Metal roof
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A metal roof is a roofing system made from metal pieces or tiles. They are components 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 countries like Australia and South Africa 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 of aluminium standing seam sheets, four acres of which are movable. Zinc / aluminium coated steel is the most commonly used roof sheeting material in Australia's cyclonic building codes.
- Durability.
- Sheet materials like stainless steel, copper, zinc, aluminium 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 aluminium 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 and are designed for different environments including the harshest of industrial or 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.
[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. Now rare and no longer manufactured.
- Galvanized steel. Still manufactured but rarely produced as mainstream roof profiles, except 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 colours. i.e."Colorbond". AKA Cool Metal Roofing.
- NOTE! Galvanized steel and Zinc/aluminum coated steel are NOT the same product. They are NOT compatible. Flashings, gutters, sealants for one should not be used with the other!
- Zinc. Standing seam wall and roof sheeting.
- Stainless steel. Available for harsh conditions, rollformed and fixed similar to corrugated steel profiles.
- Aluminum - One of the longest lasting metals, but somewhat expensive.
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Installing a copper roof in a park - 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 - Stone Coated Steel shingle panels are made from pressure formed, zinc/aluminum alloy coated steel with an acrylic, bonded, stone chip finish, which resists fading and UV penetration. The panels are lightweight (1.5 pounds per square foot) and walkable, and come in a variety of earth-toned colors. They are fireproof and come with a 120-mile (190 km)-per-hour wind rating and have a 50 yr to lifetime warranty against fading, cracking, rusting, curling and de-granulation. Stone Coated Steel panels come in a wide range of solid and Mediterranean blends and are available in both tile, shake, slate and shingle style They withstand all extreme environmental elements including Hail, Fire and Wind. Stone Coated Steel is ideal for flat to pitch conversions and can even be installed over existing roofs without the need for tear-off. Structural support is generally not required and can be walked on after installation, too. Nails are installed horizontally to provide greater resistance against vertical pullout due to high wind conditions.
- 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. 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
[edit] Further reading
- Metal Roofing Estimates
- Metal Roofing Case Studies, News and Directory
- Metal Roofing Alliance
- Metal Roofs Making A Comeback
