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How to fix a leaking galvanised iron roof?


How to fix a leaking galvanised iron roof?



What can I use to fix a leaking galvanised iron roof. The leak is probably between some joins. Its an old roof. Is there perhaps some kind of sealant that I can paint on?






Bunnings Team Member
Bunnings Team Member

Re: Fixing a leaking galvanised iron roof

Hello @MichaelB2


Welcome to the Bunnings Workshop community. It's fabulous to have you join us, and thank you for sharing your question about your leaking roof.


I'm sorry to hear that you've got a leaking roof. There are a number of factors that could contribute to your roof's failure to keep the water out. This can range from age of the roof, rust damage, dirt and debris compromising a seal and foreign object damage such as trees, stones, and hail.


Some of the most common products used on roof leaks are:



Here is a handy step-by-step guide: How to prepare your roof for the wet season.


Would it be possible for you to post a photo of the area in the roof where the leak is occurring? This will give our members a chance to assess its condition. We can then make recommendations on how to repair it. Any other information you can provide concerning the leak would be much appreciated.


If you need further assistance, please let us know.




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Trusted Contributor

Re: Fixing a leaking galvanised iron roof


"I'm sorry to hear that you've got a leaking roof."


Morning Michael. I'm with Eric here - sorry to hear your roof is leaking.

My corrugated iron is very old. I wish I could replace it - but financially this will never happen.


Over the years we have had leaks. Discovering where the rain is leaking from exactly, is very difficult.

Water is incredibly elusive and where it drips in the house/shed is not always where it's entering the roof in an imagined vertical line.

Ridiculous as it sounds - when it rained I climbed into the roof with a torch - and tried to locate the entry point.

Tough going.

I would mark areas with a pen where I saw water.

When the weather improved I got onto the roof above where I had marked the internal area.

What I found was most leaks were occurring in the length wise overlap of the sheet (one and a half corrugations?)

One of the reasons for this was past humans walking on areas where the iron is not supported.

I blame myself (hand painting the roof in the past), my children and an inept electrician.

I siliconed the area inside the roof - then quickly got onto the roof and pop-riveted the damaged edges down before the silicone could dry.

I also siliconed suspect areas around screws. Over the years I replaced all the roofing nails with Tek screws.


I'm not a professional roofer or plumber.

But so far it's been successful.



Suspect areas marked.Suspect areas marked.

Crumpled areas pop-riveted down.Crumpled areas pop-riveted down.




Super Contributor

Re: How to fix a leaking galvanised iron roof?

Hi @MichaelB2,

One other thing to check, if you are up on your roof, is that if there are "lead-head nails" holding the sheets down, that a couple of the nail heads haven't popped off.

This can cause two things to happen, obviously there could be a leak where the head is missing, leaving a gap between the hole in the sheet and the now small nail itself, these will be instantly recognisable by the lack of a mushroom shaped head on the nail.

Secondly, with the head missing, this means that the roofing sheet is not "compacted" down as it was, this is a very common fault with lead-head nails.

If this is the case, use a claw hammer to remove the nail and use a long tek-screw that you can drive in with a battery drill or even better an impact driver with the correctly sized tek-driver bit, if you are going to go down this route, you need to have tek screws with the rubber sealing washer on them and as an added barrier to moisture, run a small bead of Silicone sealant around the hole before you fit the screw.

Also, be very careful how much you tension the screw, you can badly distort the peak of the corrugation, enough to cause another leak that you didn't have in the first place.


I hope that this advice is of some use to you.


Mike T.

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