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Fixing a water leak that is making paint on the roof bubble

If you notice paint bubbling on the ceiling, wall or cornices it is usually a sign of a water leak or moisture build-up. See how our plumbing team can fix it.

Our plumbers located water leaks in the upstairs bathroom

  • Paint bubbling on a ceiling is a sign of water leaking in the roof


  • Water leaks or moisture build up can cause paint to bubble or peel


  • Hire a plumber to find the leak and repair it to avoid structural damage

What should you do if you see paint bubbling on your ceiling?

When you start to see unusual changes to your ceiling paint, or even walls, don’t immediately think it is the paint going off or getting old. Paint can last for many, many years so any changes that you witness are normally due to something effecting the surface or material they are painted onto, a lot of the time this is inside a wall or roof cavity that you can’t physically see. So you should call a plumber in Sydney that is experienced at water leak detection and repairs.

The owner of this two storey house in Blacktown needed a local Sydney plumber to find a water leak. They were starting to see paint bubbling on the roof of the downstairs rooms and this is always a sign of either water or moisture build up. In normal circumstances the flooring or ceiling materials wouldn’t be exposed to high amounts of moisture other than the normal condensation from changes in air temperature or the weather in the building.

Although, in this case water was moving somewhere within the plumbing system & pooling in the roof cavity area. This moisture can’t really travel through the porous masonry substrate on the ceiling because it is sealed on the other side by the surface paint, the water simply cannot escape anywhere and sits beneath the paint film, resulting in the formation of blisters & eventually peeling paint. This can appear worse or more intense as the volume of water increases, in worse case scenarios the ceiling material will fail and create a whole. 

Generally the leak might be quite gradual so there is some pooling of water but it dries before the volume gets too much. For some properties you might also see staining on the roof that looks a bit like cigarette smoke or a burnt area with soft brown spots or even mould forming.

There was also some damage to the cornice areas of some of the rooms, so clearly water was leaking from either one or multiple locations in the two upstairs bathrooms of the two storey house in Blacktown.

Paint bubbles can form long after the paint on your walls and ceiling has dried, in fact you might not notice anything for many, many years then one day you see little bubbles appear. When this occurs it is normally paint blisters or bubbles which is when the paint film lifts from the underlying surface which is normally a fibro or brick wall.

The loss of adhesion between the paint film and surface is usually caused by;

  • Heat
  • Moisture
  • A combination heat and moisture
Some people think it is from a poor paint job and might ignore it, although if water is leaking from failed waterproofing you can cause major damage to the structure of your property. 

Does a water leak cause damage to a house & can a plumber repair it?

WARNING – beware of anyone that suggests sanding back the bubbling paint and re-painting, this could be a disaster waiting to happen and lead to even more costly repairs down the track.
The hardest things to understand with a water leak is that most of the time you won’t even be able to see it. For this house in Blacktown the water leak was in the roof & there wasn’t any water dripping on the floor, it was ‘invisible’ as it slowly flowed into the roof cavity area undetected. What happens is damage is caused over a long period of time before you know there is a problem.
Some people will ignore the signs and let paint continue to bubble and think there is nothing wrong. Although what you can’t see is the extent of the damage being caused and this requires a licensed plumber like Nu-Trend to assess the property and provide repair solutions. 
For major damage it could mean demolishing a bathroom and starting again because the wall or floor damage could be so severe that it is unsafe to use. Water might have penetrated the timber framework & flooring causing it to rot, becoming too weak to build on. In some situations it might be isolated to an area and maybe that part of the wall can be repaired.

Nu-Trend is a licensed plumber in Sydney that can perform leak detection and repairs using a range of tools. Our experienced plumbers can quickly isolate where the leak, or leaks, are coming from to then work out how to repair them quickly. The benefit of choosing Nu-Trend is we are also bathroom plumbing renovators so we can repair the pipework & provide remedial renovation repairs too. 

How our plumbing team detected the leak in this house in Blacktown

The Nu-Trend plumbing team visited the site and we tested all the drainage, water proofing and cold/hot water piping in the upstairs bathrooms. We had to cut several access points in the roof so that we could test each of the fixtures thoroughly.

This is what we discovered;

  • Illegal sub flooring – the bathrooms had been built using Yellow Tongue sheeting instead of cement board. This means that if there are any major leaks or failed waterproofing the timbers and Yellow Tongue sheeting will suffer from water rot out below the tiled surfaces.


  • 3 x obvious water leaks – after we tested the shower, bath, toilet, basins and floor wastes for two hours we were able to identify three different leak issues;


    • The basin mini taps and flick mixer was leaking into the vanity which was then tracking down the pipe and down into the kitchen.
    • The toilet is was leaking heavily when flushed.
    • The sewer pipe work in the ceiling on the ground floor is leaking from glued joints past the floor waste.
For the taps & sewer pipe work they are relatively easy to repair because there is ample access to do so. Although completing the diagnosis of the toilet leaking is much harder because the ceiling mounted sewer pipe work is on top of the kitchen joinery. There is no water coming out onto the tiles upstairs in the toilet area however when the toilet was flushed, water was flowing downstairs. So this could mean the toilet is concealing a leak within the silicone connection to the floor or if the leak is within the pipe work penetrating through the subfloor and on top of the pantry cupboard. 

The only way to determine this would be to lift the toilet, however that means potentially cracking the toilet because it is cemented to the floor. Even if this did happen, it may be that isn’t the issue & it is the piping further along. Either way you have to get into the piping to work that out. 

So in these situations we typically recommend taking the risk of the toilet braking from being moved off its base so that the cause of the leak can be determined & repaired correctly. If it is not fixable from that level of access, then in this situation the property owner would need to engage a joiner to pull apart the pantry so the plumber can get access to replace the toilet sewer piping.

So far the scope of work would involve;

  • Replace the mini taps and basin mixer
  • Replacing the leaking pipe work within the ceiling that is accessible
  • Lifting the toilet to see if the leak is fixable from upstairs without removing joinery
  • Once all of the above has been rectified/tested and fixed, patching and painting the three access areas in the ceiling

This covered the most obvious things we could locate and due to the age of the bathroom there may have been more but the main ones of shower & bath weren’t leaking which was a good sign. There were other plumbing issues with the drainage stack work which was a result of poor plumbing installation, however, this wasn’t causing any leaks.

There was a smell in the bathroom but that was purely because the wastes had dried out due to lack of use in that bathroom, no major concern there. To fix this smell would just need running the bath, shower and flushing the toilets every so often to avoid drying up the drains.


Can a plumber find a leak between multiple bathrooms?

For the second bathroom we carried out the same testing methodology with our plumbing team inspecting the roof and service items. We didn’t find any obvious leaks in this bathroom and sometimes there could be one but there isn’t sufficient use of the bathroom to allow enough water or moisture to build up. Using the access we had through the man hole and flood testing / pressure gauging we couldn’t find any plumbing, fixture/tapware/sewer pipe related leaks in this bathroom.

The other possibility could be heavy rain overflow leaking into the roof cavity through cracked tiles, gutters that overflow or some other roof related issue. The idea here would be to monitor the situation when it rains or with heavy use of the bathroom to see if a leak is detected. 

How much does it cost to repair a water leak?

Nu-Trend recommended the most sensible solution to repair the leak & it essentially was the cost of new Gyprock, painting and potentially replacing the sewer piping. Worse case replacing the toilet and/or repairing the kitchen cabinetry. 

Some plumbers in Sydney won’t be that honest and what can happen is these three things;

  1. They recommend a quick fix that solves the immediate, visible issue, but doesn’t resolve the underlying issues in the piping. So eventually the issue will re-occur.

  2. For inexperienced plumbers they might remove larger portions of the wall, toilet or bathroom where it becomes too late to stop & the repair becomes time consuming & costly. Obviously the home owner is stuck so they are forced to get them to complete the task. 

  3. You get told it is something more major that is going to cost $50,000 or more to completely demolish the two bathrooms & upgrade all the plumbing. 


Whatever you do, if you get a handyman or even a plumber saying just ‘sand back the paint’ run. All you are doing is putting fresh paint on the surface that will start to bubble again in the near future. You are avoiding repairing the cause of the paint bubbling and this doesn’t make any sense because even more damage could be getting created that you can’t see. In this case it is two bathrooms on a second storey that has Yellow Tongue flooring, so it is a recipe for disaster waiting to happen.

What if paint in the bathroom wall is bubbling

In a bathroom sometimes the paint will begin to bubble if the wrong type of paint has been used. Sometimes we see DIY renovators paint their bathrooms but they don’t use a moisture resistant paint. So very quickly this paint will start to bubble as it can’t repel the water that is caused from steam or heat from a shower or bath. The other reason paint could be bubbling in a bathroom is because the waterproofing of the room has failed, this allows moisture to get into the room and through the wall surfaces which effects the paint.

Can water leak behind the tiles of a bathroom?

If you notice the grout in your tiling is falling away this can be a sign there is an issue with how they tiles were installed or something else relating to the wall itself. In worse scenario the waterproofing may have failed and water is penetrating the wall and tile surface area. This can begin to break down the grout, adhesive and enable moisture to penetrate into the structure of the bathroom or house. Over time this can cause different levels of damage depending how severe it is, how often the bathroom is used & things like whether the property is built out of timber, brick or is an apartment block unit.

Can a plumber repair paint bubbling on a wall in Sydney?

Fixing paint bubbling is not a simple, black and white answer as it depends on what the root cause of the issue is and how much underlying damage has been caused. Nu-Trend is a Sydney plumber that can help you identify the cause, suggest the right choices of repair & then complete the work for you. We are experienced bathroom plumbers so have extensive experience in these situations. 

Here are our tips for fixing paint bubbling;

  • Book a site free site assessment to inspect your paint bubbling.
  • Get a repair quotation to fix the pain bubbling on your wall.
  • Understand if it is possible to isolated the bubbling to an area and maybe that part of the wall can be repaired.
  • Ask for an option that includes a repair or if major damage would benefit from demolishing the bathroom to repair wall or floor damage as well as the waterproofing.
  • Check whether potential leak detection is required using our professional plumbing equipment and tools. 
  • Make sure you are dealing with someone that is qualified but also licensed, with Home Owners Warranty Insurance, to be able to then conduct remedial work from basic repairs to a complete bathroom renovation. 
  • BEWARE of anyone that suggests sanding back the wall and re-painting it, this could be a disaster waiting to happen and lead to even more costly repairs down the track as water continues to cause damage that you can’t see.


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Nu-Trend is a Sydney company with more than 15 years experience completing bathroom renovations & solving plumbing problems. he Directors Rob and Rick are hands-on, and provide a personalised service.


All the work carried out by Nu-Trend is AS/NZ3500:2018 compliant. It is the Australian Standard for Plumbing and Drainage in NSW as set down by Standards Australia and the Australian Building Codes Board. They give the plumbing industry technical direction to enable compliance with required regulatory frameworks.

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Rick and Rob are the hands-on directors for Nu-Trend. Rather than hire sub-contractors and manage their business from a distant office, they are on the tools, at your site & working towards delivering your bathroom renovation or plumbing service. It means you are talking directly to the owners of the business, the guys who are accountable and responsible rather than via email or through customer service teams.

It is why they are able to provide a written guarantee that demonstrates their confidence in standing by the quality of their workmanship and the service they deliver to every single client.

They have a very single minded commitment to deliver a high level of professionalism and quality, they’ve been doing renovation contracting in Sydney for 15+ years.

We are a bathroom renovator in Sydney that has completed thousands of bathroom renovations.

Nu-Trend has been operating since 2009 as an independent bathroom renovation and plumbing contractor in Sydney. Rick and his team provide a wide range of services for home owners in houses, units, apartments or businesses.

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