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How can I find and repair recurring ceiling leak?

Finding My Feet

How can I find and repair recurring ceiling leak?



I live in a relatively new 2 storey duplex and my downstairs ceiling is leaking. It’s happened in the past before and the builder came back to inspect and couldn’t find anything including doing some waterproofing via adding silicone everywhere, around any gaps they could find from the roof. Since then it appears to have held up ok over the last year or so including a few large weather events. However atm in Sydney we are getting some serious wind and rain and the leak happened again last night.


Previously the builder blamed that an adjacent down pipe may have been blocked and caused the water to backup and not drain properly… but this was never proven and there was no blockage even after I had an independent plumber come to do a camera inspection. We’ve even done a flood test of the balcony multiple times and detected no leak.


It’s hard to describe but directly above the ceiling where it’s getting saturated is a balcony as well as a drain. I suspect that water could be entering some crevices against the exposed wall/windows and somehow with strong winds there is enough getting in and seeping through. I'm concerned about any potential future moulding/structural impact. The leak doesn't appear to occur during regular normal rain, just when it's really windy. I could ask the builder to come inspect again, but last time they just blamed a loose roof flashing or gutter overflow and explained that water will just get in... That doesn't sit well with me.


What’s the best way I can try and find out the root cause and have the issue repaired once and for all?


Should I be drilling a small hole in the saturated ceiling panel to relieve any potential water build up? Is it likely that my ceiling panel downstairs and inside will mould? It’s discoloured a bit from the previous leak and doesn’t appear to be any mould from the last even a bit over a year ago


I lose sleep whenever there are significant rain events! :unhappy:


Thank you

Having an Impact

Re: How can I find and repair recurring ceiling leak?

Hi @wai 

First bit of advice is - This issue will not go away, and you should not let the builder walk away from it, until it is resolved. Water should not "just get in".


If you have had no luck with the builder themselves, I suggest engaging a qualified building inspector - (ie: the same people that carry out pre-purchase inspections) - you should find one by googling... This may cost a few hundred dollars - but you may be able to recover that cost from the builder, if the leak is found to be caused by a building defect.


Leaks are notoriously difficult to diagnose, so its not surprising that the builder hasn't been able to identify the cause.. But please make sure they keep investigating.. 


I would have the flashings around windows and doors checked, as well as all the roof penetrations (such as vent pipes, skylights, whirlybirds, etc). In particular, assuming the balcony above has a door, check the sill and subsill and head flashing above the door- These are typically locations which are difficult to seal properly - A suggestion, if you have carried out flood tests on the balcony, is that the leak is from the door head, if not flashed correctly, driving rain could be penetrating at that point, and "trickling" down inside.

Hope this helps.


Bunnings Team Member
Bunnings Team Member

Re: How can I find and repair recurring ceiling leak?

Hello @Wai2021


Welcome to the Bunnings Workshop community. Thank you for joining us and sharing your query about repairing a recurring ceiling leak.


I'm sorry to hear that your ceiling is leaking. It's great that you've received excellent advice from @jaga. I agree with the recommendation of trying to track down the leak using a building inspector. Checking all the individual parts of your roof is a practical way of eliminating the possible source of the leak. The only other source of the leak I can imagine would be from the gutters not being able to cope with the heavy rainfall. Please keep us updated.


Let me tag our experienced members @tom_builds and @JDE for their recommendations.


If you need further assistance, please let us know.




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Making a Splash

Re: How can I find and repair recurring ceiling leak?

Hi @Wai2021 and thanks for the tag @EricL,


I agree with both @jaga and @EricL that a building inspector is probably your best bet to find the source of the leak. It would be easier to spot the water ingress point with the ceiling removed, as you should be able to see evdience of moisture in the floor josits that the water has travelled down to reach the ceiling, but obviously that is a very costly method of finding a leak. Is it possible for you to upload some photos of the upstairs over this portion of ceiling so that we can get a begter understanding of where water may be entering inside of the building?


If it was an older house you could probably blame the construction methods for inadequate waterproofing, as I live in an old duplex where the roof pitch is nowhere near adequate, and in large rain events the valley flashing is easily overwhelmed which has led to the occasional water leak through a downlight or two... however if your house is reasonably new it is likely poor craftsmanship or some other error of the builder's.


Hope you are able to resolve this issue soon!

Re: How can I find and repair recurring ceiling leak?

Thank you for all your replies, really appreciate it. I think the building inspector method is good, but yes I do want to avoid additional cost if possible.


The house is relatively new, still under 7 years so it seems the builder I’ve contacted is happy to come and have a look again to help seal up various gaps and things. I spoke to them recently and there appears to be an expansion joint adjacent to the balcony, but a good 1.5-2m horizontally away from where the ceiling leak is appearing. He’s suggested it could be rain water being forced through that gap since it isn’t sealed and the strong westerly winds could’ve done that.


the balcony door has also had its waterproofing repaired a bit over a year ago and hasn’t leaked since - they took the balcony door off and redid the waterproofing along the floor where it was ingressing…


Im uploading some images to better explain how the balcony looks.








Bunnings Team Member
Bunnings Team Member

Re: How can I find and repair recurring ceiling leak?

Hi @Wai2021


Thank you for posting the photos. It's great that you've found a builder who will help you. Please keep us updated, we look forward to seeing all the leaks repaired.




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