ACTIVATED CARBON
A form of carbon made porous by special treatment making it capable of absorbing various odors and vapors.

ACTIVE SOLAR ENERGY SYSTEM
A system which requires the importation of energy from outside of the immediate environment: ex. energy to operate fans and pumps

AEROSOL
A gaseous suspension of small particles of a liquid or a solid.

AIR BARRIER
A material carefully installed within a building envelope assembly to minimize the uncontrolled passage of air into and out of a dwelling. (Example: Typar, Tyvek).

AIR CHANGE
The amount of air required to completely replace the air in a room or building; not to be confused with re-circulated air.

AIR CHANGE PER HOUR (ACH)
A unit that denotes the number of times a house exchanges its entire volume of air with outside air in an hour. This is generally used in two ways: 1) under natural conditions and 2) under a 50 Pascal pressure difference.

AIR LEAKAGE
The uncontrolled flow of air though a component of the building envelope itself, when a pressure difference is applied across the component. Infiltration refers to inward flowing air leakage and exfiltration refers to outward flowing air leakage.

AIR SEALING
The practice of sealing unintentional gaps in the building envelope (from the interior) in order to reduce uncontrolled air leakage.

ALBEDO
The reflectance of solar radiation for a given surface is referred to as the albedo rate.

ANGLE OF INCIDENCE
The angle that the sun's rays make with a line perpendicular to a surface. The angle of incidence determines the percentage of direct sunshine intercepted by a surface.

ATTIC OR ROOF SPACE
The space between the top floor ceiling and root and between a dwarf partition and sloping roof.

ATTIC VENTILATORS
The screened openings in houses provided to ventilate an attic space. They are located in the soffit area as inlet ventilators and in the gable end or along the ridge as outlet ventilators. They can also consist of power-driven fans used as an exhaust system. See also LOUVER.

AZIMUTH
The angular distance between true south and the point on the horizon directly below the sun.

BACKDRAFTING (FLOW REVERSAL)
The reverse flow of chimney gases into the building though the barometric damper, draft hood, or burner unit. This can be caused by chimney blockage or it can occur when the pressure differential is too high for the chimney to draw.

BASEBOARD
A molded board placed against the wall around a room next to the floor to conceal the joint between the interior wall and the floor.

BATTEN
A narrow strip of wood used to cover joints between boards or panels.

BEARING WALL
A wall that supports any vertical load in addition to its own weight.

BLOWER DOOR
Diagnostic equipment used to measure and locate air leaks within a structure.

BLOWING AGENT
A propellant used in the application of polyurethane foams. These range from CFCÕs and HCFCÕs to water and others.

BOTTOM PLATE
The lower horizontal member of a wood-frame wall nailed to the bottom of the wall studs and to the floor framing members.

BTU
An abbreviation for British Thermal Unit; the heat required to increase the temperature of one pound of water one degree Fahrenheit.

BUILDING ENVELOPE
The external components that enclose the conditioned space. (Example: walls, floor, ceiling, roof, windows and doors).

BUILT-UP ROOF
A roof covering composed of thee or more layers of roofing felt or fiberglass saturated with coal, tar or asphalt. The top is finished with crushed stone, gravel or a cap sheet. Generally used on flat or low-pitched roofs.

CASING
A form of molded trim used around window and door openings.

CAULKING
The practice of sealing a joint in a building.

CFCs / HCFCs
chlorofluorocarbons/ hydrochlorofluorocarbons are used for coolants in refrigeration systems and air conditioners, as solvents to clean electronic components, as blowing agents in the production of plastic foams, and as propellants in air conditioners.

CHIMNEY FLUE
A passage housed in a chimney through which smoke and gases are carried from a fuel burning appliance, fireplace or incinerator to the exterior.

CLERESTORY
An outside wall of a room or building, carried above an adjoining roof and pierced with windows.

COMBUSTION AIR
The air required to provide adequate oxygen for fuel burning appliances in the building. The term 'combustion air' is often used to refer to the total air requirements of a fuel burning appliance including both air to support the combustion process and air to provide chimney draft (dilution air).

CONDENSAll Tech InsulationON
The transformation of the vapor content of the air into water on cold surfaces. The beads or drops of water (and frequently frost in extremely cold weather) that accumulate on the inside of the exterior covering of a building when warm, moisture-laden air from the interior reaches a point where the temperature no longer permits the air to sustain the moisture it holds.

CONDUCTION
The transfer or travel of heat though a body by molecular action.

CONDUIT (ELECTRICAL)
A pipe, usually metal, in which wire is installed.

CONSTRUCTION DRY-WALL
A type of construction in which the interior wall finish is applied in a dry condition, generally in the form of sheet materials or wood paneling, as opposed to plaster.

CONSTRUCTION, WOOD FRAME
A type of construction in which the structural parts are wood or depend upon a wood frame for support. In codes, if masonry veneer is applied to the exterior walls, the classification of this type of construction is usually unchanged.

CONVECTION
The transfer of heat by the movement of a fluid (water, air, etc.).

CONVECTIVE LOOPS
A type of air movement occurring in and around the building envelope caused by gaps in the insulation, weather barrier or air barrier. For example, in an uninsulated wall cavity, air removes heat from the warm interior wall, then circulates to the colder exterior wall where it loses the heat.

CORNICE
A horizontal projection at the top of a wall or column; often referring to the overhang of a pitched roof at the eave line, usually consisting of a fascia board, a soffit or a closed cornice and appropriate moldings.

CRAWL SPACE
A shallow space below the living quarters of a basementless house, normally enclosed by the foundation wall.

CROSS-BRIDGING
The diagonal bracing between adjacent floor joists, placed near the center of the joist span to prevent joists from twisting.

DAMP-PROOFING
The process of coating the outside of a foundation wall with a special preparation to resist passage of moisture though the wall. Material used to resist the passage of moisture though concrete floor slabs and from masonry to wood.

DEAD AIR SPACE (STILL AIR SPACE)
A confined space of air. A dead air space tends to reduce both conduction and convection of heat. This fact is utilized in virtually all insulation materials and systems, such as double glazing, fiberglass batts, rigid foam panels and loose fill insulations, such as vermiculite and cellulose.

DECAY
The disintegration of wood or other substance though the action of fungi.

DEGREE DAY (HEAll Tech InsulationNG)
The difference between a base temperature and the average temperature of a day. The base is usually 180 (640).

DENSITY
The mass of a substance in a unit volume. When expressed in the metric system, it is numerically equal to the specific gravity of the same substance.

DEWPOINT
The temperature at which a vapor begins to deposit as a liquid. Applies especially to water in the atmosphere.

DIFFUSE RADIAll Tech InsulationON
Radiation that has traveled an indirect path from the sun because it has been scattered by particles in the atmosphere, such as air molecules, dust and water vapor.

DIFFUSION
The movement of water vapor between two areas caused by a difference in vapor pressure, independent of air movement. The rate of diffusion is determined by 1) the difference in vapor pressure, 2) the distance the vapor must travel, and 3) the permeability of the material to water vapor. Hence the selection of materials of low permeability for use as vapor retarders in buildings.

DIRECT GAIN
Solar energy collected (as heat) in a building without special solar collection devices, such as through windows or by being absorbed by a roof or by exterior walls.

DOOR JAMB
The surrounding case into and out of which a door closes and opens. It consists of two upright pieces, called side jambs, and a horizontal head jamb.

DORMER
An opening in a sloping root the framing of which projects out to form a vertical wall suitable for windows or other openings.

DRY ROT
A fungus that decays wood in the presence of moisture and warm conditions and in the absence of light.

DRYWALL FINISH
The interior wall and ceiling finish other than plaster - e.g. gypsum board, plywood, fiberboard panels, etc.

DUCTS
The round or rectangular metal pipes in a house used for distributing warm air from the heating plant to rooms, or air from a conditioning device or as cold air returns.

DUCTWORK
Pipes or channels that carry air throughout your home. The delivery system through which conditioned air from the furnace or air conditioner is brought to where it's needed. Ductwork is made of sheet metal, fiberglass, or flexible plastic, and can be round or rectangular in shape.

DWARF WALL
A framed wall of less than normal full height. (Also called a knee-wall).

EAVE
The lower part of a roof which projects beyond the face of the walls.

EAVE SOFFIT
The under surface of the eave.

EAVE TROUGH
A trough fixed to an eave to collect and cany away the run-off from the roof Also called a gutter.

EFFICIENCY
A rating on comfort equipment is similar to the miles per gallon rating on your car. The higher the rating number, the more efficient the system and the lower your fuel consumption will be. You can save a lot of money with a high efficiency unit. Depending on your local climate, lifestyle and electricity rates, savings will vary.

ERV (Energy Recovery Ventilator)
This device preheats incoming outside air during the winter and pre-cools incoming air during the summer to reduce the impact of heating and or cooling the indoor air. This means that smaller capacity heating and cooling systems can be used in homes, which results in lower installation costs, lower peak demand for energy, and lower operating costs.

EQUIVALENT LEAKAGE AREA (ELA)
The total area of all the unintentional openings in a building's envelope, generally expressed in square centimeters.

EXFILTRAll Tech InsulationON
The uncontrolled leakage of air out of a building.

FAN
An air moving device comprising a wheel or blade, and housing or office plate.

FASCIA BOARD
A finishing member around the face of eaves and roof projections.

FIRE-RESISTANCE RAll Tech InsulationNG
The time in hours or fraction thereof that a material or assembly of materials will withstand the passage of flame and the transmission of heat when exposed to fire under specified conditions of test and performance criteria.

FIRE-RESISTIVE
A designation applied, in the absence of a specific ruling by the authority having jurisdiction, to materials for construction not combustible in the temperatures of ordinary fires; materials that will withstand such fires without serious impairment of their usefulness for at least 1 hour.

FIRE-RETARDANT CHEMICAL
A chemical or preparation of chemicals used to reduce flammability or to retard spread of flame.

FIRE STOP
A solid, tight closure of a concealed space, placed to prevent the spread of fire and smoke though such a space. In a frame wall, this will usually consist of38 mm by 89 mm (2 x 4) cross blocking between studs.

FLAME SPREAD
Standard test for determining relative combustibility.

FLASHING
A material, such as sheet metal, used in roof and wall construction to shed water.

FLUE
The space or passage in a chimney though which smoke, gas, or fumes ascend. Each passage is called a flue, which together with any others and the surrounding masonry make up the chimney.

FLY RAFTERS
The end rafters of the gable overhang supported by roof sheathing and lookouts.

FOOTCANDLE
Unit of measure of the intensity of light, defined by the light at a distance of one foot from an International candle.

FOOTING
A masonry section, usually concrete, in a rectangular form wider than the bottom of the foundation wall or pier it supports.

FOUNDAll Tech InsulationON
The supporting portion of a structure below the first-floor construction, or below grade, including the footings, which transfers the weight and loads of  the structure to the ground.

FRAMING
The skeleton of the building. The rough timber work of a house, including the flooring, roofing, partitioning and beams.

FRAMING, PLATFORM
A system of framing a building in which floor joists of each story rest on the top plates of the story below or on the foundation sill for the first story and the bearing walls and partitions rest on the subfloor of each story.

FUNGI WOOD
The microscopic plants that live in damp wood and cause mold, stain, and decay.

FUNGICIDE
A chemical that is poisonous to fungi.

FURRING
The strips of wood or metal applied to a wall or other surface to even it and normally to serve as a fastening base for finish material.

GABLE
The upper triangular-shaped portion of the end wall of a house above the eave line of a double sloped roof.

GABLE END
The entire end wall of a house having a gable roof.

GEOTHERMAL ENERGY
Heat energy contained in large underground reservoirs of steam and hot water, produced by molten material from the earth's interior.

GEOTHERMAL EQUIPMENT
Heat pumps that uses the ground to transfer heat to and from the refrigerant in the unit. The unit circulates water through a heat exchanger in the to a closed loop buried in the ground or by pumping water from a well through the unit

GIRDER
A large beam supporting floor joists at the same level as the sills. A larger or principal beam used to support concentrated loads at isolated points along its length.

GUTTER OR EAVE TROUGH
A shallow channel or conduit of metal, plastic or wood set below and along the eaves of a house to catch and carry off rainwater from the roof.

HEADER (FRAMING)
A wood member at right angles to a series of joists or rafters at which the joists or rafters terminate. When used at openings in the floor or roof system the header supports the joist or rafters and acts as a beam.

HEAT EXCHANGER
A device specifically designed to transfer heat between two physically separated fluids, such as air.

HEAT GAIN
An increase in the amount of heat contained in a space, resulting from direct solar radiation and the heat given off by people, lights, equipment, machinery and other sources.

HEAll Tech InsulationNG
Air-Conditioning: The process of bringing air to a required state of temperature and humidity, and removing dust, pollen and other foreign matter. Central Heating: A heating system in which a number of rooms or spaces are heated from a central source. Convector: A heating device in which the air enters though an opening near the floor, is heated as it passes though the heating element and enters the room though an upper opening. Hot Water Heating : The circulation of hot water though a system of pipes and radiators either by gravity or a circulating pump. Radiant Heating: A heating system in which only the heat radiated from panels is effective in providing the heating requirements. Warm Air Heating: A warm air heating plant consisting of a heating unit (fuel-burning furnace) enclosed in a casing, from which the heated air is distributed to various rooms of the building though ducts.

HEAT LOSS
The amount of heat lost, measured in BTU's from a space to be conditioned, at the local winter outdoor design temperature and a specified indoor design condition.

HEAT GAIN
The amount of heat gained, measured in BTU's, from a space to be conditioned, at the local summer outdoor design temperature and a specified indoor design condition.

HEAT PUMP
A Heat Pump is a reverse cycle air conditioner. The Heat Pump uses a compression cycle system to supply heat or remove heat remove a temperature controlled space. When you run your air conditioner, your outdoor unit will be blowing hot air, (in other words, removing the heat from your home and sending it outside). When you run your heat pump, you reverse the flow of refrigerant and remove the heat from the atmosphere outside and blow it inside. When the temperature dips below 40 degrees outside, the Heat Pump labors in producing heat so they install a back up or auxiliary electric heat strip to supplement the Heat Pump. Electric Heat strips are very expensive to operate. In southern climates where it rarely dips below 40 degrees the heat pump is very efficient. A 3 to 1 savings in heating compared to electric heat strips.

HIP
The sloping ridge of a roof formed by two intersecting roof slopes.

HIP-RAFTER
The rafter which forms the hip of a roof.

HIP ROOF
A roof that rises by inclined planes from all four sides of a building.

HRV (Heat Recovery Ventilator)
This device brings fresh, outside air into a home while simultaneously exhausting stale indoor air outside. In the process of doing this, an HRV removes heat from the exhaust air and transfer it to the incoming air, pre-heating it. This allows for the reclamation of much of the energy that otherwise would simply be vented outside. The end result: home comfort systems operate more efficiently.

HUMIDIFIER
A device designed to increase the humidity within a room or a house by means of the discharge of water vapor. It may consist of an individual room-size unit or a larger unit attached to the heating plant to condition the entire house.

HUMIDISTAT
A device designed to regulate humidity input by reacting to changes in the moisture content of the air. Much like a thermostat but turns the system on & off by sensing the humidity level.

HUMIDITY
The amount of water vapor in the air.

HVAC
Heating, Ventilation, Air Conditioning

I-BEAM
A steel beam with a cross section resembling the letter I. It is used for long spans as basement beams or over wide wall openings, such as a double garage door, when wall and roof loads are imposed on the opening.

IAQ (Indoor Air Quality)
A broad term describing the overall quality of air within a commercial or residential building

IMPERMEABLE
Not permitting water vapor or other fluid to pass though.

INFILTRAll Tech InsulationON
Air flow inward into a space through walls, leaks around doors and windows or through the building materials used in the structure.

INSOLAll Tech InsulationON INCIDENT SOLAR RADIAll Tech InsulationON
The total amount of solar radiation (direct, diffused and reflected) striking a surface exposed to the sky. This solar radiation is measured in langleys per minute, or BTU's per square foot per hour or per day.

INSULAll Tech InsulationON
Any material high in resistance to heat transmission that, when placed in the walls, ceiling, or floors of a structure, will reduce the rate of heat flow.

INTERIOR FINISH
The covering used on interior walls and ceilings.

ISOLATED GAIN SYSTEM
A system where solar collection and heat storage are isolated from the living space.

JACK RAFTER
A rafter that spans the distance from the wall-plate to a hip, or from a valley rafter to the roof ridge.

JOIST
One of a series of horizontal wood members, usually 50 mm (2 inches) nominal thickness, used for support. (Example: floor joists, ceiling joist or roof joists.) A parallel beam used to support floor and ceiling loads, and supported in turn by larger beams, girders, or bearing walls.

JOIST HANGER
A steel section shaped like a stirrup, bent so it can be fastened to a beam to provide end support for joists, headers, etc.

KNEE WALL
Partitions of varying length used to support roof rafters when the span is so great that additional support is required to stiffen them.

LATENT HEAT
Heat, that when added or removed, causes a change in state - but no change in temperature.

LAll Tech InsulationTUDE
The angular distance North (+) or South (-) of the equator, measured in degrees of an arc.

LEDGER STRIP
A strip of lumber fastened along the bottom of the side of a beam on which joists rest.

LINEAR FOOT
A length of 305 mm (12 inches) independent of area or volume.

LOUVER
An opening with a series of horizontal slats so arranged as to permit ventilation but to exclude rain, sunlight, or vision.

MASTIC
A pasty material used as a cement (as for setting tile) or a protective coating (as for thermal insulation, sealing or waterproofing).

MATERIAL SAFETY DATA SHEET (MSDS)
A standard formatted information sheet, prepared by a material manufacturer, listing the potential hazards, physical properties, and procedures for safe use and handling of a material.

MILDEW
name for certain organisms and the plant diseases they cause, and for the discoloration and disintegration of materials (e.g., leather, fabrics, and paper) caused by related fungi.

MOLD
Molds are microscopic fungi that live on plant or animal matter. No one knows how many species of fungi exist but estimates range from tens of thousands to perhaps three hundred thousand or more. Most are filamentous organisms and the production of spores is characteristic of fungi in general. These spores can be air-, water-, or insect-borne.

MULLION
Vertical member between window units.

MUNTIN
A secondary framing member (horizontal, vertical or slanted) to hold the window panes in the sash. This term is often confused with Mullion.

NON-BEARING PARTITION
A wall which separates space into rooms, but supports no vertical load except its own weight.

NON-BEARING WALL
A wall supporting no load other than its own weight.

OFF-GASSING.

OUTRIGGER
An extension of a rafter beyond the wall line. Usually a smaller member nailed to a larger rafter to form a cornice or roof overhang.

OVER SPRAY
Residue left over after foam insulation has been applied. Should be minimal if spray area has been prepped properly.

PAPER, SHEATHING
A breather type tar or asphalt used under extension wall cladding as protection against the passage of air or water. A building material, generally paper or felt, used in wall and roof construction as a protection against the passage of air and sometimes moisture.

PARAPET WALL
The part of an exterior, party or firewall extending above the roof line; a wall which serves as a guard at the edge of a balcony or roof.

PARTITION
A wall that subdivides spaces within any story of a building.

PERM
An imperial unit measure of water vapor movement though a material (grains per square foot per hour per inch of mercury difference in vapor pressure.).

PERMEABILITY
A measure of the ease with which water vapor passes though a unit thickness of a material.

PERMEANCE
Water vapor permeance is the rate of water vapor diffusion though a sheet of any thickness of material (or assembly between parallel surfaces). It is the ratio of water vapor flow to the differences of the vapor pressures on the opposite surfaces. Permeance is measured in perms (m2.C/W).

PITCH
The incline slope of a roof or the ratio of the total rise to the total width of a house, i.e. a 2.4 m (8 feet) rise and 7.3 m (24 feet) width is a one-third pitch roof.

PLATE
Sill plate: a horizontal member anchored to a masonry wall. Sole plate: bottom horizontal member of a frame wall. Top plate: top horizontal member of a frame wall supporting ceiling joists, rafters or other members.

POSITIVE PRESSURE
A pressure above atmospheric. In residential construction this refers to pressure inside the house envelope that is greater than the outside pressure; a positive pressure difference will encourage exfiltration.

PRESSURE DIFFERENCE
The difference in pressure of the volume of air enclosed by the house envelope and the air surrounding the envelope.

PUTTY
A type of cement usually made of whiting and boiled linseed oil, beaten or kneaded to the consistency of dough, and used in sealing glass in sash, filling small holes and crevices in wood, and for similar purposes.

R-VALUE
Measures resistance to heat flow. The higher the R-Value, the more insulation the product provides. R-value is a measurement derived in a laboratory setting that does not take into account Air Permeability or Temperature Differential.

RADIANT HEAll Tech InsulationNG
A method of heating, usually consisting of a forced hot water system with pipes placed in the floor, wall or ceiling; or with electrically heated cables or panels.

RADIANT HEAT TRANSFER
The transfer of heat energy from a location of higher temperature to a location of lower temperature by means of electromagnetic radiation.

RADIAll Tech InsulationON, ULTRA-VIOLET (UV)
Electromagnetic radiation, usually from the sun, that consists of wavelengths shorter than the violet end of the visible spectrum (less than 0.15 microns). Five percent of the sun's radiation is emitted in the ultra-violet band.

RAFTER
A structural member of a roof designed to support roof loads. The rafters of a flat roof are sometimes called roof joists.

RAFTER, HIP
A rafter that forms the intersection of an external roof angle.

RAFTER, VALLEY
A rafter that forms the intersection of an internal roof angle. The valley rafter is normally made of double 51 mm (2 inch) thick members.

RECEPTACLE (ELECTRIC)
A mounted electrical outlet.

RECOVERED ENERGY
Energy utilized which would otherwise be wasted.

RECYCLE
Recovery and reuse of materials and resources.

RELAll Tech InsulationVE HUMIDITY
The ratio of actual pressure of existing water vapor to maximum possible pressure of water vapor in the atmosphere at the same temperature, expressed as a percentage. For example, air containing one half the amount of moisture it is capable of holding has a relative humidity of 50%.

RESISTANCE VALUE (RSI or R-VALUE)
Thermal resistance value. A metric measurement of the ability of a material to resist heat transfer.

RETROFIT
The modification of an existing structure to include newer and updated fixtures, components or systems.

RIBBON (GIRT)
A 25 mm (1 inch) by 102 mm (4 inch) let into the studs horizontally to support ceiling or second-floor joists.

RIDGE
The horizontal line at the junction of the top edges of two sloping roof surfaces.

RIDGE BEAM
A horizontal structural member usually 51mm (2 inches) thick, supporting the upper ends of rafters.

RIDGE BOARD
The board placed on edge at the ridge of the roof into which the upper ends of the rafters are fastened.

RIDGE VENT
Vents that run along the ridge of the roof to allow circulation of air within an open attic.

ROLL ROOFING
A roofing material, composed of fiber and saturated with asphalt, that is supplied in 914mm (36 inch) wide rolls with a 10 square meter (100 square feet) of material. Weights are generally 20 to 41 kg (50 to 90 lbs) per roll.

ROOF SHEATHING
The boards or sheet material fastened to the roof rafters on which the shingle or other roof covering is laid.

SASH
The framework which holds the glass in a window.

SATURATED FELT
A felt which is impregnated with tar or asphalt.

SEER
Seasonal Energy Efficiency Ratio is the approximate efficiency of an air conditioning unit over a season in a given climate. In the past, a unit with a SEER of 8.00 was considered standard efficiency, and a unit with a 10.00 SEER was considered high efficiency. After January 1, 1992, the minimum SEER required by the DOE is 10.00 and 15.00+ SEER is considered high efficiency.

SENSIBLE HEAT
Heat, that when added or removed, causes a change in temperature but not in state.

SHEATHING
The material covering the house frame on the exterior.

SHEETING
Any material applied in large sheets, usually polyethylene.

SHINGLES
Any roof covering of asphalt, asbestos, wood, tile, slate or other material cut to stock lengths, widths, and thickness.

SIDING
The finish covering of the outside wall of a frame building, whether made of horizontal weatherboards, vertical boards with battens, shingles, or other material.

SILL
The lowest member of the frame of a structure, resting on the foundation and supporting the floor joists or the uprights of the wall. The member forming the lower side of an opening, as a door sill, window sill, etc.

SILL PLATE
A structural member anchored to the top of a foundation wall, upon which the floor joists rest.

SOFFIT
The horizontal or sloping part of the eave.

SOLAR ALTITUDE
The angle of the sun above the horizon measured in a vertical plane.

SOLAR ENERGY
Energy in the form of electromagnetic radiation received from the sun.

SOLAR RADIAll Tech InsulationON
Electromagnetic radiation emitted by the sun.

SPAN
The horizontal distance between supports for beams, joists, rafters, etc.

SPRAY FOAM
A broad term referring to two-part blown insulation that will have varying densities, chemistries and applications.

SPECIFIC HEAT
The number of BTU's required to raise the temperature of one pound of a substance one degree in temperature.

STACK EFFECT
Pressure differential across a building caused by differences in the density of the air due to an indoor-outdoor temperature difference.

STUDS
The vertical framing members between the posts used to support vertical loads and provide nailing surfaces for interior and exterior sheathing.

SUBFLOOR
The boards or sheet material laid on joists under a finished floor.

THERMAL BREAK (THERMAL BARRIER)
An element of low heat conductivity placed in such a way as to reduce or prevent the flow of heat.

THERMAL BRIDGE
A low thermal resistance path connecting two surfaces; for example, framing members in insulated frame walls or metal ties in cavity wall and panel construction.

THERMOSTAT
Any device that controls a heating or cooling device by responding to changes in temperature.

THRESHOLD
A strip of wood or metal with beveled edges used over the finish floor and the sill of exterior doors.

TON
A cooling unit of measure. Each ton equals 12,000 Btuh. Heat pumps and air conditioners are generally sized in tons. Typical sizes for single family residences are between two and five tons. It is important to note that actual capacity is not constant and will change based on outdoor or indoor temperatures. The published capacity rating of air conditioners and heat pumps is based on performance at the ARI standard temperature levels of 95 F outside, 80 F inside. The number of tons a system has is the total BTU capacity of the system. The size of the area to be cooled will determine the correct size of the system in tons.

TOP PLATE
The horizontal member nailed to the top of the partition or wall studs in a building.

TRANSOM
A horizontal member separating a door from a window panel above the door, or separating one window above another.

TRUSS
Any rafter, ceiling joist and tie assembled in such a way as to span a greater distance than the rafter alone.

U-VALUE (Coefficient of heat transfer)
Imperial: The number of BTU's that flow though one square foot of a material in one hour, when there is a 10 difference in temperature between the inside and outside air, under steady state conditions. Metric: The number of watts that flow though one square meter of a material in one hour, when there is a 10 difference in temperature between the inside and outside air, under steady state conditions. The U-value is the reciprocal of the resistance or R-value.

VAPOR BARRIER
The material used to retard the movement of water vapor into walls and attics and prevent condensation in them. Applied separately over the warm side of exposed walls.

VAPOR DIFFUSION
The movement of water vapor between 2 areas caused by a difference in vapor pressure, independent of air movement. The rate of diffusion is determined by 1) the difference in vapor pressure, 2) the distance the vapor must travel, and 3) the permeability of the material to water vapor. Hence the selection of materials of low permeability for use as vapor retarders in buildings.

VAPOR PRESSURE
The pressure exerted by a vapor either by itself or in a mixture of gases. For example, when referring to water vapor, the vapor pressure is determined by the concentration of water vapor in the air.

VENT
A pipe or duct which allows a flow of air or gas as an inlet or outlet.

VENTILAll Tech InsulationON
The provision for supplying, moving or removing air, either mechanically or naturally.

VISCOSITY
The thickness or resistance to flow of a liquid. Viscosity generally decreases as temperature increases. The viscosity of the spray foam, while being applied, can affect the overall yield of the product therefore lending to prescribed temperatures and pressures for installation.

VOLAll Tech InsulationLE ORGANIC COMPOUNDS (VOC)
Any compound containing carbon and hydrogen or containing carbon and hydrogen in combination with other elements. This term is often used with off-gassing discussions.

WALL PLATES
The horizontal members in wood frame construction attached to the ends of the studs. Also called top or bottom plates, depending on their location.

WEATHER BARRIER
The outer most assembly of the building envelope, used to protect the inner structure and insulation from the effects of wind and rain. Materials typically used are siding, building paper and flashing.

WEATHERSTRIPPING
A strip of felt, rubber, metal or other material, fixed along the edges of doors or windows to keep out drafts and reduce heat loss.

WIND ENERGY
The kinetic energy of air motion over the earth's surface caused by the sun's heating of the atmosphere.

Acronyms