R-VALUE: The resistance of a material to heat transfer. Insulators have relatively high R-Values. Units are °K•m2/W (°F•ft2•hr/Btu).
RACKING TEST: Colloquial name for ASTM E 72, “Standard Methods of Conducting Strength Tests of Panels for Building Construction.” ASTM E 72 tests a stud wall’s resistance to wind, seismic, and weight loads.
RCI: Roof Consultants Institute.
RADIANT BARRIERS: Typically in the form of a single highly reflective sheet or coating (e.g., aluminum foil or metallized mylar), radiant barriers are applied as a component of the building enclosure to inhibit heat transfer by thermal radiation. They do not provide resistance to heat transfer by conduction or convection.
RECOVERING: The process of installing a new roofing system over an existing roofing system.
RECYCLE CONTENT: The proportion of material (typically percentage by weight) in an end-use product that contains previously used materials. Recycle content can be further classified as “post-industrial” or “post-consumer.” The former refers to re-use of by-product materials that are created during the manufacturing process, while the latter refers to waste materials that come from the consumer sector.
REFLECTANCE: The fraction of incident radiation (usually the visible spectrum of sunlight) that is scattered (i.e., not absorbed or transmitted) by a surface. Reflectance is expressed as a number between 0–1 or as a percentage between 0%–100%. Cool roofs and reflective coatings have high reflectance values. (See also REFLECTIVITY.)
REFLECTIVE INSULATION: Similar to radiant barriers, reflective insulations are made from multiple sheets of highly reflective film that inhibit heat transfer by radiation. Multiple sheets of the reflective film are formed to create thin air pockets that can reduce heat transfer by conduction and convection in certain applications. Examples of reflective insulation would be a metalized bubble-wrap material or foil panels that unfold or deploy into a sheet with integral air compartments.
REFLECTIVITY: See REFLECTANCE.
REGLET: (1) An interlocking two-part flashing between a wall or other vertical surface and a roof. (2) A sheet metal clamp or receiver attached to a wall to which a counterflashing may be affixed. (3) A groove in a vertical surface to which a counterflashing may be affixed.
RELATIVE HUMIDITY: The ratio of absolute humidity to saturation humidity, expressed as a percentage.
RENEWABLE CONTENT: See BIO-CONTENT.
REPLACEMENT: The process of removing an existing roof and installing a new roofing system.
RE-ROOFING: Either the recovering or the replacement of a roofing system. (See RECOVERING; REPLACEMENT.)
RESIDENTIAL ENERGY SERVICES NETWORK (RESNET): A trade association of energy raters (HERS Raters) serving the residential market. This organization provides training and certification to home energy raters. Certified home energy raters must evaluate the entire energy use of a residential building in order for the building to become EnergyStar certified.
RESIN: (1) Component-B in SPF. This component contains a polyol, catalyst, blowing agent, fire retardant, and surfactants. It is mixed with the A-component to form polyurethane. (2) General term applied to a wide variety of more or less transparent and fusible products, which may be natural or synthetic. Higher molecular weight synthetic resins are referred to as polymers. (3) Any polymer that is a basic material for coatings and plastics.
RESNET: See RESIDENTIAL ENERGY SERVICES NETWORK.
RESPIRATOR: A device designed to protect the wearer from inhaling harmful dusts, fumes, vapors, and/or gases. Respirators come in a wide range of types and sizes. There are two main categories: (1) the air purifying respirator, which forces contaminated air through a filtering element; and (2) the air-supplied respirator, in which an alternate supply of fresh air is delivered. Within each category, different techniques are employed to reduce or eliminate noxious airborne contaminants. Some respirators require medical screening and fit testing. (See AIR PURIFYING RESPIRATOR; POWERED-AIR PURIFYING RESPIRATOR; SUPPLIED-AIR RESPIRATOR.)
RESPIRATORY PROTECTION PROGRAM: An OSHA requirement whereby any employer who requires or permits employees to wear a respirator must have a written Respiratory Protection Program. The written respirator program establishes standard operating procedures concerning the use and maintenance of respiratory equipment. In addition to having such a written program, the employer must also be able to demonstrate that the program is enforced and updated as necessary. (See CPI Publication AX246, “Model Respiratory Protection Program for Compliance with the Occupational Safety and Health Administration’s Respiratory Protection Program Standard 29 CFR § 1910.134.”)
RETROFIT: The modification of an existing building or facility to include new systems or components.
ROOF CURB: Raised frame used to mount mechanical units, such as air conditioning or exhaust fans, skylights, etc.
ROOF SLOPE: The angle of a roof surface measured in the number of inches of vertical rise in a horizontal length of 12 in.
ROOFING FOAM: Spray polyurethane foam used in exterior roofing applications. Roofing foam nominal core density is typically 40–56 kg/m3 (2.5–3.5 lb/ft3) and compressive strength is typically 280 kPa (40 lb/in.2) minimum. Building codes do not limit the smoke development index (per ASTM E 84) for roofing foams; therefore, roofing foams should not be used for interior applications.RUST BLUSH: The earliest stage of rusting characterized by an orange or red color. Occurs frequently on freshly sandblasted steel if allowed to stand too long before coating.
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