A
AAMA - American Architectural
Manufacturers Association is the source of performance
standards, product certification and educational programs
for the fenestration industry.
Air Chambers
- Small honeycomb spaces within the sash and frame
which help to insulate and strengthen the window
Air Infiltration
- The amount of air that passes between a
window sash and frame. In windows it is measured in terms of
cubic feet or air per minute, per square foot of area. The
lower the number, the less air the window lets pass through.
Air Latch - Latch mechanism on the interior face of the sash
that retains the window in a partially open position for
ventilation.
Aluminum-Clad Window – A window with wood
construction covered with aluminum sheet having a
factory-applied finish (to provide a longer maintenance-free
life).
Angle Bay Window – See
Bay_Window.
Angled Exterior - A sloped extension from
the frame that adds an aesthetically-pleasing dimension to
the exterior of the window.
Architrave – The molded frame or ornament
surrounding a window, door or other rectangular opening.
Argon Gas - An odorless, colorless,
tasteless, nontoxic gas which is six times denser than air.
It is used to replace air between the glass panes to reduce
temperature transfer.
ASHRAE – American Society of Heating,
Refrigerating & Air Conditioning Engineers, Inc., 1791
Tullie Circle, NE Atlanta, GA 30329.
ASTM – American Society for Testing and
Materials, 1916 Race Street, Philadelphia, PA 19103.
Astragal – An interior molding attached to
one of a pair of doors or side-hinged windows in order to
prevent swing through; also used with sliding doors to
insure a tighter fit where the doors meet; often found on
older casements or swinging screens.
Awning Window –
A top-hinged window that swings outward for ventilation.
A top-hinged sash. See
Jal-Awning Window. Introduced in
the 1950’s.
Balance – See
Sash_Balance.
Balance System - Device for holding
vertically sliding sash in any desired position through the
use of a spring or weight to counterbalance the weight of
the sash.
Basement Window – (Basement Sash) – (Cellar
Sash) – A wood or metal in-swinging sash that is hinged at
either the top or the bottom.
Bay Window –
Windows that project out from the wall and extend to the
ground. An Angle Bay Window refers to the angle departure
from the plane of the wall. See also
Bow Window.
Beveled Exterior - An angled extension from
the frame that adds an aesthetically-pleasing dimension to
the exterior of the window.
Bottom Rail – The bottom horizontal member
of a window sash.
Bow Window – (Compass Window) – (Radial Bay
Window) – A rounded bay window that projects from the wall
in the shape of an arc; commonly consisting of five sash.
See also Bay Window.
Boxed Mullion – A hollow mullion between
two double-hung windows to hold the sash weight.
Brick Molding – A standard milled wood trim
piece to cover the gap between the window frame and masonry.
B.T.U. – (Btu) – An abbreviation for
British Thermal Unit, commonly shown as “Btu”; the heat
required to increase the temperature of one pound of water
one degree Fahrenheit, about the heat from burning one
wooden match.
Butyl - A rubber material that seals the
glass to the spacer, creating an airtight and watertight IG
unit. Butyl has the lowest gas permeability of all rubbers.
Cam Lock and Keeper - The mechanisms which
pull the sash together when placed in the locked position.
Capillary Tubes - Small hollow tubes
which penetrate the spacer system of an insulating glass
unit. They allow pressure equalization between manufacturing
locations, shipping, and installation locations. Since the
insulating glass unit is not permanently sealed, the air
space cannot be filled with Argon gas.
Casement – A window sash which swings open
on side hinges; inswinging are French in origin while
outswinging are from England.
Casement Window – A window with one or more
casements.
Casing – (Trim) –
Exposed molding or framing around a window or door, on
either the inside or outside, to cover the space between the
window frame or jamb and the wall.
Caulking – A mastic compound for filling
joints and sealing cracks to prevent leakage of water and
air; commonly made of silicone- bituminous- acrylic- or
rubber-based materials.
Celsius – A centigrade scale of temperature
measurement based on 0° as the freezing point and 100° as
the boiling point of water. Abbreviated °C.
Check Rail – (Meeting Rail) – (Lock Rail) –
The horizontal members (of a double-hung window) which come
together.
Clerestory – (also Clearstory – High-Light
Window) – A window in the upper part of a lofty room that
admits light to the center of the room.
Coated Glass – A window glass with an
outside surface provided with a mirror reflective surface;
the shading coefficient ranges from 20% to 45%. See
Shading_Coefficient.
Colonial – An architectural style
associated with an early American period; Early American
style c. 1730.
Colonial Windows – Windows with small
rectangular panes, or divided lites, designated as 12-lite,
16-lite, etc.
Combination Window Unit – (Combination
Storm Sash and Screen) – A window assembly containing a half
screen and two glass storm panel; in frame, exposing the
screen panel.
Commercial Standard – A voluntary set of
rules and regulations covering quality of product (or
installation), method of testing, rating of the product,
certification, and labeling of manufactured products.
Condensation – The deposit of water vapor
from the air on any cold surface whose temperature is below
the dew point, such as a window glass or frame that is
exposed to cold outdoor air. See
Dew_Point_Temperature.
Condensation Resistance Factor - A measure
of the effectiveness of a window or glazing system to reduce
the potential for condensation. The higher the condensation
resistance factor, the more efficient the window and glazing
system.
Conduction - Energy transfer from
one material to another by direct contact.
Convection – See Natural Convection and
Forced Convection. A heat transfer process resulting from
the circulation or movement of fluids, such as air.
Cove Molding – Trim molding with a concave
face.
Coved Exterior - An arced extension from
the frame that adds an aesthetically-pleasing dimension to
the exterior of the window.
Crack Perimeter – The total length of the
crack around a sash through which outdoor air could leak
into the room. In a double-hung window, the total crackage
is 3 times the width plus 2 times the height of the sash.
Dado - A rectangular slot or groove (with 3
surfaces) cut across the grain of a wood member, into which
another board is fitted. See also Plough.
Dead-air space - The space between the
panes of glass of an I.G. Unit.
Deadlite - A piece of glass or IGU
with a sash profile around it; not set within the main frame
of a window unit.
Degree-Day – A measure of heating demand,
based on the difference between the mean daily outdoor
temperature and 65°F. Cumulative totals for the month or
heating season are used by engineers for estimating heating
energy requirements.
Design Heat Loss – The calculated values,
expressed in units of Btu per hour (abbreviated Btuh), for
the heat transmitted from a warm interior to a cold outdoor
condition, under some prescribed extreme weather conditions.
The values are useful for selecting heating equipment and
for estimating seasonal energy requirements. Infiltration
heat loss is a part of the design heat loss.
Desiccant – A drying agent, such as silica
gel, used by some manufacturers between the panes of
insulating glass to prevent fogging between the panes.
Dew Point
Temperature – The temperature of the air at
which the water vapor in the air starts to condense in the
form of liquid or as frost.
Double-Hung Window – Window with two
vertically moving sashes, each closing a different part of
the window.
Double-Strength Glass – Sheet glass with a
thickness between 0.115” to 0.133” (3 to 3.38mm).
Double Windows – (Double Glazing) – Two
windows, such as a regular window plus a storm sash; also an
insulating window with air space between panes.
Double Window – Two windows separated by a
mullion, forming a unit. Also called a coupled window.
Drip Cap – A horizontal molding to divert
water from the top casing so that the water drips beyond the
outside of the frame.
Dry Glazing – A form of glazing in which
the glass is secured in the frame with a dry gasket, wood
stops, or metal stops, instead of by a glazing compound. See
also Reglet.
Dual-durometer
- An elastomeric material with two different degrees of
hardness.
Egress Code - The code that requires a
minimum opening of a window for persons to exit or
firefighters to enter a building.
Emergency Exit Window – (Egress Window) –
Fire escape window; large enough for a person to climb out;
each bedroom should be provided with exit windows.
ENERGY STAR® - ENERGY STAR® is an
independent U.S. government program establishing a standard
set of guidelines to recognize the energy efficiency of
various products. ENERGY STAR® guidelines are used in
conjunction with a variety of building materials, including
windows and patio doors. Over the past ten years, ENERGY
STAR® guidelines have helped double the efficiency of
windows they endorse
Extension Jamb – (Jamb Lining) – (Jamb
Extender) – A board used to increase the depth of the jambs
of a window frame to fit a wall of any given thickness.
Exterior Casing – See
Casing.
Extruded screen frame
- Different from a Roll formed frame, this frame is pressed
through a form or die.
Fahrenheit – A temperature scale based on
32° as the freezing point and 212° as the boiling point of
water at sea level. Abbreviated °F.
Fanlight - (Sunburst
Light) - (Fan Window) - (Circle-Top Transom) - A half-circle
window over a door or window, with radiating bars. See
Lunette.
Fasteners – Devices for jointing two parts
together, such as screws nails and bolts.
Fenestration – The placement of window
openings in a building wall; one of the important elements
in controlling the exterior appearance of a building.
Finish Casing – (Finish Trim) – Interior
trim boards around a window unit.
Fire-Escape Window – (Emergency Exit
Window) – Window which opens onto fire escape; window
designed for emergency exit.
Fixed Light – (Fixed Sash) – Window which
is non-operative (does not open).
Flashing – Sheet metal provided for
drainage of water and to prevent water penetration into
building.
Flat Glass –
(Window Glass) – (Plate Glass) – (Float Glass) – (Rolled
Glass) – (Cylinder Glass) – Glass sold in flat sheets and
named according to the method used in its manufacture.
Float Glass – Smooth glass formed on the
top of molten tin surface; a flat glass sheer.
French Window – Two casement sash hinged on
the sides to open in the middle; the sash extends to the
floor and serves as a door to a porch or terrace.
Forced Convection - A heat transfer
process, aided by mechanical circulation of a liquid (such
as water) or a gas (such as air). This applies to natural
wind flow over a window.
Fusion-welded
- Different from a Roll formed frame, this frame is
pressed through a form or die.
Geometric - Specially designed windows
classified as either Straight line Geometrics such as
rectangles, triangles, trapezoid, octagons, pentagons, etc.,
or Radius Geometrics which include half-rounds,
quarter-rounds, full-rounds, sectors, ellipses, eyebrows,
etc.
Glass - An elastic transparent material
composed of silica (sand), soda (sodium carbonate), and lime
(calcium carbonate) with small quantities of aluminum,
boric, or magnesia oxides. See
Flat_Glass.
Glazing - The installation of glass in a
window opening; also the fenestration or windows.
Glazing Bead - (Glass Stop) - (Wood Stop) -
(Sill Bead) - A removable trim that holds the glass in
place.
Glazing Channel - A groove cut into the
sash for the mounting of glass.
Glazing Rabbet - See Rabbet.
Grids - Decorative horizontal or vertical
bars installed between the glass panes to create the
appearance of the sash being dividing into smaller lites of
glass
Groove - A long, narrow cut on the face of
a wood member; a groove across the grain is a Dado; one
parallel with the grain is a Plough. A groove exposes three
surfaces, in contrast with the two surfaces exposed in a
Rabbet or Notching. See
Rabbetted_Joint and Plough.
Hanging - Mounting a sash in its frame.
Hanging Sash - (Hung Sash) - Sash hung on a
cord connected to a counterweight.
Head - The top or upper member of any
element or structure; in windows, it refers to the top of
the frame, as in Round Head Window. See
Head_Jamb.
Head expander - A vinyl shape cut the width
of a product and placed on the head, fitting over it snugly.
This piece is used as a filler to expand or lengthen the
unit from the head and take up the gap in the opening
between the unit and the opening in the unit.
Head Jamb - (Head) - All of the horizontal
members at the top of the window frame.
Header - (Lintel) - (Beam) - Supporting
member or beam above window opening which transfers building
weight above to the supporting wall structure on each side
of the window. The term header is generally in reference to
a wood beam, whereas Lintel often refers to a steal beam.
Heat-Absorbing Glass - (Tinted Glass) -
Window glass containing chemicals (with gray, bronze, or
blue-green tint) which absorb light and heat radiation, and
reduce glare and brightness. Shading coefficient of this
glass varies from about 50% to 70%.
Heat Transfer Coefficient - (U-value) - A
value indicating the rate of heat flow through a building
construction, expressed in units of 'Btuh per square foot of
surface per degree F. difference between indoor and outdoor
air temperature.' This is numerically equal to the 'inverse
of the sum of H-values' for the construction.
Hinge - A movable joint enabling a window
to swing open.
Hopper Light - (Hopper Vent) - (Hopper
Ventilator) – inward opening sash hinged at the bottom.
Horizontal Sliding Window - (Horizontal
Slider) Windows which slide horizontally.
Hung Window - Window with one or more
hanging sashes.
Hygroscopic - The ability to 'give off' and
'take on' moisture, as in wood exposed to changes in
relative humidity of air.
Infiltration - Leakage of outdoor air into
a house, such as through cracks around sash or window frame.
See also Crack_Perimeter.
Infiltration Heat Loss - The heat loss,
expressed in units of Btu per hour (Btuh), resulting from
leakage of outdoor air into a structure and the escape of
indoor air. The loss depends upon the indoor and outdoor
temperatures, the crack perimeter, and the rate of air
leakage per foot of crack (See also
Design_Heat_Loss).
Insect Screen - (Window Screen) - (Screen)
– Woven mesh of metal, plastic, or fiberglass stretched over
a window opening to permit air to pass through, but not
insects.
Inside Casing - (Interior Casing) -
(Interior Finish) -(Interior Trim) - The inside visible
molding surrounding the interior of the window frame, See
Casing.
Insulating Glass - Double- or
triple-glazing with an enclosed, dehydrated, and
hermetically sealed air space between the panes; the space
is commonly from 3/16" to ¾".
Insulated Window – A window with multiple
glazing that provides one or more air spaces between layers
of glazing.
Interior Glazes - Glazing installed from
inside of building.
Interior Mullion Casing - The inside trim
between adjacent windows. See Mullion.
Jal Awning -
(Awning Window) - Window with several out-swinging,
awning-type windows that pivot near the top of the glass and
operate in unison.
Jamb - A vertical member at the side of the
window frame; also refers to the horizontal member at the
top of the window frame, as in Head Jamb and Window Jamb.
Jamb - All of the vertical members at the
side of the window frame.
Jamb Depth - Width of the window frame from
inside to outside.
Knocked-Down - Not assembled; parts for a
window frame pre-manufactured for assembly at a later date
on the job site.
Latch - (Catch) - (Lock) - A device which
holds a window shut, such as the latch at the meeting rail
of a double-hung window or one mounted on the stile of
casement windows, often referred to as a Lock.
Lead Light - (Lead Glazing) - (Stained
Glass) - Window with small panes of glass set in grooved
rods of cast lead (or came). The glass can be clear, color,
or stained.
Light - (Lite) - A window; a pane of glass
within a window. Double-hung windows are designated by the
number of lights in upper and lower sash, as in
six-over-six.
Lintel - Horizontal member (wood, steel, or
stone) over a window opening to support the weight of the
wall above (See also Header).
Lock - A fastening device in which a bolt
is secured and can be operated by a key. Commonly used to
refer to Latches or Catches.
Lock Stile - The vertical member (stile) of
a casement sash which closes against the surrounding frame.
Low Emissivity Coating (Low-e) - Coating
for glass surfaces which reflect radiant heat energy rather
than allowing that energy to radiate through the glass
surface. The lower the emissivity of the glass the lower the
heat transfer coefficient.
Lunette - A
crescent-shaped window framed by moldings or an arch.
Meeting Rail - (Lock Rail) - One of the two
horizontal members of a double-hung sash which come together
See Check_Rail.
Member - Any structural part of a window,
such as a rail, stile, or lintel.
Millwork - Window sash and other wood
products made in a wood-working plant.
Miter Joint - Two members joined at an
angle, commonly 45 degrees.
Moisture Barrier - (Vapor Barrier) - A
material which retards the passage of water vapor from one
space to another. Polyethylene sheet is commonly used as a
vapor retarder.
Moisture Content - Percentage of dry weight
of material which is composed of water, such as in wood.
Mold - (Molding) – A relatively narrow
strip of wood used to conceal a joint or to emphasize
ornamentation of a structure.
Mould - (Moulding) - British spelling of
mold, and molding.
Mullion - Vertical member between window
units.
Muntin - (Sash Bar) -
(Window Bar) - (Glazing Bar) - a secondary framing member
(horizontal, vertical, or slanted) to hold the window panes
in the sash. This term is often confused with Mullion.
Muntin Grilles - Wood, plastic, or metal
grilles designed for a single-lite sash to give the
appearance of muntins in a multi-lite sash, but are
removable for ease in cleaning the window.
Multi-Life Sash - A sash divided into many
lites.
Mylar – Trade name for a clear, durable
plastic sheet used for covering an inside storm panel or for
removable, roll-up glazing over an entire window frame.
Natural Convection - A heat transfer
process involving motion in a fluid (such as air) caused by
difference in density of the fluid and the action of gravity
This is an important pail of heat transfer from the glass
surface to room air. See
Forced_Convection.
Notching - A rectangular cut across the
grain of the wood member at the end of the board (See
Rabbet).
Obscure Glass - (Visionproof Glass) - Any
textured glass (frosted, etched, fluted, ground, etc.) used
for privacy, light diffusion, or decorative effects.
Operator - Crank-operated device for
opening and closing casement or jalousie windows.
Oriel Window – A window projecting from the
wall and carried on brackets, corbels, or a cantilever.
Unlike a Bay Window, the projection of an Oriel does not
extend all the way to the ground.
Orientation - The placement of a room,
window, or building with respect to sun, wind, earth,
access, or view (See also
Solar_Orientation).
Outside Casing - (Outside Facing) -
(Outside Trim) - (Exterior Casing) - That portion of the
window frame which is exposed to the outdoors, See
Casing.
Outside Glazing - Glazing installed from
the outside.
Pane - A sheet of glass for glazing a
window. After installation, the pane is referred to as a
'light' (lite) or 'window light.'
Parting Bead – (Parting Strip) – (Parting
Stop) – A vertical strip on each jamb that separates the
sashes of a double-hung window.
Patterned Glass - One or both surfaces of
glass with a rolled design; used for privacy and light
diffusion.
Percentage Humidity - Weight of water vapor
in air divided by weight of vapor contained in saturated
air, expressed as a percentage.
Picture Window - Large fixed windows;
introduced in the 1940's.
Plastics - Artificial substances made of
organic polymers that can be extruded or molded into various
shapes, some of which have been adapted to windows. The
material is commonly stiffer than rubber.
Plough - (Plow) - A
rectangular groove or slot (with 3 surfaces) cut parallel
with the grain (See Dado_).
Polyvinylchloride - See PVC.
Prime Sash - The balanced or moving sash of
a window unit.
Prime Window - Window with single or
multiple glazing to which storm sash may be installed.
Projected Window - An awning type window
that swings either inwards or outwards at the top or the
bottom. The 'PIB' or 'project in at bottom' window can be
cleaned from the inside.
Psychrometric Chart - A chart which shows
dry bulb and wet bulb temperatures used to determine the
relative humidity of air and the dew point temperature.
Other engineering data referring to moisture in air are also
shown.
PVC - (Polyvinylchloride) - An extruded or
molded plastic material used for window framing and as a
thermal barrier for aluminum windows.
No words in this glossary begin with the
letter Q.
Radiation - The transmission of energy
through space without heating the air between, as in Solar
Radiation.
Rabbet - A rectangular notch (consisting of
two surfaces) cut parallel with the grain of wood along the
edge. See Notching.
Rabbetted Joint - The joint formed by two
boards with rabbetted ends, as in some window frames.
Rail - (Head Rail) - (Top Rail) - (Bottom
Rail) -(Meeting Rail) - Horizontal member of a window sash.
Reflective Glass - Window glass coated to
reflect radiation striking the surface of the glass.
Reglet - A plastic or
wood molding placed in a concrete or masonry opening to
provide a uniform groove for a spline-type gasket to hold
window glass. See Dry_Glazing.
Relative Humidity - Weight of water vapor
in air divided by the weight of water vapor in completely
saturated air at the same temperature, expressed as a
percentage.
R-Value - (Thermal Resistance) A measure of
resistance to heat flow of a material or construction a
higher value indicates a better heat insulating property.
The R-value of an ordinary single-pane sash with a 15 mph
wind on one side is about 0.9.
Safety Glass - A strengthened or reinforced
glass that is less subject to breakage or splintering, such
as glass for storm doors and some windows. See
Tempered_Glass,
Shatter-Proof_Glass, and
Plexiglas.
Sash - (Window Sash) - Framework of stiles
and rails in which the lights of a window are set.
Sash and Frame – A window and its casing
frame.
Sash Balance - A
device for counter-balancing a sash of a double-hung window
to hold it in the up position.
Sash Stop - A molding that covers the joint
between window sash and the jamb.
Screen - Wire Cloth - A close-mesh woven
screening material of metal, plastic, or fiberglass for a
window screen, to block the entry of insects but permit
light, air, and vision through the screen.
Sealant - A
compressible plastic material used to seal any opening or
junction of two parts, such as between the glass and a metal
sash, commonly made of silicone, butyl tape, or polysulfide.
Sealed Double Glass - Two panes separated
by a sealed space. See also
Insulating_Glass.
Shade Screen - (Sun Screen) - A specially
fabricated window screen of sheet material with small narrow
louvers formed in place to intercept solar radiation
striking a window; the louvers are so small that only
extremely small insects can pass through. Also, an awning
with fixed louvers of metal or wood construction.
Shading Coefficient
- A decimal value which is the solar gain of a window,
divided by the solar gain for a clear single-glass window of
the same size. The shading coefficient of clear,
double-glazing is about 0.85 to 0.9.
Shatter-Proof Glass - (Laminated Glass) -
Two sheets of glass with a transparent plastic sheet
sandwiched between to form a pane resistant to shattering.
Side Light - (Margin Light) - A fixed often
narrow glass window next to a door opening (or window).
Silicone - (Silicone Sealer) - An enduring
sealing agent that resists water. See Sealant.
Sill - (Sill Plate) - (Inside Sill) -
(Outside Sill) - The horizontal members at the bottom of the
window frame; a masonry sill or sub-sill can be below the
sill of the window unit.
Single-Hung Window - A window that is
similar to a double-hung window except that the top sash is
stationary.
Single-Strength Glass - Glass with
thickness between 0.085 to 0.100" (2.16 mm to 2.57 mm).
Sliding Sash - (Sliding Windows) - A window
which moves horizontally in grooves or tracks.
Sling Psychrometer – A measuring instrument
with two thermometers(dry-bulb and wet-bulb) used for
determining the dewpoint and relative humidity of air; its
relation to windows is ascertaining the point at which
moisture will condense on the inside surface of the glass.
See Psychrometric_Chart.
Solar Heat Gain - Heat from solar radiation
that enters a building.
Solar Orientation - A building placed on a
lot so that the long dimension faces south and a majority of
the windows are south-facing.
Sound-Insulating Glass - Sound-Resistive
Glass -Double glass fixed on resilient mountings and
separated so as to reduce sound transmission.
Spacer - The linear object that separates
and maintains the space between the glass surfaces of
insulating glass.
Spline - A rectangular strip of wood or
metal inserted between two boards, which have been slotted
to receive it.
Spring Bolt - A fastener for holding the
sash in a fixed location by means of a spring-loaded bolt in
the stile entering a hole in the jamb.
Stacked Window Units - A combined grouping
of awning, hopper, casement, or non-operative windows to
form a large glazed unit.
Stained Glass Window - A window with a
painted scene or pattern that has been fired into the glass.
Windows with plain colored glass set in lead are also called
stained glass. See Lead_Light.
Stationary Sash - A fixed sash; also
referred to as a picture, studio, vista, or view sash.
Stile - The vertical-edge members of a
window sash.
Stool - A shelf-like board of the interior
part of the window sill, against which the bottom rail of
the sash closes.
Stop - (Bead, Side Stop, Window Stop,
Parting Stop) - The molding on the inside of the window
frame against which the window sash closes, or in the case
of a double-hung window, the sash slides against the stop.
Storm Sash - (Storm Window) - An extra
window on the outside to protect an existing window, but
mainly to increase the thermal resistance of the window.
Sweep Lock - A sash fastener located at the
meeting rails of a double-hung window, which rotates and
clamps the two rails closer together.
Tempered Glass - Special heat-treated,
high-strength safety glass which shatters into pebble-sized
particles but not into slivers.
Therm - In technical usage, the term is a
convenient measure of heating value, namely 100,000 Btu. One
therm is roughly equivalent to the heating value of 100
cubic feet of natural (methane) gas.
Thermal Barrier – (Thermal Break) - A
material of high thermal resistance placed between two metal
sash, or installed between adjoining metal framing of metal
windows, in order to reduce thermal conduction from indoors
to outdoors.
Thermal Conduction - Heat transfer through
a material by contact of one molecule to the next. Heat
flows from a high temperature area to one of lower
temperature.
Thermal Conductivity - Heat transfer
property of materials expressed in units of 'Btu per hour
per inch of thickness per square foot of surface per one
degree F. temperature difference.' Referred to by the letter
'k.'
Thermal Conductance - Same as Thermal
Conductivity except thickness is 'as stated' rather than one
inch. Referred to by the letter 'C.'
Thermal Insulation - A material that
resists heat flow. Material having a high R-value.
Thermal Resistance - (R-value) - A property
of a substance or construction which retards the flow of
heat; one measure of this property is R-value. See
Heat_Transfer_Coefficient.
Transom - (Transom Bar) - A horizontal
member separating a door from a window panel above the door,
or separating one window above another.
Transom Light - (Transom Window) - The
window sash located above a door.
Trim - Visible molding surrounding a window
opening. See Casing.
Triple Glazing - Three panes of glass with
two air spaces between, commonly consisting of an insulating
glass with a separate storm sash. Also available as an
Insulating Window in a single frame.
Triple Window - A term generally referring
to any tripartite group of windows with square heads. These
are frequently found on Colonial Revival houses; they
suggest Palladian Windows but are less expensive to build.
Ultra-violet Radiation - Extremely short
wave length invisible radiation, which is a component of
solar radiation, and merges into the visible spectrum;
attributed as a source of skin sunburn and color fading of
draperies and carpeting.
Vapor Barrier - (Vapor Retarder) - A
membrane or coating which resists passage of water vapor
from a region of high vapor pressure to low pressure, more
accurately called a Vapor Retarder.
Vertical Sliding Window - One or more
sashes that move in a vertical direction.
Visible Spectrum - That portion of the
total radiation that is visible to the human eye and which
lies between the ultra-violet and the infra-red portions of
the electromagnetic spectrum. The colors associated with the
visible spectrum range from violet, indigo, blue, green,
yellow, orange, through red.
Weatherstrip - A strip of resilient
material for covering the joint between the window sash and
frame in order to reduce air leaks and prevent water from
entering the structure.
Weathertight - Sealed to prevent entry of
air and precipitation into the structure.
Weephole - Small holes drilled along the
bottom edge of storm sash or combination storm-screens to
permit moisture condensation or wind-driven rain to drain
away from the sill to the outdoors.
Window – A glazed opening in an external
wall; an entire unit consisting of a frame, sash and
glazing, and any operable elements.
Window Frame –
The fixed frame of a window, which holds the sash or
casement as well as hardware.
Window Hardware – Various devices and
mechanisms for the window including: catches, cords and
chains, fasteners and locks, hinges and pivots, lifts and
pulls, pulleys and sash weights, sash balances, and stays.
Window Unit – A complete window with sash
and frame.
Wind Pressure – The pressure produced by
stopping the wind velocity; the main cause of air
infiltration.
There are no words in this glossary which
begin with X, Y or Z.
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