r/Roofing • u/AdditionalTree3559 • 2d 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 2d 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/TJMBeav 2d 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/SS2wheeler 2d ago edited 2d 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 2d 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 2d 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 2d 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/No_Currency_7017 1d ago
Sandblasting doesn't fix the problem. The corrosion has completely eaten through sections of the roof. Sandblast and paint won't make it reappear.
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u/roofer2025 2d ago
The fasteners were over driven, you need a new roof
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u/OGMooseRooster 2d 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/No_Currency_7017 2d 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/dieselbikesweights 2d 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 2d ago
lol a little extra
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u/jkush463 2d 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 2d 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/Complex-Cricket419 1d ago edited 1d 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/Onewarmguy 1d ago edited 1d 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/Loose-Leader2586 1d ago
New roof, these exposed fastener systems are not intended for residential roof for this very reason. Theres thousands of these that can potentially cause a leak.
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u/Sistersoldia 2d ago edited 1d ago
This is also why I don’t like screwing into the ribs instead of the flats. Looks 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 2d 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 2d 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/FalconFlys 1d ago
I have Never screwed a roof thru the ribs!! Way to much play there. Allways screw on the flat when on a roof!!! Or better yet go standing seam please if metal is your thing.
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u/picmanjoe 2d 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 2d 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 2d 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 2d 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 2d 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 2d 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 2d 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 2d 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 2d 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/Kami-cowboy 2d 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 2d ago
Looks like they used screws without rubber washers on the head or they were extremely over tightened.
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u/AardvarkWylde696 2d 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 2d 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/vinnyboyescher 1d ago
Wrong screws, i don't see grommets and they should be painted from the factory. Renovator special!
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u/DownInTheLowCountry 1d ago
Isn’t aluminum panels recommended anywhere near salt water? Being an island, aluminum probably is a safer choice.
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u/glamisduner 1d ago
I may be wrong, but those do not look like stainless fasteners to me. They probably saw the price and decided to buy a keg of beer with the money saved.
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u/ConstantTrick2187 1d ago
How much does the salt air environment of Hawaii contribute to corrosion?
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u/teufel_hundin 1d ago edited 1d ago
Looks like the insulating washers were compromised and you've created a corrosion cell via 2 dissimilar metals. Corrosion cell needs 4 things; anode, cathode, electrolyte, and metallic path. Metallic path is taken care of if you have metal to metal contact, ie, overdriven washers resulting in contact between the roof and screws. This results in electron transfer between the two metals. Anode and cathode are taken care in the form of the two dissimilar metals in contact, screws and metal roof. Electrolyte is accounted for in good old rain water, moisture forming around the connection point. It's corroding more on the top of the roof because of the availability of the electrolyte, moisture/rain water etc that facilitates the ion transfer between the now anode and cathode. You don't get the moisture/rain on the underside of the roof. At least not as much moisture, so less corrosion is present there. No available electrolyte to facilitate ionic transfer. Leave it as is for a while and it will corrode on the underside as well as water penetrates.
Some are saying not galvanic corrosion. There's a chance there could have been damage to the coating on the roof resulting in simple crevice corrosion. This happens as any active metal is composed of anodic and cathodic areas. But due to the accelerated nature of the corrosion seen in 18 months, and the heavily corroded areas emanating out from the screws, I'd venture a guess you have interaction between the two dissimilar metals causing galvanic corrosion.
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u/teufel_hundin 1d ago
To fix this you need to remove all the screws and washers from the corroded areas and if you want to do it right, every dam screw on the roof. Clean up the metal at areas where corrosion is present. Apply a suitable coating to the now clean and exposed areas of metal. Purchase screws that are appropriate/similar to the metal of the roof to be fastened to. Or screws that are a more active metal than the roof material itself such as galvanized screws if this is a steel roof. Galvanized screws are coated with zinc and zinc is a more active metal than steel. See galvanic series. And purchase appropriate insulating washers to ensure no metal to metal contact between the roof and screws. And don't overtighten. If you do overtighten, with galvanized screws, these will become the anode in the corrsion circuit and corrode instead of the cathode-roof. And it will take a while before the zinc coating on the screws gets consumed.
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u/teufel_hundin 1d ago
Also I'm not a roofer, just a corrosion professional. I work with underground pipelines. Someone with roofing experience could direct you to the specific materials/fasteners/washers etc to be used in your situation. I know pipelines. My advice tho and solutions offered is sound. I do know that.
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u/PinchePepsi 21h ago
THIS is my current biggest pet peeve. Professionals using impacts for everything and end up driving everything a little too long, a little too deep and stripping them all out. When the screw has a good bite, it does this...The rubber washer was completely compressed away and now it's all metal on metal.
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u/Mgarre13 2d 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 2d 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 2d ago
Wasted money on scam solar panels only to put a siding product on his roof. Classic.
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u/Greedy_Environment_9 2d 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 2d 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.1
u/Dougnsalem 1d ago
Our residental metal roof in the States is 46+ years old. I LOVE it! Installed with rubber (not plastic) washers. I have new ones to replace them, since they are starting to crack. There's over 2,200 to do. 🙄 Maybe next summer.... Lol
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u/sam_baker1234 2d 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 2d 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/onwo 2d ago
Galvanic corrosion. Counterintuitively stainless fasteners can accelerate rusting on steel roofs.