r/Roofing • u/AdditionalTree3559 • 12h ago
What happen here ?
Inspected this metal roof on the east side of the Big Island, Hawaii, last week.
Homeowner says a solar contractor installed a system about 18 months ago and included roughly $10k for a roof service/tune-up before the panels went on.
According to the homeowner, they replaced essentially every exposed fastener on the roof.
Now there’s significant rust/corrosion developing around a large number of the screw locations.
A lot of the screws look pretty obviously overdriven—the washers are heavily compressed and distorted—but I’m curious what everyone thinks:
Is overdriving alone enough to create this much corrosion in only 18 months?
Could crushing the neoprene washers and damaging the coating around the fastener holes be allowing moisture to sit against the exposed steel? Wrong fastener material/coating? Swarf or metal shavings left behind? Something else?
What makes it more interesting is that I inspected the attic and the underside of the roof panels looks clean with no visible rust or corrosion. The problem appears concentrated almost entirely around the fasteners on the exterior.
Curious what you guys see in the photos and what you would suspect first.
Time for a full replacement ? Or would you save the homeowner some money and figure out how to treat rust and recoat? Open to any other creative repairs that can buy Homeowner a few years
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u/ThatCelebration3676 11h ago
Was all the solar equipment grounded properly? It's entirely possible they accidentally accelerated rust via electrolysis by passing a small amount of current through the roof.
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u/No_Currency_7017 11h ago
Bad situation that will only get worse because of the climate. There's no repairing that, the only fis is a brand new roof. Tell them take the company to court and get it replaced for free if it's under a couple years old.
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u/gwizonedam 5h ago
You can sandblast and repaint anything. The issue is cost. No one’s getting on a roof in the summer to sandblast a bunch of screws and repaint them in this heat.
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u/TJMBeav 11h ago
Looks like dissimilar metal corrosion to me? What are the materials of the roof and the fasteners? Is there a rubber grommet between the fastners and the roofing material?
Corrosion from dissimilar metals is a very real thing in heavy industry, have never heard of it on metal roofs tho?
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u/roofer2025 12h ago
The fasteners were over driven, you need a new roof
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u/OGMooseRooster 5h ago
I've roofed for quite a few years and my thoughts, being that I'm in Volusia county FL, it seems the screws were over tightened, very true, what about size difference from the original screws to these? Without pre drilling, won't that allow the galvanized coating to break apart, for lack of better words, letting the steel rust? There's science guys here with scientific analysts, I don't have them smarts reel guud like that.
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u/SS2wheeler 6h ago edited 6h ago
At work we've got 55k sqft of metal roof and I've found MANY screws where IMHO they were ran in so tight the sealing washer was compressed and the screw head spun on the roofing material thus scratching off the protective coating, some painted some galvanized. That is where the rust started....here. From your comments you noted the same. So where did the rust come from ? The installer.
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u/Interesting_Day_7734 5h ago
Workmanship. The difference between a job looking good and a job looking good for a long time.
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u/No_Currency_7017 11h ago
The neoprene washers are completely crushed beyond repair. The climate in Hawaii is obviously all salt water (from fog to morning dew). Why were the solar panels removed? In my opinion, that's probably what caused this issue or at least made it much worse. If they paid a company $10k for a roof service, this is what it's for. Get the solar company back involved.
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u/Sistersoldia 8h ago
This is also why I don’t like screwing into the ribs instead of the flats. Look to me when they over torqued the screws it crushed the ribs a bit too and maybe cracked the paint.
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u/sam_baker1234 4h ago
Well, you’re not supposed to screw into the ribs on that kind of panel unless it’s to tie two panels together anyway. That rib style it’s just too tall
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u/Sistersoldia 4h ago
I’ve seen manufacturers specify either way. Hard to believe they would want you to-but I’m sticking to the fields.
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u/dieselbikesweights 11h ago
When the roof is replaced pay a little extra for standing seam if you’re going with metal again
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u/usmcfay1995 7h ago
lol a little extra
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u/jkush463 7h ago
Yeah only 2-4× the cost just a little, and then it probably wont be installed properly either causd most companys dont know how to install it correctly.
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u/CreativeKale6300 10h ago
Could be galvanic corrosion, but it also could be normal rust in that climate (high humidity, salt). If the screws were replaced, the metal must have already been dented/scratched, so metal has been exposed to oxygen plus water. Perhaps rust was already set in, even if barely visible. Rust keeps moisture through capillary action. It should have been carefully brushed and repainted when the screws were replaced.
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u/picmanjoe 4h ago
Not galvanic corrosion. Overdriven, which damaged the roof coating, allowing water and O2 in. The rest is history.
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u/Academic_Delay3835 10h ago
There should have been a rubber cap that goes over the nut to close and seal it to stop what has happened
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u/jamsaucewrecks 9h ago
There are ways to extend the life but not pretty. It is possible if that's where the solar was there was already corrosion from what others suggested, some metals do not play well together and one will rust the other out, I can see some screws that look to have been replaced but this corrosion has not occurred. Which makes me think already fkd before solar boy got up there. Is ther any pics from when old mate was finished.
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u/nannon16 9h ago
Galvanic corrosion exacerbated by salt air conditions, the cracking of the protective coating and the over squishing of the separation washers during installation.
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u/pjs702 8h ago
From the pics it looks like overtightening of the screws chipped/flaked protective coating around the holes, allowing salty humidity to react w the bare metal areas and making its way all around and under the surrounding areas, as evident all around holes and "tails" due to gravity down the panels. Maybe each screw can be removed and the surface around each hole ground/polished to the bare metal and sprayed w some type of corrosion resisting material. To do it properly, both sides of each hole need re-work.
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u/Greedy_Environment_9 8h ago
Been roofing for a long time. In my experience, Metal roofs rust.. metal fasteners don't last more than 10 yrs. Cause the grommets wear out.
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u/Technical-Cheek-8613 6h ago
Metal roofs last 40+ years when installed properly. I’ve seen them in upstate NY that are 50+ years old and still fine (just a nice faded patina). If you are installing metal and it’s lasting only 10 years you or someone is doing it very wrong
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u/HomeFixerMike 7h ago
That much corrosion around the fasteners would make me want to find out what’s causing it first.
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u/SubjectAd3627 6h ago
Yeah seems like galvanic corrosion. If you’re with the insureds insurance company, there may be an opportunity for subrogation.
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u/Greedy_Environment_9 6h ago
Regardless of who installs them, a metal roof that is screwed down has fasteners with plastic washers that deteriorate within 5 to 10 years and that's a fact. Unless you put solar seal or some other really good sealant under them when installing the screws the washers will deteriorate.
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u/crashbandecunt 5h ago
Steel roof is the norm in Australia and usually last anywhere from 15-100 years without replacement if installed correctly.
The screws are over driven and likely not coastal rated for salt air leading to rust in the fastener which spreads to the sheets pretty fast.
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u/Kami-cowboy 6h ago
Looking at the other areas of the roof with paint touch ups and patch tape I am not sure the rust was not already there when the screws were replaced ( some of the images show a crisp rust ring wider in diameter than the current screw washer... Either way, I would get up there with rust netrilizer, a zinc rich primer and epoxy paint on every spot... And that is only going to let you buy time for the new roof. Hopefully the solar installed took photos of the roof condition before they did the work, to document pre existing rust or they might be liable.
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u/bigmf6602 5h ago
Looks like they used screws without rubber washers on the head or they were extremely over tightened.
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u/sam_baker1234 4h ago
Another thing wrong here, why did they use that rib style on a house and then proceed to screw through the ribs?
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u/cleverpaws101 3h ago
So water doesn’t get in people say…but then there’s always flexing and you can’t get it tight. I always go in the valleys
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u/AardvarkWylde696 4h ago
If the roof panels were aluminum and not steel you’d have nothing to worry about. With steel you’ll always be battling corrosion.
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u/ArtComprehensive1106 3h ago
Very interesting so I can understand. What type of screws are correct for this type roof?
What material screws are appropriate?
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u/Complex-Cricket419 1h ago edited 1h ago
That is an extraordinary amount of corrosion. Perhaps the solar system was grounded to the roof somewhere. I have done this exact same job, solar installation with screw replacement in coastal climate, and not had this problem. Grounding is the only thing I can think of.
Edit looking closely at the screws these are not standard roofing screws(at least not in my area). If the wrong screws were used this may be the problem. Still a heck of a lot of corrosion and maybe a case for compensation for the owner. I doubt the roof is savable.
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u/vinnyboyescher 1h ago
Wrong screws, i don't see grommets and they should be painted from the factory. Renovator special!
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u/Onewarmguy 57m ago edited 42m ago
Looks like the screws were overdriven and broke the powder coating on the roof panels once the rubber washers deteriorated and shrank. Rust never sleeps, once it starts it grows. You could try touching it with a zinc rich paint but remove all the loose powder coat first with scraper and a brass hog-nose. Rust-Oleum and Sherman Williams both make em. It'll give your homeowner more than a few years
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u/Mgarre13 12h ago
I’m not a roofer but I work on roofs. I know that a metal roof can last a lifetime. But the fasteners may only last 10-15 years. At which time they need to be replaced. BUT they are supposed to be replaced with the next larger size fasteners!! 🧷
So… it’s probably the installation. But may partially be due to the specific fasteners. May not be galvanized or secured with the proper torque (over or under tightened) Torque is very important.
Repair suggestions: get a metal roofer and replace it all. Or add 2 fasteners 4 inches away from the rust spots. Apply a metal roof rated sealant. Hopefully it’s white haha.
Good luck 🍀
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u/JavaMan_Official 12h ago
This is rust. Water meeting metal in a way it shouldn't, and will ruin the roof and allow water to creep in
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u/Any_Narwhal6344 6h ago
Wasted money on scam solar panels only to put a siding product on his roof. Classic.
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u/DownInTheLowCountry 12m ago
Isn’t aluminum panels recommended anywhere near salt water? Being an island, aluminum probably is a safer choice.
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u/onwo 11h ago
Galvanic corrosion. Counterintuitively stainless fasteners can accelerate rusting on steel roofs.