| abrasion resistance | Durability that enables interior partitions in high-traffic areas to resist surface damage from contact with people, furniture, etc.; achieved by increasing the surface and core strength of the partition facing, by applying a coating or wall covering over the surface, or by increasing the thickness of the partition facing |
| absorption | The taking up and holding (or sometimes dissipating) of matter or energy, as a sponge takes up water; absorption is the opposite of reflection; also see porosity |
| abuse resistance | Durability that helps protect a material such as gypsum board from surface damage (abrasion and indentation) |
| acoustical ceiling | A system with highly effective sound-absorbing and/or sound attenuating qualities |
| acoustical ceiling board (lay-in panel) | Acoustical material used in conjunction with a lay-in grid system, usually in 24" x 24" or larger panels |
| acoustical consultant (acoustical engineer, acoustician) | A trained professional qualified to recommend solutions to sound problems and to design facilities to meet specific sound criteria |
| acoustical sealant | Special caulking material designed to seal gaps and cracks to reduce sound flanking in an assembly |
| acoustical tile | Normally a 12" x 12" or 12" x 24" piece of pre-finished material (with various surface finishes) installed in a concealed suspension system or adhered to a ceiling or upper wall surface to provide sound absorption |
| acoustic privacy | Prevention of the passage of airborne sound and dampening of impact sound - achieved by installing assemblies between two spaces |
| acoustics | A science dealing with the production, control, transmission, reception and effects of sound, and the process of hearing |
| airborne sound | Sound traveling through air and subsequently through partitions and openings |
| ambient light | Generally available surrounding or pervading light in an interior space, including outside light entering through windows |
| amplitude (sound) | Maximum pressure displacement from the at-rest position of the particles of the transmitting medium; the amplitude of a sound wave is determined by the energy of the sound source |
| ANSI | Comprised of government agencies, organizations, companies, academic and international bodies and individuals, the American National Standards Institute (ANSI) coordinates the development and use of voluntary consensus standards in the United States and represents the needs and views of U.S. stakeholders in standardization forums around the globe. The Institute oversees the creation and use of norms and guidelines in nearly every business sector such as acoustical devices and energy distribution. |
| antimicrobial | A substance that kills or slows the growth of microbes such as fungi; Antimicrobial treatments are used to help control fungi, mold and mildew. Treatment areas in ceiling panels include face and back surfaces, as well as the formulation of the materials used to create the ceiling substrate. |
| architectural acoustics | The handling of sound within a single area (reflection, reverberation, absorption, etc.); does not address sound transmission through elements of the structure from adjacent areas or the exterior |
| Architecture 2030 | A U.S. nonprofit environmental advocacy group that addresses climate change and the global greenhouse gas (GHG) emissions produced by the built environment |
| area separation wall | A residential fire wall, usually with a two- to four-hour rating, designed to prevent the spread of fire from an adjoining occupancy; extends from the foundation to or through the roof; identified by codes as a fire wall, party wall or townhouse separation wall |
| articulation class | A classification that rates the degree of speech recognition that can be transmitted through ceilings or partitions |
| ASHRAE | Founded in 1894, the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) is an international organization dedicated to advancing heating, ventilation, air conditioning and refrigeration to serve humanity and promote a sustainable world. The society provides research, standards writing and continuing education for its members from more than 100 nations. |
| ASTM International | Formerly American Society for Testing and Materials; a non-profit technical society that publishes definitions, standards, test methods, recommended installation practices and materials specifications |
| attenuation | In acoustics, the diluting or holding back of the energy of sound waves as they pass through a material; materials are rated for their ability to prevent sounds from traveling through them; also see ceiling attenuation class, CAC |
| basecoat | AThe first layer or layers of plaster applied over a lath or other substrate; the first application is normally called a scratch coat; the second application is a brown coat |
| bonding agent | A material applied to a surface to improve the quality of the bond between it and the succeeding plaster application; For instance, monolithic concrete and cement board require the addition of a bonding agent before plaster is applied. |
| brick veneer | Non-load-bearing brick facing applied to a wall to present the appearance of solid-brick construction; bricks are fastened to a backup structure with metal ties embedded in mortar joints |
| brown coat | The second coat in three-coat gypsum plaster application |
| building codes | Legal requirements concerning construction and occupancy intended to safeguard public health and safety; Sustainable building design must be supported with construction methods and technologies that comply with relevant building codes and that adhere to the specific products recommended installation procedures. |
| CAC | See ceiling attenuation class |
| calcine | To change the chemical composition of a mineral by heating it, ranging from the removal of chemically combined water through the reduction of the mineral to its oxide state |
| calcined gypsum | A dry powder, primarily calcium sulfate hemihydrate, resulting from calcination of gypsum; a cementitious base used in the production of most gypsum plasters; also called plaster of Paris; sometimes called stucco |
| calcium sulfate | Compound with the molecular formula CaSO4 comprised of calcium, sulfur and oxygen with no bound molecules of water; Calcium sulfate is the chemical formula of the naturally occurring mineral anhydrite also known as anhydrous gypsum. Can also be created by heating gypsum or calcium sulfate dihydrate, this dehydration process is known as calcinations; The vast majority of gypsum construction products, such as plaster of Paris, only undergo a partial calcination, as is the case with wallboard manufacturing. Calcium sulfate can react slowly with water to return to the dihydrate state, leading to its use as commercial a desiccant, but much less effectively than the hemihydrate form. Also see calcium sulfate hemihydrate and plaster of Paris |
| calcium sulfate dihydrate | Compound with the molecular formula CaSO4 ï 2H2O comprised of calcium, sulfur and oxygen bound to two molecules of water; the chemical formula of the naturally occurring mineral gypsum and the chemically identical compound produced by synthetic means (see also gypsum, synthetic gypsum); Gypsum, known for its affordability, abundance and fire-resistant properties, is widely used in multiple construction products and is the primary component of the most common type of wallboard panel. |
| calcium sulfate hemihydrate | Compound with the molecular formula CaSO4 ïΩH2O comprised of calcium, sulfur and oxygen bound to one-half a molecule of water; can be created by heating gypsum or calcium sulfate dihydrate to remove three-quarters of its combined water, this partial dehydration process is known as calcinations; commonly referred to as plaster of Paris and is the primary component of setting-type joint compounds and an intermediate compound in the wallboard production process; In contrast to most minerals, calcium sulfate hemihydrate quickly reverts chemically to the dihydrate form when mixed with water at normal (ambient) temperatures, while physically "setting" to form a rigid and relatively strong gypsum crystal lattice. This process can be reversed and repeated almost indefinitely, with important implications for recycling. Also see plaster of Paris |
| calcium sulfite | Compound with the molecular formula CaSO3 comprised of calcium, sulfur and oxygen; often an intermediate compound in the production of flue gas desulfurization (FGD) gypsum; In order to produce wallboard grade synthetic gypsum, calcium sulfite must be converted into calcium sulfate dihydrate. |
| carbon-neutral | A building that produces net zero carbon emissions; can be achieved by calculating emissions, reducing them through design and conservation, substituting renewable energy for fossil energy, and offsetting remaining emissions through actions such as purchasing carbon offsets or planting trees that absorb carbon |
| ceiling attenuation class (CAC) | A numerical rating used to characterize sound traveling between two horizontally adjacent spaces sharing a common ceiling plenum; measured using test standard ASTM E1414 |
| Ceiling STC (CSTC) | Now obsolete; see ceiling attenuation class (CAC) |
| certification, whole building | A nationally recognized benchmarking system for sustainable construction; An example, USGBCs LEEDÆ, provides technical guidance and third-party certification measures that evaluate project sustainability by analyzing critical aspects of building design and construction. A project may receive one of four levels of LEED certification by earning points in six categories of assessment. |
| certification | A process that ensures that products and/or systems adhere to formal and established requirements that are well documented and authorized; To ensure market relevancy, conformance is established based on a set of recognized standards, developed within a consensus-based forum representing all relevant parties. |
| CHPS | Collaborative for High Performance Schools (CHPS) is an organization that promotes research, testing and development of effective environmental management strategies for schools and other specialized building projects, such as healthcare facilities. CHPS limits formaldehyde concentration in school classrooms to 13.5 parts per billion (ppb). |
| Class A | The National Fire Protection Association(NFPA) Standard No. 101, the Life Safety Code (NFPA 101) sets out five classes, A through E, of building materials. Class A is the fire classification for a product with a flame spread rating of no more than 25 and a smoke-developed rating not exceeding 50, when tested in accordance with ASTM E84. |
| Coefficient of Thermal Conductance (c) | The amount of heat (in Btu) that passes through a specific thickness of a material (either homogeneous or heterogeneous) per hr., per SF, per ∫F; measured as the temperature difference between the materials two surfaces; The c value of a homogeneous material equals the k value divided by the material thickness: c = k/t where t = thickness of material in inches. It is impractical to determine a k value for some materials, such as building paper or materials formed as a thin membrane; only c values are given for these. |
| Coefficient of Thermal Conductivity (k) | A convenient factor that represents the amount of heat (in Btu) that passes by conduction through a 1" thickness of homogeneous material, per hr., per SF, per ∫F; measured as temperature difference between the materials two surfaces |
| Coefficient of Heat Transmission (U) | Total amount of heat that passes through an assembly of materials, including air spaces and surface air films; expressed in Btu per hr., per SF, per ∫F temperature difference between inside and outside air (beyond the surface air films); ìUî values are often used to measure heat transmission through wall and ceiling assemblies, floors and windows; Note: ìkî and ìcî values cannot simply be added to obtain ìUî values. ìUî can be obtained only by adding the thermal resistance (reciprocal of ìcî) of individual items and dividing the total into 1. |
| combustible | Capable of burning; also see noncombustible |
| comfort, occupant | Characteristics including humidity, ventilation, air circulation, acoustics and lighting, used to form a comprehensive assessment of IEQ |
| condensation | The water produced when warm, moist air is cooled |
| conduction, thermal | The transfer of heat from one part of a body to another part of that body, or to another body in contact, without any movement of bodies involved; the hot handle of a skillet is an example since the heat travels from the bottom of the skillet to the handle by conduction |
| construction waste | Construction or demolition materials requiring disposal |
| convection | Transmission of heat from one point to another by movement of a liquid or a gas (e.g., water or air); Natural convection is caused by expansion of a liquid or gas when it is heated. Expansion reduces the density of the medium, causing it to rise above the cooler, denser portions of the medium. Gravity heating systems are examples of the profitable use of natural convection. The air, when heated by the furnace, becomes less dense (consequently lighter) and rises, distributing heat to the various areas of the building without any type of blower. When a blower is used, the heat transfer method is called ìforced convection.î |
| cradle to cradle | A calculation of environmental impacts (both negative and positive) across a materials life cycle; Product cradle to cradle may evaluate the embodied energy of the product and would include energy needed to extract and transport raw materials used as product ingredients, to manufacture the item ready for installation or use, to transport the finished product to the distributor, to install, use and maintain it, to deconstruct it at the end of its useful life, and then to reuse or recycle it. Other terms describing the products life stages for energy use and other life cycle assessment criteria include ìcradle to grave,î which includes all the same processes as cradle to cradle, except the product is disposed in a landfill versus being recycled or reused at the end of its use. |
| cradle to gate | A portion of a products life cycle covering manufacture (ìcradleî) and handling up until it leaves the factory (ìgateî); does not include transportation or use of the product, nor its disposal at the end of its use; Environmental product declarations (EPD) are used to assess sustainability for this phase. |
| critical light | Strong, angular or harsh light that can show imperfections in reflecting surfaces; most common sources are skylights, wall sconces and directed track lights such as those used in art galleries |
| cycle (acoustic) | One full repetition of a motion sequence during periodic vibration; movement from zero to +1, then back to zero to -1, then back to zero; frequency of vibration is expressed in Hertz (cycles per second); also see frequency |
| daylighting | The use of natural lighting to illuminate buildings; There are many daylighting techniques, the most successful being ìcoolî daylighting, which controls light entering into a building through techniques such as exterior shading, carefully placed windows and low-transmittance glass. Properly designed daylighting can reduce the need for electric lighting and cooling, and increase lighting comfort. |
| decibel (dB) | A measure adopted for convenience to represent vastly different sound pressures; The SPL is 20 times the logarithm to the base 10 of the ratio of the sound pressure to a reference pressure of 20 micropascals. This reference pressure is considered the lowest value at 100 Hz that the ear can detect. For every 10 dB increase or decrease in SPL, a sound is generally judged to be about twice or half as loud as before the change. |
| decoupling | Separation of elements to reduce or eliminate the transfer of sound, heat or physical loads from one element to the other |
| degree day | A unit representing daily mean temperature of one degree below 65∫F; an indication of heat load required over a given period of time |
| density | The mass of a substance per unit volume |
| dew point | The temperature at which air becomes saturated with moisture and below which condensation occurs |
| direct lighting | Lighting aimed at objects or surfaces; Direct lighting mounted in ceilings de-emphasizes the ceiling surface and highlights horizontal surfaces below, such as work surfaces and the floor. |
| drywall | Generic term for interior surfacing material, such as gypsum panels, applied to framing using dry construction methods, e.g., mechanical fasteners or adhesive in contrast to the wet application of plaster or cement; also see SHEETROCKÆ brand gypsum panels |
| echo | Sound reflected back to the source from a reflective surface, received with enough interval and loudness to be distinguished from the original sound |
| ecological footprint | The impact that an entity such as an operating facility, individual, city or nation has on the local, regional or global ecosystem; factors include direct and indirect consumption of natural resources and waste production |
| efflorescence | A deposit of white, powdery, water-soluble salts on the surface of masonry or plaster; caused by the migration of the dissolved salts to the surface; also called ìwhiskering or saltpeteringî |
| embodied energy | The total amount of energy used across a products life; Usually cradle to gate or cradle to market embodied energies are used to compare construction products and are a critical measure of a products sustainability. Generally, the lower the products measure of embodied energy, the higher its sustainability rating. |
| emissions | Vapors that may be off-gassed by building components; some are harmful, others are harmless in themselves but may react with moisture or vapors from other products, including carpeting, paint and adhesives, and even furnishings, to form potentially hazardous airborne compounds emissivity The relative ability of a surface to emit radiant heat; this does not refer to the emissions of vapors |
| emissivity | The relative ability of a surface to emit radiant heat; this does not refer to the emissions of vapors |
| energy conservation | Reducing energy use and waste by various means, including equipment efficiencies, insulation and business practices |
| EPA | The United States Environmental Protection Agency (EPA) |
| EPD | Environmental product declarations (EPD); a standardized tool based on life cycle analysis used to rate the environmental performance of a product |
| EIFS | exterior insulation and finish systems (EIFS); a proprietary exterior cladding assembly consisting of a polymer finish over a reinforcement(usually a fiberglass mesh) adhered with cementitious basecoat to foam plastic insulation that is fastened to masonry, concrete, or the building sheathing; The sheathing may be cement board, gypsum sheathing or another acceptable substrate. |
| extrapolate | To project tested values, assuming a continuity of an established pattern, to obtain values beyond the limit of the test results; not necessarily reliable |
| F & T ratings | Flame-resistance and temperature ratings usually associated with ìthrough-penetrationî testing; F rating (flame-resistance rating) is the time period a firestop system remains in place during an ASTM E814 fire test. T rating is the time period it takes for the temperature on the unexposed surface, the firestop and the penetrating item to rise 325 ∫F above the initial temperature. |
| factor of safety | Ratio of the ultimate unit stress to the working or allowable stress |
| finish coat | Final layer of plaster applied over a basecoat or other substrate |
| fire blocking | A construction element used as an obstruction in a cavity for the purpose of resisting the passage of flame |
| fire endurance | Measure of elapsed time during which an assembly continues to exhibit fire resistance under specified conditions of test and performance; As applied to elements of buildings, fire endurance is measured by the methods and to the criteria defined in ASTM E119, Standard Test Methods for Fire Tests of Building Construction and Materials and ASTM Methods E814, Fire Tests of Penetration Firestop Systems. |
| fire hazard classification | Rating of interior and surface materials based on testing according to ASTM Standard E84 |
| fireproof | Able to withstand damage from fire; Use of this term in reference to buildings is discouraged because few, if any, building materials can withstand extreme heat for an extended time without some effect. The term ìfire-resistive or resistantî is more descriptive for this purpose. |
| fire resistance | A relative term, used with a numerical rating or modifying adjective to indicate the extent to which a material or structure resists the effects of fire |
| fire-resistive | Refers to properties or designs that resist effects of any fire to which a material or structure may be expected to be subjected |
| fire-retardant | Denotes a substantially lower degree of fire resistance than ìfire-resistive;î often used to describe materials that are combustible, but have been treated to retard ignition or spread of fire under conditions for which they were designed |
| firestop system | A system for protecting against the spread of fire through a penetration in a wall or floor where a pipe or other penetrant passes through a fire-rated system; A firestop is the specific construction using materials designed to fill the annular space around the penetrant for the purpose of preventing the passage of fire through the fire-resistive partition or floor/ceiling assembly. |
| fire wall | A fire-resistant partition extending to or through the roof of a building to resist the spread of fire; also see area separation wall |
| flame-proof | Able to resist ignition and flame propagation under test conditions |
| flame spread | An index of the capacity of a material to spread fire under test conditions, as defined by ASTM Standard E84; materials are rated by comparison with the flame-spread index of red oak flooring (assigned a value of 100) and inorganic reinforced cement board (assigned a value of 0) |
| flammable | A combustible materials capability to ignite easily, burn intensely or have rapid rate of flame spread |
| flanking paths | Paths by which sound travels around an element intended to impede it, usually a structural component that is continuous between rooms and rigid enough to transmit the sound; For example, a partition separating two rooms can be ìflankedî by the floor, ceiling or walls surrounding the partition if they run uninterrupted from one room to the other. Ducts, conduits, openings, structural elements, rigid ties, etc. can be sound flanking paths. The acoustic effect of sound flanking paths is dependent on many factors. |
| flexural strength | The maximum load sustained by a standard specimen of a sheet material when subjected to a bending force |
| flue gas desulfurization (FGD) gypsum | A type of synthetic gypsum which is the product of an engineered process to form calcium sulfate dihydrate which is chemically identical to the naturally occurring mineral gypsum; Flue gas desulfurization refers to the removal of sulfur compounds such as sulfur dioxide from the flue gas or gaseous stack emissions of a coal-fired power plant. The sulfur compounds chemically combine with a calcium-based compound such as limestone or lime to ultimately form calcium sulfate dihydrate. Sulfur compounds released into the atmosphere have the potential to contribute to acid rain and overall degraded air quality. Because the sulfur compounds are prevented from entering the atmosphere and are otherwise captured for use in a benign, economically viable product, this material is also referred to as ìrecaptured gypsum.î |
| footcandle | Measurement of light emitted over distance; One foot- candle is the amount of direct light thrown by one candela onto a surface one foot away and equal to one lumen per square foot. |
| formaldehyde | This colorless and pungent gas is one of the more commonly occurring VOCs, as well as a naturally occurring substance. Commonly used in various industrial applications as well as a preservative, Formaldehyde can cause extreme discomfort and adverse reactions such as watery eyes, burning sensations in the eyes and throat, nausea, asthma attacks, wheezing, coughing, fatigue, skin rash and severe allergic reactions. Formaldehyde is classified as a probable carcinogen by the EPA. |
| frequency (sound) | The number of complete vibrations or cycles or periodic motion per unit of time |
| gauging plaster | Used in combination with lime putty, this material provides setting properties to increase dimensional stability during drying, and provides initial surface hardness in lime finish coats |
| global warming | Increase in global temperatures resulting from many natural and man-made causes including the emission of gases that trap the sun's heat within Earth's atmosphere |
| green building | Design, construction and product selection that minimizes a structures impact on the natural environment |
| Green Cross International | An organization whose mission is to ìhelp ensure a just, sustainable and secure future for all by fostering a value shift and cultivating a new sense of global interdependence and shared responsibility in humanity's relationship with natureî |
| Green Globes | An international organization that provides a rating system for building owners and managers to assess the environmental performance of existing buildings |
| GreenGuard Environmental Institute (GEI) | An industry-independent, ANSI-authorized, nonprofit developer of standards for indoor products, environments and buildings |
| Green Building Resource Guide | A database of green building materials and products for schools, healthcare and other facilities |
| greenhouse effect | The effect when light transfers through a medium (e.g., the atmosphere or glass) and is refracted and reflected, giving off heat upon impact; the more the light bounces around and is trapped, the more the light transfers into heat |
| greenwash | The overstating of benefits or the sustainable properties of a product, process or structure; to market a product as sustainable even though its green characteristics may be minimal or offset by other unsustainable factors |
| gypsum | The mineral consisting primarily of fully hydrated calcium sulfate, CaSO4ï2H2O or calcium sulfate dihydrate |
| gypsum fiber panels | Gypsum panels with cellulose fiber reinforcement diffused throughout the core; part of a relatively new-technology series of panel products called FIBEROCKÆ brand panels, which produce stronger, more abuse-resistant, water-resistant walls than those produced with conventional drywall; There are variations for interior drywall applications in dry and wet areas, sheathing applications and flooring applications. Very-high impact (VHI) products are further reinforced on the backside by a fiberglass mesh. |
| gypsum lath | Gypsum board used as the base for application of gypsum plaster |
| gypsum moulding plaster | Calcined gypsum plaster used primarily for plaster casts or molds, sometimes used as a gauging plaster |
| gypsum neat plaster | Calcined gypsum plaster without aggregate; common usage is for gypsum plaster as a basecoat |
| gypsum plaster | The generic name for a family of powdered cementitious products consisting primarily of calcined gypsum with additives to modify physical characteristics, and having the ability, when mixed with water, to produce a plastic mortar or slurry that can be formed to the desired shape by various methods and will subsequently set to a hard, rigid mass |
| gypsum sheathing | Gypsum board used as a backing for exterior surface materials, manufactured with water-repellent paper and a water-resistant core; newer versions have a glass mat facing |
| gypsum, synthetic | See synthetic gypsum |
| harmonic (acoustics) | A secondary tone of a frequency that is a whole-number multiple of the frequency of a fundamental tone |
| high-performance building | A building that is energy- and water-efficient, healthy and comfortable for its occupants |
| heat | A form of energy thought to be characterized by the rate of vibration of the molecules of a substance; the hotter the substance, the faster the molecules vibrate; On the other hand, when there is no heat present, it is thought the molecules will be at rest, which theoretically occurs at absolute zero, -459.7 ∫F (-273.2 ∫C or 0.0 K). |
| heat quantity (Btu) | A common unit of measure of the quantity of heatóBritish thermal unit (Btu).; One Btu is the amount of heat required to raise one pound of water from 63∫F to 64∫F (1 Btu = 1055.06 J); this is about the amount of heat given off by one wooden match; A pound of coal can produce 13,000 Btu. |
| heat transfer | Heat always flows toward a substance of lower temperature until the temperatures of the two substances equalize; Heat travels by one or more of three methods: conduction, convection or radiation. |
| hemihydrate | The dry powder, calcium sulfate hemihydrate, resulting from calcination of CaSO4ï2H2O, calcium sulfate dehydrate; also see calcined gypsum |
| Hertz | Unit of measure of sound frequency, named for Heinrich H. Hertz; one Hertz (Hz) equals one cycle per second |
| holistic design | Integration of all buildings systems to maximize sustainable and/or economic functioning by considering many factors including use of energy and other resources, building materials, site preservation and indoor air quality; The goal is a structure that can operate at its maximum efficiency, enhance user health, comfort and productivity and have the least environmental impact. |
| HUD | U.S. Department of Housing and Urban Development (HUD), a federal agency |
| HUD Manufactured Home Standards | Officially, the Manufactured Home Construction and Safety Standards, a national, pre-emptive building code covering manufactured homes; includes the following agencies: DAPIAóDesign Approval Primary Inspection Agency, and IPIAóProduction Inspection Primary Inspection Agency |
| HVAC | Heating, ventilating and air conditioning; ASHRAE Guide is a leading technical reference source |
| hydrate | To chemically combine with water, as in the hydration of calcined gypsum or slaking of quicklime; also, the product resulting from this combination |
| hydrogen sulfide | An odorous gas often described as a ìrotten eggî smell; Naturally occurring in volcanic gases, natural gas and some well waters, hydrogen sulfide is also known to result from the bacterial breakdown of sulfur compounds in the absence of oxygen. Landfills supporting such conditions may produce hydrogen sulfide emissions. Gypsum, the primary component of drywall, also known by its chemical formula calcium sulfate dihydrate (CaSO4 ? 2H2O), is considered a sulfur compound that could be decomposed into hydrogen sulfide in these conditions. Hydrogen sulfide and other landfill gas emissions can be minimized and controlled by instituting proper operation and maintenance at a landfill. |
| hygrometric expansion | All materials, particularly those of organic origin, expand and contract in relation to their moisture content, which varies with environment. The Hygrometric Coefficient of Expansion is expressed in inches per inch per percent of relative humidity. As an example, gypsum board has a coefficient of 7.2 x 10-6 in. per in per % R.H. This means that with an increase in relative humidity of from 10% to 50%, a gypsum board wall 300 long will have an unrestrained linear expansion of 1.0368" or 1-1/32". |
| IAQ | Indoor air quality (IAQ) is the quality of the air in an indoor environment including the presence (or lack of) pollutants or odors; the design, maintenance and operation of the building's ventilation systems; moisture and humidity; and occupants' perceptions and susceptibilities |
| IEQ | Indoor environmental quality (IEQ) refers to all environmental factors that affect the health and wellbeing of building occupants. Includes such factors as indoor air quality (IAQ), comfort, humidity, air exchange, acoustics and lighting quality |
| IIC | Impact isolation class (IIC) is a single number rating used to compare and evaluate the performance of floor-ceiling constructions in isolating impact noise. |
| ISPM | Impact sound pressure level (ISPM) is the sound (in decibels), measured in a receiving room, resulting from the transmission of impact sound through floor construction, produced by a standard ìtappingî machine. |
| impact sound transmission | Sound that originates by contact with the structure and travels through the structure |
| incident sound | Noise that is directly received from the source, as distinguished from sound that is reflected from a surface |
| incombustible | See noncombustible |
| indirect lighting | Reflected light; for ceilings, this is typically light from luminaires, distributed upward; This type of lighting is used to reduce glare and hot spots, providing a more uniform source of light. |
| insulation (thermal) | Any material that measurably retards heat transfer; there is wide variation in the insulating value of different materials; a material having a low density (weight/volume) will usually be a good thermal insulator |
| integrated design | A design method that integrates, early in the process, the whole building team, including all disciplines; for a sustainable building, resource efficiencies, indoor air quality and other goals can be achieved most effectively with this approach; also referred to as ìholisticî or ìwhole building designî |
| intensity | A measure of acoustic energy per unit area of a sound wave; measured in watts per square meter or micro-watts per square centimeter; The intensity is proportional to the square of the amplitude. |
| interpolate | To estimate untested values that fall between tested values |
| ISO | International Standards Organization (ISO), an organization similar in nature to ASTM |
| Keenes cement | An anhydrous gypsum plaster characterized by a low mixing water requirement and special setting properties; primarily used with lime to produce a hard, dense finish coat |
| kiln-dried lumber | Lumber that has been dried and seasoned with carefully controlled heat in a kiln |
| Label Service (UL) | A program allowing a manufacturer to place Underwriters Laboratories Inc. labels on its products that have met UL requirements; a UL representative visits the manufacturing location to obtain samples of the products for testing; In some cases, UL also purchases samples on the open market for testing. The public is thereby assured that products bearing the UL label continually meet its specifications. |
| landfill avoidance | Practices that minimize the amount of debris that goes into landfills; approaches include deconstruction, in which materials from an existing building are methodically removed, separated and either reused in the new structure or recycled |
| leaks (sound) | Small openings at electrical boxes and plumbing, cracks around doors, loose-fitting trim and closures that allow sound to pass through, reducing the acoustical isolation of a wall, floor or ceiling system |
| LEED | Leadership in Energy and Environmental Design (LEED) is a whole building rating system developed by the U.S. Green Building Council (USGBC) to evaluate project sustainability by analyzing critical aspects of building design and construction. Developed and refined by USGBC members, the Leadership in Energy and Environmental Design (LEED) Green Building Rating SystemÆ is a voluntary, consensus-based national standard for developing high-performance, sustainable buildings. LEED was created to define ìgreen buildingî by establishing a common standard of measurement and promote integrated, whole-building design practices. A project may receive one of four levels of LEED certification by earning points in six categories of assessment. LEED is the most widely accepted national guideline for environmentally responsible building. It also provides technical guidance and third-party certification measures. |
| LEED credits | Provides a framework for assessing building performance and meeting sustainability goals by assigning points for certain criteria; Specific products cannot be LEED-certified because there are many contingent factors on each project that must be considered. |
| life cycle assessment (LCA) | An approach used to measure a products or buildings environmental performance, from raw materials through manufacture, transportation, installation, use, recycling and waste management; USG defines sustainability in terms of building and resource economics as well, including life cycle costs. |
| life cycle cost (LCC) | The cost of a building system over its useful life, including installation, use (e.g., related energy costs), anticipated repairs and maintenance |
| life-cycle costing | Selection of the most economical material and systems based on initial costs, maintenance costs and operating costs for the life of the building |
| life cycle inventory (LCI) | A collection of data to facilitate life cycle assessment and environmental impact studies; NREL (the National Renewable Energy Laboratory) and its partners have created the U.S. LCI Database to provide ìa cradle-to-grave accounting of the energy and material flows into and out of the environment that are associated with producing a material, component or assembly.î |
| locally sourced material | Construction materials that are extracted and processed near the location where these materials are used (in the manufacturing and installation into a finished building); use of local materials minimizes energy consumption for transportation |
| loudness | A subjective response to sound pressure; The loudness of sound is not directly proportional to the amount of sound pressure or energy. Moreover, the apparent loudnessóthe way the sound is heard by a humanóvaries from person to person. Also see decibel |
| louver | An opening with slanted fins (to keep out rain and snow) used to ventilate attics, crawl spaces and wall openings |
| lumen | A standard unit for measuring light emission; generally speaking, one lumen is the amount of light emitted by one candle; More specifically, a lumen is the unit of measure for the flow of light through a defined angle from a uniform point source equal to one candela. One candela roughly approximates the intensity of light emitted by a single burning candle. |
| luminaire | A complete lighting unit, consisting of a lamp or lamps, together with parts designed to distribute the light, to position and protect the lamps and to connect to the power source |
| masking sound | Background noise used to cover unwanted sounds, provide privacy or avoid a ìquietî area that otherwise may be acoustically ìdeadî |
| mass | Property of a body that resists acceleration and produces the effect of inertia; The weight of a body is the result of the pull of gravity on the bodys mass. |
| mechanical bond | The attachment created when plaster penetrates into or through the substrate or envelops irregularities in the substrates surface |
| model code | Building code written and published by a building-official association, available to states, counties and municipalities for adoption (for a fee), e.g., the International Building Code (IBC) |
| modular building | A structure intended for residential or commercial use that is at least partially completed in a factory complying with state or local code requirements |
| modulus of elasticity (E) | Ratio between stress and unit deformation, a measure of the stiffness of a material |
| moisture management | Construction and maintenance methods that protect a building from the structural and indoor air quality problems that can result from condensation or water intrusion |
| moment of inertia (I) | Calculated numerical relationship (expressed in inches to the 4th power) of a members resistance to bending; a function of the members cross-sectional shape and size; a measure of the stiffness of a member based on its shape; Larger moments of inertia indicate greater resistance to bending for a given material. |
| MTS | The Institute for Market Transformation to Sustainability; an organization that promotes sustainable product standards |
| NBS | National Bureau of Standards, a federal agency |
| NFPA | National Fire Protection Association; an international technical society that disseminates fire prevention, fire fighting and fire protection information; NFPA technical standards include the National Electrical Code, which is widely adopted. |
| NIOSH | The Occupational Safety and Health Act of 1970 created both the National Institute for Occupational Safety and Health (NIOSH) and OSHA. NIOSH is part of the Centers for Disease Control and Prevention (CDC) in the Department of Health and Human Services and is the federal agency responsible for conducting research and making recommendations for the prevention of work-related injury and illness. |
| National Green Building Standards | A whole-building rating system for single family and multi-unit homes developed by the National Association of Home Builders |
| noise reduction coefficient (NRC) | A scalar representation of the amount of sound energy absorbed upon striking a particular surface; an NRC of 0 indicates perfect reflection; An NRC of 1 indicates perfect absorption. |
| noncombustible | Definition paraphrased from the ICC 2009 International Building Code: 1) Material of which no part will ignite and burn when subjected to fire; 2) Material having a structural base of noncombustible materials as defined, with a surface not over 1/8" thick that has a flame spread rating of 50 or less; Note: the term does not apply to surface finish materials |
| octave | Interval between two sounds having a basic frequency ratio of two; The formula is 2n times the frequency, where n is the desired octave interval. The octave band frequency given in sound test results is usually the band center frequency. Thus the 1,000 Hz octave band encompasses frequencies from 707 Hz to 1,414 Hz (n=+ 1/2). The 1,000 Hz one-third octave band encompasses frequencies from 891 Hz to 1,122 Hz (n = + 1/6). |
| OEHHA | California's Office of Environmental Health Hazard Assessment (OEHHA) aims to protect and enhance public health and the environment by scientific evaluation of risks posed by hazardous substances. OEHHA works with federal agencies, the scientific community, industry and the general public. |
| off-gassing | The emission of volatile chemicals at normal atmospheric pressure and temperature; Building materials such as paints, carpet, insulation, woods, laminates, and flooring can off-gas. |
| OSHA | The U.S. Department of Labor Occupational Safety & Health Administration (OSHA) was established in 1971 to ensure worker safety and health in the United States. OSHA has defined permissible exposure limits for formaldehyde and other hazardous and toxic substances. |
| passive solar | Design strategies that contribute to a buildings needed supply of heat (water and air) without an energy input (pumps or fans); For example, windows and building mass collect heat without the need for power. Passive solar designs are categorized as direct gain, sunspaces or Trombe walls. |
| PEL | Permissible exposure limit (PEL); regulatory limits on the amount or concentration of a substance in the air; may also contain a skin designation; PELs are set by OSHA to protect workers against the health effects of exposure to hazardous substances, and are based on an 8-hour time-weighted average (TWA) exposure. |
| performance specification | A statement of how a building element must performóas opposed to describing equipment, products or systems by name |
| perimeter relief | A gap left around the perimeter of a wall, floor or ceiling membrane, such that it will not be in direct contact with the membrane of adjoining assemblies; gap is normally caulked with acoustical sealant |
| perm | A unit of measurement of Water Vapor Permenance (ASTM E96); also see permeance |
| permeability | The property of a porous material that permits a fluid (or gas) to pass through it; In construction, commonly refers to water vapor permeability of a sheet material or assembly and is defined as water vapor permeance per unit thickness, using a metric unit of measure (metric perms per centimeter of thickness); also see permeance |
| permeance (water vapor) | The ratio of the rate of water vapor transmission (WVT) through a material or assembly (between its two parallel surfaces) to the vapor pressure differential between the surfaces; The metric unit for measuring permeance is the metric perm, 1 g/24 h. x m2 x mm Hg; U.S. unit, 1 grain/h x ft.2 x in. Hg. |
| photographing | See shadowing |
| photovoltaics (PVs) | Devices that convert sunlight directly into electricity; PVs generate power without noise, pollution or fuel consumption |
| plenum | (1) Chamber in which the air pressure is higher (as in a forced-air furnace system) than that of the surrounding air; (2) The space above a suspended ceiling |
| plenum barrier | Vertical surface framed from the structure above to the finished ceiling and sealed to prevent the passage of air |
| porosity | The propensity of certain materials, such as wallboard paper, to absorb water |
| post-consumer waste | Recycled materials that have been used and discarded by households or commercial uses |
| Post-consumer material | Material or finished product that has served its intended use as a consumer item and has now been diverted or recovered from waste; New products can then be created partially or wholly from post-consumer material ñ more commonly known as recycling. |
| Post-industrial material | Manufacturing waste or sub-standard products that have not been used; Some post-industrial materials can be reclaimed and turned into new products instead of landfill. |
| pre-consumer waste | Materials and by-products of manufacturing; also known as ìpost-industrial waste;î includes waste generated by manufacturers, such as trimmings and overruns that are used to manufacture additional products |
| radiation | Transfer of heat energy through space by wave motion; Although the radiant energy of heat is transmitted through space, no heat is present until this energy strikes and is absorbed by an object. Not all of the radiant heat energy is absorbed; some is reflected to travel in a new direction until it strikes another object; the amount reflected depends on the nature of the surface the energy strikes. This fact explains the principle of insulating foil and other similar products that depend on reflection of radiant heat for their insulating value. |
| rapidly renewable materials (RRM) | Raw materials such as cork, bamboo and straw, that can be re-grown quickly and are therefore considered sustainable |
| recycled content | The percent of the total material content (by the combination of post-consumer waste, pre-consumer material and post-industrial material) versus the percent of content that is virgin material |
| reflected heat | See radiation |
| reflected sound | Sound that has struck a surface and ìbounced off;î Sound reflects at the same angle as light reflects in a mirror. The angle of incidence equals the angle of reflection. Large curved surfaces tend to focus (concave) or diffuse (convex) the sound when reflected. However, when the radius of the reflecting surface is less than the wavelength of the sound, this does not hold true. Thus, a rough-textured surface has little effect on diffusion of sound. |
| reflective insulation | Material that reflects and thus retards the flow of radiant heat; The most common type is aluminum foil. The effectiveness of reflective barriers is diminished by the accumulation of dirt and by surface oxidation. |
| relative humidity | The ratio of actual water vapor pressure to the saturation water vapor pressure at the same temperature, expressed as a percentage |
| renewable energy | Energy from natural resources that replenish themselves, such as the sun, wind, rain, tides and geothermal sources |
| resonance | The production of relatively intense sound vibrations by exposure to a small sound stimulus; Every medium and object has a resonant frequency at which it will, under favorable conditions, re-radiate a received sound of the same frequency. |
| retarder | An admixture used to delay the setting action of plasters or other cementitious materials |
| sabin | Measure of sound absorption of a surface, equivalent to 1 SF of a perfectly absorptive surface |
| safing | Firestop material in the space between a floor slab and a curtain wall in multi-story construction |
| safing off | Installation of fire safety insulation around floor perimeters, between floor slab and spandrel panels; insulation helps retain integrity of fire-resistance ratings |
| section modulus (S) | Numerical relationship, expressed in inches to the third power, of the resistance to the stress of a member; Section modulus is equal to the moment of inertia divided by the perpendicular distance from the neutral axis to the extremity of the member. |
| set | The hardening and hydration of a gypsum plaster or setting-type joint compound; Once set, many gypsum materials still need to dry off excess moisture; also see setting time |
| setting time | The elapsed time required for a gypsum plaster or setting-type joint compound to attain a specified hardness and strength after mixing with water |
| shadowing | An undesirable condition where the joint finish shows through the surface decoration often caused by temperature variation |
| shaft wall | Fire-resistant wall that isolates the elevator, stairwell and vertical mechanical chase in high-rise construction; This wall must withstand the fluctuating (positive and negative) air-pressure loads created by elevators or air distribution systems. |
| sheathing | Plywood, gypsum, wood fiber, expanded plastic or composition boards encasing walls, ceilings, floors and roofs of framed buildings; may be structural or non-structural, thermal-insulating or non-insulating, fire-resistant or combustible |
| SHEETROCK® | Leading brand of gypsum panel for interior wall and ceiling surfaces and other products, developed by United States Gypsum Company |
| SMaRT© | Sustainability Materials Rating technology (SMarT) promoted by MTS; a life cycle based, multi-attribute product rating system/standard that provides multiple environmental, social and economic benefits over the supply chain |
| sound | A wave motion in an elastic medium caused by a vibrating object |
| sound absorption | The dissipation of sound by conversion of the acoustical energy into heat or another form of energy; friction produces heat as the energy passes over and agitates the fibers of a sound-absorbing material |
| sound attenuation | Reduction of sound energy as it passes through a conductor (which resists the transmission) |
| sound barrier | A material installed in a plenum or partition to prevent the passage of sound from one area to another; Sound-deadening board and lead sheet or special insulations make good sound barriers. |
| sound control | Measures taken to control three types of sound: airborne sound transmission, impact sound transmission and architectural acoustics |
| sound damping | The use of fibrous sound-absorbing material in a partition to reduce sound transmission; Damping in floor/ceiling construction has a wider application for impact sound than for airborne sound. |
| sound insulation, isolation | Use of building materials or constructions that reduce or resist the transmission of sound; Decoupling is one isolation method, in which the elements of a partition are separated to retard transmission of structure-borne sound. |
| sound leak | Opening in a partition that allows air (and sound) to pass through; Examples include small holes in a wall, openings for electrical boxes and plumbing, and cracks around doors. |
| sound pressure | The change in pressure resulting from vibration in the audible frequency range; Conversational speech at close range produces a sound pressure of about one dyne per sq. cm. |
| sound pressure level (SPL) | Expressed in decibels, the SPL is 20 times the logarithm to the base 10 of the ratio of the sound pressure to a reference pressure of 20 micropascals; also see decibel |
| sound transmission | The transfer of sound energy from one space to another, through air, structure or other conductor; Unwanted sound in a room may be the result of sound transmission from sources outside the room. The degree to which sound transmission is acceptable depends on the quantity and source of the sound and the use of the adjacent space. Sound transmitted at a level below the receiving room ambient level would be acceptable. |
| sound transmission class (STC) | A single-number rating for evaluating the effectiveness of a construction system in isolating audible airborne sound transmission across 16 frequencies; higher numbers indicate more effectiveness; tested per ASTM E90 |
| speed of sound | In air, varies with atmospheric pressure and temperature, but is the same at all frequencies; For most architectural work, the speed of sound should be taken as 1,130' per second. |
| structure-borne sound | Sound energy imparted directly to and transmitted by the elements of a structure; Plumbing noises traveling through pipes are a good example. |
| stucco | (1) A mixture of Portland cement and aggregate designed for use on exterior or interior surfaces exposed to high levels of moisture; may also contain hydrated lime to improve working characteristics; (2) A gypsum plaster mix including aggregate for use on interior surfaces; (3) Calcined gypsum used to produce plaster, gypsum wallboard and related products; This use is specific to the gypsum processing industry. |
| substrate | Underlying material to which a finish is applied, or by which it is supported |
| surface burning characteristic | Rating of interior and surface finish material providing indexes for flame spread and smoke developed, based on testing conducted according to ASTM Standard E84 |
| suspended ceiling | A ceiling that is hung from the structure typically with wire hangers |
| sustainable design | Design that considers all environmental and human health and well-being aspects, as well as resource efficiency |
| synthetic gypsum | Product of an engineered process to form calcium sulfate dihydrate (CaSO4ï2H2O) which is chemically identical to the naturally occurring mineral gypsumóoften a byproduct of other industrial processes; the production process may be included as a descriptor of the material, e.g., Flue-gas desulfurization (FGD) gypsum, titanogypsum, phosphogypsum (also see flue gas desulfurization (FGD) gypsum). |
| temperature | Measurement of the intensity (not quantity) of heat; The Fahrenheit (∫F) scale places the freezing point of water at 32∫ and the boiling point at 212∫. The Centigrade or Celsius (∫C) scale, used by most countries and in scientific work, places the freezing point of water at 0∫ and the boiling point at 100∫. On the Kelvin (K) scale, the unit of measurement equals the Celsius degree and measurement begins at absolute zero 0∫ (-273∫C). |
| thermal expansion | All materials expand and contract to some extent with changes in temperature. The thermal coefficient of linear expansion is expressed inches per inch per degree Fahrenheit. For example, gypsum board has a coefficient of 9.0 x 10-6 in. per in. per ∫F. This means that with an increase in temperature of 50∫, a gypsum board wall 100' in length will have a linear expansion of 0.54" or an excess of 1/2". The expansion characteristics of some other building materials are more pronounced. For example, a 50∫ temperature increase would produce expansion in a 100' length of approx. 3/4" in aluminum, and 1.7î in PVC. |
| thermal resistance (R) | Resistance of a material or assembly to the flow of heat; it is the reciprocal of the heat transfer coefficient: (1/c, or 1/U); For insulating purposes, low ìcî and ìUî values and high ìRî values are the most desirable. |
| thermocouple | A thermoelectric junction of two dissimilar metals used to measure temperature difference used in fire-resistance tests conducted under ASTM E119 |
| through-penetration | An opening through a fire-resistive partition or floor/ceiling assembly to provide for an item (such as piping) to pass through it; Through-penetrations usually require the use of a firestop system to protect against the spread of fire through the opening. |
| through-penetration firestop | A system for sealing through-penetrations in fire-resistant floors, walls and ceilings |
| time-temperature curve | Rate at which the temperature increases in a fire-testing furnace; Developed by ASTM, NFPA and UL, this curve is adhered to in all fire-resistive testing. |
| transmission loss (TL) | The decrease in energy during transmission from one surface of a medium to another, such as, through a panel or wall |
| TSP (trisodium phosphate) | A cleaning agent used to remove grease, soot and paint dust from a surface, usually in preparation for painting |
| TWA (time-weighted average) | Refers to an employee's average exposure to a substance in any eight-hour work shift of a 40-hour work week; OSHA sets PELs per TWA to protect workers against the health effects of exposure to hazardous substances. |
| ìUî factor | The coefficient of heat transfer, ìUî equals 1 divided by (hence, the reciprocal of) the total of the resistances of the various materials, air spaces and surface air films in an assembly. Also see ìthermal resistanceî |
| Underwriters Laboratories, Inc. (UL) | A not-for-profit laboratory operated for the purpose of testing devices, systems and materials as they relate to life, fire and casualty hazards, in the interest of public safety |
| UL Environment | A new source for independent green claims validation, product certification,training, advisory services and standards development |
| USGBC | The U.S. Green Building Council (USGBC) is a coalition of leaders from all sectors of the building industry working to promote environmentally responsible, profitable and healthy places to live and work. USGBC members develop and continually refine the Leadership in Energy and Environmental Design (LEED) Green Building Rating SystemÆ, a voluntary, consensus-based national standard for developing high-performance, sustainable buildings. USGBC also offers green building education and training. |
| validation | A confirmation of a claim regarding a defined characteristic of a product or system, typically by a third-party entity, to document, verify and ensure a consistent level of determined accuracy |
| vapor retarder | A material used to retard the flow of water vapor through walls and other spaces where it may condense at a lower temperature |
| velocity | The speed of sound in air at room temperature is 1,130' per second; in steel, 16,500' per second; in hardwood, 13,000' per second; The speed sound travels depends only on the density and elasticity of the medium through which it passes. Its speed is unaffected by loudness and frequency. |
| veneer plaster | Calcined gypsum plaster specially formulated to provide specific workability, strength, hardness and abrasion resistance characteristics when applied in thin coats (1/16" to 3/32" nom.) over veneer gypsum base or other approved base; The term thin-coat plaster is sometimes used in reference to veneer plaster. |
| volatile organic compounds (VOCs) | Chemicals, such as formaldehyde, that are harmful when released (off-gassed) from building products after installation; VOCs are also found in cleaning supplies and furnishings and are also emitted by some plants, trees, microorganisms, and even by humans. VOCs may be present during all stages of a buildings life cycleómaterials manufacturing, construction/installation and occupancyóand may pose real health and comfort issues. |
| water-absorption | The amount of water absorbed by a material under specified test conditions; commonly expressed as a weight percent of the test specimen |
| water-repellent paper | Gypsum board paper surfacing that has been formulated or treated to resist water penetration |
| water vapor transmission | The rate of water vapor flow, under steady specified conditions, through a unit area of a material, between its two parallel surfaces; metric unit of measurement is 1 g/24 h. x m2 x mm Hg; also see permeance |
| watt | A basic unit of measurement of electrical power; One watt is defined as one ampere of current flowing at 1 volt. One watt equals 1/746 HP. |
| wave front | The surface of the wave sphere created when sound waves radiate from the source in all directions, forming a spherical shape |
| wavelength (sound) | A wave is one complete cycle of sound vibration passing through a medium (such as air) from compression through rarefaction and back to compression again. The physical length of this cycle is termed the wavelength. Wavelengths in air vary from about 11/16" for a 20,000-cycle per second (also see frequency) sound, to approximately 56'-6" for a 20-cycle per second sound (the two approximate extremes of human hearing sensitivity). There are waves outside of this range, but generally, they cannot be heard by humans. |
| whole design solution | A design approach that considers and integrates all building systems, starting with the early design stagesófor optimum efficiency and sustainability in the structure; also see holistic, integrated or whole building design. |
| wind power | Energy from wind, usually collected by wind turbines |
| zero-net energy building (ZEB) or net zero energy building | A building that has a net energy consumption of zero over a year |
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