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I want to replace my roof. Exposed-fastener metal roofs are popular and common where I live, but nobody nearby has owned one long enough to really comment on the longevity. I worry that over time, the metal's thermal expansion and contraction with ambient temperature changes will eventually enlarge the screw holes to the point where a million tiny leaks will appear. That doesn't sound good. It seems that rubber or neoprene washers are used to alleviate this danger but that seems like putting a band-aid on it.

For this reason, I'm looking at metal shingle and standing seam roofs, but both are more expensive. Are my concerns about an exposed-fastener metal roof justified? Or are we talking about a difference in longevity of like 50 compared to 100 years?

  • The better systems use EPDM rubber which has a much longer life than Neoprene or whatever generic rubber you mention. – Fiasco Labs Apr 19 '14 at 2:33
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I work for a metal roofing company, and this is a big area of concern for a lot of homeowners.

Here's what I can say: based on experience and facts.

8-10 years ago, the fasteners on exposed metal roofing were terrible. They failed CONSISTENTLY. There were very few competing fastener companies and rubber washers cracked and leaked like crazy. And when your next best option is a concealed fasten standing seam at twice the price, metal roofing was unpopular. At the time, metal roofing only represented about 2% of the residential market.

Fastforward to present day. There are several large fastener companies and there is a ton of competition for the best performing screw. Our company uses screws with a neoprene washer (already light years better than traditional rubber) that is independent from the screw head allowing overcorrection during install. They also have a slightly larger and slightly domed metal washer stacked on top which creates an umbrella for the neoprene that guards it against the UV rays that cause cracking. We are seeing screws that at this point can live roughly 50 years if not longer without failed washers. Some companies are now even offering screws with oversized heads and washers with military grade strength that are guaranteed for life, even against backing out! This year, in the Southeast, metal roofing saw a rise in popularity to 14% of the residential market, and the majority of it is an exposed fasten system. 2% to 14% in 8 years and we wouldn't have that kind of growth if the roof systems were failing consistenly.

Of course, DO YOUR RESEARCH. Buy from a reputable company that uses good screws and make sure that your installer is experienced with metal.

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  • Hello, and welcome to Home Improvement. Excellent answer; keep 'em coming. And, you should probably take our tour so you'll know how best to contribute here. – Daniel Griscom Jan 16 at 19:44
  • Your answer matches my recent experience. Since asking this question years ago, I've actually had an exposed fastener roof installed, and indeed, the installers used high-tech fasteners just like the ones you describe. They have very coarse threads to prevent backing out, with a neoprene washer fastened to a domed metal "umbrella" that's captured but independent of the screw head. The screws are very impressive, and I have high confidence in them after learning more about screw tech and watching the installation. – iLikeDirt Jan 17 at 20:18
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It depends on the quality of installation, but on average exposed fastener metal roofs (which do, indeed, use EDPM washers if not of very low quality and life-expectancy) are a 15-25 year roof, while a quality standing seam job is a 50 year roof. The EDPM washer is not a band-aid - it's a part of this roofing system design (and most of the fasteners are located on top of ribs so they see very little water - also part of the design.)

Standing-seam should be very similar for the basic cost of material and forming, but is always quoted much higher (IME) making it economically dubious despite the potential longer life.

A bad job of either may not be leak-free for a month.

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  • Thanks. How about metal shingles? Can a good metal shingle roofing job last as long as standing seam? – iLikeDirt Apr 19 '14 at 20:43
  • I doubt it, though I lack data. There are specific aspects of how standing seam works that make for long, leak-free life when done correctly. I doubt metal shingles replicate those aspects, but there are many ways to make metal shingles (not a product I've seen much, though) and some may work in favor of a long useful life. Many more joints probably work against them, though. – Ecnerwal Apr 20 '14 at 1:03
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    True, though the joints are hidden and lapped like other shingles. Rally they're very much like regular shingles that just happen to be metal. So wind-driven rain could infiltrate underneath them, for example. But they could probably be expected to physically last longer than asphalt shingles. – iLikeDirt Apr 20 '14 at 1:28
  • It's things like the wind being able to get under them (period) that make them (in my estimation) probably inferior to standing seam, which manages a system that holds the metal firmly on the roof and yet also lets it move with temperature changes. A strong wind event could wreak the sort of havoc it does on other shingles, where standing seam would be much more resistant to that type of damage. Standing seam also keeps the exposure of the edge of the sheet to a minimum - that's the Achilles heel of otherwise corrosion resistant coated steel roofing materials. I presume they cost less than SS. – Ecnerwal Apr 20 '14 at 1:39
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Your concern with exposed-fastener metal roofs is justified. But neoprene washers aren't a band-aid. They form a part of the design of metal roofs. If you want to go for exposed-fastener metal roofs be sure you get them of good quality and their installation is done correctly. Another solution is you can opt for a fastener with a non-metallic head fully covering the neoprene washer available at metal buildings colorado. This kind of fasteners makes the head of the fastener rust-proof, and thus the washer becomes virtually a lifetime product. On an average, the lifetime of such a metal roof is 20-30 years.

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  • You must disclose any affiliation you have with the linked website. – Doresoom Dec 11 '14 at 18:02
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I think it depends on where you live.

I live where we get a ton of rain and it blows sideways. When the metal roofing expands and contracts, it causes the head of the screw to move, thus the neoprene washer moves. It often gets “tweaked” from the movement causing one side of the washer to curl up. This allows wind blown rain to penetrate the roofing system.

Here, we use concealed fasteners. The cost is nearly the same and there’s no chance of leakage, because the fasteners are protected from the environment and the metal panels are connected together...but can slide due to expansion and contraction.

If you get much rain (or snow) I’d consider concealed fastener metal roof over exposed fastener metal roof.

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