'll be free to use your choice of ceiling paint to finish the area. The stain blocker stops the watermarks from transferring through your topcoat and re-appearing. 

I trust you'll find these step-by-step guides useful: How to paint a ceiling and How to remove mould stains from walls. - MitchellMc

Please note that if you have mould, it is already inside the plasterboard panel and there is nothing we can do to remove it from the inside. Using cleaning methods such as vinegar will only provide a surface clean and eventually, the mould will return. The sugar soap is to prepare the surface for painting, it will not remove the mould that is already there.

My colleague recommended using Dulux 1L PRECISION Stain & Mould Blocker to block the mould from coming out.  Once the primer is dry you can then use your choice of ceiling paint. - EricL

[Shareen]

What are your options if that doesn't work? I had my ceilings professionally painted and they used 2 coats of the stain block paint and then went back to a paint place to get a spray as the stains came through. The spray worked temporarily but with even a hint of humidity, the stains reappear and appear damp. Yes I've had the roof checked 3 times for leaks. It's not a leak. At least not now. 

Do I have to replace the ceiling?

[JacobZ]

Hi @Shareen,

Thank you for your question.

Based on what you've said, it sounds like there is a moisture issue that would need to be rectified before considering what to do with the ceiling. If you were to replace the ceiling and the moisture issue continues, you would essentially be throwing money down the drain.

Did the people checking for leaks give you any idea what they think is going on?

Is there maybe a ventilation issue in your ceiling that is trapping moisture? Do you know what kind of insulation you have in the ceiling cavity?

Any further information you can provide will help us narrow down the approach to fixing this issue. If you have some photos, this would also certainly help.

Allow me to tag @Dave-1, @Nailbag and @DIYGnome for their thoughts.

Jacob

[Nailbag]

Hi @Shareen 

One thing I have learnt over the years is that water can travel well beyond the area where it is causing damage. In other words a cracked tile several metres away that allows water to enter the roof space can drip on the rafter and run down them to an areas well past the cause.

As @JacobZ mentioned it's good money thrown away repairing the result if the issue isn't repaired first. This is how I would approach it.

1. check or have checked the roof for issues like cracked tiles, broken flashing and silicone seals and dislodged coping tiles mortar. A decent roof restoration company can help here.

2. get in the roof above the water damage next heavy rainfall and check where the water is entering.

Once this is established and repaired THEN repair the ceiling. If stain blocker primer is failing then it's most likely that the plasterboard is still damp. If it was dry the stain blocker should work. If the plasterboard is that sodden then I would replace it because it's structural integrity is now compromised.

Nailbag

[Dave-1]

Good Evening @Shareen 

I am in agreement with @JacobZ and @Nailbag  

In fact if I look up at my ceiling above my head I can see a "patch" that I had repaired probarlly around 12 years ago when I renovated my loungeroom. It last a few years and then that stain came back. I know what it is, but trying to fix it is exactly what @Nailbag has described about it could be comeing from a long way away. 

I do suspect its the bolt that holds the stay wire for my tv aerial. I have silasticed the roof but getting to that point in the roof space is another thing entirely  

One "dodgy bro" work around is to actually place something hard plastic wise above where the stain is. Water does get in yes but it cant be that much or you would really know about it. The drip, drip, drip is what drives my spot so having something that deflects that heavy drip.... Cant hurt

Dave

[Shareen]

Thanks everyone for your feedback.

I'll give a bit more history and welcome further advice.
We bought the place December 2021.
There had been a water leak before we moved in. The previous owner had the leak fixed but I also think the moisture is somehow trapped in the ceiling. I've had a roof restoration guy come out when i thought it was old stains. He checked over the entire roof before painting it. Flipped a couple of tiles but everything else including the seals along the crest were all intact. I called him back after the 'leak' and he checked over everything again, even put a bit of silicon against some tiny spots he really didn't think would be the cause. I've had 3 separate plumbers and the painters all take a look at it. 3 plumbers also climbed in the roof. They could see some sites where vermin had been living but no current activity at the time it appeared to be wet. 

It seems the ceiling plaster might've been made with horse hair? One of the plumbers sent pics to a builder friend but they couldn't be sure. House was built in probably 1980 in Latrobe, Victoria. When humidity is low you can't see anything. When it's high the spots in the ceiling are damp. I've been here 3 years and it hasn't flooded in that time. 

I had 2 whirly birds installed this summer to see if we could disperse some of the heat/humidity in the roof cavity. If it made any difference, the spots still appear, so it wasn't enough. 

It's hard to really capture in photos but i've managed these since my last post so i could show you what i'm seeing.

The marks often seem to follow our outline the roof beams/framing (i know i'm not using the right words but assuming you know what i mean) which i guess could mean vermin or leak, but there's no new leaks, and no current vermin infestations.
These marks on the ceiling also appear in the corners. They're not connected, but are scattered across the ceiling.
There's also another across from the hallway one and one further up the hallway but they're even harder to see

 looking wetceiling 'stains' from previous leak

The hallway 'vermin' stain makes a square outline and is directly above where the old heat bank used to be. I didn't notice the staining until about a year after the heat bank was removed.

hallway - evidence of past verminceiling stainsstains on the loungeroom ceiling

I don't know what the insulation is made from. I think it looks like old pink batts. Still plenty of it and they moved the pieces to confirm there was no new leak on top. One of them did get a moisture reading from the underside in the hallway. The whole thing is frustrating as I 

[Shareen]

@Dave-1 @JacobZ @Nailbag 
I'm clearly not very proficient at Bunnings workshop

I've added some photos above. I'm frustrated because i seem to have engaged the right people to help me work this out and fix it and they all seem as confused as I am. 
I'm leaning to the moisture is just trapped in the plaster and only removing and replacing it will fix it. 
But i'm really hopeful i'm wrong as replacing the entire lounge room ceiling and patches of the hallway doesn't sound like a fun time.

@Dave-1 - I wonder if you could run a pvc pipe (like a gutter pipe) away from the bolt to the side of the roof and run into the guttering? Bit left field but leaks on bolts/screws is a new passion of mine. 
I have a patio roof thats leaking despite replacing the patio sheets and having a 'handyman' come and fix it for me as the screws he used were too long. so now i get drips all through the patio from the screws as well. .....it was already leaking, but now i've paid more for the privilege of it continuing. Oh well, it's back on the 'to-do' list

[Dave-1]

Afternoon @Shareen 

Tracking down issues can be a time consuming thing 😕 The insulation on top could be masking the water drips, but thos spots coming through the paint still like watermarks. Maybe pull back the insulation above the spots and lay out paper so when it has water drip on it then you can say "ahhh" thats a spot. I also had a thought that possums could be weeing up there and the wetness is soaking through? I would try to find a way of marking the potential drips in the ceiling space (via paper or dust) before replacing the sheets of plaster.

As a side note

There are a few types of paint made to cover these type of marks so they dont show through. I dont know the names of them off the top of my head but remember using them in my mums kitchen decades ago.

Dave

[Nailbag]

Hi @Shareen 

As per my initial post, it's VERY important that all water leaks within the roof are fixed first thats caused the damage. It might be best to engage a "Water Leak Detection" service who specialise in these issues and can advise on exactly whats required and by what trade/s to rectify. Once thats fixed then you can repair.

Soft sections of the plasterboard ceiling can be replaced in slightly larger sections of the damaged area, so no full sheet replacement is required. This needs to be done by a "Plasterer" who can also advise on areas that may only be water stained with no loss of strength and integrity of the plasterboard. This can be stain blocked prime coated.

Engage a "Plumber" to replace the sheet screws the handyman used with proper length rubber sealed screws and he will also silicone seal any related issues.

Its important to engage the right qualified people when it comes to water damage and ingress.

Nailbag

[MitchellMc]

Hi @Shareen,

As mentioned, I'd be engaging a leak detection specialist. Their sole job is to find the source of leaks, whereas that's not necessarily the expertise of a plumber. Provided they've confirmed that these are no actively leaks then you can have the heavily damaged areas of plaster replaced and the do two solid coats of Zinsser CoverStain Primer Sealer Stain Blocker on the other areas.

These might just be old stains that are set in the plaster and keep rearing their heads, but it's important to be 100% sure before committing to a fix.

Mitchell