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Metal Roofing Materials for Building

Metal roofing materials are being used extensively due to their durability, ease of installation, and other favorable characteristics. If the metal roofing materials are correctly selected, installed, and properly maintained, they will have an extended life. A metal roof is a roofing system made from metal pieces or tiles. It is a component of the building envelope. One of the main disadvantages of a metal roof is the noise created when it rains outside. According to the National Roofing Contractors Association, the popularity of metal roofing products has increased dramatically over the past decade, a clear sign that homeowners and builders are growing more and more aware of this product’s benefits. 

In fact, during the last 20 years, a whole new genre of metal roofing materials has hit the market. These are a far cry from the corrugated “tin” barn roofs that leap to mind at the mention of metal. They are high-tech answers to the need for durable, fire-resistant, lightweight roofing that looks at home on a house.

Advantages
Metal roofs can last up to 100 years, with installers providing 50 year warranties. Because of their longevity, most metal roofs are less expensive than asphalt shingles in the long term.

Metal roofing can consist of a high percentage of recycled material and is 100% recyclable. It does not get as hot as asphalt, a common roofing material, and it reflects heat away from the building underneath in summertime. On a larger scale, its use reduces the heat island effect of cities when compared to asphalt. Coupled with its better insulating abilities, metal roofs can offer not only a 40% reduction in energy costs in the summer, but also up to a 15% reduction in the energy costs in the winter according to a 2008 Study by Oak Ridge National Laboratory. This finding is based on the use of a strapping system of four inches between the plywood and "cool-color" metal on top, which provides an air gap between the plywood roof and the metal. Cool-color metals are light, reflective colors, like white. The study went on to say that re-sealing and insulating air ducts in the attic will save even more money.

Metal roofing is also lightweight, and can be installed on top of an existing roof. A lightweight roof is very useful for large and or old structures, as it helps to maintain the overall structural integrity of the building. Despite its light weight, metal roofing provides increased wind resistance when compared to other roofing materials. This is because metal roofing systems use interlocking panels.

Metal Roofing Materials
A huge variety of metal roofing materials with different characteristics of weight, color, durability, and cost is currently on the market. Roofing materials are selected during the design of structures. Mostly, the selection of roofing materials is influenced by the geographic and climate conditions of the area. All the metal roofing materials should be considered from the types of residential metal roofing that are available.

A roof in a locality that experiences extensive snow would require a particular slope angle for the discarding of snow. If the snow is not removed, the structure of the roof may be damaged due to pitting corrosion. Thus, the roofing materials selected accordingly will facilitate snow removal. Similarly, if the roofing materials are affixed simply with a few nails, high speed winds may be harmful. Metal roofs that are located near industrial sites or the sea may be seriously affected by corrosion.

The colors of metal roofs have an influence on the heat absorption and the energy costs. To ensure human safety, some states have regulations concerning the use of roofing materials. All of these aspects should be taken into account while selecting roofing materials. Roofing materials are permanent structures with long life, and therefore need to be carefully selected.

Characteristics of Metal Roofs Used in Residential Construction
Metal roofs applications
Metal roofing is an excellent material that is suitable for residential construction. Metal roofs are being utilized globally for the coverage of huge buildings due to their high ratio of strength to weight.

Metal roofs are expensive, and may be three to five times compared to the asphalt shingle roofs. Though metal roofing is expensive, it is widely being used due to its durability. The roofing can be shingled or flat. A large variety of metals are being used for the roofing materials, including steel, zinc, copper, and aluminum. All these materials have different characteristics that influence the quality, cost, and durability.

Advantages of Metal Roofing
There are numerous advantages of using metal roofs, including the following:metal roofs characteristics

Estimated Life
If the metal roof is installed correctly, it can endure as long as the building, sealing the water completely, enduring high speed winds, and detaching snow easily. Its resistance to fire, rot, and insects is excellent.

Weight
Metal roofs are lightweight compared to tiles, and are thus portable. Some form of metal shingle structure may be fixed with the existing roofing materials without any extra structural backing.

Simple Installation
Metal roofing materials are characterized by their simplicity in installation. Single metal shingles can be installed rapidly.

Fire Resistance
Since the metal roofs are noncombustible, they are considered to be the most fire resistant roofing materials.

Heat Conduction
Metals reflect heat from the sun, thus reducing the heat gain. The dead air space amid the roof deck and the metal is utilized to raise the energy efficiency. When fixed properly, metal roofs may reflect a substantial fraction of the sun's radiant energy, thus reducing the cooling costs.

Environmentally Friendly
Metal roofs are prepared by using environmentally friendly metals that are recyclable like steel, aluminum, tin, and copper.

Applications of Metal Roofing
Metal roofing is a multipurpose material for building construction that is used extensively for residential, industrial, and commercial buildings. It is also used for the covering of walls. There are numerous profiles available that are fitted according to the building structure. Shapes can also be varied to improve the aesthetic impact.

Coating 
Several different types of coatings are used on metal panels to prevent rust, provide waterproofing, or reflect heat. They are made of various materials such as epoxy and ceramic.

Ceramic coatings can be applied on metal roof materials to add heat-reflective properties. Most ceramic coatings are made from regular paint with ceramic beads mixed in as an additive.

Coatings are sometimes applied to copper. Clear coatings preserve the natural color, warmth, and metallic tone of copper alloys. Oils exclude moisture from copper roofs and flashings and simultaneously enhance their appearance by bringing out a rich luster and depth of color. The most popular oils are lemon oil, U.S.P., lemongrass oil, Native E.I., paraffin oils, linseed oil, and castor oil. On copper roofing or flashing, reapplication once every three years can effectively retard patina formation. In arid climates, the maximum span between oilings may be extended up to five years. Opaque paint coatings are primarily applied over copper when substrate integrity and longevity are desired but a specific color other than the naturally occurring copper hues is required. Lead-coated copper coatings are used when the appearance of exposed lead is desired or where water runoff from uncoated copper alloys would ordinarily stain lighter-colored building materials, such as marble, limestone, stucco, mortar, or concrete. Zinc-tin coatings are an alternative to lead coatings since they have approximately the same appearance and workability.

Material types
Originally, metal roofs were made of corrugated galvanized steel: a wrought iron–steel sheet was coated with zinc and then roll-formed into corrugated sheets. Another approach is to blend zinc, aluminum, and silicon-coated steel. These products are sold under various trade names like "Zincalume" or "Galvalume". The surface may display the raw zinc finish, or it may be used as a base metal under factory-coated colors. Another metal roofing product comes in a rolled form of various widths of so-called standing seam metal. The material is "seamed" together using a special seaming tool that is run vertically up the panel to seal the joints and prevent water intrusion.

Metal tile sheets can also be employed. These are usually painted or stone-coated steel. Stone coated steel roofing panels are made from zinc/aluminium-coated steel with an acrylic gel coating. The stones are usually a natural product with a colored ceramic coating. Stainless steel is another option. It is usually roll-formed into standing seam profiles for roofing; however, individual shingles are also available. Other metals used for roofing are lead, tin and aluminium and copper.

Copper is used for roofing because it offers corrosion resistance, durability, long life, low maintenance, radio frequency shielding, lightning protection, and sustainability benefits. Copper roofs are often one of the most architecturally distinguishable features of prominent buildings, including churches, government buildings, and universities. Today, copper is used in not only in roofing systems, but also for flashing and copings, rain gutters and downspouts, domes, spires, vaults, and various other architectural design elements. At the Lyle Center for Regenerative Studies in Pomona, California, copper was chosen for the roofing on regenerative principles: if the building were to be dismantled the copper could be reused because of its high value in recycling and its variety of potential uses. A vented copper roof assembly at Oak Ridge National Laboratories (U.S.) substantially reduced heat gain compared with stone-coated steel shingle (SR246E90) or asphalt shingle (SR093E89), resulting in lower energy costs.

Sheets are available in different sizes that are cut according to the requirement to precise lengths. The coil metals can be formed at site into panels. Metal roofing is also generally applied on an existing roof. In situations where the cost of labor is high, the application of metal roofing on an existing roof can save substantial expenditures as well as extending the useful life of the structure.

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