Metal roof
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A metal roof is a roofing system made from metal pieces or tiles. It is a component of the building envelope.
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[edit] Advantages of a metal roof
- Light Weight.
- One of the major advantages of metal roof sheeting is that, in most of its forms, it is light weight, and therefore portable.
- Metal roof sheeting in the form of Corrugated galvanized iron was a great aid to opening up in their early days. This is still happening today in parts of the developing world.
- Metal roofs are used almost universally to cover large buildings because of their high strength to weight ratio. The roof of the new Wembley Stadium is an example. It consists of approximately 40,000m² or 11 acres (45,000 m2) of aluminium standing seam sheets, 4 acres (16,000 m2) of which are movable. Zinc / aluminum coated steel is the most commonly used roof sheeting material in Australia's cyclonic building codes.
- Durability.
- Sheet materials like stainless steel, copper, zinc, aluminum and lead are inherently durable; the oxidization of the base material forms a protective patina.
- Modern steel roof sheeting is coated with an alloy of zinc and aluminum to give it some of the durability of each of those materials at a lower cost and higher strength than either.
- The coatings and fixings on steel roof sheeting can be designed for different environments including industrial and marine locations.
- Design flexibility
- Large sprung curves.
- Rolled bullnose shapes.
- Copper Cupolas.
- Energy efficiency.
- Coatings with high reflective values to steel sheeting increase the thermal efficiency of buildings in high temperature areas.
- Fire and spark resistant.
- Metal is readily recyclable.
- Long Lasting Roof Material
- The average life-span of asphalt shingles is 10-17 years, while metal roofing usually lasts from 40-75 years, depending on the type.
- Labor efficient
- Steel roofing can be installed over open framing, or on a solid substrate. Many metal roofing materials are either screwed in place, or snap together. The amount of labor required to install a metal roof, is less than conventional roofing methods.
[edit] Applications of Metal Roofing
- Metal Roofing is a very versatile building material. It is durable. It can be used on residential, commercial, industrial, or agricultural buildings. It is not only used in roofing applications, but also may be used as a wall covering. There are many different profiles and styles available to fit most every building situation.
- Metal roofing in New Construction
- Metal roofing is ordered per each piece, whether it be in sheets, trims, or ridge material. When properly estimated, there is very little waste material in a new project. Sheets can be ordered and cut to exact lengths, allowing for less on the job cutting.
- Metal roofing in Remodeling
- Metal roofing is easily applied over an existing roof. Especially in situations where labor cost cutting is essential, the added value of not having to remove the existing roof material can be of a large help.
- Metal roofing in New Construction
[edit] Disadvantages
- Care must be taken on large roofs to provide for thermal movement.
- Movement caused by differences in temperature may cause objectionable noises in some roofs, for example curved roof surfaces.
- Care must be taken with all metal roof products to avoid incompatible materials. Dissimilar metals can cause unexpected and rapid corrosion.
- Metal extraction, refining, and production and transport of metal roof components is energy-intensive and almost always a non-local activity.
[edit] Types of Metal Roof
- Corrugated galvanized iron describes the original product that was wrought iron plate coated with zinc and then roll formed into corrugated sheets. This product is still used in some areas.
- Galvanized steel. Still manufactured but mostly used for heritage products.
- Zinc 55% / aluminum 43% / silicon 1.6% coated steel. Sold under various trade names. i.e. "Zincalume". Often left in the zinc finish, but more widely with factory coated colors.
- Metal tile sheets.
- Stainless steel. Available for harsh conditions, rollformed and fixed similar to corrugated steel profiles.
- Aluminum - One of the longest lasting metals, but somewhat expensive. Aluminum roofs are lightweight, corrosion-resistant, and have high reflectivity, which may help increase a building's energy efficiency.
- Copper - Usually used for flashing or very small sections like covered entryways. Expensive. At the Lyle Center for Regenerative Studies copper is used for regenerative principles of sustainable design: if the building were ever to be dismantled the copper would be reused because of its high value and variety of possible uses.
- Stone coated steel - Panels made from zinc/aluminum coated steel with acrylic chip.
- IBR or Inverted Box Rib is a low-cost corrugated square-fluted iron roofing used mainly in the South African market. It can be commonly seen all the way from industrial sites to low-income shacks.
[edit] Maintenance
Metal roofs will need recoating once the factory finish wears off or corrosion will occur. Roof coatings are the preferred material since they are able to stay elastic and withstand the thermal cycling that occurs in metal roofs.
[edit] Metal Roof Coatings
Many different types of coatings are used to coat metal panels. These types include asphalt or polymeric (elastomeric) coatings. Each Coating has its own advantages and disadvantages.
[edit] See also
- Metal Roofing Alliance
- Corrugated galvanized iron
- Cool roof
- Green building
- Metal Building Manufacturers Association
