The Pros and Cons of Metal Roofing
Published: Sep. 26, 2018
What is Metal Roofing?
How is Metal Roofing Made?
When purchasing a metal roof, there are multiple materials to choose from. The most commonly used metals are galvalume coated steel, galvanized steel, stainless steel, aluminum, zinc, and copper. While these metals come from different sources, many are manufactured with the same method into standing seam roofing panels. The metals must go through a “roll former” - a machine that converts metal coils into roofing panels. This machine has many technical components that enable it to customize the panels for the correct design and fit.
History of Metal Roofing
The history of metal roofing dates back to the 1700s when lead and copper were the main metals used for roofs. At the turn of the 18th Century, the first facilities for rolling copper sheet metal were developed in America. Sheet iron was also first manufactured in the United States by Revolutionary War financier, Robert Morris, and the English created the first method for corrugating iron in 1829. From there, the history of metal roofing continued as a patchwork of experimental practices.
Advantages of Metal Roofing
- Durability: Metal roofing is relatively durable in comparison to other roofing materials. Some metal roof types can withstand winds of up to 140 mph, won’t corrode or crack, and can be impact resistant depending on the size of the hail and the type of metal. This durability prevents leaks from rain or snow.
- Lifespan:: The average lifespan of an asphalt roof is between 12-20 years, while the average lifespan of a metal roof is 40-70 years. In fact, most metal roofs come with a lifetime limited warranty that guarantees at least 50 years of use.
- Environmental Impact:: Unlike asphalt shingles, metal roofs are made of 25-95% recycled material and can be recycled again at the end of their lifespan. Many other roofing products, like asphalt shingles, can’t be recycled and end up in landfills. Additionally, metal has great solar reflectivity which can lead to reduced energy bills.
- Safety:: Metal can be an electrical conductor, but contrary to popular belief, metal roofing does not attract lightning, nor is it any more likely to be struck than any other type of roofing. Furthermore, metal roofing is fire resistant. External fire dangers like embers from bonfires, neighborhood fireworks, or lightning pose less of a threat to a metal roof than cedar shakes or other roofing materials.
- Rain and Snow Shedding:: Because of the often sleek, hard surface of metal roofing panels, snow and rain easily slide off.
- Easy Installation:: Metal roof materials typically come in multi-shingle sections or 12-36 inch-wide panels. Therefore, the process for installing a metal roof is oftentimes faster than other roofs.
Disadvantages of Metal Roofing
- Initial Cost: The initial cost of a metal roof can be triple the cost of other types of roofs. Additionally, before purchasing a metal roof, it’s important to consider if you’ll be moving any time soon. Metal roofs generally don’t pay themselves off for many years.
- Paint Peeling and Denting: While metal roofs are durable, they aren’t immune to paint peeling or denting. However, many metal roofs have paint warranties for up to 30 years. Because of their sleek, hard surfaces, metal roofs sometimes require being hosed down every now and then to keep them clean. Additionally, contractors must be careful not to dent or scratch the roof during the installation process. Aluminum and copper roof materials are more susceptible to denting during installation or hailstorms because they’re softer metals. However, strong metal roof materials that aren’t as susceptible to hail (like steel) are available.
- Slippery and Difficult to Cut: In case of a fire or other household emergency, working on a metal roof can be tricky. The sleek surface is often slippery, so you must use extra caution if you or a contractor needs to walk on it. This is usually only an issue if there’s an emergency or home repair project, however, because most metal roofs are installed from the top down making it unnecessary to walk on them during the installation process. While a metal roof acts as great protection from external fire dangers, they can act as a hindrance for internal house fires in which firefighters have to cut into the roof to put out the fire. This is less of an issue for asphalt roofing and other roofing materials that are less dense.
- Expansion, and Contraction: Metal has a tendency to expand in heat and contract in cold. Therefore, metal roofing must be installed with fasteners that allow for some movement among the panels and shingles. Otherwise, the roofing may come loose or develop a wavy appearance.
- Noisiness: Most people are familiar with the sound of rain hitting a tin roof. Some people enjoy this sound, while others are annoyed by it. In fact, rain hitting a metal roof is typically noisier than rain hitting a slate, cedar, or asphalt roof. Either way, it’s important to consider the noise level of a metal roof before purchasing one.
Alternatives to Metal Roofing
There are multiple alternatives to metal roofing in addition to the more obvious ones (asphalt shingles and cedar shakes). Slate tiles and composite polymer roofing materials can offer a durability and recyclability similar to metal roofing. Additionally, asphalt corrugated roof panels look similar to metal roofing and also come in sheets.
Hail isn’t likely to penetrate a metal roof, unless it’s old and rusted, but large hailstones can leave indentations. In a study on impact resistance conducted by the Roofing Industry Committee on Weather Issues, hail damage was viewed as mostly cosmetic for the metal roofing materials. Additionally, many metal roofing materials have a Class 4 hail rating given by the Underwriters’ Laboratory.
With regard to wind, some of the most wind-resistant roofs are made of metal. In fact, according to State Farm, some metal roofs can withstand winds up to 140mph. In contrast with asphalt shingles or other shingle roofing, many metal roofs have panels with fewer seams for wind to penetrate. This helps prevent splitting or lifting of roofing materials during windstorms.
All metal roofing is fire resistant and has a Class A fire resistance rating. The metal used in metal roofing is non-combustible.
Metal Roofing and Solar Reflectance
Metal roofing reflects radiant heat from the sun and reduces excess heat absorption that occurs in the middle of the day. During the summer months, this can help keep your house cool and reduce your air conditioning bills.
The raw materials for a metal roof are relatively inexpensive. Metal panels often cost around $1 per square foot, which puts them on-par with architectural shingles and 20-40% more expensive than asphalt 3-tab shingles.
However, there are many variables that impact how much you’ll pay for having a metal roof installed, including the size of your house, the metal you choose, and your location. The best way to receive the most accurate quotes for your prospective installation is to call your local roofing contractors and manufacturers.