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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?

iLikeDirt
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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.

Samantha
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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.

Lee Sam
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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.

Ecnerwal
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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.

Marvin Williams
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Don't smash the neoprene washer when screwing. 10 more years of life. I've done many 5-V roofs down south and seen lots of rubber washers degrade before their time due to this. Also depends on the steepness of the roof, I love a metal roof. Bob from Philly

Bob Law construction
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