The Merits and Drawbacks of Metal Roofs

Metal Roofs Do Not Attract Lightning

House roof
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Metal roofs are an increasingly common choice, both in new construction and when an aging roof needs to be replaced. Metal roofing products can be made from a variety of metals, including galvanized steel, copper, aluminum, or tin, and they can use several different installation systems. There are a great many advantages to a metal roof, but also a few disadvantages to consider.

Surprisingly, one of the main fears people hold about metal roofs is entirely without merit: metal roofs do NOT attract lightning.


Metal Roofs and Lighting

The misconception that metal roofs attract lighting is probably owing to the fact that metal itself is known as a good conductor of electricity, and people therefore assume that a metal roof must attract lightning. In reality, though, when lightning strikes, it is seeking a path to ground, and almost always will strike whatever object is highest in the area that also has a direct path to ground. Your metal roof is not grounded, and thus lighting has no reason to strike it.

A metal roof in no way makes your home more vulnerable or susceptible to lightning strikes. 

Some Actual Disadvantages to Metal Roofs

Fear of lightning strikes may be an imaginary problem, but there are a few genuine disadvantages to metal roofs.

The one disadvantage that poses an actual safety risk is the fact that metal roofs are indeed slippery when wet or when covered with snow. It is never a good idea to climb on a metal roof when it is moist or covered with snow.

They are so slippery, in fact, that snow "avalanching" off the roof is a definite hazard in areas that experience heavy snowfalls in winter. There are some advantages to this since snow that slips off the roof can't build up on top of it. People owning asphalt-shingled homes in heavy snow areas may need to rake snow off their roofs in winter, but this is never an issue on a home with metal roofs.

But it is also possible for snow to avalanche off a metal roof in such quantities that it can damage decks, shrubs, cars, or even people. 

In ski areas notorious for heavy snowfalls, metal roofs are often equipped with snow guards—metal or plastic clips or even horizontal bars mounted to sturdy brackets. Homeowners can employ the same technology to prevent avalanches from the roofs of their homes

Even when dry, metal roofs will be more slippery than other types of roofing. If you do need to climb on a metal roof, your first line of protection is a good pair of boots that grip to your type of metal roofing (ask the roofing manufacturer or a local installer for recommendations). If you're doing any significant work on the roof or moving any materials around, you should use standard fall-arrest equipment, including as a harness with a safety rope attached to a roof anchor. Anchors for standing seam metal roofs clamp onto the seams so you don't have to drill holes in your roof. 

Other disadvantages of metal roofs are not matters of safety, but merely issues of convenience or affordability: 

  • Metal roofs can be loud during rainstorms or when hail falls. It's a simple fact that any object falling on a metal roof will be louder than objects falling on an asphalt shingle or wood shake roof. Modern installation processes can insulate somewhat against this noise, though, and over time, owners of metal roofs seldom view this as a serious disadvantage. 
  • Metal roofs can fade in time or may be susceptible to staining. 
  • If not installed correctly, metal roofs can fail at the seams. It's essential to have a metal roof installed by a qualified, experienced contractor. 
  • Metal roofs are considerably more expensive than most other options. When compared to an asphalt shingle roof, for example, a metal roof is at least twice as expensive. Remember, though, that the average metal roof lasts much longer than an asphalt shingle roof. 

The Advantages Greatly Outweigh the Drawbacks

Metal roofs continue to grow in popularity, and one of their "disadvantages" actually turns out to be an advantage when viewed from the big picture. Although initially much more expensive than an asphalt shingle roof (for example), a metal roof lasts much, much longer, and in the final measure is usually the better investment.

Among the many advantages of a metal roof: 

  • Typically lasts for 50 to 75 years or even more, vs. the 15 to 25 years of life expectancy for an asphalt shingle roof
  • Surface reflects heat, lowering cooling costs in hot climates
  • Less susceptible to leaking than shingles, when installed correctly
  • Resists wind damage better than other roofing choices
  • Metal roofs are fireproof, making them good choices in areas where wildfire is a risk
  • Metal roofs are recyclable when they reach the end of their useful life