We humans have been trying to find the most durable materials to put over our heads for quite some time, so metal has been a natural candidate (since we can’t make roofs out of diamonds). Copper was used as a roofing material as far back as the 3rd century BC on Sri Lanka’s Loha Maha Paya Temple and on Rome’s Pantheon in the year 27 BC. Metal makes up approximately 10% of the residential roofing market in America today.
There are several advantages to using metal as a roof covering:
- Durability: Some metal roofing materials will last over a century with only minor maintenance, and they can stand up to some of the most intense weather. Contrary to a common misconception, metal roofs are the safest in lightning storms because they disperse the electrical energy and are not combustible.
- Energy Efficiency: Modern metal roofing systems often employ reflective pigment technology, which results in lower energy costs for cooling the building.
- Less Waste: Conventional roofing materials like asphalt shingles contribute an estimated 20 billion pounds of waste to US landfills annually. Meanwhile, metal roofs are made out of 30-60% recycled materials (some are 100% recyclable).
- Aesthetics: Metals are very versatile materials and can be made into any number of shapes and can simulate the profile of any other roofing material, like asphalt shingles, wood shake, or ceramic tiles. They can also be painted any color imaginable (for full irony, go with a metallic shade!).
- Effective Watershed: On high slope roofs, metal is very effective at shedding water quickly and preventing leaks.
But, as with every material, metal has its fair share of disadvantages:
- Rust: Corrosion can form if the iron in steel becomes oxidized, causing discoloration and disintegration in places.
- Robbery: Valuable metals like copper and lead can occasionally be targeted by metal thieves. Yep, people steal roofs.
- Cellular/Radio Interruption: Some frequencies can be negatively impacted by metal roofs. Unless you stand on the roof, in which case your reception is phenomenal.
- Heat Conductivity: Metal conducts heat and expands and contracts as a result. If improperly fastened, this can lead to broken clips or unforeseen gaps in seams.
There are three notable types of metal roofs:
Corrugated metal roofs, also called roll-formed roofs, are made of metal panels that are rolled out in ridged patterns for stability and different aesthetic finishes. They are externally fastened (meaning that the screws go through the panels into the decking). They are generally the cheapest metal roofs on the market. Pro-panel roofs are roll-formed panels designed to look like standing seam.
Standing seam metal roofs are the most typical metal roofing system in the US. Also called “vertical seam,” these panels come together and join at seams that run perpendicular to the roof slope. These raised seams prevent water intrusion and run all the way from the ridge to the eave, making the roof look like a series of playground slides.
Modular press-formed panels are growing in popularity. They are essentially rolls of treated metal that a roofing manufacturer punches panel shapes out of, which can look like wood shake, tiles, shingles, or whatever else they fancy. These can be pre-painted in any number of pleasing hues, or can be granular-coated (given an acrylic coating and embedded with stone granules). That’s right; you can have a metal shingle shaped like wood and textured like stone.