Ballast, as defined by Wikipedia, is a “material that is used to provide stability to a vehicle or structure.” The use of ballast is the original method of waterproofing, and utilizes dirt, sod, palm leaves and other natural materials to shed water. These items, along with gravel and stones, are subsequently used to ballast rags, paper, felts and membranes on a roof.
Today’s ballast remains primarily gravel and stone, but also includes concrete and polymer paver blocks, garden roofs and other multi-purpose components.
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Simply stated, mechanical attachment refers to the use of galvanized steel, stainless steel, polymer, or aluminum nails or screws to attach the paper, felts, or membrane directly to or through the structural decking. A steel or plastic plate is used to distribute the strength of the fastener over a broader area.
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Adhered roofing systems use adhesives to “completely” bond the felt or membrane to suitable substrata which have been bonded or attached to the structural component. Adhesives are applied as either contact (single-side) or bonding (double-side) applications using water, solvent, urethane or asphaltic based compounds.
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Partially Adhered roofing systems use urethane adhesives in a ribbon attachment to membrane to suitable substrata which have been bonded or attached to the structural component.
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Induction Welded roofing systems are similar to mechanically attached application in that a nail, screw or fasteners and a coated metal plate are used to distribute the strength of the fastener over a broader area. This plate includes a coating to allow for the induction welding of the top surface of the plate to the bottom of the membrane.
Learn more about Induction Welded roofing systems here.
Which roofing system do you prefer to specify/install? Share your thoughts in the comments.