How to repair corrugated metal roof leak? (ponding)

[monkeyspearfish]

Hi all

My roof seems to be leaking. Upon inspection it looks like the leaking area (roof sheets) may have sagged which has caused ponding. Does anyone have any suggestions on how to fix this?

FYI I have plans to pull off the tape, apply rust remover and waterproof mud (link below) for a complete seal. Any advice would be appreciated.

Thanks

 

  

  

https://www.bunnings.com.au/fastfix-wet-shield-1kg-one-coat-instant-waterproofing_p0098155?store=643...

[MitchellMc]

Hi @monkeyspearfish,

Are you sure the roof is leaking? Perhaps run a hose over the area for a while and check beneath for leaks. Your image from underneath looks suspiciously like condensation rather than a leak. However, you are right in wanting to address the roof as it doesn't look far off rusting through. 

To reverse the sagging roof sheets, you'd likely need to install some timber bracing from underneath, which will push them back in position. Installing a timber beam between the existing ones could be all that is needed.

For the rusted section, I recommend removing as much of the rust as possible with a wire brush, converting the rust with a rust converter and then painting Fastfix Wet Shield 1kg One Coat Instant Waterproofing over the entire area.

Please let me know if you have any questions.

Mitchell

[monkeyspearfish]

Thanks Mitchell, I had that in mind and glad to know I was on the right track.

I don’t think it’s condensation because it’s only leaking at sections of the roof where ponding occurs. I’m not sure why and how water is dripping like that or how it even gets through. 

I’ll give your suggestion a shot and see how I go. Much appreciated 

[MitchellMc]

My theory is that the pooling water on top is lowering the temperature of the steel underneath @monkeyspearfish, and when the warmer, moisture-laden air comes in contact with the cold sheet, it hits the dew point and forms condensation on the underside. 

If it were a hole, you'd see a drip forming and dropping in one or a few locations. That moisture all over the surface looks very much like condensation.

It's good to have all your cases covered, though.

Mitchell

[monkeyspearfish]

Hi Mitchell

I think you’re right about the pooling water theory. The problem is the sagging of the sheets is almost unnoticeable. I tried pushing the sheets back up from underneath with my hands and it barely moves, so I’m not sure if a brace underneath would fix the ponding. 

I’m thinking if I just apply the waterproof mud, whether this would fix the drainage issue and stop the dripping condensation. 

[EricL]

Hi @monkeyspearfish 

I say give the Fastfix Wet Shield 1kg One Coat Instant Waterproofing a go and observe your roof for several weeks or when it's raining. Or perhaps use your garden hose and test the roof yourself.

Please keep us updated with your progress, we look forward to seeing your roof fixed.

If you have any other questions, we can help with, please let us know.

Eric

[monkeyspearfish]

 

Hi all

I want to install some ceiling insulation into my garage with metal roof but I need help deciding between rigid foam (foilboard) or batt insulation (space blanket). Links of products below:

https://www.bunnings.com.au/foilboard-20-x-2400-x-1200mm-ultra-20-insulation_p0125956

https://www.bunnings.com.au/earthwool-space-blanket-r1-8-75mm-x-1200mm-x-10000mm-12m-insulation-meta...

I also want to aim for highest possible R value, which would provide the best R value for money? Because I couldn't find much information on R values for the foilboard.

I note that I get condensation on the metal ceiling where drops of water form, this is why I've chosen the space blanket because it as a vapour barrier.

In terms of installation, for space blanket, I thought about stapling packaging straps across the wooden beams to hold up the rolls of insulation. I dont plan to cover it with dry wall or anything. For rigid foam, I thought about resting the rigid foam on some screws at the ends of each wooden beam (to hold them up the rigid foam like brackets). I'm trying to find the easiest way to install them without too much handyman work involved. Would I need to have the space blanket or foilboard touching the metal ceiling or do I need to have an air gap between the ceiling and insulation? Any tips or thoughts would be appreciated, thank you

[monkeyspearfish]

Thanks Eric, update - I had some buckets of water sitting under the condensation. Once I removed the buckets of water, the condensation was gone in some areas of the ceiling.

Once I apply the exterior waterproofing, I would like insulate the ceiling which I guess would help control the moisture and condensation.

I’ve made a seperate post in the link below about it as I’m unsure which type of insulation would be best for my roof.

https://www.workshop.bunnings.com.au/t5/Garage-and-Shed/Metal-roof-insulation/td-p/221423

[JacobZ]

Hi @monkeyspearfish,

I've merged your other post with this one so our members can get all the information on the circumstances surrounding your insulation project.

With the condensation issue in mind, as @EricL has suggested, you should apply the waterproofing membrane and then monitor it prior to installation of any insulation material. 

Looking at the spacing of the rafters, I'd suggest using the Foilboard 2400 x 1200mm Ultra 20 Insulation, with the seams taped using Foilboard Aluminium Tape. Foilboard is larger meaning it will fit the gap better and is waterproof so it can be used in this application.

You might like to check out Foilboard's Roof Installation Guide for some guidance on the installation process. 

Unfortunately, the Flexi-fast Fasteners would not be easy to use as you need access to the top of them to screw them in place. It might be possible to flex the Foilboard to attach them after the flexi-fast fasteners have been installed, but this would add some difficulty. If you didn't want to do this, you could use Zenith Poly Pro Insulation Strapping stapled to the rafters to support the foil board.

Installing the foil board with an air gap will increase its insulative ability and is definitely advisable.

Let me know if you have any further questions.

Jacob