Aleksandr Biyevestskly- try spelling that five times fast- wrote an excellent article about myths of metal roofs- he cites 6 big ones:

Myth 1: Metal roof has a higher risk of getting struck by a lightning.

Reality; No metal roofing does not increase the chances of your house getting struck by a lightning. In fact, if your house does get struck, metal roof will help to dissipate the charge, and because metal is a non combustible material, your roof will not catch fire.

Myth 2: Metal roof makes a lot of noise when it rains.

Reality; You are probably thinking about that old cheap metal roof over the barn that used to sound like a machine gun burst when it is raining… Modern metal roofing is usually installed over a plywood, solid sheathing, or over your existing roof. It will make no more noise than a regular asphalt shingle roof. Oftentimes metal roof will be quieter than a non metal roof, and will shield the noise from rain and bad weather.

Myth 3: Metal roofing costs a lot of money.

Reality; It may seem like it does, but it really does not! You may be surprised, but metal roof will actually costs less than the asphalt shingle roof if you stay in your house long enough. Not only will it increase the value of your house, but it will also help you save money on cooling costs. Metal roofing can result in up to 50% savings in energy costs during summer months. And finally, metal roof may well be the last roof you will ever have to install on your house. Ever! Provided you get a quality installation from a qualified metal roofing contractor….

Myth 4: Metal Roof is susceptible to rust.

Reality; Modern metal roofing is built to last for decades. Steel metal roofing has a metal coating protection layer made with zinc or aluminum, which is bonded to the steel and then painted with a high quality paint designed to withstand the toughest abuse from bad weather, and provide the desirable color and looks that homeowners want.

Myth 5: Metal Roof is susceptible to dents.

Reality; Modern metal roofs are built to withstand years of abuse from severe weather such as hail, extreme winds, and snow. Hail will not dent a metal roof, and extremely high winds are not a threat either, as many modern metal roofing systems are rated for 120mph winds. In fact, metal roofs perform extremely well in the hurricane. It is not unusual to see the metal roof with no damage, next to naked regular roofs that have lost all its shingles and plywood in hurricane….

Myth 6: You cannot walk on metal roof without damaging it.

Reality; While you should definitely take all the necessary precautions before venturing out for a walk on your roof, metal roofs are completely walkable. I would recommend using running shoes…, because they will provide good traction for your feet when on the roof. Avoid walking on your roof when its raining as you could easily slip and fall. Rule of thumb is to stay of the roof whenever its surface is wet. Contact your roofing contractor for special techniques on how to walk on the metal roof they have installed.

via Metal Roofing-Top 5 Metal Roof Myths Dispelled!.

And, of course there is the reality- that some people like the sound of rain on a metal roof- but, again, it all depends on insulation, sub-deck and other factors. When you realize that any additional costs of the metal are balanced out by the less expensive labor, the longer life, and that metal roofs don’t fill landfills- there are really no down sides to installing metal roofs.

Historically- metal roofs were sold as “fireproof roofs” and were often installed over wooden shakes- which were prone to catching fire. If you live in an area that’s susceptible to wildfires- a metal roof is a very good investment.

Roofs typically don’t get attention until they leak, often by that time, it’s a little late. It really doesn’t matter what kind of roof system you have- keeping it clear of debris and not having tree branches beating on it- are all good basic concepts.

The debris from a black walnut tree can stain and discolor a roof- as well as hold water that can begin the process of deterioration. A simple sweep of the roof with a soft broom- or using a leaf blower- can make sure all this detritus doesn’t start to cause problems.

Preventive maintenance is covered nicely in this post from FacilitiesNet:

Proper maintenance plans for metal roofing include regular inspections to check for distress conditions, which can include: movement distress of panels and fasteners; sealant failures; fastener gaskets; damage from snow, ice or hail; failures of surface coatings; and drains and gutters clogged with debris.

Technicians should replace fastener gaskets when they reach the end of their expected service lives. They also should inspect and replace sealants at penetrations and perimeters as needed. Most sealants will not last more than 20 years, but some butyl sealants retain their bond and elasticity far longer.

Maintenance technicians should walk directly over joists and purlins to prevent accidental bending or dishing of sheet metal roof panels. They also should minimize foot traffic on sheet metal roofs because scratches can expose the steel sheet, creating the potential for corrosion. Technicians also should be careful not to scratch the surface when walking on or cleaning debris off a sheet metal roof.

via Maintenance Best Practices for Metal Roofing.

Caulk and sealers should be checked annually- and gutters should be cleaned at least twice a year. Clogged gutters are the number one cause of ice damns which then cause roofing failures.

Standing seam metal roofs can get extremely hot in direct sunlight- so it’s best to inspect roofs early in the day, before the surface gets too hot to walk safely. On steeply pitched roof- a safety harness is highly recommended because of the slick footing of metal compared to composite shingles or rubber.

With proper care, a metal roof will outlast any asphalt roof by a factor of 3 or 4. These simple maintenance routines should help guarantee it.

Galvanized steel drip edges are used at the eave of the roof to protect the fascia, provide support for the shingles, and to create an edge where water can shed either into a gutter or away from the fascia. Xebec3 offers a wide variety of painted and unpainted drip edges suitable for a broad range of weather conditions. In general, areas with snow and ice or high winds use drip edges with larger decks and heavier gauges. Galvanized steel drip edges are the strongest option for severe conditions.

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“REPEL™ Synthetic Underlayment offers a superior performing alternative to conventional asphalt-based roof underlayments and is ideally suited for metal roofing applications. This metal roof underlayment is constructed of a high-strength woven polypropylene fabric coated on both sides with a specially formulated anti-slip walking surface, REPEL™ Synthetic Underlayment offers outstanding nail sealing ability and UV resistance and can be exposed for up to six months. This REPEL™ Synthetic Underlayment’s light gray color reduces heat gain and provides a cooler working roof underlayment.

REPEL™ Synthetic Underlayment was designed with the metal roof contractor in mind and is seven times lighter than 30 lb asphalt felt paper. This metal roof underlayment comes in 48” wide, high coverage 10 square rolls which allow for easy installation with less waste material. REPEL Synthetic Underlayment’s productivity savings allow you to offer your customers a better performing metal roof underlayment without adding cost to your project.

* 25 Year Limited Warranty
* 6 Month UV Exposure Rating
* UL Class A Fire Rated
* Code Approved
* Anti-Slip Surface
* Lightweight
* Tear-Resistant

Please Click here for the REPEL Synthetic Underlayment sell sheet

Aluminum drip edges are used at the eave of the roof to protect the fascia, provide support for the shingles, and to create an drip edge where water can drip either into a gutter or away from the fascia. Xebec3 offers a wide variety of painted and unpainted aluminum drip edges suitable for a broad range of weather conditions. In general, areas with snow and ice or high winds use aluminum drip edges with larger decks and thicker metal. Aluminum drip edges are light and corrosion resistant, but not as strong as galvanized steel drip edges.

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Copper roll flashing can be used in a wide variety of applications and is especially popular with treated lumber or in areas requiring a very high level of corrosion resistance. Xebec’s copper flashing utilizes a polymer backing to isolate it from dissimilar metals. As copper weathers, it retains a light green patina. Union offers 3 ounce copper in 8″ and 20″ wide rolls that are 20′ in length.

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Union’s patented bendable vinyl roll flashing can be used much like aluminum, steel, or copper flashing and is completely this vinyl flashing is corrosion resistant and safe to use with treated lumber. The vinyl flashing’s patented technology allows the vinyl to hold a bend without breaking so complex parts can be formed in the field with a typical metal brake. Xebec3′s vinyl flashing is 0.015″ thick and comes in 10″ to 20″ widths up to 50′ in length. Both white and tan vinyl flashings are offered.

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Galvanized steel roll flashing, sometimes referred to as valley metal, is used in a wide variety of applications. The galvanized metal roofing flashing is typically field formed and used in a flashing or trim capacity for various areas of a home which may include valleys, chimneys, fascia, endwalls, sidewalls, and many others. Galvanized metal flashing has the best strength of comparable flashing materials but the galvanized metal flashings can eventually rust, especially along cut or exposed edges. Union offers mill finished galvanized steel flashing in widths from 10″ to 20″ and up to 50′ in length.

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Aluminum roll flashing, sometimes referred to as valley metal, aluminum roll flashing is used in a wide variety of applications. Aluminum roll flashing is typically field formed and used in a flashing or trim capacity for various areas of a home which may include valleys, chimneys, fascia, endwalls, sidewalls, and many others. Aluminum roll flashing will not rust and is light and easy to work with, but it’s not as strong as galvanized steel flashing. Union offers both painted and unpainted aluminum flashing rolls ranging from 6″ to 20″ in width and up to 50′ in length.

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Unionís ML200 panel is a mechanically seamed standing seam system that can be used for structural or architectural applications. The mechanically seamed standing seam system panel is secured with concealed clips and the panel side laps are locked together using a rooftop seaming machine. This type of standing seam system provides very high wind uplift resistance and structural integrity. ML200 standing seam system can be specified as an accent feature or a total roof system for schools, shopping centers, banks, hotels, offices, and a variety of other applications.

Gauge Options:
24

Finish Options:
Painted Grades
KYNAR

Unpainted Grades: Acrylic coated Galvalume

Available Colors for 26 Gauge:

Click here for care and maintenance instructions

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Testing and Certifications
Testing and Certifications
ASTM E-1592 Wind Uplift
ASTM E-1646 Water Infiltration
ASTM E-1680 Air Leakage
UL-90 Wind Uplift
UL Class A Fire Resistance

Installation
The ML200 mechanically seamed standing seam system can be installed on a solid deck or open steel framing with slope greater than 1/2 :12.