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  • Square (unit)


    The square is an Imperial unit of area that is used in the construction industry in the United States and Canada, and was historically used in Australia. One square is equal to 100 square feet. Examples where the unit is used are roofing shingles, metal roofing, vinyl siding, and fibercement siding products. Some home builders use squares as a unit in floor plans to customers. When used in reference to material that is applied in an overlapped fashion, such as roof shingles or siding, a square refers to the amount of material needed to cover 100 square feet when installed according to a certain lap pattern. For example, for a shingle product designed to be installed so that each course has 5" of exposure, a square would actually consist of more than 100 square feet of shingles in order to allow for overlapping of courses to yield the proper exposed surface. Buildings in Australia no longer use the square as a unit of measure, and has been replaced by square metres. The measurement was often used by estate agents to make the building sound larger as the measure includes the areas outside under the eaves, and so cannot be directly compared to the internal floor area.

  • List of roof shapes


    Roof shapes differ greatly from region to region. The main factors which influence the shape of roofs are the climate and the materials available for roof structure and the outer covering. Roof terminology is also not rigidly defined. Usages vary slightly from region to region, or from one builder or architect to another. Roof shapes vary from almost flat to steeply pitched. They can be arched or domed; a single flat sheet or a complex arrangement of slopes, gables and hips; or truncated (terraced, cut) to minimize the overall height.

  • Tar paper


    300pxTar paper is a heavy-duty paper used in construction. Tar paper is made by impregnating paper or fiberglass mat with tar, producing a waterproof material useful for roof construction. Tar paper is distinguished from roofing felt which is impregnated with asphalt instead of tar; but these two products are used the same way, and their names sometimes are used informally as synonyms. Tar paper has been in use for centuries. Originally felt was made from recycled rags but today felts are made of recycled paper products (typically cardboard) and sawdust. The most common product is #15 felt. Before the oil crisis, felt weighed about 15 pounds per square (one square = 100 square feet) and hence the asphalt-impregnated felt was called "15#" and "15-pound felt". Modern, inorganic mats no longer weigh 0.73 kg/m2, and to reflect this fact the new felts are called "#15". In fact, #15 mats can weigh from 7.5 to 12.5 pounds/sq depending on the manufacturer and the standard to which felt is made (i.e., CGSB, ASTM D227 Standard Specification for Coal-tar saturated Organic Felt Used in Roofing and Waterproofing, ASTM D4990, Standard Specification for Coal Tar Glass Felt Used in Roofing and Waterproofing, or none). Thirty-pound (30#) felt is now #30 felt, and usually weighs 16 to 27 pounds per square. Tar paper is more accurately a Grade D building paper (the Grade D designation derives from a federal specification in the United States), which is widely used in the West. Building paper is manufactured from virgin kraft paper, unlike felts, and then impregnated with asphalt. The longer fibres in the kraft paper allow for a lighter weight product with similar and often better mechanical properties than felt. Grade papers are rated in minutes—the amount of time it takes for a moisture sensitive chemical indicator to change colour when a small boat-like sample is floated on water. Common grades include 10, 20, 30, and 60 minute. The higher the rating the more moisture resistant and the heavier. A typical 20 minute paper will weigh about 3.3 lbs per square, a 30-minute paper 3.75, and a 60-minute paper about six. The smaller volume of material however does tend to make these papers less resistant to moisture than heavier felts.

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