Flat Metal Roof Rusting. How do I repair?

[Widget1983]

Hi guys,

We have a flat metal roof, I'm assuming galvanized steel maybe, but it's now got a fair bit of rust with some minor sections rust holes. A couple of years ago during the floods (NSW), we had water coming in behind a wall & after investigating I noticed there was a large enough hole that the water was flowing along the roof (roof has slight angle to move water) and down the hole. i ended up getting some silicone and bogging it all up. Probably not the correct thing to do but I'm clueless & it was more of an emergency patch considering the weather.

Anywho, I'd like to get up there, treat the rust and coat the roof, though I don't know where to start or what correct procedure would be. I was considering getting the pressure washer out, hosing it down, scuffing back the rust to knock the loose stuff, then mixing up some rust converter in a spray bottle and trying to neutralize the rust then paint over it. Not sure if this is correct, so hopefully someone can point me in the right direction.

I considered replacing the sheets but it worked out to be thousands just for the sheets (roughly 100m2). Are there any 'clearance' or 'excess building material' type places that sell good condition stuff at discounted prices? (NSW)

I've attached some pictures for reference. The image with the green pipe, there's a patch there which appears to be a sheet of lead , assuming someone's installed it in the past. This was split and a fair bit of water was going through there during the heavy rain. You can see where I bogged it up with silicone which helped. There's another images with a couple of spots of silicone too, that appears to have rust holes. Another image has a possible screw hole, not sure what it is, assuming water will be able to get in there.

Any tips on how to tackle this?

Thanks,

20240217_162939.jpg20240217_162610.jpg20240217_162614.jpg20240217_162621.jpg20240217_163248.jpg

[ErrolFlynn]

If the roof was strong enough for you to walk on it’s not paper-thin. But if rust holes are appearing then it’s way past its use-by date.

I believe new sheets are supplied cut to the required length. A demolition site might be useful, but any of those sheets may well have holes in the wrong places. I’ve seen them advertised on Facebook. You are unlikely to find anything in the dimensions you need. Transportation could be a problem too. Then there’s the issue of installing them. It wouldn’t be every contractor who is willing to work with second-hand materials.

Anything you do to repair the roof is putting off the inevitable. You best start saving. It would give you the chance to check out and possibly upgrade the insulation that’s under your roof.

[Wimmera Jack]

Trim deck. Well beyond its use by date.
Not sure of the price difference, but what is wrong with normal corrugated profile either in zincalume or colorbond?

John

[capt'ngrumpy]

To give yourself some breathing space, treat the worst affected areas, ie rust holes lead collar etc with fillcoat fibre.

Although there is a lot of surface rust to the roof , depending on the BMT/ gauge thickness of the roof sheets it maybe feasible to apply a coating of noxyde to prolong the life of the sheets for say 5 to 10 years.
This is a cheaper alternative to roof replacement and something you could do yourself to save on labour costs.

If you are to go down the track of roof replacement. The pitch/fall of roof, will dictate what profile roof sheet is required.

[ian]

Trim deck. Well beyond its use by date.
Not sure of the price difference, but what is wrong with normal corrugated profile either in zincalume or colorbond?

I suspect that the existing roof sheeting is Klip-Lok not Trim Deck. The problem is that both profiles are designed for very flat roofs -- Klip-Lok is designed for a minimum slope of 1°, Trim Deck a minimum slope of 2°.
Corrugated profile -- custom orb -- is designed for a minimum slope of 5°.

So normal corrugated profiles won't work.

[rambunctious]

Trim deck. Well beyond its use by date.
Not sure of the price difference, but what is wrong with normal corrugated profile either in zincalume or colorbond?

John

Trim deck is a screwed roof whereas the profile here looks very much like the old Brownbuilt profile with clips fixed to the battens then the roof is clipped in place and the ribs were usually button punched, so possibly 1960's early 70's and without a doubt galvanised steel.

https://files.autospec.com/za/global...re-2021-r1.pdf

As already noted the roof pitch/fall would have to be available before suggesting replacement roofing profile.

[Wimmera Jack]

Ian. You are correct. Clip lock. I have some on my home on a very shallow fall. And it is held with button punch to the clips.
Difficult from the photographs to work out the pitch. And yes, if shallow fall, Corrigated iron is not much use.

Hooroo

John

[ian]

To give yourself some breathing space, treat the worst affected areas, ie rust holes lead collar etc with fillcoat fibre.

Although there is a lot of surface rust to the roof , depending on the BMT/ gauge thickness of the roof sheets it maybe feasible to apply a coating of noxyde to prolong the life of the sheets for say 5 to 10 years.
This is a cheaper alternative to roof replacement and something you could do yourself to save on labour costs.

If you are to go down the track of roof replacement. The pitch/fall of roof, will dictate what profile roof sheet is required.

Can I suggest that the existing Klip-Lok (or Trim-Lok?) roofing may be at too low shallow an angle for fillcoat fibre to work.

I haven't looked for a spec sheet for the fillcoat fibre, or noxyde, but the issue could easily be that Widget's roof is already at near to minimum slope and the suggested treatments requires a greater roof slope than is available.

[rambunctious]

Ian. You are correct. Clip lock. I have some on my home on a very shallow fall. And it is held with button punch to the clips.
Difficult from the photographs to work out the pitch. And yes, if shallow fall, Corrigated iron is not much use.

Hooroo

John

Confusion reigns supreme.

This is kliplock

COLORBOND(R) Roofing Klip-Lok | Metal Roofing Online

but I am going to walk away from this post now because I can imagine Widget is getting confused with the info provided.

[Widget1983]

Thanks everyone for the feedback,

If the roof was strong enough for you to walk on it’s not paper-thin. But if rust holes are appearing then it’s way past its use-by date.

I believe new sheets are supplied cut to the required length. A demolition site might be useful, but any of those sheets may well have holes in the wrong places. I’ve seen them advertised on Facebook. You are unlikely to find anything in the dimensions you need. Transportation could be a problem too. Then there’s the issue of installing them. It wouldn’t be every contractor who is willing to work with second-hand materials.

Anything you do to repair the roof is putting off the inevitable. You best start saving. It would give you the chance to check out and possibly upgrade the insulation that’s under your roof.

From what I could see, the only places with rust holes were the small sections that I used silicone on, which where the stink-pipe from the bathroom and just near it. I had a brief walk around the roof when I took the photos and I was able to carefully walk on the flat sections that are rusty. It held my weight (100kg) *knock on wood*, though probably not the smart thing to do. I'll have to have a more thorough inspection, but in the event I use a wire wheel to clean the rust and pin holes show up, are these easily patched with an undercoat primer? The house is from the 70's and it's in a state where if we were to sell, it would be better suited for a knockdown-rebuild (old 70s fibro flat roof)

To give yourself some breathing space, treat the worst affected areas, ie rust holes lead collar etc with fillcoat fibre.

Although there is a lot of surface rust to the roof , depending on the BMT/ gauge thickness of the roof sheets it maybe feasible to apply a coating of noxyde to prolong the life of the sheets for say 5 to 10 years.
This is a cheaper alternative to roof replacement and something you could do yourself to save on labour costs.

If you are to go down the track of roof replacement. The pitch/fall of roof, will dictate what profile roof sheet is required.

5-10years would be fine in this instance. The house is a 70s fibro style, so if we sell in the next 5-10years it would likely be a knockdown-rebuild, I don't mind doing the work to restore it, even if it only gives an extra handful of years, just don't know how to go about it, what steps to take (treating, priming, sealing, painting etc..). I'll check out the 'Noxyde' you mentioned though, much appreciated .

I suspect that the existing roof sheeting is Klip-Lok not Trim Deck. The problem is that both profiles are designed for very flat roofs -- Klip-Lok is designed for a minimum slope of 1°, Trim Deck a minimum slope of 2°.
Corrugated profile -- custom orb -- is designed for a minimum slope of 5°.

So normal corrugated profiles won't work.

klip-lock sounds familiar, but unsure of the angle. I only have a bubble-level but doesn't give detailed readings.

Trim deck is a screwed roof whereas the profile here looks very much like the old Brownbuilt profile with clips fixed to the battens then the roof is clipped in place and the ribs were usually button punched, so possibly 1960's early 70's and without a doubt galvanised steel.

https://files.autospec.com/za/global...re-2021-r1.pdf

As already noted the roof pitch/fall would have to be available before suggesting replacement roofing profile.

I was told it was built int he 70s, so quite old. Thanks for the link, that looks like what we have.

Can I suggest that the existing Klip-Lok (or Trim-Lok?) roofing may be at too low shallow an angle for fillcoat fibre to work.

I haven't looked for a spec sheet for the fillcoat fibre, or noxyde, but the issue could easily be that Widget's roof is already at near to minimum slope and the suggested treatments requires a greater roof slope than is available.

Are there any rust inhibitors/primers/sealers that work for low-angled roofs ?

[capt'ngrumpy]

Can I suggest that the existing Klip-Lok (or Trim-Lok?) roofing may be at too low shallow an angle for fillcoat fibre to work.

I haven't looked for a spec sheet for the fillcoat fibre, or noxyde, but the issue could easily be that Widget's roof is already at near to minimum slope and the suggested treatments requires a greater roof slope than is available.

Nonsense. Fillcoat fibre & noxyde can be applied to a box gutter, which has a minimum fall requirment of 1 in200.
Also, Widget has not specified what the roof pitch is, and has only stated if anything that it is low. Just because
klip-lok has been used doesn't necessarily mean the pitch is at 2 degrees or less. Although it is most likely.

[capt'ngrumpy]

A cheaper alternative to Fillcoat fibre is Fastfix Wetshield (available from bunnings). Can be applied over silicone. For the
small amount you need , a 500l litre tin would be ample.
Noxyde has poor adhesion to silicone but is okay over products mentioned above once dry. Curing time of fillcoat fibre
can be quite lengthy due to it being a solvent but has waterproofing qualities from the moment it is applied.
On the downside noxyde is not cheap (approx. $580 for 20 kg) from memory a tint may be added. Don't quote me on this you would have to check with supplier.

[Beardy]

The roof is really due for replacement but if you are not wanting to do that Google metal roof restoration and you will find a number of options to recoat the roof to extend its life both as a diy job or there are contractors who will do the job for you. First check there are no holes in under your flashings and capping as that is usually where they fail first

[ian]

klip-lok sounds familiar, but unsure of the angle. I only have a bubble-level but doesn't give detailed readings.

I'm not sure how long your "bubble-level" is, but there are ways of determining the slope of your "flat" roof.

If your bubble level is 1.2 or 1.8 metres long, just lay it on the roof and chock-up the low end till the bubble is level.
The height of the chock DIVIDED by the level's length will give you an idea of the roof's slope.
1° degree is 1 in 50, 2° is 1 in 30.


If your bubble level is 600 mm long or shorter, lay the level on a longer straight piece of wood and chock-up the low end.
Again determine the fall by dividing the height of the chock by the length of the timber.

I was told it was built in the 70s, so quite old.

"70s construction is not "quite old".
I'm not sure a '70s house even starts to qualify for "old", let alone "quite old".


The fibro house I grew up in was built prior to WW2 and apart from the increased tree canopy is still largely as it was when mum and dad sold the place in 1982. Being pre WW2, the house might qualify as "sort of old"


The terrace house I lived in after I married, was built prior in the early 1890s.
That terrace would qualify as old, but not very old.

[mature one]

corrupted profile would not be suitable not enough fall if you use corrupted roofing t will leak where it goes into the gutter.